WO1997025916A1 - Structures d'electrodes a dilatation-compression, pourvues de parois conductrices - Google Patents

Structures d'electrodes a dilatation-compression, pourvues de parois conductrices Download PDF

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Publication number
WO1997025916A1
WO1997025916A1 PCT/US1997/000698 US9700698W WO9725916A1 WO 1997025916 A1 WO1997025916 A1 WO 1997025916A1 US 9700698 W US9700698 W US 9700698W WO 9725916 A1 WO9725916 A1 WO 9725916A1
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WIPO (PCT)
Prior art keywords
electrode
electrically conductive
geometry
maximum diameter
shell
Prior art date
Application number
PCT/US1997/000698
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English (en)
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WO1997025916A9 (fr
Inventor
James G. Whayne
Jerome Jackson
Dorin Panescu
Thomas F. Kordis
Russell B. Thompson
Patrick M. Owens
David K. Swanson
David Mcgee
Sidney D. Fleischman
Original Assignee
Ep Technologies, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US08/630,721 external-priority patent/US5891136A/en
Priority claimed from US08/629,171 external-priority patent/US5871483A/en
Priority claimed from US08/630,113 external-priority patent/US5891135A/en
Priority claimed from US08/629,363 external-priority patent/US5853411A/en
Priority claimed from US08/628,980 external-priority patent/US5846238A/en
Application filed by Ep Technologies, Inc. filed Critical Ep Technologies, Inc.
Publication of WO1997025916A1 publication Critical patent/WO1997025916A1/fr
Publication of WO1997025916A9 publication Critical patent/WO1997025916A9/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00—Electrotherapy; Circuits therefor
    • A61N1/02—Details
    • A61N1/04—Electrodes
    • A61N1/06—Electrodes for high-frequency therapy
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/14—Probes or electrodes therefor
    • A61B18/1492—Probes or electrodes therefor having a flexible, catheter-like structure, e.g. for heart ablation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L29/00—Materials for catheters, medical tubing, cannulae, or endoscopes or for coating catheters
    • A61L29/08—Materials for coatings
    • A61L29/085—Macromolecular materials
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L29/00—Materials for catheters, medical tubing, cannulae, or endoscopes or for coating catheters
    • A61L29/14—Materials characterised by their function or physical properties, e.g. lubricating compositions
    • A61L29/145—Hydrogels or hydrocolloids
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/08—Materials for coatings
    • A61L31/10—Macromolecular materials
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/14—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
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    • A61B2018/00083—Electrical conductivity low, i.e. electrically insulating
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    • A61B2018/00095—Thermal conductivity high, i.e. heat conducting
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    • A61B2018/00148—Coatings on the energy applicator with metal
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    • A61B2018/00214—Expandable means emitting energy, e.g. by elements carried thereon
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    • A61B2018/00214—Expandable means emitting energy, e.g. by elements carried thereon
    • A61B2018/00267—Expandable means emitting energy, e.g. by elements carried thereon having a basket shaped structure
    • A—HUMAN NECESSITIES
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    • A61B2018/00773—Sensed parameters
    • A61B2018/00839—Bioelectrical parameters, e.g. ECG, EEG
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/1206—Generators therefor
    • A61B2018/1246—Generators therefor characterised by the output polarity
    • A61B2018/1253—Generators therefor characterised by the output polarity monopolar
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B18/00—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body
    • A61B18/04—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating
    • A61B18/12—Surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body by heating by passing a current through the tissue to be heated, e.g. high-frequency current
    • A61B18/14—Probes or electrodes therefor
    • A61B2018/1472—Probes or electrodes therefor for use with liquid electrolyte, e.g. virtual electrodes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
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    • A61B2218/001—Details of surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body having means for irrigation and/or aspiration of substances to and/or from the surgical site
    • A61B2218/002—Irrigation

Definitions

  • the invention generally relates to electrode structures deployed in interior regions of the body. In a more specific sense, the invention relates to electrode structures deployable into the heart for diagnosis and treatment of cardiac conditions.
  • the treatment of cardiac arrhythmias requires electrodes capable of creating tissue lesions having a diversity of different geometries and characteristics, depending upon the particular physiology of the arrhythmia sought to be treated.
  • a conventional 8F diameter/4mm long cardiac ablation electrode can transmit radio frequency energy to create lesions in myocardial tissue with a depth of about 0.5 cm and a width of about 10 mm, with a lesion volume of up to 0.2 cm 3 .
  • VT ventricular tachycardia
  • Multi-purpose cardiac ablation electrodes that can selectively create lesions of different geometries and characteristics.
  • Multi-purpose electrodes would possess the flexibility and maneuverability permitting safe and easy introduction into the heart. Once deployed inside the heart, these electrodes would possess the capability to emit energy sufficient to create, in a controlled fashion, either large and deep lesions, or small and shallow lesions, or large and shallow lesions, depending upon the therapy required.
  • One aspect of the invention provides improved collapsible electrode assemblies and associated methods for using them.
  • One preferred embodiment comprises a structure having an electrically conductive wall adapted to selectively assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter.
  • a section of the wall carries a shell of electrically conductive material, which forms an electrode surface adapted to transmit electrical energy to tissue.
  • Another preferred embodiment comprises a structure having a wall comprising a distal region and a proximal region.
  • the structure is adapted to selectively assume an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first maximum diameter.
  • a section of the wall carries an electrically conductive material, which forms an electrode surface adapted to transmit electrical energy to tissue.
  • the electrode surface occupies more of the distal region of the wall than the proximal region.
  • At least l/3rd of the proximal region of the wall is free of electrically conductive material.
  • Another aspect of the invention provides a system for ablating body tissue comprising a family of electrode assemblies.
  • Each electrode assembly includes an extruded wall carrying an amount of electrically conductive material coextruded within it.
  • the extruded walls possess different electrical resistivity values by virtue of different amounts of electrically conductive material coextruded within the walls.
  • the system also includes means for specifying, among the family, use of the electrode assemblies according to a function that correlates desired tissue ablation effects with electrical resistivity values of the walls.
  • the system includes an element adapted to couple the wall of a specified one of the electrode assemblies to a source of electrical energy. This enables transmission of the energy by the wall to achieve a desired tissue ablation effect.
  • the tissue ablation effect correlates to the electrical resistivity value of the wall.
  • the means for specifying correlates a first electrical resistivity value with a first tissue lesion characteristic and a second electrical resistivity value different than the first electrical resistivity with a second tissue lesion characteristic different than the first lesion characteristic.
  • the means for specifying correlates a first electrical resistivity value with a deep tissue lesion geometry and a second electrical resistivity value greater than the first electrical resistivity value with a shallow tissue lesion geometry.
  • Fig. 1 is a plan view of a system for ablating heart tissue, which includes an expandable electrode structure that embodies the features of the invention
  • Fig. 2 is a side elevation view of an expandable electrode structure usable in association with the system shown in Fig. 1, in which an inflation medium is used to expand the structure
  • Fig. 3A is a side elevation view of an alternative expandable electrode structure usable in association with the system shown in Fig. 1, in which an inflation medium is used to expand separate multiple chambers within the structure
  • Fig. 3B is a side elevation view of an alternative expandable electrode structure usable in association with the system shown in Fig. 1, in which an inflation medium is used to expand integrally formed multiple chambers within the structure
  • Fig. 3C is a top section view of the electrode structure shown in Fig. 3B, taken generally along line 3C-3C in Fig. 3B;
  • Fig. 3D is a side elevation view of an alternative expandable electrode structure usable in association with the system shown in Fig. l, in which an inflation medium is used to expand a single chamber within the structure;
  • Fig. 3E is a top view of an alternative expandable-collapsible electrode structure with a body having interior coextruded webs that compartmentalize the body into multiple interior chambers;
  • Fig. 4 is a side elevation view of an alternative expandable electrode structure usable in association with the system shown in Fig. 1, in which an open spline structure is used to expand the structure;
  • Fig. 5 is the expandable electrode shown in Fig. 4, in which a slidable sheath is used to collapse the structure;
  • Fig. 6 is a side elevation view of an alternative expandable electrode structure usable in association with the system shown in Fig. 1, in which an interwoven mesh structure is used to expand the structure;
  • Fig. 7 is the expandable electrode shown in Fig. 6, in which a slidable sheath is used to collapse the structure;
  • Fig. 8 is a side elevation view of an alternative expandable interwoven mesh electrode structure usable in association with the system shown in Fig. 1, in which an interior bladder is used to expand the structure;
  • Fig. 9 is a side elevation view of an alternative expandable foam electrode structure usable in association with the system shown in Fig. i;
  • Fig. 10 is a side elevation view of an alternative expandable electrode structure usable in association with the system shown in Fig. 1, in which an electrically actuated spline structure is used to expand the structure;
  • Fig. 11A is a side elevation view of an alternative expandable electrode structure usable in association with the system shown in Fig. 1, in which the electrode structure is pleated or creased to promote folding upon collapse;
  • Fig. IIB is the electrode shown in Fig. HA in the process of folding while collapsing
  • Fig. IIC is the electrode shown in Fig. 11A as folded upon collapse
  • Fig. 12 is a side elevation view of an expandable electrode structure usable in association with the system shown in Fig. 1, in which a steering mechanism proximal to the structure steers the structure at the end of a catheter tube;
  • Fig. 13 is a side elevation view of an expandable electrode structure usable in association with the system shown in Fig. 1, in which a steering mechanism within the structure steers the structure at the end of a catheter tube;
  • Fig. 14 is a side elevation view of an expandable electrode structure usable in association with the system shown in Fig. l, in which an axially and radially movable stilette in the structure is used to alter the shape of the structure;
  • Figs. 15A to 15E are plan views of an assembly process for manufacturing an expandable electrode structure using an inflation medium to expand the structure;
  • Figs. 16A to 16D are plan views of an assembly process for manufacturing an expandable electrode structure using an interior spline structure to expand the structure;
  • Fig. 17 is a side elevation view of an expandable electrode structure usable in association with the system shown in Fig. 1, in which an electrically conductive shell is deposited on the distal end of the structure;
  • Fig. 18 is a side elevation view of an expandable electrode structure usable in association with the system shown in Fig. 1, in which an electrically conductive foil shell is positioned for attachment on the distal end of the structure;
  • Fig. 19 is an enlarged section view of the wall of an expandable electrode structure usable in association with the system shown in Fig. 1, in which an electrically conductive material is coextruded within the wall;
  • Fig. 20 is a top view of an expandable electrode structure having an exterior shell of electrically conductive material formed in a segmented bull's-eye pattern
  • Figs. 21 and 22 are, respectively, side and top views of an expandable electrode structure having an exterior shell of electrically conductive material formed in a segmented pattern of energy transmission zones circumferentially spaced about a preformed, foldable body, and including multiple temperature sensing elements;
  • Figs. 23, 24A, and 24B are enlarged side views showing the deposition of electrically conductive material to establish fold lines on the exterior of an expandable electrode structure;
  • Fig. 25 is a top view of an expandable electrode structure showing the preferred regions for attaching signal wires to an electrically conductive shell deposited on the distal end of the structure;
  • Fig. 26 is a side view of an expandable electrode structure showing the preferred regions for attaching signal wires to an electrically conductive shell deposited in a circumferentially segmented pattern on the structure;
  • Fig. 27 is a top view of an expandable electrode structure showing the preferred regions for attaching signal wires to an electrically conductive shell deposited in a bull's-eye pattern on the structure;
  • Figs. 28A and 28B are, respectively side section and top views showing the attachment of signal walls to an electrically conductive shell deposited on the distal end of the structure, the signal wires being led through the distal end of the structure;
  • Fig. 29A is an enlarged side view of the distal end of an expandable electrode structure usable in association with the system shown in Fig. 1, showing the attachment of an ablation energy signal wire to the electrically conductive shell using a mechanical fixture at the distal end of the structure;
  • Fig. 29B is an enlarged exploded side view, portions of which are in section, of the mechanical fixture shown in Fig. 29A;
  • Figs. 30 and 31 are side section views showing the attachment of a signal wire to an electrically conductive shell, the signal wire being snaked through the wall of the structure either one (Fig. 30) or multiple times (Fig. 31) ;
  • Fig. 32 is an enlarged section view of the wall of an expandable electrode structure usable in association with the system shown in Fig. 1, showing the laminated structure of the wall and the attachment of an ablation energy signal wire to the electrically conductive shell using laser windowing techniques;
  • Fig. 33 is a side view, with portions broken away and in section, of an expandable electrode structure usable in association with the system shown in Fig. l, showing the attachment of a temperature sensing element to a fixture at the distal end of the structure;
  • Fig. 34 is an enlarged side section view of the wall of an expandable electrode structure usable in association with the system shown in Fig. 1, showing ways of attaching temperature sensing elements inside and outside the wall;
  • Fig. 35 is an enlarged side section view of the wall of an expandable electrode structure usable in association with the system shown in Fig. 1, showing a laminated structure and the creation of temperature sensing thermocouples by laser windowing and deposition;
  • Fig. 36 is a top view of an expandable electrode structure showing the preferred regions for attaching temperature sensing elements with respect to an electrically conductive shell deposited on the distal end of the structure;
  • Fig. 37 is a side view of an expandable electrode structure showing the preferred regions for attaching temperature sensing elements with respect to an electrically conductive shell deposited in a circumferentially segmented pattern - li ⁇
  • Fig. 38 is a top view of an expandable electrode structure showing the preferred regions for attaching temperature sensing elements with respect to an electrically conductive shell deposited in a bull's-eye pattern on the structure;
  • Fig. 39 is a side view of an expandable electrode structure showing a pattern of holes for cooling the edge regions of an electrically conductive shell deposited in a circumferentially segmented pattern on the structure, the pattern of holes also defining a fold line between the segments of the pattern;
  • Figs. 40A and 4OB are enlarged views of a hole formed in the structure shown in Fig. 39, showing that the hole defines a fold line;
  • Fig. 41A is a side sectional view of an expandable electrode structure usable in association with the system shown in Fig. 1, which is capacitively coupled to tissue;
  • Fig. 4IB is a diagrammatic view showing the electrical path that ablation energy follows when the electrode shown in Fig. 40A is capacitively coupled to tissue;
  • Fig. 42A is an side sectional view of an alternative expandable electrode structure usable in association with the system shown in Fig. 1, which is capacitively coupled to tissue;
  • Fig. 42B is a diagrammatic view showing the electrical path that ablation energy follows when the electrode shown in Fig. 41A is capacitively coupled to tissue;
  • Fig. 43 is a diagrammatic view of neural network usable for predicting maximum temperature conditions when the expandable-collapsible electrode structure carries multiple ablation energy transmitting segments;
  • Fig. 44 is a side elevation view of an expandable electrode structure that embodies the features of the invention, used in association with pacing and sensing electrodes.
  • FIG. 1 shows a tissue ablation system 10 that embodies the features of the invention.
  • the system 10 includes a flexible catheter tube 12 with a proximal end 14 and a distal end 16.
  • the proximal end 14 carries a handle 18.
  • the distal end 16 carries an electrode structure 20, which embodies features of the invention.
  • the purpose of the electrode structure 20 is to transmit ablation energy.
  • the electrode structure 20 includes an expandable-collapsible wall forming a body 22.
  • the geometry of the body 22 can be altered between an enlarged, or expanded, geometry having a first maximum diameter (depicted in various forms, for example, in Figs. 2, 3, 4, 6, and 11A) and a collapsed geometry having a second maximum diameter less than the first maximum diameter (depicted in various forms, for example, in Figs. 5, 7, 11B/C) .
  • This characteristic allows the expandable- collapsible body 22 to assume a collapsed, low profile (ideally, less than 8 French diameter, i.e., les ⁇ than about 0.267 cm) when introduced into the vasculature.
  • the expandable-collapsible body 22 can be urged into a significantly expanded geometry of, for example, approximately 7 to 20 mm.
  • All or a portion of the wall forming the body 22 carries an electrically conductive material that forms an electrode surface.
  • the electrically conductive material comprises an electrically conductive shell 24 overlying all or a portion of the expandable-collapsible body 22.
  • the shell 24 serves as the transmitter of energy that ablates body tissue. While the type of ablation energy used can vary, in the illustrated and preferred embodiment, the shell 24 serves to transmit radio frequency (RF) electromagnetic energy.
  • RF radio frequency
  • the shell 24 is flexible enough to adopt to the range of geometries, from collapsed to expanded, that the expandable-collapsible body 22 assumes. Still, the shell 24 preferably resists stretching within this range, to thereby minimize "thinning.” Thinning of the shell 24 creates localized changes to the shell 24, with attendant increases in resistance and "hot spots.” For this reason, the elasticity of the expandable-collapsible body 22 and shell 24 should be selected to fall within acceptable bounds so that the ability to fold is retained while preserving stability during inflation. Further details of the energy transmitting shell 24 will be provided later.
  • the shell 24 is coupled to one or more signal wires 26.
  • the signal wires 26 extend from the shell 24, through the catheter tube 12, to external connectors 28 on the handle 18 (see Fig. 1) .
  • the connectors 28 electrically couple the shell 24 to a radio frequency generator 30.
  • a controller 32 is associated with the generator 30, either as an integrated unit or as a separate interface box.
  • the controller 32 governs the delivery of radio frequency ablation energy to the shell 24 according to preestablished criteria. Further details of this aspect of the system 10 will be described later.
  • the system 10 as just described is suited for ablating myocardial tissue within the heart.
  • a physician moves the catheter tube 12 through a main vein or artery into a heart chamber, while the expandable-collapsible body 22 of the electrode structure 20 is in its low profile geometry.
  • the expandable-collapsible body 22 is enlarged into its expanded geometry, and the shell 24 is placed into contact with the targeted region of endocardial tissue.
  • Radio frequency energy is conveyed from the generator 30 to the shell 24, as governed by the controller 32.
  • the shell 24 transmits radio frequency energy into tissue to a return electrode. which is typically an external patch electrode (forming a unipolar arrangement) .
  • the transmitted energy can pass through tissue to an adjacent electrode in the heart chamber (forming a bipolar arrangement) , or between segments in the shell 24, as will be described later (also forming a bipolar arrangement) .
  • the radio frequency energy heats the tissue forming a lesion.
  • the expanded geometry of the expandable- collapsible body 22 enhances the energy transmission characteristics of the structure 20.
  • the structure 20, when expanded, is able to form tissue lesions that are significantly larger in terms of size and volume than the body's initial collapsed profile during introduction would otherwise provide.
  • the expandable-collapsible electrode structure 20 as just described is also suited for mapping myocardial tissue within the heart.
  • the shell 24 senses electrical activity in the heart.
  • the sensed electrical activity is conveyed to an external monitor, which processes the potentials for analysis by the physician.
  • the use of an expandable- collapsible electrode structure for this purpose is generally disclosed in Edwards et al. U.S. Patent 5,293,869.
  • the expandable-collapsible electrode structure 20 can be used alternatively, or in combination with sensing electrical activities, to convey pacing signals. In this way, the structure 20 can carry out pace mapping or entrainment mapping.
  • the expanded electrode structure 20 can also be used to convey pacing signals to confirming contact with tissue before ablating. The ability to carry out pacing to sense tissue contact is unexpected, given that the expanded structure 20 presents a surface area significantly greater than that presented by a conventional 4mm/8F electrode.
  • the catheter tube 20 can also carry one or more conventional ring electrodes 21 for bipolar sensing.
  • a conventional pacing or unipolar sensing electrode 23 may also be provided, appended at the distal end of the structure 20.
  • the expandable-collapsible body 22 is made from a material selected to exhibit the following characteristics:
  • the material must be capable, in use, of transition between an expanded geometry having a first maximum diameter and a collapsed geometry having a second maximum diameter less than the first diameter.
  • the material can be formed into an expandable-collapsible bladder or balloon body having an open interior.
  • the body is flexible enough to assume the expanded geometry as a result of a normally open solid support structure within the interior, or the opening of a normally closed support structure within the interior, or the introduction of fluid pressure into the interior, or a combination of such interior forces.
  • the body is caused to assume the collapsed geometry by an exterior compression force against the normally open interior support structure, or the closing of the interior support structure, or the removal of the interior fluid pressure, or a combination of such offsetting forces.
  • the material can be a preformed body with a memory urging it toward a normally expanded geometry.
  • the preformed body is caused to assume the collapsed geometry by the application of an external compression force.
  • the preformed body can have an open interior, or can comprise, for example, a collapsible composite foam structure.
  • the material must be biocompatible and able to withstand high temperature conditions, which arise during manufacture and use.
  • the material must possess sufficient strength to withstand, without rupture or tearing, external mechanical or fluid forces, which are applied to support and maintain its preformed geometry during use.
  • the material must lend itself to attachment to the catheter tube 12 through the use of straightforward and inexpensive adhesive, thermal, or mechanical attachment methods.
  • the material must be compatible with the electrically conductive shell 24 to achieve secure adherence between the two.
  • Thermoplastic or elastomeric materials that can be made to meet these criteria include polyimide (kapton) , polyester, silicone rubber, nylon, mylar, polyethelene, polyvinyl chloride, and composite structures using these and other materials.
  • the incidence of tissue sticking to the exterior of the body 22 during use can be mediated by the inclusion of low friction materials like PTFE.
  • the propensity of the exterior of the body 22 to cause blood clotting and/or embolization can be reduced by incorporating non-thrombogenic material onto or into the exterior of the body 22.
  • Polyimide is particularly preferred for the expandable-collapsible body.
  • Polyimide is flexible, but it is not elastic. It can withstand very high temperatures without deformation. Because polyimide is not elastic, it does not impose stretching forces to the shell, which could lead to electrical conductivity decreases, as above described.
  • the expandable-collapsible body 22 can be formed about the exterior of a glass mold. In this arrangement, the external dimensions of the mold match the desired expanded internal geometry of the expandable-collapsible body 22.
  • the mold is dipped in a desired sequence into a solution of the body material until the desired wall thickness is achieved. The mold is then etched away, leaving the formed expandable-collapsible body 22.
  • Various specific geometries can be selected.
  • the preferred geometry is essentially spherical and symmetric, with a distal spherical contour, as Figs. 2 to 11 show in various forms. However, nonsymmetric geometries can be used.
  • the expandable-collapsible body 22 may be formed with a flattened distal contour, which gradually curves or necks inwardly for attachment with the catheter tube 12.
  • the expandable-collapsible body 22 may also be blow molded from extruded tube.
  • the body 22 is sealed at one end using a mechanical clamp, adhesive, or thermal fusion.
  • the opposite open end of the body 22 is left open.
  • the sealed expandable-collapsible body 22 is placed inside the mold.
  • An inflation medium, such as high pressure gas or liquid, is introduced through the open tube end.
  • the mold is exposed to heat as the tube body 22 is inflated to assume the mold geometry.
  • the formed expandable-collapsible body 22 is then pulled from the mold.
  • fluid pressure is used to inflate and maintain the expandable-collapsible body 22 in the expanded geometry.
  • the catheter tube 12 carries an interior lumen 34 along its length.
  • the distal end of the lumen 34 opens into the hollow interior of the expandable-collapsible body 22, which has been formed in the manner just described.
  • the proximal end of the lumen 34 communicates with a port 36 (see Fig. 1) on the handle 18.
  • An inflation fluid medium (arrows 38 in Fig. 2) is conveyed under positive pressure through the port 36 and into the lumen 34.
  • the fluid medium 38 fills the interior of the expandable-collapsible body 22.
  • the fluid medium 38 exerts interior pressure to urge the expandable-collapsible body 22 from its collapsed geometry to the enlarged geometry desired for ablation.
  • the inflating fluid medium 38 can vary. Preferably, it comprises a liquid such as water, saline solution, or other biocompatible fluid. Alternatively, the inflating fluid medium 38 can comprise a gaseous medium such as carbon dioxide or air.
  • the inflation preferably occurs under relatively low pressures of up to 30 psi.
  • the pressure used depends upon the desired amount of inflation, the strength and material used for the body 22, and the degree of flexibility required, i.e., high pressure leads to a harder, less flexible body 22.
  • More than one fluid conveying lumen 34 may be used.
  • the multiple lumens 34 can, for example, speed up the introduction or removal of the inflating medium 38 from the body 22.
  • Multiple lumens can also serve to continuously or intermittently recycle the inflating medium 38 within the body 22 for controlling the temperature of the body, as will be described in greater detail later.
  • Multiple lumens can also be used, with at least one of the lumens dedicated to venting air from the structure 20.
  • a group of sealed bladders compartmentalize the interior of the formed body into chambers 40.
  • One or more lumens 42 passing through the catheter tube 12 convey the inflating gas or liquid medium 38 into each chamber 40, as described above.
  • the inflated chambers 40 collectively hold the expandable- collapsible body 22 in its expanded condition. Removal of the inflation medium 38 deflates the chambers 40, collapsing the expandable-collapsible body 22.
  • the bladders defining the chambers 40 may be separately formed by molding in generally the same fashion as the main expandable-collapsible body 22.
  • the bladder material need not have the same resistance to high temperature deformation as the expandable-collapsible body 22.
  • the bladders may also be deposition coated with a thermal insulating material to thermally insulate them from the main expandable-collapsible body 22.
  • the interior chambers 40 can take the form of tubular, circumferentially spaced ribs 41 attached to the interior of the body 22. In this arrangement, the ribs 41 preferable constitute integrally molded parts of the body 22. As explained in connection with the Fig.
  • a single lumen may service all chambers ribs 41.
  • multiple lumens individually communicating with each rib 41 provide the ability to more particularly control the geometry of the expanded body 22, by selectively inflating some but not all the ribs 41 or chambers 40.
  • the body 22 may be extruded with interior webs 43.
  • the interior webs 43 compartmentalize the body 22 into the interior chambers 40, as already described.
  • multiple lumens preferably individually communicate with each formed chamber 40 for conveying inflation medium and for venting air.
  • a separate, single interior chamber 124 can be used instead of the compartmentalized chambers 40 or ribs 41 shown in Figs. 3A, 3B, and 3C to receive the inflation medium for the exterior body 22.
  • this arrangement creates an intermediate region 126 between the interior of the body 22 and the exterior of the chamber 124, through which signal wires 26 can be passed for coupling to the shell 24.
  • collapsible, interior structures 44 sustain the expandable-collapsible body 22 in the expanded geometry.
  • the presence of the interior support structure 44 eliminates the need to introduce air or liquid as an inflation medium 38. Possible difficulties of fluid handling and leakage are thereby avoided.
  • the expandable-collapsible body 22 is held in its expanded geometry by an open interior structure 44 formed by an assemblage of flexible spline elements 46.
  • the spline elements 46 are made from a resilient, inert wire, like nickel titanium (commercially available as Nitinol material) , or from a resilient injection molded inert plastic or stainless steel.
  • the spline elements 46 are preformed in a desired contour and assembled to form a three dimensional support skeleton, which fills the interior space of the expandable-collapsible body 22.
  • the supported expandable- collapsible body 22 is brought to a collapsed geometry by outside compression applied by an outer sheath 48 (see Fig. 5) , which slides along the catheter tube 12.
  • an outer sheath 48 see Fig. 5 shows, forward movement of the sheath 48 advances it over the expanded expandable-collapsible body 22.
  • the sliding sheath 48 encompasses the expandable-collapsible body 22, compressing the interior spline elements 46 together.
  • the expandable-collapsible body 22 collapses into its low profile geometry within the sheath 48.
  • Rearward movement of the sheath 48 retracts it away from the expandable-collapsible body 22.
  • the interior support structure 44 of spline elements 46 springs open into the three dimensional shape.
  • the expandable-collapsible body 22 returns to its expanded geometry upon the spline elements 46.
  • the expandable-collapsible body 22 is supported upon a closed, three dimensional structure 44 formed by a resilient mesh 50.
  • the mesh structure 50 is made from interwoven resilient, inert wire or plastic filaments preformed to the desired expanded geometry.
  • the mesh structure 50 provides interior support to hold the expandable- collapsible body 22 in its expanded geometry, in the same way as the open structure of spline elements 46 shown in Fig. 4.
  • a sliding sheath 48 (as previously described) can also be advanced along the catheter tube 12 to compress the mesh structure 50 to collapse mesh structure 50 and, with it, the expandable-collapsible body 22. Likewise, retraction of the sheath 48 removes the compression force (as Fig. 6 shows) , and the freed mesh structure 50 springs open to return the expandable- collapsible body 22 back to its expanded geometry.
  • the mesh structure 50 itself could serve as the support for the electrically conductive shell 24, without need for the intermediate expandable- collapsible body 22. Indeed, all or a portion of the mesh filaments could be made electrically conductive to themselves serve as transmitters of ablation energy. This arrangement of interwoven, electrically conductive filaments could supplement or take the place of the electrically conductive shell 24.
  • the mesh structure 50 can be made to normally assume the collapsed geometry.
  • one or more interior bladders 126 can accommodate the introduction of an inflation medium to cause the mesh structure 50 to assume the expanded geometry.
  • Fig. 9 shows yet another alternative expandable- collapsible structure.
  • a foam body 128 molded to normally assume the shape of the expanded geometry forms the interior support structure for the body 22.
  • the presence of the foam body 128 eliminates the need to introduce air or liquid as an inflation medium.
  • a sliding sheath (not shown but as previously described) can be advanced along the catheter tube 12 to compress the foam body 128 and overlying body 22 into the collapsed geometry. Likewise, retraction of the sheath removes the compression force. The foam body 128, free of the sheath, springs open to return the expandable-collapsible body 22 back to the expanded geometry. It should be appreciated that the foam body 128 can provide interior, normally expanded support to the mesh structure 50 in the same way.
  • the geometry of the expandable-collapsible body 22 can be controlled electrically.
  • This arrangement includes an assemblage of spline elements 132 within the body 22.
  • the spline elements 132 are made of a material that undergoes shape or phase change in response to heating. Nickel titanium wire is a material having this characteristic.
  • the spline elements 132 could comprise an assembly of two metals having different coefficients of expansion.
  • the body 22 overlies the spline elements 132.
  • the spline elements 132 are coupled to an electrical current source 134. Current flow from the source 134 through the spline elements 132 resistively heats the elements 132. As a result, the spline elements 132 change shape. As Fig. 10 shows, the spline elements 132 normally present the collapsed geometry. Current flow through the spline elements 132 causes expansion of the elements 132, thereby creating the expanded geometry (as shown by arrows and phantom lines in Fig. 10) . It should be appreciated that the spline elements 132 could alternatively normally present the expanded geometry and be made to contract, thereby assuming the collapsed geometry, in response to current flow. c. Folding
  • the expandable-collapsible body 22 can be molded with preformed regions 52 (see Figs. llA/B/C) of reduced thickness, forming creases.
  • the mold has a preformed surface geometry such that the expandable-collapsible material would be formed slightly thinner, indented, or ribbed along the desired regions 52.
  • the use of interior coextruded webs 43 as Fig. 3E shows, also serves to form the crease regions 52 along the area where the webs 43 contact the interior wall of the body 22.
  • the expandable-collapsible body 22 collapses about these regions 52, causing the body 22 to circumferentially fold upon itself in a consistent, uniform fashion.
  • the resulting collapsed geometry can thus be made more uniform and compact.
  • an inflation medium 38 applies positive pressure to expand the expandable- collapsible body 22
  • a negative fluid pressure can be applied inside the expandable-collapsible body 22 to draw the fold regions 52 further inward.
  • the fold regions 52 are preferably aligned in the spaces between the spline elements 46 to take best advantage of the prearranged folding action. Alternative ways of creating fold regions 52 in the body 22 will be described in greater detail later.
  • a distal steering mechanism 54 enhances the manipulation of the electrode structure 20, both during and after deployment.
  • the steering mechanism 54 can vary.
  • the steering mechanism 54 includes a rotating cam wheel 56 coupled to an external steering lever 58 carried by the handle 18.
  • the cam wheel 56 holds the proximal ends of right and left steering wires 60.
  • the wires 60 pass with the ablation energy signal wires 26 through the catheter tube 12 and connect to the left and right sides of a resilient bendable wire or leaf spring 62 adjacent the distal tube end 16 (see Fig. 12) .
  • Further details of this and other types of steering mechanisms are shown in Lundquist and Thompson U.S. Patent 5,254,088, which is incorporated into this Specification by reference.
  • the leaf spring 62 is carried within in the distal end 16 of the catheter tube 12, to which the electrode structure 20 is attached.
  • Figs. 1 and 12 show, forward movement of the steer- ing lever 58 pulls on one steering wire 60 to flex or curve the leaf spring 62, and, with it, the distal catheter end 16 and the electrode structure 20, in one direction.
  • Rearward movement of the steering lever 58 pulls on the other steering wire 60 to flex or curve the leaf spring 62, and, with it, the distal catheter end 16 and the electrode structure 20, in the opposite direction.
  • the leaf spring 62 is part of a distal fixture 66 carried within the electrode structure 20 itself.
  • the leaf spring 62 extends beyond the distal catheter end 16 within a tube 64 inside the expandable-collapsible body 22.
  • the distal end of the leaf spring 62 is secured to a distal fixture 66.
  • the distal fixture 66 is itself attached to the distal end of the body 22. Further details of attaching the fixture 66 to the distal end of the body 22 will be described in greater detail later.
  • forward movement of the steer ⁇ ing lever 58 bends the leaf spring 62 in one direction within the expandable-collapsible body 22, deflecting the distal fixture 66 with it.
  • the steering mechanism 54 is usable whether the expandable-collapsible body is in its collapsed geometry or in its expanded geometry.
  • a stilette 76 is attached to the distal fixture 66.
  • the stilette extends inside the body 22, through the catheter tube 12, to a suitable push-pull controller 70 on the handle 18 (see Fig. 1) .
  • the stilette 76 is movable along the axis of the catheter tube 12. Moving the stilette 76 forward pushes axially upon the distal fixture 66. Moving the stilette 76 rearward pulls axially upon the distal fixture 66.
  • the geometry of the body 22 elongates or expands accordingly.
  • the stilette 76 can be used in association with an expandable-collapsible body 22 that is expanded by an inflation medium 38. In this arrangement, when the expandable-collapsible body 22 is collapsed, forward movement of the stilette 76, extends the distal fixture 66 to further urge the expandable-collapsible body 22 into a smaller diameter profile for introduction.
  • the stilette 76 When used in association with an expandable- collapsible body 22 that is internally supported by the spline structure 46 or the mesh structure 50, the stilette 76 can be used instead of the slidable outer sheath 48 to expand and collapse the expandable-collapsible body 22. Pushing forward upon the stilette 76 extends the spline structure 46 or mesh structure 50 to collapse the expandable- collapsible body 22. Pulling rearward upon the stilette 76, or merely releasing the pushing force, has the opposite effect, allowing the spline structure 46 or mesh structure 50 to assume its expanded geometry.
  • the stilette 76 When used with either inflated or mechanically expanded expandable-collapsible bodies 22, pulling rearward upon the stilette 76 also has the effect of altering the expanded geometry by flattening the distal region of the expandable-collapsible body 22. While the stilette 76 can be used by itself, in the illustrated embodiment (see Fig. 14) , the distal end of the stilette 76 near the fixture 66 comprises the bendable leaf spring 62, thereby providing a radial steering function in tandem with the axial push-pull action of the stilette 76.
  • a collar 136 is retained by a heat-shrink fit within tubing 64.
  • the collar 136 has a central aperture 138 through which a leaf spring 62 at the end of the stilette 76 passes for movement along the axis of the catheter tube 12.
  • Steering wires 60 are attached to the collar 136. Pulling on the steering wires 60 radially deflects the collar 136, thereby bending the leaf spring 62 at the end of the stilette 76 in the direction of the pulled steering wire 60.
  • a sleeve 78 (see, e.g., Fig. 2) couples the near end of the expandable-collapsible body 22 to the distal end 16 of the catheter tube.
  • the sleeve 78 withstands the forces exerted to expand the expandable-collapsible body 22, resisting separation of the body 22 from the catheter tube 12.
  • the sleeve 78 also forms a fluid seal that resists leakage of the medium at inflation pressures.
  • the sleeve 78 can be secured about the catheter tube in various ways, including adhesive bonding, thermal bonding, mechanical bonding, screws, winding, or a combination of any of these.
  • Figs. 15A to 15E show the details of a preferred assembly process for an expandable-collapsible body 22 whose geometry is altered by use of fluid pressure, such as previously shown in Figs. 2 and 3.
  • the body 22 is extruded as a tube 140 having an extruded interior diameter, designated ID, (see Fig. 15A) .
  • ID is selected to be less than the exterior diameter of the distal stem 142 of the catheter tube 12 to which the body 22 will ultimately be attached.
  • the stem 142 comprises an elongated, stepped-down tubular appendage, which extends beyond the distal end 16 of the catheter tube 12.
  • the distal end of the stem 142 is sealed.
  • the exterior diameter of the stem 142 is designated in Fig. 15D as ED S .
  • the stem 142 includes a central lumen 152 for carrying inflation medium. Spaced apart holes 154 on the stem 142 communicate with the lumen to convey the inflation medium into the body 22, when attached to the stem 142.
  • the material of the extruded tube 140 is preferably cross linked by exposure to gamma radiation 168 or an equivalent conventional treatment.
  • the cross linking enhances the capability of the material of the tube 140 to recover its shape after mechanical deformation.
  • the extruded tube 140 is mechanically deformed by heat molding into the body 22 having the de ⁇ ired collapsed geometry, in a manner previously described.
  • the body geometry includes proximal and distal neck regions 144 and 146 and an intermediate main body region 148.
  • the neck regions 144 and 146 have an enlarged interior diameter (designated ID 2 in Fig. 15B) that is slightly greater than catheter stem diameter ED S , to permit a slip fit of the body 22 over the stem 142.
  • the intermediate main body region 148 has an enlarged exterior diameter selected for the - 31 -
  • the enlarged exterior diameter of the tube 140 should be about twice the original extruded outer diameter of the tube 140.
  • the tubing ends 150 extending beyond the neck regions 144 and 146 are cut away.
  • the body 22 is slip fitted over the stem 142. Heat is applied to shrink fit the neck regions 144 and 146 about the stem 142 (see Fig. 15E) . Due to molding, the memory of these regions 144 and 146, when heated, seek the original interior diameter ID, of the tubing 140, thereby proving a secure interference fit about the stem 142.
  • the sleeve 78 is heat-shrunk in place about the proximal neck region 144 (see Fig. 15E) .
  • the sleeve 78 can comprise a heat- ⁇ hrink plastic material or phase changeable metal material, like nickel titanium.
  • the sleeve 78 can be heat-shrunk into place without an intermediate thermal fusing step. Figs.
  • FIG. 16A to 16D show the details of a preferred assembly process for an expandable-collapsible body 22 whose geometry is altered by use of an interior support structure 44 of spline elements 46, such as previously shown in Figs. 4 and 5.
  • the distal neck region 146 is secured by heat shrinking about the distal fixture 66 (see Fig. 16A) .
  • the distal fixture 66 has, preattached to it, the distal end of the spline element structure 44, as well as any desired steering mechanism 54, stilette 76, or combination thereof (not shown in Figs. 16A to 16D) .
  • the main region 148 of the body 22 is oriented in a direction opposite to the spline element structure 44.
  • the body 22 is everted about the distal fixture 66 over the spline element structure 44 (see Fig. 16B) .
  • the proximal end of the spline element structure 44 is secured to an anchor 156 carried by the distal catheter end 16 (see Fig. 16C) , and the everted proximal neck region 144 is then slip fitted over the catheter stem 158.
  • the catheter stem 158 in this arrangement does not extend beyond the neck region 144 of the body 22.
  • Heat is then applied to shrink fit the neck region 144 about the stem 158 (see Fig. 16D) .
  • additional heat is provided to thermally fuse the region 144 to the stem 158.
  • the sleeve 78 is heat-shrunk in place about the proximal neck region 144.
  • the sleeve 78 can be heat- shrunk into place without an intermediate thermal fusing step.
  • the Electrically Conducting Shell 24 The purpose of the electrically conducting shell 24 is to transmit ablation energy, which in the illustrated and preferred embodiment comprises electromagnetic radio frequency energy with a frequency below about 1.0 GHz. This type of ablating energy heats tissue, mostly ohmically, to form lesions without electrically stimulating it. In this arrangement, the shell 24 should posse ⁇ s the characteristics of both high electrical conductivity and high thermal conductivity. It should also be appreciated that the shell 24 could form an antenna for the transmission of higher frequency microwave energy.
  • the electrode structure 20 is able to create lesions of different size and geometries.
  • the shell creates lesion patterns greater than about 1.5 cm deep and/or about 2.0 cm wide. These lesion patterns are significantly deeper and wider than those created by conventional 8F diameter/4 mm long electrodes, which are approximately 0.5 cm deep and 10 mm wide.
  • the deeper and wider lesion patterns that the shell 24 can provide are able to destroy epicardial and intramural ventricular tachycardia (VT) substrates.
  • VT ventricular tachycardia
  • Finite element analysis was performed for a flexible, expanded electrode structure 20 having a 1.4 cm diameter and a wall thickness of approximately 200 ⁇ m.
  • the model assumed a 100 ⁇ m thick coating of gold over the distal hemisphere of the structure 20, forming the electrically conductive shell 24.
  • the constraint for the model was a lower limit on thickness and therefore the thermal conductivity of the shell 24.
  • the lesions created in the above Table 1 are capable of making transmural lesions in the left ventricle and can therefore ablate epicardial VT substrates.
  • the Table 1 shows that lesion size increases with an electrically conductive shell 24 presenting less percentage contact with tissue than blood.
  • the shell presenting 100% contact with tissue (and none with blood) compared to the shell 24 presenting up to 41% percent of its surface to tissue had lower lesion depths.
  • the shell 24 With less relative contact with tissue than blood, the shell 24 is more exposed to the blood pool and its convective cooling effect.
  • the blood cools the shell 24 it contacts. Heat is lost from tissue under the shell 24 into the blood pool. This emulation of active cooling of the shell 24 causes more power to be transmitted to the tissue before maximum tissue temperatures are achieved, thereby creating larger lesions.
  • Table 1 highlights the importance of relatively high thermal conductivity for the shell 24, which can be achieved by material selection and controlling thickness. Given the same percentage contact with tissue versus blood, a higher thermal conductivity results in a higher cooling effect and a corresponding increase in lesion size.
  • the above Table 1 demonstrates the ability of the structure 20 carrying the shell 24 to transmit the proper amount of radio frequency energy to create large and deep lesions.
  • Table 2 demonstrates the ability of the structure carrying the shell 24 to transmit the proper amount of radio frequency energy to create wide and shallow lesions. The effect is achieved by controlling both the delivered radio frequency power and the time of radio frequency energy application. Wide and shallow lesion patterns are effective in the treatment of some endocardially located substrates and atrial fibrillation substrates.
  • Tables 1 and 2 demonstrate the capability of the same expandable-collapsible electrode structure 20 with the desirable lower percentage contact with tissue relative to blood (less than 50%) to ablate epicardial, intramural, or endocardial substrates with a range of lesion patterns from wide and shallow to large and deep.
  • the electrically conductive shell 24 may be deposited upon the exterior of the formed expandable-collapsible body 22.
  • a mask is placed upon the surface of the expandable-collapsible body 22 that i ⁇ to be free of the shell 24.
  • the shell 24 is not deposited on at least the proximal l/3rd surface of the expandable-collapsible body 22. This requires that at least the proximal l/3rd surface of the expandable-collapsible body 22 be masked, so that no electrically conductive material is deposited there.
  • the masking of the at least proximal l/3rd surface of the expandable-collapsible body 22 is desirable for several reasons. This region is not normally in contact with tissue, so the presence of electrically conductive material serves no purpose.
  • this region also presents the smallest diameter. If electrically conductive, this region would possess the greatest current density, which is not desirable. Masking the proximal region of smallest diameter, which is usually free of tissue contact, assures that the maximum current density will be distributed at or near the distal region of the expandable-collapsible body 22, which will be in tissue contact.
  • the presence of the steering mechanism 54, already described, also aids in placing the shell-carrying distal tip in tissue contact.
  • the shell 24 comprises a material having a relatively high electrical conductivity, as well as a relative high thermal conductivity. Materials possessing these characteristics include gold, platinum, platinum/iridium, among others. These materials are preferably deposited upon the unmasked, distal region of the expandable- collapsible body 22.
  • Usable deposition proces ⁇ es include sputtering, vapor deposition, ion beam deposition, electroplating over a deposited seed layer, or a combination of these processes.
  • an undercoating 80 is first deposited on the unmasked distal region before depositing the shell 24.
  • Materials well suited for the undercoating 80 include titanium, iridium, and nickel, or combinations or alloys thereof.
  • the total thickness of the shell 24 deposition, including the undercoating 80, can vary. Increasing the thickness increases the current-carrying and thermal conductive capacity of the shell 24. However, increasing the thickness also increases the potential of shell cracking or peeling during enlargement or collapse of the underlying expandable-collapsible body 22.
  • the deposition of the electrically conductive shell material should normally have a thickness of between about 5 ⁇ m and about 50 ⁇ m.
  • the deposition of the adherence undercoating 80 should normally have a thickness of about 1 ⁇ m to about 5 ⁇ m.
  • the shell 24 comprises a thin sheet or foil 82 of electrically conductive metal affixed to the wall of the expandable-collapsible body 22.
  • Materials suitable for the foil include platinum, platinum/iridium, stainless steel, gold, or combinations or alloys of these materials.
  • the foil 82 is shaped into a predetermined geometry matching the geometry of the expandable-collapsible body 22, when expanded, where the foil 82 is to be affixed.
  • the geometry of the metal foil 82 can be accomplished using cold forming or deep drawing techniques.
  • the foil 82 preferably has a thickness of less than about .005 cm (50 ⁇ m) .
  • the foil 82 is affixed to the expandable-collapsible body 22 using an electrically insulating epoxy, adhesive, or the like.
  • the shell 24 of foil 82 offers advantages over the deposited shell 24. For example, adherence of the shell foil 82 upon the expandable-collapsible body 22 can be achieved without using the deposited undercoating 80.
  • the shell foil 82 also aids in the direct connection of ablation energy wires 26, without the use of additional connection pads and the like, as will be described in greater detail later.
  • the shell foil 82 also offers greater resistance to stretching and cracking in response to expansion and collapse of the underlying expandable- collapsible body 22. This offers greater control over resistance levels along the ablation energy transmitting surface.
  • all or a portion of the expandable-collapsible wall forming the body 22 is extruded with an electrically conductive material 84.
  • Materials 84 suitable for coextrusion with the expandable-collapsible body 22 include carbon black and chopped carbon fiber.
  • the coextruded expandable- collapsible body 22 is itself electrically conductive.
  • An additional shell 24 of electrically conductive material can be electrically coupled to the coextruded body 22, to obtain the desired electrical and thermal conductive characteristics. The extra external shell 24 can be eliminated, if the coextruded body 22 itself possesses the desired electrical and thermal conductive characteristics. - 40 -
  • the integral electrically conducting material 84 coextruded into the body 22 offers certain advantages over the external deposited shell 24 (Fig. 17) or shell foil 82 (Fig. 18) . Coextrusion avoids the necessity of adherence between the shell 24 and the expandable-collapsible body 22.
  • a body 22 coextruded with electrically conducting material 84 also permits more direct connection of ablation energy wires 34, without the use of additional connection pads and the like.
  • the integrated nature of the coextruded material 84 in the body 22 protects against cracking of the ablation energy transmitting surface during expansion and collapse of the expandable-collapsible body 22.
  • the integral electrically conducting material 84 coextruded into the body 22 also permits the creation of a family of electrode structures 20, with the structures 20 differing in the amount of conductive material 84 coextruded into the wall of the respective body 22.
  • the amount of electrically conductive material coextruded into a given body 22 affects the electrical conductivity, and thus the electrical resi ⁇ tivity of the body 22, which varies inversely with conductivity. Addition of more electrically conductive material increases electrical conductivity of the body 22, thereby reducing electrical resistivity of the body 22, and vice versa. It is thereby possible to specify among the family of structures 20 having electrically conductive bodies 22, the use of a given structure 20 according to a function that correlates desired lesion characteristics with the electrical resistivity values of the associated body 22.
  • EXAMPLE 2 A three-dimensional finite element model was created for an electrode structure having a body with an elongated shape, with a total length of 28.4 mm, a diameter of 6.4 mm, and a body wall thickness of .1 mm.
  • the body of the structure was modeled as an electric conductor.
  • Firm contact with cardiac tissue was assumed along the entire length of the electrode body lying in a plane beneath the electrode.
  • Contact with blood was assumed along the entire length of the electrode body lying in a plane above the electrode.
  • the blood and tissue regions had resistivities of 150 and 500 ohm*cm, respectively.
  • Table 3 shows the depth of the maximum tissue temperature when RF ablation power is applied to the electrode at various power levels and at various levels of resistivity for the body of the electrode.
  • the electrode body with higher resistivity body was observed to generate more uniform temperature profiles, compared to a electrode body having the lower resistivity value. Due to additional heating generated at the tissue-electrode body interface with increased electrode body resistivity, less power was required to reach same maximal temperature. The consequence was that the lesion depth decreased.
  • the shell 24 should, of course, be oriented about the distal tip of the expandable- collapsible body 22.
  • the shell 24 may comprise a continuous cap deposited upon the distal l/3rd to 1/2 of the body 22, as Fig. 17 shows.
  • the preferred embodiment segments the electrically conductive shell 24 into separate energy transmission zones 122 arranged in a concentric "bull's-eye" pattern about the distal tip of the body 22.
  • the concentric bull's-eye zones 122 are formed by masking axially spaced bands on the distal region of the body 22, to thereby segment the deposit of the electrically conductive shell 24 into the concentric zones 122.
  • preformed foil shells 82 can be applied in axially spaced bands on the distal region to form the segmented energy transmitting zones 122.
  • the shell 24 is preferably segmented into axially elongated energy transmission zones 122, which are circumferentially spaced about the distal l/3rd to 1/2 of the body 22 (see Figs. 21 and 22) .
  • the circumferentially spaced zones 122 are formed by masking circumferentially spaced areas of the distal region of the body 22, to thereby segment the deposit of the electrically conductive shell 24 into the zones 122.
  • preformed foil shells 82 can be applied in circumferentially spaced-apart relationship on the distal region to form the segmented energy transmitting zones 122.
  • the circumferentially segmented energy transmission zones 122 may take the form of semi-rigid pads carried by the expandable- collapsible body 22. Adjacent pads overlap each other when the body 22 is in its collapsed geometry. As the body 22 assumes its expanded geometry, the pads spread apart in a circumferential pattern on the body 22.
  • each energy transmission zone 122 is coupled to a dedicated signal wire 26 or a dedicated set of signal wires 26. This will be described later in greater detail.
  • the controller 32 can direct ablation energy differently to each zone 122 according to prescribed criteria, as will also be described in greater detail later.
  • the interior surface of the body 22 can carry electrodes 402 suitable for unipolar or bipolar sensing or pacing. Different electrode placements can be used for unipolar or bipolar sensing or pacing. For example, pairs of 2-mm length and 1-mm width electrodes 402 can be deposited on the interior surface of the body 22. Connection wires 404 can be attached to these electrodes 100. Preferably the interelectrode distance is about 1 mm to insure good quality bipolar electrograms. Preferred placements of these interior electrodes are at the distal tip and center of the body 22. Also, when multiple zones are used, it is desired to have the electrodes 402 placed in between the ablation regions.
  • opaque markers 406 are on the interior surface of the body 22 so that the physician can guide the device under fluoroscopy to the targeted site.
  • Any high-atomic weight material is suitable for this purpose.
  • platinum, platinum-iridium. can be used to build the markers 406. Preferred placements of these markers 106 are at the distal tip and center of the structure 22.
  • segmented energy transmitting zone ⁇ 122 are well suited for use in association with folding expandable-collapsible bodies 22, as previou ⁇ ly de ⁇ cribed in connection with Figs. llA/B/C.
  • the regions that are masked before deposition of the electrical conductive shell comprise the folding regions 52.
  • the regions 52 of the expandable- collapsible body 22 that are subject to folding and collapse are those that do not carry an electrically conductive shell 24.
  • the electrically conductive shell 24 is thereby protected against folding and stretching forces, which would cause creasing and current interruptions, or increases in resi ⁇ tance, thereby affecting local current densities and temperature conditions.
  • the selective deposition of the shell 24 in segmented patterns can itself establish predefined fold lines 52 on the body 22, without special molding of preformed regions of the body 22 (as Figs. llA/B/C contemplate).
  • predefined fold line ⁇ 52 can be created at the boarder ⁇ between the ⁇ hell ⁇ egments 122. These fold lines 52 are created due to the difference in thickness between adjacent regions which are coated with the shell 24 and those which are not.
  • the region between segmented shell coatings will establish a fold line 52, when the distance between the coatings (designated x in Figs. 24A and B) is greater than or equal to twice the thickness of the adjacent shell coatings 122 (designated t in Figs. 24A and B) divided by the tangent of one half the minimum selected fold angle (de ⁇ ignated MIN in Fig. 24A) .
  • This fold line relationship is mathematically expres ⁇ ed as follows:
  • the minimum selected fold angle 2 ⁇ MIN can vary according to the profile of the body 22 desired when in the collapsed geometry.
  • the minimum fold angle 2 ⁇ MIN is in the range of 1° to 5°.
  • the fold lines 52 created by controlled deposition of shell segments lie uniformly along (i.e., parallel to) the long axis of the body 22 (designated 170 in Fig. 23) .
  • the uncoated fold lines 52 created at the boarders between the thicker coated shell segments 122 can also be characterized in terms of relative electrical resi ⁇ tivity values.
  • the coated segments 122 of electrically conductive material possess higher electrical conductivity than the uncoated fold lines 52.
  • the re ⁇ i ⁇ tivity of the fold line ⁇ 52 which varie ⁇ inver ⁇ ely with conductivity, is thereby higher than the resistivity of the segment ⁇ 122.
  • the region in which folding occurs should have a resi ⁇ tivity that is greater than about ten times the re ⁇ i ⁇ tivity of the segments 122 carrying electrically conductive material.
  • connection between the signal wires 26 and the shell 24, whether deposited, foil layered, or coextruded, must remain intact and free of open circuits as the expandable-collapsible body 22 and ⁇ hell 24 change geometries.
  • the electrical connection is preferably oriented proximate to the geometric center of the pattern that the a ⁇ ociated ablation zone 122 defines.
  • the geometric center (designated GC) varies depending upon whether the zone 122 comprises a cap pattern (as Fig. 25 shows) , or a circumferential segment pattern (as Fig. 26 show ⁇ ) , or a circumferential band or bull' ⁇ -eye pattern (a ⁇ Fig. 27 ⁇ how ⁇ ) .
  • a cap pattern as Fig. 25 shows
  • a circumferential segment pattern as Fig. 26 show ⁇
  • a circumferential band or bull' ⁇ -eye pattern (a ⁇ Fig. 27 ⁇ how ⁇ )
  • At lea ⁇ t one electrical connection should be present proximate to the respective geometric center of the pattern.
  • Thi ⁇ en ⁇ ures that maximum current density is distributed about the geometric center of the zone and that similar current densities are distributed at the edges of the pattern.
  • additional electrical connections are preferably made in each ablation zone.
  • the additional electrical connection ⁇ (de ⁇ ignated AC in, respectively, Figs. 25 and 26) are distributed uniformly about the geometric center.
  • the additional electrical connections (de ⁇ ignated ACG in Fig. 27) are di ⁇ tributed uniformly along the arc along which the geometric center of the band lies.
  • Multiple electrical connections, at least one of which occurs proximate to the geometric center, provide more uniform current density distribution in the zone. These multiple connections are especially needed when the resistivity of the shell 24 or of the corresponding patterns is high. These connections prevent inefficient RF energy delivery due to RF voltage drops along parts of the shell 24 or the corresponding patterns.
  • multiple ⁇ ignal wires 26 are lead through the interior of the body 22 and out through a center aperture 74 in the distal fixture 66.
  • Multiple signal wires 26 are preferred, as multiple electrical connections provide a more uniform current density distribution on the shell 24 than a single connection.
  • the signal wires 26 are enclosed within electrical insulation 160 (see Fig. 28B) except for their distal ends. There, the electrical insulation 160 is removed to exposed the electrical conductor 162.
  • the exposed electrical conductor 162 is also preferably flattened by mechanical means to provide an increased surface area.
  • the flattened conductors 162 are affixed by an electrically conductive adhesive proximate to the geometric center and elsewhere at additional uniformly spaced intervals about it on the cap pattern, as well as along the geometric center of the concentric bands of the bull's-eye pattern, which the shell 24, when deposited, will create.
  • the adhesive connections of the conductors 162 to the body 22 be positioned, when pos ⁇ ible, relatively clo ⁇ e to an established support area on body 22, such as provided by the distal fixture 66.
  • the shell 24 is deposited in the desired pattern on the body 22, over the adhesively attached conductors 162, in a manner previously described.
  • the center aperture 74 in the distal fixture 66 is sealed closed by adhesive or equivalent material.
  • the distal fixture 66 can also be u ⁇ ed to create a mechanical connection to electrically couple a ⁇ ingle ⁇ ignal wire 26 to the geometric center of the cap of the bull's-eye pattern.
  • the fixture 66 is made from an electrically conductive material.
  • the signal wire 26 is connected by spot welding, soldering, or electrically conductive adhesive to the fixture 66 within the expandable- collapsible body 22.
  • a nut 74 engaging a threaded fixture end 164 sandwiches the distal tip of the body 22 between it and the collar 68 (see Fig. 29B) .
  • Epoxy which could be electrically conductive, could be used to further strengthen the mechanical connection between the nut 74 and the body 22 sandwiched beneath it.
  • the shell 24 is next deposited on the body 22 and nut 74 in a manner previously described.
  • the shell 24 can be deposited on the body 22 before attachment of the nut 74.
  • the nut 74 ⁇ andwiches the shell 24 between it and the collar 68, mechanically establishing the desired electrical connection between the signal wire 26 and the ⁇ hell 24.
  • a heat shrunk slip ring of nickel titanium material can be used instead of a threaded nut connection.
  • any riveting, swagging, electrically conductive plating, or bonding technique can be used to hold the ⁇ hell 24 in contact again ⁇ t the collar 68.
  • additional solid fixtures 66 and as ⁇ ociated electrical connection techniques can be used in other regions of the shell 22 distant from the distal tip of the body 22 to establish electrical contact in the circumferential bands of the bull's-eye pattern or proximate the geometric center and elsewhere on the circumferential segment ⁇ .
  • electrical connections can be made in these regions without using fixtures 66 or equivalent structural elements. For example, as Fig.
  • insulated ⁇ ignal wire ⁇ 26 passed into the interior of the body can be snaked through the body 22 at the desired point of electrical connection.
  • the electrical insulation 160 of the distal end of the snaked-through wire 26 is removed to exposed the electrical conductor 162, which is also preferably flattened.
  • the flattened conductors 162 are affixed by an electrically conductive adhesive 172 to body 22, over which the shell 24 is deposited.
  • Adhesive 172 is also preferable applied in the region of the body 22 where the wire 26 passes to seal it.
  • the same signal wire 26 can be snaked through the body 22 multiple times to establish multiple electrical connections within the same ablation zone.
  • the expandable-collapsible body 22 can be formed as a laminate structure 90.
  • the laminate structure 90 comprises a base layer 92, formed from an electrically insulating material which peripherally surrounds the interior of the body 22.
  • the laminate structure 90 further includes one or more intermediate layers 94 formed on the base layer 92.
  • An ablation energy wire 26 pas ⁇ e ⁇ through each intermediate layer 94.
  • Each intermediate layer 94 i ⁇ itself bounded by a layer 96 of electrically insulating material, so that the wires 26 are electrically insulated from each other.
  • the laminate structure 90 also includes an outer layer 98 which is likewi ⁇ e formed from an electrically in ⁇ ulating material.
  • the laminate ⁇ tructure 90 can be formed by successively dipping a mold having the desired geometry in a sub ⁇ trate solution of electrically insulating material.
  • the ablation energy wires 26 are placed on sub ⁇ trate layer ⁇ between ⁇ uccessive dippings, held in place by electrically conductive adhesive or the like.
  • one or more windows 100 are opened through the outer insulation layer 98 in the region which the electrically conductive shell 24 will occupy. Each window 100 exposes an ablation energy signal wire 26 in a chosen layer.
  • windowing technique ⁇ can be employed for this purpose.
  • C0 2 laser, Eximer laser, YAG laser, high power YAG laser, or other heating techniques can be used to remove insulation to the desired layer and thereby expose the desired signal wire 26.
  • the formed expandable- collapsible body 22 is masked, as before described.
  • the shell 24 of electrically conductive material is deposited over the unma ⁇ ked area, including the windows 100, which have been previously opened.
  • Fig. 32 shows, the deposited shell 24 enters the windows 100, making electrically conductive contact with the exposed wires 26.
  • a plating or other deposition process may be used in the window 100, before depositing the electrically conductive shell 24.
  • the plating fills in the window 100 to assure good electrical contact with the over-deposit of shell 24.
  • Fig. 3D shows an alternative equivalent laminated structure, in which the chamber 124 occupies the interior of the body 22. This creates a multiple layer structure equivalent to the laminated structure just described.
  • An open intermediate layer 126 exists between the interior of the body 22 and the exterior of the chamber 124, through which signal wire ⁇ 26 can be passed for electrical connection to the ⁇ hell 24.
  • the electrical connection can be made u ⁇ ing either a di ⁇ tal fixture 66 or by ⁇ naking the wire ⁇ through the exterior body 22 (as Fig. 3D shows) , both of which have already been described.
  • a controller 32 preferably govern ⁇ the conveyance of radio frequency ablation energy from the generator 30 to the shell 24.
  • the collapsible electrode structure 20 carries one or more temperature sensing elements 104, which are coupled to the controller 32. Temperatures sensed by the temperature sensing element ⁇ 104 are proce ⁇ sed by the controller 32. Based upon temperature input, the controller adjust ⁇ the time and power level of radio frequency energy transmis ⁇ ions by the shell 24, to achieve the desired lesion patterns and other ablation objectives.
  • the temperature sensing elements 104 can take the form of thermi ⁇ tor ⁇ , thermocouple ⁇ , or the equivalent.
  • a temperature sensing element 104 may be located within the distal fixture 66 to sense temperature at the distal tip, as Fig. 33 show ⁇ .
  • multiple temperature sensing elements may be scattered at spaced apart locations on the shell 24 or expandable-collapsible body 22, as Fig. 34 shows.
  • connection of temperature sensing elements 104 to the shell 24 or expandable-collapsible body 22 can be achieved in various ways.
  • the temperature sensing element when the expandable- collapsible body 22 comprises a thermal conductive material, the temperature sensing element (de ⁇ ignated 104A in Fig. 34) can be attached to the interior ⁇ urface of the body 22 in the region where mea ⁇ urement of exterior ⁇ urface temperature i ⁇ desired.
  • a thermally conductive, but electrically insulating adhesive 106 can be used to secure the temperature sensing element 104A to the inside of the body 22.
  • the temperature sen ⁇ ing element wire ⁇ 110 extend through the catheter tube 12 for coupling (using a suitable connector 28, shown in Fig. l)to the controller 32.
  • the temperature sensing element (designated 104B and 104C in Fig. 34) can be attached to the exterior ⁇ urface of the body 22 in the region where mea ⁇ urement of temperature ⁇ i ⁇ desired.
  • a thermally conductive, but electrically in ⁇ ulating adhesive 106 can be used to secure the temperature sensing element to the out ⁇ ide of the body 22.
  • the electrically conductive shell 24 can be deposited over the temperature sen ⁇ ing element 104B, in the manner previously described. In this way, the temperature sensing element 104B resides under the electrically conductive shell 24, and no discontinuitie ⁇ in the shell 24 are present.
  • the element 104C can be masked at the time the electrically conductive shell 24 is deposited. In this arrangement, there is no electrically conductive material over the temperature sensing element 104C.
  • the signal wires 110 attached to the temperature sensing element 104C can be attached by electrically insulating adhesive to the outside the expandable- collapsible body 22.
  • the signal wires 110 can be brought from the interior of the expandable-collapsible body 22 through the expandable-collapsible body 22 for attachment by a thermally conductive, but electrically insulating adhesive 106 to the outside of the body 22.
  • the ⁇ ame type of adhe ⁇ ive 106 can also be used to anchor in signal wires 110 to the inside of the expandable-collapsible body 22.
  • thermocouples 112 may also be integrally formed by deposition on the expandable-collap ⁇ ible body.
  • the body 22 compri ⁇ e ⁇ a laminated ⁇ tructure 114, like that previously shown in Fig. 31, comprising a base layer 92, an outer layer 98, and one or more intermediate layers 94.
  • the intermediate layers 94 formed in this ⁇ tructure thermocouple wires 116 (t- type or other combinations) .
  • windowing of the laminated expandable-collapsible body 116 in the manner previously described exposes the thermocouple wires.
  • a conducting material 118 which, for a t- type thermocouple is copper or constantan, is deposited over the exposed thermocouple wires, forming the thermocouple 112.
  • An electrically insulating material 120 like aluminum oxide or silicon dioxide, is then applied over the thermocouple 112.
  • thermocouple 112A shows in Fig. 35, the thermocouple 112A can be masked at the time the electrically conductive shell 24 is deposited. In this arrangement, there is no electrically conductive material over the thermocouple 112A.
  • thermosensors 104 are located on and about the ⁇ hell 24 to a ⁇ certain temperature condition ⁇ during radio frequency energy ablation.
  • the controller 32 u ⁇ e ⁇ temperature information from temperature sensing elements to control the transmi ⁇ ion of ablation energy by the ⁇ hell 24.
  • At least one temperature sensing element 104 is preferably placed proximal to the geometric center of the energy transmitting shell 24.
  • the shell 24 is segmented (as Figs. 20 and 21A/B ⁇ how)
  • at least one temperature sensing element 104 ⁇ hould be proximal to the geometric center of each energy tran ⁇ mitting ⁇ egment 122.
  • temperature sensing elements 104 are also placed along the edge ⁇ of the shell 24, where it adjoins a masked, electrically non-conductive region of the body 22.
  • temperature sen ⁇ ing elements 104 ⁇ hould be placed along the edge of each energy transmitting segment 122. High current densitie ⁇ occur along these regions where energy transmitting material adjoins non-energy transmitting material. These edge effects lead to higher temperatures at the edges than elsewhere on the shell 24. Placing temperature sensing elements 104 along the edges assures that the hottest temperature conditions are sensed.
  • any given transmission zone like the continuous, non-segmented shell 24 shown in Fig. 25 or each segmented zone 122 shown in Figs. 26 and 27
  • it is desirable to allow some contact with the blood pool to allow beneficial convective cooling effects it is not desirable that any given zone contact only or substantially only the blood pool.
  • Los ⁇ of power into the blood pool with no tissue ablation effects occurs.
  • segmented zones 122 it is pos ⁇ ible to sense, using the temperature sensing elements 104, where insubstantial tissue contact exists. It is thereby possible to sense and to channel available power only to those zones 122 where substantial tissue contact exist ⁇ . Further details of tissue ablation using segmented electrode structures are disclo ⁇ ed in copending U.S. Patent Application Serial No. 08/139,304, filed October 19, 1993 and entitled "System ⁇ and Methods for Creating Lesion ⁇ in Body Ti ⁇ sue Using Segmented Electrode Assemblies.”
  • Fig. 36 show ⁇ a preferred representative embodiment when the shell 24 comprises a continuous cap pattern.
  • the structure 20 carries five temperature sen ⁇ ing elements 104 spaced apart on the shell 24.
  • the temperature sen ⁇ ing element ⁇ 104 are connected in a ⁇ elected one or more of the manner ⁇ previou ⁇ ly de ⁇ cribed.
  • sensing elements Tn, and Tp are placed at diametrically opposite regions at the most proximal edge of the shell 24.
  • Sensing elements Tm, and Tm- are placed at diametrical sides of the middle region of the shell 24, for example, at about 50% of the radius of the structure.
  • the sensor Tc i ⁇ placed proximal the geometric center of the shell 24. All temperature sensors are coupled to a temperature controller, which proces ⁇ e ⁇ information from the sensors.
  • the temperature controller 32 infers the percentage of tis ⁇ ue contact with the shell 24 contact based upon where significant increases in temperature conditions from an established baseline level (for example, 37° C) are sensed on the shell 24. These increased temperature conditions indicate the absence of convective cooling effects, a ⁇ would occur with contact with the blood pool, thereby ⁇ ugge ⁇ ting ti ⁇ ue contact.
  • percentage of contact between the ⁇ hell 24 and ti ⁇ sue dictate effective power levels to achieve the type of lesion desired.
  • the relationship between percentage shell-ti ⁇ ue contact and power desired for a given lesion characteristic can be based upon empirical or theoretical data in the manner set forth in the preceding Example. These relationship ⁇ can be set forth in look up table format or incorporated in equivalent decision matrices, which the controller 32 retains in memory.
  • significant increase in temperature above the baseline at Tc, but not elsewhere indicates a 20% tissue contact condition, and a first power level is commanded for the generator 30 based upon the selected power criteria.
  • Significant increase in temperature above the baseline also at Tm, and Tm indicates a 50% ti ⁇ sue contact condition, and ⁇ econd power level le ⁇ than the fir ⁇ t is commanded for the generator 30 based upon the selected power criteria.
  • Significant increase in temperature above the baseline also at Tn, and Tn 2 indicates a 100% tissue contact condition, and third power level les ⁇ than the second is commanded based upon the selected power criteria.
  • Fig. 37 shows a preferred representative embodiment when the shell 24 comprises a circumferentially spaced, segmented pattern.
  • the structure 20 carries at least four temperature sensing elements on each shell segment.
  • the sensor Tc is common to all segments and is located at the distal end of the pattern.
  • the sensor T ⁇ . is located at the geometric center of each segment, while the sensors T E , and z are located along opposite edges of each segment, where the shell 24 adjoins the non-electrically conductive regions separating the segments.
  • An additional sensor T M is preferably also located generally between the segments for the reason ⁇ di ⁇ cussed before.
  • Fig. 38 shows a preferred representative embodiment when the shell 24 compri ⁇ es a bull's-eye pattern.
  • Sen ⁇ or ⁇ T GC are located at the geometric center of each segment of the pattern, while the sensors T E1 and T £2 are located along opposite edges of each segment, where the shell 24 adjoins the non- electrically conductive regions separating the segments.
  • An additional sensor T H is preferably also located generally between the segments for the reasons discussed before.
  • Active cooling can be accomplished by the use of multiple lumen ⁇ to cycle a cooled fluid through the expandable-collapsible body 22 while transmitting ablation energy.
  • a high pressure gas can be transported by the lumens for expansion within the expandable-collapsible body to achieve a comparable active cooling effect.
  • the cooled medium can be conveyed outside the expandable-collapsible body 22 to achieve an active cooling effect.
  • the entire ⁇ urface of the ⁇ hell 24 need not be cooled to achieve at least some of the benefits of active cooling.
  • the edge effects on current densities occur at the boundary between the shell 24 and expandable- collapsible body 22 that is free of the shell 24 create higher temperatures. Localized cooling of these edge regions can help minimize the effects of hot spots on lesion formation.
  • a pattern of small holes 174 is created in the region between segmented shell patterns 122.
  • Liquid cooling medium is perfused from inside the body 22 through the holes 174 to provide localized cooling adjacent the edges of the shell segments 122. It should be appreciated that hole patterns 174 could be used elsewhere on the body 22 to provide active cooling effects.
  • the selective establishment of hole patterns 174 on the body 22 can also itself establish predefined fold lines 52, eliminating the need to specially mold preformed folding region ⁇ the body 22.
  • the pattern of ⁇ mall holes 174 create fold lines 52 by the removal of material, thereby increasing the flexibility of the body 22 along the holes 174 between adjacent regions 122.
  • the fold line ⁇ 52 created by hole pattern ⁇ 174 lie uniformly along (i.e., parallel to) the long axis of the body 22.
  • a desired therapeutic result in terms of (i) the extent to which the desired lesion should extend beneath the tissue-electrode interface to a boundary depth between viable and nonviable tissue and/or (ii) a maximum tis ⁇ ue temperature developed within the lesion between the tissue-electrode interface and the boundary depth.
  • the controller 32 also includes a processing element 302, which retains a function that correlates an observed relationship among lesion boundary depth, ablation power level, ablation time, actual or predicted ⁇ ub- ⁇ urface ti ⁇ ue temperature, and electrode temperature.
  • the proce ⁇ sing element 302 compares the de ⁇ ired therapeutic result to the function and selects an operating condition based upon the comparison to achieve the desired therapeutic result without exceeding a prescribed actual or predicted sub-surface tis ⁇ ue temperature.
  • the operating condition ⁇ elected by the proce ⁇ sing element 302 can control variou ⁇ aspects of the ablation procedure, such as controlling the ablation power level, the rate at which the structure 20 is actively cooled, limiting the ablation time to a selected targeted ablation time, limiting the ablation power level subject to a prescribed maximum ablation power level, and/or the orientation of the shell 24, including prescribing a desired percentage contact between the shell 24 and tissue.
  • the processing element 302 can rely upon temperature sensors carried by or otherwise associated with the expandable-collapsible structure 20 that penetrate the tissue to sense actual maximum tissue temperature. Alternatively, the proces ⁇ ing element 302 can predict maximum tissue temperature based upon operating conditions.
  • the electrode structure 20 carries at least one temperature sensing element 104 to sense ⁇ instantaneous localized temperatures (Tl) of the thermal mass of the shell 24.
  • Tl instantaneous localized temperatures
  • the temperature Tl at any given time is a function of the power supplied to the shell 24 by the generator 30 and the rate at which the shell 24 i ⁇ cooled, either by convective cooling by the blood pool, or active cooling by another cooling medium brought into contact with the ⁇ hell 24, or both.
  • the characteri ⁇ tic of a le ⁇ ion can be expressed in terms of the depth below the tissue surface of the 50° C isothermal region, which will be called D 50c .
  • the depth ⁇ c is a function of the physical characteristics of the shell 24 (that i ⁇ , it ⁇ electrical and thermal conductivities and size) ; the percentage of contact between the tis ⁇ ue and the ⁇ hell 24; the localized temperature Tl of the thermal mas ⁇ of the shell 24; the magnitude of RF power (P) transmitted by the shell 24 into the tis ⁇ ue, and the time (t) the tissue is exposed to the RF power.
  • the maximum temperature condition TMAX lies within a range of temperatures which are high enough to provide deep and wide lesions (typically between about 85° C and 95° C) , but which are safely below about 100° C, at which tis ⁇ ue desiccation or tis ⁇ ue micro-explo ⁇ ion ⁇ are known to occur. It i ⁇ recognized that TMAX will occur a distance below the electrode-ti ⁇ sue interface between the interface and
  • the maximum power level PMAX takes into account the phy ⁇ ical characteri ⁇ tics of the electrode and the power generation capacity of the RF generator 30.
  • the D50C function for a given shell 24 can be expressed in terms of a matrix listing all or some of the foregoing values and their relationship derived from empirical data and/or computer modeling.
  • the physician also uses the input 300 to identify the characteristics of the structure 20, using a prescribed identification code; set a de ⁇ ired maximum RF power level PMAX; a desired time t; and a desired maximum tis ⁇ ue temperature TMAX. Based upon these inputs, the proces ⁇ ing element
  • the master controller 58 selects an operating condition to achieve the desired therapeutic result without exceeding the prescribed TMAX by controlling the function variables.
  • This arrangement thereby permits the physician, in effect, to "dial-a-lesion" by specifying a desired D 50C .
  • the processing element can achieves the desired D 50c without the need to sense actual tissue temperature conditions.
  • the structure 20 is cooled either by convective blood flow (depending upon percentage contact between the shell 24 and tissue) , or by actively using another cooling medium, or both.
  • the level of RF power delivered to the cooled structure 20 and/or the cooling rate can be adjusted based upon a prediction of instantaneous maximum tis ⁇ ue temperature, which i ⁇ de ⁇ ignated T ⁇ (t) .
  • the prediction of T MA ⁇ i ⁇ derived by a neural network, which has as inputs a prescribed number of previous power levels, previous rates at which heat has been removed to cool the structure 20, and previou ⁇ ⁇ hell temperature.
  • the heat removal rate is identified by the expres ⁇ ion A, where
  • RATE is the mass flow rate of the cooling medium through the structure (kg/sec) .
  • Tl and A are therefore predictive of the depth and magnitude of the hottest sub-surface ti ⁇ ue temperature T ⁇ , and thu ⁇ indirectly predictive of the lesion boundary depth D 50c .
  • Tl is maintained at a low relative temperature (by controlling cooling rate) and the maximal predicted tissue temperature, TMAX, is maintained at approximately 85°C to 95° C by controlling RF power.
  • TMAX maximal predicted tissue temperature
  • the generator 30 is conditioned through an appropriated power ⁇ witch interface to deliver RF power in multiple pul ⁇ es of duty cycle 1/N.
  • AMP E(J) is the amplitude of the RF voltage conveyed to the electrode region E(J) .
  • DUTYCYCLE E(J) is the duty cycle of the pulse, expres ⁇ ed as follows:
  • TON E(J) is the time that the electrode region
  • T0FF E(J) is the time that the electrode region
  • E(J) does not emit energy during each pulse period.
  • the generator 30 can collectively e ⁇ tablish duty cycle (DUTYCYCLE E(J) ) of 1/N for each electrode region (N being equal to the number of electrode regions) .
  • the generator 30 may sequence successive power pulses to adjacent electrode regions so that the end of the duty cycle for the preceding pulse overlaps slightly with the beginning of the duty cycle for the next pulse. This overlap in pulse duty cycles assures that the generator 30 applies power continuously, with no periods of interruption caused by open circuit ⁇ during pul ⁇ e ⁇ witching between successive electrode regions.
  • the temperature controller 32 makes individual adjustments to the amplitude of the RF voltage for each electrode region (AMP E(J) ) , thereby individually changing the power P E(J) of ablating energy conveyed during the duty cycle to each electrode region, as controlled by the generator 30.
  • the generator 30 cycles in successive data acquisition ⁇ ample period ⁇ . During each ⁇ ample period, the generator 30 select ⁇ individual sensors S(J,K), and temperature codes TEMP(J) (highest of S(J,K)) sensed by the sensing elements 104, as outputted by the controller 32.
  • the controller 32 registers all sensed te perature ⁇ for the given electrode region and selects among these the highest sensed temperature, which constitutes TEMP(J) .
  • the generator 30 compares the temperature TEMP(J) locally sensed at each electrode E(J) during each data acquisition period to a set point temperature TEMP SET established by the physician. Based upon this comparison, the generator 30 varies the amplitude AMP E(J) of the RF voltage delivered to the electrode region E(J) , while maintaining the DUTYCYCLE E(J) for that electrode region and all other electrode regions, to establi ⁇ h and maintain TEMP(J) at the ⁇ et point temperature TEMP SET .
  • the set point temperature TEMP SET can vary according to the judgment of the physician and empirical data.
  • a representative set point temperature for cardiac ablation is believed to lie in the range of 40°C to 93 C, with 70 C being a representative preferred value.
  • the manner in which the generator 30 governs AMP E(J) can incorporate proportional control methods, proportional integral derivative (PID) control methods, or fuzzy logic control methods.
  • the control signal generated by the generator 30 individually reduces the amplitude AMP E(1) of the RF voltage applied to the fir ⁇ t electrode region E(l) , while keeping the duty cycle DUTYCYCLE E(1) for the fir ⁇ t electrode region E(l) the same.
  • the control signal of the generator 30 increases the amplitude AMP E(2) of the pulse applied to the second electrode region E(2), while keeping the duty cycle DUTYCYCLE E(2) for the second electrode region E(2) the ⁇ ame as DUTYCYCLE ⁇ ,., and so on. If the temperature sensed by a given sensing element is at the set point temperature TEMP SET , no change in RF voltage amplitude i ⁇ made for the a ⁇ ociated electrode region.
  • the generator continuously proces ⁇ e ⁇ voltage difference input ⁇ during successive ⁇ ive data acquisition periods to individually adjust AMP E(J) at each electrode region E(J) , while keeping the collective duty cycle the same for all electrode regions E(J) . In this way, the mode maintains a desired uniformity of temperature along the length of the ablating element.
  • PID proportional integral differential
  • the generator will respond differently to a given proportionally large instantaneous difference between TEMP (J) and TEMP SET , depending upon whether the difference i ⁇ getting larger or smaller, compared to previous instantaneous differences, and whether the rate at which the difference is changing since previous sample periods is increasing or decreasing.
  • the controller 32 selects at the end of each data acquisition phase the sen ⁇ ed temperature that is the greatest for that phase (TEMP SMA ⁇ ) .
  • the controller 32 also selects for that phase the sensed temperature that is the lowest (TEMP SHIN ) .
  • the generator compares the selected hottest sensed temperature TEMP g ⁇ to a selected high set point temperature TEMP HISET .
  • the comparison generates a control signal that collectively adjusts the amplitude of the RF voltage for all electrodes using proportional, PID, or fuzzy logic control techniques.
  • This implementation computes the difference between local sensed temperature TEMP(J) and TEMP SHIN and compares this difference to a selected set point temperature difference ⁇ TEMP SET . The comparison generates a control signal that governs the delivery of power to the electrode regions.
  • the generator turns the given segment E(J) off.
  • the generator turns the given segment E(J) back on when TEMP(J) - TEMP SMIN ⁇ ⁇ TEMP SET .
  • TEMP SHJN equals or exceeds a predetermined amount ⁇ TEMP SET
  • the generator turns all segments off, except the segment where TEMP SM]N exist ⁇ .
  • the controller 231 turn ⁇ the ⁇ e segments back on when the temperature difference between TEMP SMAX and TEMP SMIN is less than ⁇ TEMP SET . Further details of the use of differential temperature disabling are found in copending U.S. Patent Application Serial No. 08/286,930, filed August 8, 1994, and entitled "Systems and Methods for Controlling Ti ⁇ sue Ablation Using Multiple Temperature Sensing Elements," which is incorporated herein by reference.
  • the temperature sensing elements 104 may not measure exactly the maximum temperature at the region 122. This is because the region of hottest temperature occurs beneath the surface of the tissue at a depth of about 0.5 to 2.0 mm from where the energy emitting electrode region 122 (and the associated sensing element 104) contacts the tis ⁇ ue. If the power i ⁇ applied to heat the tissue too quickly, the actual maximum tissue temperature in this subsurface region may exceed 100° C and lead to tissue desiccation and/or micro-explosion ⁇ .
  • the predictor 400 outputs a predicted temperature of the hottest tissue region T ⁇ Ct) .
  • the generator 30 derive ⁇ the amplitude and duty cycle control signals based upon T ⁇ p ⁇ t), in the ⁇ ame manner ⁇ already described using TEMP(J) .
  • the predictor 400 uses a two-layer neural network, although more hidden layers could be used.
  • the predictor 300 includes a first and second hidden layers and four neurons, designated N (L X) , where L identifies the layer 1 or 2 and X identifies a neuron on that layer.
  • TSl(n) and TS2(n) are shown for purpose ⁇ of illu ⁇ tration, are weighed and inputted to each neuron N ( , , ⁇ ; N ( , 2) ; and N ( , 3) of the fir ⁇ t layer.
  • Fig. 43 represents the weight ⁇ a ⁇ W- (
  • cM> , where L l; k i ⁇ the input sensor order; and N is the input neuron number 1, 2, or 3 of the first layer.
  • the output neuron N (2 of the second layer receives as inputs the weighted outputs of the neurons N (1 1 ⁇ ; N ( , 2) ; and 1 ⁇ , 3) .
  • D Predicts ⁇ (t). Alternatively, a ⁇ equence of past reading sample ⁇ from each sensor could be used as input. By doing this, a history term would contribute to the prediction of the hottest ti ⁇ ue temperature.
  • the predictor 400 mu ⁇ t be trained on a known ⁇ et of data containing the temperature of the sensing elements TS1 and TS2 and the temperature of the hottest region, which have been previously acquired experimentally. For example, using a back- propagation model, the predictor 400 can be trained to predict the known hottest temperature of the data set with the least mean square error. Once the training phase is completed, the predictor 300 can be used to predict T HA ⁇ pRE0 (t).
  • T MAXPRED W can be used to derive T MAXPRED W • See, e.g., copending Patent Application Serial No. 08/266,934, filed June 27, 1994, and entitled "Tissue Heating and Ablation System ⁇ and Methods Using Predicted Temperature for Monitoring and Control.”
  • the illustrated and preferred embodiments use digital processing controlled by a computer to analyze information and generate feedback signals. It should be appreciated that other logic control circuits using micro-switches, AND/OR gates, invertors, analog circuit ⁇ , and the like are equivalent to the micro-proce ⁇ sor controlled techniques shown in the preferred embodiments. VIII.
  • the electrode ⁇ tructure 20 transmits ablation energy to tis ⁇ ue by exposing ti ⁇ sue to an electrically conductive surface 24 carried about the exterior of the expandable-collapsible body 22.
  • the alternative embodiments ⁇ hown in Fig ⁇ . 41A and 42A include an electrode ⁇ tructure 176 comprising an expandable- collapsible body 178 having an exterior free of an electrically conductive surface.
  • the body 178 is capacitively coupled to tissue for the purpose of transmitting ablation energy.
  • the expandable-collapsible body 178 is molded in same fashion as the body 22 previously described.
  • the body 178 includes an electrically conductive structure 180 in contact with at least a portion of the interior surface 182 of the body 178.
  • the interior conductive structure 180 can be assembled in various ways.
  • the ⁇ tructure 180 compri ⁇ es an interior shell 184 of electrically conductive material deposited on at least a portion of the interior ⁇ urface 182 of the body 178.
  • the interior shell 184 comprises a material having a relatively high electrical conductivity, as well as a relative high thermal conductivity, such a ⁇ gold, platinum, platinum/iridium, among other ⁇ .
  • the shell 184 is preferably deposited upon the exterior of the body 178 after molding u ⁇ ing depo ⁇ ition proce ⁇ s like sputtering, vapor deposition, ion beam deposition, electroplating over a depo ⁇ ited seed layer, or a combination of these proces ⁇ e ⁇ .
  • the body 178 i ⁇ then everted in the manner previou ⁇ ly de ⁇ cribed (a ⁇ Fig. 16B ⁇ how ⁇ ) to place the depo ⁇ ited shell 184 inside the everted body 178.
  • One or more signal wires 186 are coupled to the interior shell 184 using electrically conductive adhesive, soldering, or equivalent connection techniques.
  • the body 178 can be caused to assume expanded and collapsed geometries by the introduction of an air or liquid inflation medium, as previously described.
  • the body 178 can employ any previously described interior support structure 44 to affect expansion and collapse.
  • the support structures 44 could also by electrically conductive to affect capacitive coupling, with or without the presence of the deposited shell 184.
  • an electrically conductive interior resilient mesh structure like that shown in Fig. 6)
  • a skeleton of flexible, electrically conductive spline elements like that shown in Fig. 4
  • an open cell foam structure coated with an electrically conductive material like that shown in Fig.
  • Fig. 41B shows the electrical equivalent circuit 188 of the capacitive coupling effect that the structure 176 in Fig. 41A provides.
  • the interface 194 formed among the expandable-collapsible body 178, the conductive structure 180 contacting the inside the body 178, and the tissue 196 contacting the outside of the body 178 functions as a capacitor (designated C ) , whose impedance X c is expressed as:
  • f is the frequency of the radio frequency ablation energy 192
  • ⁇ is the dielectric constant of the material of the expandable-collapsible body 178, which ranges from about 1.2 to about 10.0
  • s is the ⁇ urface area of the electrically conductive structure 184
  • t is the thickness of the body 178 located between the electrically conductive structure 180 and the contacted tis ⁇ ue 196.
  • the tissue 196 functions as a resi ⁇ tor (de ⁇ ignated R TISSUE ) ⁇ eries coupled to C.
  • R ⁇ jSSUE is about 100 ohms.
  • X c of the structure 180 must be les ⁇ than R TISSUE . This relationship assures that the desired ohmic heating effect is concentrated in tis ⁇ ue.
  • FIG. 42A how ⁇ an alternative embodiment of an expandable-collap ⁇ ible electrode ⁇ tructure 198 that provides capacitive coupling to tissue.
  • the structure 198 comprise ⁇ an interior electrode 200 of electrically conductive material located within interior of the body 178.
  • the interior electrode 200 co pri ⁇ es a material having a relatively high electrical conductivity, as well a ⁇ a relative high thermal conductivity, such as gold, platinum, platinum/iridium, among others.
  • a signal wire 202 is coupled to the electrode to conduct ablation energy to it.
  • a hypertonic (i.e., 9%) saline solution 204 fills the interior of the body 178.
  • the saline solution 204 serves as an electrically conductive path to convey radio frequency energy from the electrode 200 to the body 178.
  • the saline solution 204 also serves as the inflation medium, to cause the body 178 to assume the expanded geometry. Removal of the saline solution 204 causes the body 178 to assume the collapsed geometry.
  • Fig. 42B shows the electrical equivalent circuit 206 of the capacitive coupling effect that the structure 198 shown in Fig. 42A provides.
  • the interface 212 formed among the expandable-collapsible body 178, the hypertonic saline solution 204 contacting the inside the body 178, and the tis ⁇ ue 196 contacting the out ⁇ ide of the body 178 function ⁇ as a capacitor (designated C ) , whose impedance X c i ⁇ expressed as:
  • f is the frequency of the radio frequency ablation energy 210
  • ⁇ is the dielectric constant of the material of the body 178
  • S B is the area of the body 178 contacting the hypertonic saline solution 204
  • t is the thicknes ⁇ of the body 178 located between the electrically conductive saline solution 204 and the tissue 196.
  • the ti ⁇ ue 196 functions as a resi ⁇ tor (designated R ⁇ j ⁇ ) memori ⁇ coupled to C, which value i ⁇ about 100 ohms.
  • R pATH resistor
  • K is a constant that depends upon the geometry of the structure 198
  • S E is the surface area of the interior electrode 200
  • p is the re ⁇ i ⁇ tivity of the hypertonic saline 204.
  • the u ⁇ e of capacitive coupling provide ⁇ structural benefits. It isolates possible shell adherence problems to inside the body 178 of the structure 176, where flaking and chipping of the shell 184 can be retained out of the blood pool. Capacitive coupling also avoids potential problems that tissue sticking to exterior conductive materials could create. In addition to the ⁇ e structural benefits, the temperature control of the ablation process (as described above in conjunction with the structure 20) is improved using capacitive coupling. When using a metal surface to ablate tissue, the tis ⁇ ue- electrode interface i ⁇ convectively cooled by surrounding blood flow. Due to these convective cooling effects, the region of maximum tissue temperature is located deeper in the tissue.
  • the temperature conditions sensed by sen ⁇ ing element ⁇ associated with metal electrode elements do not directly reflect actual maximum tissue temperature.
  • maximum tissue temperature conditions must be inferred or predicted from actual sensed temperatures, as set forth above.
  • capacitive coupling in structures 176 or 198 convective cooling of the tissue-electrode interface by the surrounding blood flow is minimized.
  • the region of maximum temperature is located at the interface between tissue and the porous electrode.
  • the temperature conditions sensed by sensing elements associated with the capacitively coupled structures 176 or 198 will more closely reflect actual maximum tis ⁇ ue.
  • the body 22 can comprise an electrically conductive polymer.
  • the conductivity of the polymer used preferably has a re ⁇ i ⁇ tivity close to the resistivity of tissue (i.e., about 500 ohm*cm) .
  • the electrically conductive body 22 can be used in association with an interior electrode 200, like that shown in Fig. 42A.
  • a hypertonic saline solution 204 also fills the interior of the electrically conductive body 22 (as also shown in Fig. 42A) , to serve as an electrically conductive path to convey radio frequency energy from the electrode 200 to the body 22.
  • the electrically conductive body 22 functions as a "leaky” capacitor in transmitting radio frequency energy from the interior electrode 200 to tissue.
  • Various methodologies can be used to control the application of radio frequency energy to capacitively coupled electrode structures and to electrode structures having electrically conductive bodies.
  • the previously described D 50c Function can be used, as can the previously described Duty Cycle and Temperature Disabling techniques.
  • capacitively coupled electrode structures and electrode structures having electrically conductive bodies With capacitively coupled electrode structures and electrode structures having electrically conductive bodies, the minimal effects of convective cooling by the blood pool enables the use of actual sensed temperature conditions as maximum tis ⁇ ue temperature TMAX , instead of predicted temperatures. Because of this, such structure ⁇ al ⁇ o lend them ⁇ elve ⁇ to the use of a proportional integral differential (PID) control technique.
  • PID proportional integral differential

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Abstract

L'invention porte sur des dispositifs destinés à l'ablation de tissus corporels comportant un jeu d'ensembles électrodes. Chaque ensemble électrode (22) est pourvu d'une paroi extrudée porteuse d'une certaine quantité d'un matériau conducteur y ayant été extrudé. Ces parois obtenues par extrusion sont dotées des valeurs de résistivité électrique différentes du fait de la diversité des quantités de matériau conducteurs co-extrudés dans lesdites parois. Les dispositifs comportent également des organes permettant de préciser, dans le jeu d'électrodes, l'utilisation des ensembles électrodes suivant une fonction qui établit une corrélation entre les effets souhaités d'une ablation de tissu et les valeurs de résistivité des parois.
PCT/US1997/000698 1996-01-19 1997-01-17 Structures d'electrodes a dilatation-compression, pourvues de parois conductrices WO1997025916A1 (fr)

Applications Claiming Priority (18)

Application Number Priority Date Filing Date Title
US1035496P 1996-01-19 1996-01-19
US1022596P 1996-01-19 1996-01-19
US1022396P 1996-01-19 1996-01-19
US63071996A 1996-04-08 1996-04-08
US08/630,113 1996-04-08
US60/010,225 1996-04-08
US08/630,721 1996-04-08
US08/630,721 US5891136A (en) 1996-01-19 1996-04-08 Expandable-collapsible mesh electrode structures
US08/629,171 US5871483A (en) 1996-01-19 1996-04-08 Folding electrode structures
US60/010,354 1996-04-08
US08/628,980 1996-04-08
US08/630,113 US5891135A (en) 1996-01-19 1996-04-08 Stem elements for securing tubing and electrical wires to expandable-collapsible electrode structures
US08/629,363 1996-04-08
US08/629,363 US5853411A (en) 1996-01-19 1996-04-08 Enhanced electrical connections for electrode structures
US08/630,719 1996-04-08
US08/628,980 US5846238A (en) 1996-01-19 1996-04-08 Expandable-collapsible electrode structures with distal end steering or manipulation
US60/010,223 1996-04-08
US08/629,171 1996-04-08

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WO2000025685A1 (fr) * 1998-10-31 2000-05-11 Akbar Abdolmohammadi Systeme de catheter endocardiaque permettant de mesurer une longueur d'onde, d'effectuer un mappage et de pratiquer une ablation
US6475179B1 (en) 2000-11-10 2002-11-05 New England Medical Center Tissue folding device for tissue ablation, and method thereof
US6527767B2 (en) 1998-05-20 2003-03-04 New England Medical Center Cardiac ablation system and method for treatment of cardiac arrhythmias and transmyocardial revascularization
EP1321166A3 (fr) * 2001-12-21 2004-01-21 Ethicon Inc. Electrode de retour de masse déployable et méthode d'utilisation
WO2008027629A1 (fr) * 2006-08-31 2008-03-06 Boston Scientific Scimed, Inc. Insert utérin en mousse pour ablation
WO2014047068A1 (fr) * 2012-09-18 2014-03-27 Boston Scientific Scimed, Inc. Cartographie et retrait de cathéter d'ablation refroidi à boucle fermée
US8932208B2 (en) 2005-05-26 2015-01-13 Maquet Cardiovascular Llc Apparatus and methods for performing minimally-invasive surgical procedures
US9055959B2 (en) 1999-07-19 2015-06-16 St. Jude Medical, Atrial Fibrillation Division, Inc. Methods and devices for ablation
US9211156B2 (en) 2012-09-18 2015-12-15 Boston Scientific Scimed, Inc. Map and ablate closed-loop cooled ablation catheter with flat tip
US9283033B2 (en) 2012-06-30 2016-03-15 Cibiem, Inc. Carotid body ablation via directed energy
US9393070B2 (en) 2012-04-24 2016-07-19 Cibiem, Inc. Endovascular catheters and methods for carotid body ablation
US9393072B2 (en) 2009-06-30 2016-07-19 Boston Scientific Scimed, Inc. Map and ablate open irrigated hybrid catheter
US9398930B2 (en) 2012-06-01 2016-07-26 Cibiem, Inc. Percutaneous methods and devices for carotid body ablation
EP2658605B1 (fr) * 2010-12-28 2016-07-27 Cibiem, Inc. Catheter d'ablation endovasculaire du corpuscule carotidien pour le rééquilibrage sympathique d'un patient
US9402677B2 (en) 2012-06-01 2016-08-02 Cibiem, Inc. Methods and devices for cryogenic carotid body ablation
US9433784B2 (en) 2008-08-11 2016-09-06 Cibiem, Inc. Systems and methods for treating dyspnea, including via electrical afferent signal blocking
US9463064B2 (en) 2011-09-14 2016-10-11 Boston Scientific Scimed Inc. Ablation device with multiple ablation modes
US9603659B2 (en) 2011-09-14 2017-03-28 Boston Scientific Scimed Inc. Ablation device with ionically conductive balloon
US9743854B2 (en) 2014-12-18 2017-08-29 Boston Scientific Scimed, Inc. Real-time morphology analysis for lesion assessment
US9757191B2 (en) 2012-01-10 2017-09-12 Boston Scientific Scimed, Inc. Electrophysiology system and methods
US9955946B2 (en) 2014-03-12 2018-05-01 Cibiem, Inc. Carotid body ablation with a transvenous ultrasound imaging and ablation catheter
US10058380B2 (en) 2007-10-05 2018-08-28 Maquet Cordiovascular Llc Devices and methods for minimally-invasive surgical procedures
US10420605B2 (en) 2012-01-31 2019-09-24 Koninklijke Philips N.V. Ablation probe with fluid-based acoustic coupling for ultrasonic tissue imaging
US10524684B2 (en) 2014-10-13 2020-01-07 Boston Scientific Scimed Inc Tissue diagnosis and treatment using mini-electrodes
US10603105B2 (en) 2014-10-24 2020-03-31 Boston Scientific Scimed Inc Medical devices with a flexible electrode assembly coupled to an ablation tip
US11684416B2 (en) 2009-02-11 2023-06-27 Boston Scientific Scimed, Inc. Insulated ablation catheter devices and methods of use

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Cited By (36)

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US6527767B2 (en) 1998-05-20 2003-03-04 New England Medical Center Cardiac ablation system and method for treatment of cardiac arrhythmias and transmyocardial revascularization
WO2000025685A1 (fr) * 1998-10-31 2000-05-11 Akbar Abdolmohammadi Systeme de catheter endocardiaque permettant de mesurer une longueur d'onde, d'effectuer un mappage et de pratiquer une ablation
US9055959B2 (en) 1999-07-19 2015-06-16 St. Jude Medical, Atrial Fibrillation Division, Inc. Methods and devices for ablation
US6475179B1 (en) 2000-11-10 2002-11-05 New England Medical Center Tissue folding device for tissue ablation, and method thereof
US6907297B2 (en) 2001-09-28 2005-06-14 Ethicon, Inc. Expandable intracardiac return electrode and method of use
EP1321166A3 (fr) * 2001-12-21 2004-01-21 Ethicon Inc. Electrode de retour de masse déployable et méthode d'utilisation
US8932208B2 (en) 2005-05-26 2015-01-13 Maquet Cardiovascular Llc Apparatus and methods for performing minimally-invasive surgical procedures
WO2008027629A1 (fr) * 2006-08-31 2008-03-06 Boston Scientific Scimed, Inc. Insert utérin en mousse pour ablation
US10993766B2 (en) 2007-10-05 2021-05-04 Maquet Cardiovascular Llc Devices and methods for minimally-invasive surgical procedures
US10058380B2 (en) 2007-10-05 2018-08-28 Maquet Cordiovascular Llc Devices and methods for minimally-invasive surgical procedures
US9433784B2 (en) 2008-08-11 2016-09-06 Cibiem, Inc. Systems and methods for treating dyspnea, including via electrical afferent signal blocking
US9795784B2 (en) 2008-08-11 2017-10-24 Cibiem, Inc. Systems and methods for treating dyspnea, including via electrical afferent signal blocking
US11684416B2 (en) 2009-02-11 2023-06-27 Boston Scientific Scimed, Inc. Insulated ablation catheter devices and methods of use
US9393072B2 (en) 2009-06-30 2016-07-19 Boston Scientific Scimed, Inc. Map and ablate open irrigated hybrid catheter
CN106264720A (zh) * 2010-12-28 2017-01-04 西比姆公司 用于患者的交感再平衡的方法
EP2658605B1 (fr) * 2010-12-28 2016-07-27 Cibiem, Inc. Catheter d'ablation endovasculaire du corpuscule carotidien pour le rééquilibrage sympathique d'un patient
US9603659B2 (en) 2011-09-14 2017-03-28 Boston Scientific Scimed Inc. Ablation device with ionically conductive balloon
US9463064B2 (en) 2011-09-14 2016-10-11 Boston Scientific Scimed Inc. Ablation device with multiple ablation modes
US9757191B2 (en) 2012-01-10 2017-09-12 Boston Scientific Scimed, Inc. Electrophysiology system and methods
US10420605B2 (en) 2012-01-31 2019-09-24 Koninklijke Philips N.V. Ablation probe with fluid-based acoustic coupling for ultrasonic tissue imaging
US10219855B2 (en) 2012-04-24 2019-03-05 Cibiem, Inc. Endovascular catheters and methods for carotid body ablation
US9393070B2 (en) 2012-04-24 2016-07-19 Cibiem, Inc. Endovascular catheters and methods for carotid body ablation
US9757180B2 (en) 2012-04-24 2017-09-12 Cibiem, Inc. Endovascular catheters and methods for carotid body ablation
US9808303B2 (en) 2012-06-01 2017-11-07 Cibiem, Inc. Methods and devices for cryogenic carotid body ablation
US9402677B2 (en) 2012-06-01 2016-08-02 Cibiem, Inc. Methods and devices for cryogenic carotid body ablation
US9398930B2 (en) 2012-06-01 2016-07-26 Cibiem, Inc. Percutaneous methods and devices for carotid body ablation
US9283033B2 (en) 2012-06-30 2016-03-15 Cibiem, Inc. Carotid body ablation via directed energy
CN104640513A (zh) * 2012-09-18 2015-05-20 波士顿科学医学有限公司 映射以及消融闭环冷却的消融导管
US9211156B2 (en) 2012-09-18 2015-12-15 Boston Scientific Scimed, Inc. Map and ablate closed-loop cooled ablation catheter with flat tip
WO2014047068A1 (fr) * 2012-09-18 2014-03-27 Boston Scientific Scimed, Inc. Cartographie et retrait de cathéter d'ablation refroidi à boucle fermée
US9370329B2 (en) 2012-09-18 2016-06-21 Boston Scientific Scimed, Inc. Map and ablate closed-loop cooled ablation catheter
US9955946B2 (en) 2014-03-12 2018-05-01 Cibiem, Inc. Carotid body ablation with a transvenous ultrasound imaging and ablation catheter
US10524684B2 (en) 2014-10-13 2020-01-07 Boston Scientific Scimed Inc Tissue diagnosis and treatment using mini-electrodes
US11589768B2 (en) 2014-10-13 2023-02-28 Boston Scientific Scimed Inc. Tissue diagnosis and treatment using mini-electrodes
US10603105B2 (en) 2014-10-24 2020-03-31 Boston Scientific Scimed Inc Medical devices with a flexible electrode assembly coupled to an ablation tip
US9743854B2 (en) 2014-12-18 2017-08-29 Boston Scientific Scimed, Inc. Real-time morphology analysis for lesion assessment

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