WO2022172179A1 - Dérivation pour redistribution du volume sanguin auriculaire - Google Patents

Dérivation pour redistribution du volume sanguin auriculaire Download PDF

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Publication number
WO2022172179A1
WO2022172179A1 PCT/IB2022/051177 IB2022051177W WO2022172179A1 WO 2022172179 A1 WO2022172179 A1 WO 2022172179A1 IB 2022051177 W IB2022051177 W IB 2022051177W WO 2022172179 A1 WO2022172179 A1 WO 2022172179A1
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WIPO (PCT)
Prior art keywords
shunt
sheath
region
anchor
atrial septum
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PCT/IB2022/051177
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English (en)
Inventor
Neal Eigler
Nir Nae
Lior Rosen
Werner Hafelfinger
Erez Rozenfeld
James S. Whiting
Menashe Yacoby
Yaacov Nitzan
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V-Wave Ltd.
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Priority claimed from US17/175,549 external-priority patent/US20210161637A1/en
Application filed by V-Wave Ltd. filed Critical V-Wave Ltd.
Publication of WO2022172179A1 publication Critical patent/WO2022172179A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/11—Surgical instruments, devices or methods, e.g. tourniquets for performing anastomosis; Buttons for anastomosis
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/00234—Surgical instruments, devices or methods, e.g. tourniquets for minimally invasive surgery
    • A61B2017/00238—Type of minimally invasive operation
    • A61B2017/00243—Type of minimally invasive operation cardiac
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
    • A61B2017/00831—Material properties
    • A61B2017/00867—Material properties shape memory effect
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
    • A61B17/11—Surgical instruments, devices or methods, e.g. tourniquets for performing anastomosis; Buttons for anastomosis
    • A61B2017/1139—Side-to-side connections, e.g. shunt or X-connections
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B90/00—Instruments, implements or accessories specially adapted for surgery or diagnosis and not covered by any of the groups A61B1/00 - A61B50/00, e.g. for luxation treatment or for protecting wound edges
    • A61B90/39—Markers, e.g. radio-opaque or breast lesions markers
    • A61B2090/3966—Radiopaque markers visible in an X-ray image

Definitions

  • This application generally relates to percutaneously placed implants and methods for redistributing blood from one cardiac chamber to another to address pathologies such as heart failure (HF), myocardial infarction (MI) and pulmonary arterial hypertension (PAH).
  • HF heart failure
  • MI myocardial infarction
  • PAH pulmonary arterial hypertension
  • Heart failure is the physiological state in which cardiac output is insufficient to meet the needs of the body or to do so only at a higher filing pressure.
  • HF cardiovascular disease
  • Chronic heart failure is associated with neurohormonal activation and alterations in autonomic control. Although these compensatory neurohormonal mechanisms provide valuable support for the heart under normal physiological circumstances, they also play a fundamental role in the development and subsequent progression of HF.
  • one of the body’s main compensatory mechanisms for reduced blood flow in HF is to increase the amount of salt and water retained by the kidneys.
  • Retaining salt and water instead of excreting it via urine, increases the volume of blood in the bloodstream and helps to maintain blood pressure.
  • the larger volumes of blood also cause the heart muscle, particularly the ventricles, to become enlarged.
  • the wall thickness decreases and the heart’s contractions weaken, causing a downward spiral in cardiac function.
  • Another compensatory mechanism is vasoconstriction of the arterial system, which raises the blood pressure to help maintain adequate perfusion, thus increasing the load that the heart must pump against.
  • Pressure in the left atrium may exceed 25 mmHg, at which stage, fluids from the blood flowing through the pulmonary circulatory system transudate or flow out of the pulmonary capillaries into the pulmonary interstitial spaces and into the alveoli, causing lung congestion and if untreated the syndrome of acute pulmonary edema and death.
  • Table 1 lists typical ranges of right atrial pressure (RAP), right ventricular pressure (RVP), left atrial pressure (LAP), left ventricular pressure (LVP), cardiac output (CO), and stroke volume (SV) for a normal heart and for a heart suffering from HF.
  • RVAP right atrial pressure
  • RVP right ventricular pressure
  • LAP left atrial pressure
  • LVP left ventricular pressure
  • CO cardiac output
  • SV stroke volume
  • HF systolic heart failure
  • DHF diastolic heart failure
  • ejection fraction a function of the blood ejected out of the left ventricle (stroke volume) divided by the maximum volume in the left ventricle at the end of diastole or relaxation phase.
  • stroke volume blood ejected out of the left ventricle
  • a normal ejection fraction is greater than 50%.
  • systolic heart failure generally causes a decreased ejection fraction of less than 40%.
  • HFrEF heart failure with reduced ejection fraction
  • a patient with HFrEF may usually have a larger left ventricle because of a phenomenon called “cardiac remodeling” that occurs secondarily to the higher ventricular pressures.
  • HFpEF preserved ejection fraction
  • assist devices such as mechanical pumps are used to reduce the load on the heart by performing all or part of the pumping function normally done by the heart.
  • Chronic left ventricular assist devices (LVAD), and cardiac transplantation often are used as measures of last resort.
  • LVAD left ventricular assist devices
  • Such assist devices typically are intended to improve the pumping capacity of the heart, to increase cardiac output to levels compatible with normal life, and to sustain the patient until a donor heart for transplantation becomes available.
  • Such mechanical devices enable propulsion of significant volumes of blood (liters/min), but are limited by a need for a power supply, relatively large pumps, and pose a risk of hemolysis, thrombus formation, and infection.
  • Temporary assist devices, intra-aortic balloons, and pacing devices have also been used.
  • U.S. Patent No. 6,120,534 to Ruiz is directed to an endoluminal stent for regulating the flow of fluids through a body vessel or organ, for example, for regulating blood flow through the pulmonary artery to treat congenital heart defects.
  • the stent may include an expandable mesh having lobed or conical portions joined by a constricted region, which limits flow through the stent.
  • the mesh may comprise longitudinal struts connected by transverse sinusoidal or serpentine connecting members. Ruiz is silent on the treatment of HF or the reduction of left atrial pressure.
  • U.S. Patent No. 6,468,303 to Amplatz et al. describes a collapsible medical device and associated method for shunting selected organs and vessels.
  • the device may be suitable to shunt a septal defect of a patient’s heart, for example, by creating a shunt in the atrial septum of a neonate with hypoplastic left heart syndrome (HFHS).
  • HFHS hypoplastic left heart syndrome
  • That patent also describes that increasing mixing of pulmonary and systemic venous blood improves oxygen saturation, and that the shunt may later be closed with an occluding device. Amplatz is silent on the treatment of HF or the reduction of left atrial pressure, as well as on means for regulating the rate of blood flow through the device.
  • Implantable interatrial shunt devices have been successfully used in patients with severe symptomatic heart failure. By diverting or shunting blood from the left atrium (FA) to the right atrium (RA), the pressure in the left atrium is lowered or prevented from elevating as high as it would otherwise (left atrial decompression). Such an accomplishment would be expected to prevent, relieve, or limit the symptoms, signs, and syndromes associated of pulmonary congestion. These include severe shortness of breath, pulmonary edema, hypoxia, the need for acute hospitalization, mechanical ventilation, and death.
  • Shunt flow is generally governed by the pressure gradient between the atria and the fluid mechanical properties of the shunt device.
  • the latter are typically affected by the shunt’s geometry and material composition.
  • the general flow properties of similar shunt designs have been shown to be related to the mean interatrial pressure gradient and the effective orifice diameter.
  • transseptal catheterization immediately preceding shunt device insertion.
  • the transseptal catheterization system is placed from an entrance site in the femoral vein, across the interatrial septum in the region of fossa ovalis (FO), which is the central and thinnest region of the interatrial septum.
  • FO fossa ovalis
  • LA chamber access may be achieved using a host of different techniques familiar to those skilled in the art, including but not limited to: needle puncture, stylet puncture, screw needle puncture, and radiofrequency ablation.
  • the passageway between the two atria is dilated to facilitate passage of a shunt device having a desired orifice size. Dilation generally is accomplished by advancing a tapered sheath/dilator catheter system or inflation of an angioplasty type balloon across the FO. This is the same general location where a congenital secundum atrial septal defect (ASD) would be located.
  • ASD congenital secundum atrial septal defect
  • U.S. Patent Publication No. 2005/0165344 to Dobak, III describes apparatus for treating heart failure that includes a tubular conduit having a emboli filter or valve, the device configured to be positioned in an opening in the atrial septum of the heart to allow flow from the left atrium into the right atrium.
  • shunting of blood may reduce left atrial pressures, thereby preventing pulmonary edema and progressive left ventricular dysfunction, and reducing LVEDP.
  • the device may include deployable retention struts, such as metallic arms that exert a slight force on the atrial septum on both sides and pinch or clamp the device to the septum.
  • the first type of shunt is henceforth referred to as an orifice -plate mesh shunt.
  • Orifice -plate mesh shunts comprise a metallic mesh that wraps around both sides of the septum with a hole in the center and anatomically mimics the location and geometrical characteristics of a small congenital secundum ASD.
  • the shunt geometry generally resembles a thin plate with a hole in it.
  • the “plate” comprises both mesh material and atrial septal tissue encased by the mesh.
  • One example of such devices designed by Corvia Medical, Inc., Tewksbury MA, consists of a self-expanding nitinol mesh that forms a pair of disc-like flanges with an open orifice in the center. The maximal diameter of the discs is 19.4 mm and the orifice diameter is 8 mm.
  • Each disc flange has multiple truss-like legs that deploy into a preset configuration that wraps around the LA and RA sides of the interatrial septum and applies a clamping force to the tissue.
  • FIG. 1 Another example of such a mesh type device, developed by Occlutech International AB, Helsingborg, Sweden, resembles a dual-disc occluder used for closing congenital secundum ASDs, which additionally includes a short open barrel orifice in the center that connects the two discs.
  • a first drawback of orifice-plate devices is the susceptibility to narrow or close during the post-implantation healing period.
  • neoendocardial tissue ingrowth referred to as pannus
  • pannus grows from the underlining tissue to cover the mesh and narrow or partially occlude the shunt orifice.
  • pannus neoendocardial tissue ingrowth
  • This response entails activation of an inflammatory process, attracting lymphocytes and macrophages to the area of tissue injury.
  • inflammatory cells in turn release a variety of cytokines that signal fibroblasts and smooth-muscle cells from the wound margins to dedifferentiate, migrate, proliferate and encapsulate affected portions of the implanted device.
  • the fibroblasts and smooth muscle cells then secrete extracellular matrix material composed of collagen and proteoglycans, which extracellular matrix forms the bulk of the pannus.
  • the duration of this healing phase in humans is typically up to 6-9 months, but may be longer if there is a chronic source for tissue injury such as device compression or erosion of adjacent tissue.
  • this pannus is covered with neoendothelial cells, causing the pannus growth to stop or stabilize.
  • the collagen of the pannus remodels, but generally retains its space occupying properties.
  • tissue ingrowth typically spreads over the surfaces of the implant’s struts, mesh, or discs, and may substantially narrow the orifice lumen or even entirely occlude the shunt. Narrowing or occlusion of the shunt prevents LA decompression and limits any positive effect for the patient.
  • the degree of luminal narrowing may be quite variable between patients due to differences in the severity of local injury —the more injury, the more exaggerated the pannus formation. Also, variability results from differences in host wound healing responses. For example, the amount and character of extracellular matrix may affect the duration of healing and amount of material deposited. Thus, for an orifice-plate mesh shunt, the eventual orifice lumen size will be highly variable. These processes will be familiar to one skill in the art as it is generally analogous to the type of late lumen loss that occurs in arteries when bare metal stents are used to treat atherosclerotic stenosis.
  • a second drawback of an orifice -plate mesh shunt is the potential for paradoxical embolization.
  • Paradoxical embolization refers to thromboembolism originating in the venous vasculature (venous thromboembolism or VTE), such that an embolus traverses right-to-left through a cardiac shunt into the systemic arterial circulation.
  • VTE venous thromboembolism
  • the most severe complication of paradoxical embolization occurs when an embolus lodges in the cerebral circulation with resulting cerebral infarction (stroke).
  • stroke cerebral infarction
  • MI myocardial infarction
  • embolic syndromes result from embolization to the mesenteric, renal, and peripheral arteries supplying the limbs. These may cause respectively, ischemic bowel syndrome, hematuria with worsening renal function, and gangrene requiring amputation.
  • VTE in adults is the consequence of in situ thrombosis in the deep veins (deep venous thrombosis or DVT) of the lower extremities or pelvis.
  • DVT deep venous thrombosis
  • clinically relevant venous emboli develop in the popliteal veins or more proximally in larger veins of the upper thigh or pelvis.
  • the venous diameter averaged 11.4 mm (range from 6.2 mm to 20.1 mm).
  • emboli are described as having the form of a cast of the vein’s lumen with a width equal to the diameter of the vein of origin. These thrombi also tend to be elongated, corresponding to the length of the occluded venous segment.
  • the risk factors associated with thromboembolic disease include a variety of anatomic, physiological, rheological variables and disease states.
  • Heart failure is a well- recognized risk factor for DVT and VTE, especially in patients with reduced left ventricular systolic function. About 3% of deaths in heart failure patients are due to VTE, usually associated with pulmonary embolism.
  • Patients with transvenous endocardial pacing leads and an intracardiac shunt have a 3 -fold increased risk of systemic thromboembolism, suggesting that paradoxical embolism is a contributing underlying cause.
  • Valsalva increases intrathoracic pressure, which causes the RA and LA pressures to equalize after several seconds and then for the RA pressure to transiently exceed LA pressure on exhalation. Intermittent bidirectional flow also may be observed at rest when the interatrial pressure gradient is low, or intermittently during the cardiac cycle when LA contraction is delayed compared to RA contraction (interatrial conduction delay). This is seen especially when the atria are enlarged or diseased, such as in heart failure. In this setting, interatrial electrical conduction delay results in retardation of LA contraction. Bidirectional shunting can also be seen transiently during inspiration, when venous return to the RA is increased, during coughing, with abdominal compression, during forced exhalation, or in the presence of severe tricuspid valve regurgitation. Chronically increased pulmonary arterial pressure, as seen in severe pulmonary hypertension, whether primary or secondary to chronic lung disease, recurrent pulmonary embolism, or due to chronic right ventricular volume overload, has been associated with chronic and more severe RA to LA shunting.
  • the statistical likelihood of traversing retrograde across the shunt and into the LA would be expected to be a complex function of the duration of pressure gradient reversal, flow patterns in the RA, shunt tunnel distance affecting the length of the flow velocity streamlines, and flow velocity and orifice or lumen size.
  • a third drawback of an orifice-plate mesh shunt is that percutaneous removal from the shunt body is only possible at the time of implantation. Should the shunt become a nidus for infection, develop fatigue or corrosion fractures of its metallic framework, or erode or otherwise impinge on other vital cardiac structures, it cannot be removed by percutaneous retrieval/removal techniques. This is because the shunt, with its large “footprint” on the interatrial septum, is encased in pannus tissue. Attempts at percutaneous removal may result in tearing of the septum, pericardial tamponade, and device embolization into the systemic circulation, resulting in death or the need for emergency surgery. Safe removal would require performing open heart surgery.
  • a fourth drawback of an orifice -plate mesh type of shunt is that its geometry renders it relatively inefficient in supporting high flow.
  • the geometry of an orifice plate requires a larger orifice because it has a reduced effective orifice size compared with other geometries, such as a venturi-shaped lumen, or a conical shaped nozzle. This is because with an office -plate, there are more energy losses associated with eddy currents at the edges of the plate.
  • Orifice-plate geometries may be categorized as having a relatively low discharge coefficient, which is a dimensionless fluid-mechanical parameter that relates flow to actual orifice size.
  • the discharge coefficient is the ratio of areas of the exiting jet vena contracta, which is the narrowest portion of the jet, compared to the shunt orifice.
  • the coefficient of discharge for orifice plates placed in pipes tends to be approximately 0.6, but rarely exceeds 0.65.
  • the discharge coefficient is affected by the orifice and chamber dimensions, the pressure gradient, and the viscosity of blood and/or the Reynolds number of the specific flow condition. This differs from the more efficient passage of flow through a classic venturi type of narrowing, where the discharge coefficient usually exceeds 0.9 and is typically in the range of 0.94 to 0.98.
  • an orifice -plate mesh shunt requires a larger orifice diameter to accommodate the same amount of flow for any given pressure differential across the shunt.
  • a fifth drawback of an orifice -plate mesh shunt is that it occupies a large area or footprint on the interatrial septum.
  • the flanges of the device that anchor the shunt typically occupy the entire area of the fossa ovalis and may overlap adjoining muscular portions of the interatrial septum. These flanges exert persistent pressure on the septum, causing injuring and stimulating an exaggerated healing response as described above. Also, the rigidity of the mesh may interfere with the normal motion of the muscular septum.
  • the flanges additionally may impinge on adjacent cardiac structures such as the roof of the left atrium, the ostia of the pulmonary veins, and the aorta root and sinuses of Valsalva, where due to chronic rubbing contact or sandwiching compressive forces, they may erode into these vital structures.
  • Such erosion has been associated with severe complications including cardiac tamponade and death.
  • the similarly sized Amplatzer ASD disc occlusion device described above has been occasionally associated with erosion into adjoining tissues with resulting catastrophic outcomes.
  • the large footprint on the atrial septum may hinder or render impossible performing other interventional procedures that require transseptal access.
  • the large flange diameter and small mesh pore sizes generally make catheter crossing of the atrial septum possible only through the central shunt orifice itself.
  • Transseptal procedures using small diameter catheters, such as atrial fibrillation RF ablation may be conducted through the orifice- plate lumen only if it is not obstructed by pannus and the orifice location permits entry into all four pulmonary veins.
  • Other structural heart disease procedures that have large diameter delivery systems and/or require crossing the FO in specific locations may encounter difficulties or simply not be possible.
  • valved unidirectional shunt The second type of shunt is referred to as a valved unidirectional shunt.
  • valved unidirectional shunts attempt to overcome some of the drawbacks of orifice -plate devices.
  • valved unidirectional shunts have embodiments containing a one-way or check-valve to limit reverse shunting and paradoxical embolization.
  • Some of the valve configurations are designed to open when the LA-RA pressure gradient exceeds a predefined threshold.
  • Other valve configurations close only when the RA pressure exceeds LA pressure (reversed gradient).
  • Nitzan-type shunt comprises an hourglass or diabolo outer shape, having a small FO footprint minimizing septal injury, which is expected to minimize pannus growth and obliteration of the shunt lumen. Its one-way valve also is designed to reduce the potential for reverse shunting and paradoxical embolization.
  • the relatively small footprint of the shunt in contact with the septum and encapsulated collapsible nitinol frame is designed to facilitate percutaneous extraction from the septum and retrieval from the body using a standard goose neck snare and large-bore sheath, thus making the device more easily retrieved.
  • the venturi tube-like inner lumen of the diabolo shape provides better bulk flow characteristics, permitting a smaller orifice for the same amount of flow compared to orifice plate shunts.
  • the small footprint on the FO and the hourglass shape are designed to facilitate accurate placement and retention during implantation. This geometry also minimizes interference with normal motion of the interatrial septum, and the small footprint provides space surrounding the shunt for other potential interventional procedures that require transseptal catheterization.
  • Nitzan design manufactured by V-Wave, Ltd (Caesarea, Israel), designed to support unidirectional left-to-right flow, comprises a self-expanding frame constructed from a laser-cut nitinol tube.
  • the frame includes five sinusoidal circumferential struts interconnected by six longitudinal bars.
  • the frame is heat-set so that it has an asymmetrical hourglass shape or a diabolo shape.
  • the shunt is deployed so that the neck (5.3 mm outer diameter) is placed across the FO and secured in place by its external surface geometry.
  • the shunt’s widest portion has a conical shape with an approximately 14.3 mm outer diameter at the LA end of the shunt, which serves as an “entry” port on the distal end of the entry funnel.
  • the entry funnel is deployed in the left atrium, and registers the neck of the shunt to the region of the FO.
  • a second, slightly narrower bell-shaped portion forms the exit portion of the shunt, which expands to a maximum outer diameter of 11.4 mm at the RA end of the shunt.
  • the shunt does not require flanges, discs, or tissue anchors to secure it in place. Septal retention is achieved without applying persistent pressure, tension or rubbing contact on the tissue adjoining the device neck.
  • the V-Wave shunt has a single inner lumen where flow is entrained into the entry funnel in the LA and passes through the constricted neck having a 5.1 mm inner diameter, which resembles a venturi-type orifice, and then exits through a bioprosthetic valve positioned near the RA end of the shunt.
  • the entry funnel and the central neck region are encapsulated with expanded polytetrafluoroethylene (“ePTFE”) to form a skirt or cover over the frame.
  • ePTFE expanded polytetrafluoroethylene
  • the exit bell-shaped portion contains three, glutaraldehyde-fixed, porcine pericardial leaflets sutured to the frame at the right atrial extent of the ePTFE encapsulation.
  • the leaflets are designed to create a smooth exit channel and remain in the open position, closing only when the RA pressure exceeds LA pressure by 1-2 mmHg, thus preventing reverse right-to-left shunting.
  • the V-Wave shunt is compressed in a loading tube where it is attached to a triple-latch cable delivery catheter.
  • the loading tube is inserted into a 14F delivery sheath that has been previously placed after a transseptal catheterization from the right femoral vein across the FO.
  • the shunt then is advanced through the sheath until the entry funnel has been deployed in the LA.
  • the entire system is withdrawn as a unit until the LA funnel is in contact with the left side of the FO.
  • the delivery catheter latches are unhooked from the shunt, the delivery catheter withdrawn so the right atrial side of the shunt is held only by its radial force against the delivery sheath.
  • the delivery sheath is withdrawn, thereby deploying the exit bell-shaped portion of the shunt on the RA side of the FO.
  • Device placement may be guided and confirmed by fluoroscopy and echocardiography, e.g., intracardiac echo or transesophageal echo.
  • U.S. Patent Publication Nos. 2017/0348100 and 2020/0188091 to Lane describe systems and methods for deploying a self-expanding cardiac prosthetic device, e.g., a mitral valve prosthesis.
  • the deployment procedures described therein require maintaining the position of the delivery catheter, e.g., a mandrel/tether system, after the prosthetic device is unsheathed, rather than permitting the local anatomy to exert a counterforce to position the valve during unsheathing.
  • V-Wave shunt Pre-clinical testing on the V-Wave shunt was performed in an established juvenile ovine (sheep) model that created an ischemic cardiomyopathy form of heart failure.
  • the sheep were pre-treated with sequential coronary artery microembolization as described in the publication, “Chronic Heart Failure Induced by Multiple Sequential Coronary Microembolization in Sheep” by Schmitto et al. After several weeks, the sheep manifested evidence of severe left ventricular systolic dysfunction and develop elevated LV, LA, and pulmonary artery pressures. In a 12-week survival study, this V-Wave shunt was associated with significant improvements in LA pressure and left ventricular ejection fraction.
  • Naturally occurring ASDs with a Qp/Qs less than 1.5, are generally left untreated as they are well tolerated for decades by the compliant right heart and pulmonary vasculature, without evidence of worsening right ventricular failure despite mild chronic volume overload. This was confirmed in the sheep model where RA and pulmonary artery pressures decreased to baseline levels with shunting, but progressively worsened in the control animals.
  • NYHA New York Heart Association heart failure classification
  • DM diabetes mellitus
  • AFIB atrial fibrillation
  • ACEi-ARB receiving angiotensin converting enzyme inhibitor or angiotensin receptor blocker
  • BB receiving beta blocker
  • MRA receiving mineralocorticoid antagonist
  • DIUR receiving loop diuretic
  • CRT-D implanted with combination cardiac resynchronization therapy pacemaker with ICD;
  • ICD implantable cardioverter/defibrillator;
  • CRT-P implanted with cardiac resynchronization therapy pacemaker without combination ICD;
  • NT-proBNP N-terminal pro b-type natriuretic peptide;
  • eGFR estimated glomerular filtration rate;
  • 6MWT 6 minute walk test distance;
  • PCWP pulmonary capillary wedge pressure;
  • RAP right atrial pressure
  • PAP pulmonary artery pressure
  • PVR pulmonary vascular resistance
  • LVEF left ventricular ejection fraction
  • HFrEF heart failure with reduced ejection fraction
  • HFpEF heart failure with preserved ejection fraction.
  • Implantation of the V-Wave shunt was successful in all 38 patients and no device replacements were performed. Shunts remained implanted in the atrial septum without dislodgements, migrations or apparent interference with normal septal motion on fluoroscopic or echocardiographic imaging. No shunts have required removal or replacement for infection or strut fracture.
  • follow-up imaging studies show that there are adjacent locations on the FO, that are available and amenable for performing transseptal procedures to treat other cardiac conditions, including, for example, atrial fibrillation ablation, left atrial appendage occlusion, and mitral valve repair. The valve apparatus, when functioning normally, has been shown to effectively prevent reverse (right-to-left) shunting.
  • Echocardiographic contrast and Doppler studies during rest or Valsalva maneuver show that there is no reverse shunting in the early months after human implantation. Furthermore, no thromboembolic clinical events, including paradoxical embolization, have been observed during the first year of follow-up.
  • Shunt patency is defined as LA to RA flow through the shunt as observed during transesophageal echo/Doppler study. At 3-months after implantation of the V-Wave shunts, patency was confirmed in all patients.
  • the pulmonary to systemic flow ratio (Qp/Qs) as measured by echocardiography, increased from 1.04 ⁇ 0.22 at baseline to 1.18 ⁇ 0.16 shortly after implantation (p ⁇ 0.03).
  • Qp/Qs pulmonary to systemic flow ratio
  • shunts having undetectable LA to RA flow
  • device occlusion e.g., shunts having undetectable LA to RA flow
  • shunts may develop bidirectional shunting that was not present early on. Bidirectional shunting is indicative of an incompetent valve, e.g., a valve where one or more leaflets do not fully coapt during closure, resulting in an open channel for reversed flow, and depending on the severity of the incompetence, may create a potential path for paradoxical embolus to traverse from the RA to LA.
  • Clinical effectiveness also may be measured by the rate of hospitalization for worsening heart failure.
  • the hospitalization rate was 0.16 per patient year, which increased to 0.40 per patient year between months 6-12.
  • a third potential cause of occlusion is neoendocardial tissue overgrowth or pannus formation that narrows the lumen at the neck of the hourglass-shaped shunt.
  • Applicants’ earlier ovine studies suggest otherwise.
  • the shunt lumen surface at the neck of the hourglass contained only microscopic amounts of cellular material.
  • On gross pathological examination there was no visible loss of the lumen area in neck region.
  • a human shunt specimen has been examined in an explanted heart from a patient that underwent cardiac transplantation 2.5 years after shunt implantation.
  • the ePTFE surfaces of the shunt including the lumen at the neck contained no pannus formation or narrowing of any kind.
  • a left atrial pressure sensor implanted across the FO by transseptal catheterization and used for guiding the medical therapeutic dosing in symptomatic patients with severe heart failure was observed to experience pannus formation.
  • the sensing diaphragm located at the distal end of the sensor module body, protruded into the left atrium by 1-mm beyond its three anchoring legs that rested on the left atrial side of the septum.
  • the legs were placed more proximal on the sensor module body so that sensing diaphragm protruded into the LA by an additional 1.5 mm.
  • the time course of tissue encapsulation of the sensing diaphragm could be estimated by assessing LA pressure waveforms for baseline drift with or without the development of artifacts. It was hypothesized that as neoendocardial tissue grows over the sensing diaphragm, measured LA pressure increased due to a drifting baseline caused by tension applied from the tissue capsule covering the diaphragm through its contiguous connection with the atrial wall. This healing phenomenon may be initiated as early as several weeks’ post implant in animals and starts around 3-4 months in humans.
  • Pannus formation on devices that traverse the interatrial septum has been observed to start at the portions of the device in contact with the septum in the region of local tissue injury. Tissue growth progresses contiguously, extending translationally along the external surfaces of the device that protrude into each atrial chamber. This pannus growth thins as a function of distance from the sites of cardiac contact until it becomes essentially a monolayer of neoendothelial cells. The process naturally stops after about 6-12 months in humans.
  • tissue coverage typically grows a distance of about 3 mm from its starting place on the septal wall before stopping or becoming thin enough so as not to impede device function.
  • Pannus formation affecting the valve leaflets is the most likely stand-alone mechanism that explains all of the untoward observations seen in human subjects implanted with V-Wave shunts, including progressive shunt narrowing, incompetence of the valve with bidirectional flow, and eventual loss of shunt flow with associated loss of clinical efficacy.
  • Tissue overgrowth affecting the valve leaflets bases and commissures was the predominant histopathological finding in the ovine pre-clinical study described above.
  • Gross pathological examination of shunts implanted for 3 months showed pannus infiltration extending from the adjacent FO into the valve leaflet bases with thickening of the leaflet bodies in 5 out of 6 shunts.
  • In 4 shunts there was fusion of at least 2 of the 3 valve commissures where the leaflet edges were sutured to the shunt frame. Fusion of all 3 commissures was observed in 3 shunts.
  • pannus thickness tends to be greater on the side of the leaflets facing the atrial septum where the ePTFE/leaflet junction was infiltrated with pannus that was contiguous with the adjoining atrial tissue.
  • Pannus extended from the atrial septum on and around the right atrial edge of the ePTFE skirt and into the base and commissures of the valve leaflets.
  • the pericardial leaflets showed varying degrees of pannus coverage ranging from mild to marked. In general, pannus is thickest at the leaflet bases and commissures, and tapers toward the free edges. In 2 sheep, the pannus on the leaflets measured 2 to 3 times the original thickness of the leaflets.
  • pannus was generally well healed or organized by 3 months. It was composed of collagen and proteoglycan matrix surrounding smooth muscle cells, fibroblasts and rare focal areas of inflammation with lymphocytes, macrophages, and occasional multinucleated (foreign body type) giant cells. The pannus tissue was mostly covered with neoendothelium consistent with near complete healing. No leaflet calcification or thrombi were observed.
  • the bioprosthetic valve material and its attaching polypropylene suture were removed and the ePTFE encapsulation was extended to cover the entire nitinol frame of the shunt except for the last 1.5 mm on the RA side where the shunt was coupled to its delivery system for deployment.
  • the ePTFE used had an internodal distance of up to 30 microns.
  • the sheep where euthanized.
  • the gross pathology findings showed that the 3 valved shunts were heavily infiltrated with pannus formation, extending from the septum into the regions containing the bioprosthetic leaflets. The leaflets were fused, immobile and highly stenotic leaving only a pinhole opening.
  • pannus formation was much exaggeration versus prior experience in the ovine heart failure model. Thick pannus extended retrograde contiguously from the leaflet bases toward the hourglass neck of the shunts. The pannus growth from the original septal site of injury to the tips of the valve leaflets exceeded 3 mm in distance. Pannus appeared to grow through the valve commissures and through the suture holes attaching the porcine pericardial leaflets to the frame and the ePTFE skirt. Pannus formation was associated with mononuclear inflammatory cell infiltrates and multinucleated giant cells.
  • pannus formation severe enough to interfere with device function tends to translate a maximum of about 3 mm from the site of injury, whereas in the case of the bioprosthetic valve material tested, the amount of pannus formation and translational length of pannus tissue growth were exaggerated.
  • a shunt constructed in accordance with the principles of the present disclosure provides a more durable configuration that maintains luminal patency for extended periods of time.
  • the inventive shunt further enables redistribution of interatrial blood volumes and pressure imbalances while reducing a risk of paradoxical embolism caused by emboli moving through the shunt from the right to left atria.
  • Shunts constructed in accordance with the principles of the present disclosure also provide greater safety by enhancing long-term patency and reducing the risk of pannus formation after a prolonged period of implantation by reducing the impact of the manner in which the shunt is implanted in the interatrial septum.
  • shunts having an anchor and conduit are provided for redistributing atrial blood volumes, in which the shunt dimensions, contours and materials maintain long-term patency while reducing the risk of paradoxical embolism. It is hypothesized that such shunt designs will provide reductions in left atrial pressure, relieve pulmonary congestion, and lower pulmonary artery pressure, among other benefits.
  • the inventive devices are configured for implantation through the atrial septum, and preferably through the fossa ovalis.
  • shunts designed in accordance with the principles of the present disclosure are designed to control LAP by transferring a small portion of the blood normally flowing from the left atrium to the left ventricle and diverting it instead to the right atrium, thereby modestly reducing LV end-diastolic filling volume.
  • the LV operates on a steeper portion of its diastolic compliance curve. Accordingly, even a modest reduction in LV end-diastolic volume leads to a substantial fall in LV end-diastolic pressure. That reduction causes a commensurate reduction in upstream filling pressures including LAP, pulmonary venous pressure, and pulmonary artery pressure.
  • the inventive devices include an anchor configured to be implanted in the interatrial septum, preferably the FO, and a conduit affixed to the anchor.
  • the conduit includes a luminal wall defining a lumen, such that the luminal wall comprises a biocompatible material that is resistant to transmural tissue growth, and that limits translational tissue growth to 3 mm or less from the site of contact to the nearest cardiac structure.
  • that anchor may have an hourglass or “diabolo” shaped frame with a neck region adjoining flared end regions, and the conduit may comprise a biocompatible material that encapsulates the frame.
  • the frame may be formed of a biocompatible elastically or plastically deformable material, or shape memory material.
  • the device may be implanted by forming a puncture through the atrial septum, particularly through the FO, and then percutaneously inserting the device therethrough, such that the neck region lodges in the puncture, the first end region extends into the left atrium, and the second end region extends into the right atrium.
  • the biocompatible material that may be a polymer, such as expanded polytetrafluoroethylene (ePTFE), polyurethane, DACRON (polyethylene terephthalate), silicone, polycarbonate urethane, Ultra High Molecular Weight Polyethylene (UHMWPE) or PTFE.
  • the biocompatible material may also be a metal, ceramic, carbon nanotube array or any other suitable material known to those familiar with the art that provides the shunt with the following properties.
  • One purpose of the biocompatible covering is to form a conduit, with the biocompatible material serving as a barrier to isolate the shunt lumen from the exterior of the conduit.
  • the biocompatible material isolates the lumen from penetration by cellular proliferation (pannus formation) occurring on the exterior surface of the conduit, where it contacts the septum or FO, which result from the processes associated with device healing.
  • the biocompatible material should also impede translational growth of pannus along the outer wall of the conduit for more than about 3 mm from the site of contact with any cardiac structure.
  • anchor or frame used interchangeably throughout this specification should be considered in the general sense to refer to any composition of linked physical members that contribute in substantial part to the shunt device’s shape and other physical properties that govern the shunt’s transition from pre deployment constrainment to the expanded and deployed state where it is in contact with tissue.
  • All of the shunt device embodiments described in this patent application can be understood in terms of component parts (anchor and conduit) or as a unitary device with certain specified physical properties including shape geometry in pre-and post-deployment states and biocompatible surface properties.
  • the cross-sectional profile of shunt lumen perpendicular to its axis of flow may be round, oval, rectangular, or any other regular or irregular polygonal shape.
  • the cross-sectional profile may vary from one shape to another along the axis of flow, which may be a straight line or may be curvilinear.
  • the cross-sectional profile may rotate along the axis of flow.
  • the shunt may have a single lumen or there may be a plurality of lumina.
  • a device for regulating blood distribution between a patient’s left atrium and right atrium comprises an anchor having a neck region joining first and second end regions, the neck region configured to engage the fossa ovalis of the patient’s atrial septum; and a conduit affixed to the anchor so that the conduit extends into the right atrium by a distance selected to reduce the risk of paradoxical embolism.
  • the conduit preferably comprises a biocompatible material that limits (or inhibits excessive) tissue ingrowth into the lumen of the conduit.
  • the anchor and conduit are configured to accommodate endothelial or neointima layer growth up to a thickness of about 0.6 mm or less, so as to render such material inert, inhibit hyperplasia, and substantially inhibit obstruction of the flow path through the device.
  • the anchor comprises hourglass-shaped frame having a plurality of circumferential struts interconnected by longitudinal struts that, when deployed, form first and second flared end regions connected by a neck.
  • first flared end region protrudes 3 to 10 mm into the left atrium beyond the surface of the left septal wall.
  • the second flared end region may protrude 5 to 10 mm into the right atrium beyond the surface of the right septal wall.
  • the neck has an inner diameter of 4 to 8 mm, where preferably the inner diameter is in a range of 5 to 6.5 mm.
  • the first flared end region preferably has a diameter selected in the range of between 10 and 20 mm
  • the second flared end region preferably has a diameter selected in the range of between 9 and 15 mm.
  • the first and second flared end regions each preferably flare outward from the longitudinal axis of the shunt by an amount selected from between about 25 to 60 degrees, although such angles may be different for each of the first and second flared regions.
  • the steepest part of the outer surface of the first flared end region is at an angle of approximately 40 degrees relative to the longitudinal axis of the device, while the steepest part of the outer surface of the second flared end region may be at an angle of approximately 37.5 degrees relative to the longitudinal axis of the device.
  • the shunt is configured to transition between a collapsed state suitable for percutaneous delivery and an expanded state when deployed across the patient’s fossa ovalis, such that the shunt assumes an hourglass configuration in the expanded state.
  • the hourglass configuration may be asymmetric.
  • the shunt may be configured for implantation through a portion of the fossa ovalis, away from the surrounding limbus, inferior vena cava, and atrial wall.
  • Methods of treating a subject with heart pathology including providing a shunt having first and second end regions and a neck region disposed therebetween; deploying the shunt across a puncture through the subject’s interatrial septum, preferably through the FO, such that the neck region is positioned in the puncture with the first end region disposed in the left atrium, and the second end region disposed in the right atrium, such that flow through the device redistributes blood between the left atrium and the right atrium through the device when the left atrial pressure exceeds the right atrial pressure.
  • Subjects with a variety of heart pathologies may be treated with, and may benefit from, the inventive device.
  • reducing the left atrial pressure and left ventricular end diastolic pressure may provide a variety of benefits, including but not limited to decreasing pulmonary congestion; decreasing pulmonary artery pressure; increasing ejection fraction; increasing fractional shortening; and decreasing left ventricle internal diameter in systole.
  • myocardial infarction which may be treated by deploying the device during a period immediately following the myocardial infarction, e.g., within six months after the myocardial infarction, or within two weeks following the myocardial infarction, to reduce myocardial remodeling.
  • PAH pulmonary arterial hypertension
  • other disorders such as connective tissue diseases, drugs or toxins, HIV infection, portal hypertension, or congenital heart disease
  • PAH procedures that cause interatrial shunting from the right to the left atrium (right to left shunt).
  • These procedures include blade or balloon septostomy or placement of devices such as uncovered diabolo stents or fenestrated atrial septal occlusion devices.
  • a system for treating a heart condition may include a sheath having a lumen and distal end sized and shaped to be positioned through an opening of an atrial septum of a patient, and a shunt including an anchor and a conduit, e.g., a biocompatible material that encapsulates at least a portion of the anchor.
  • the anchor may have a first region, a second region, and a neck region joining the first and second regions, and the conduit may be affixed to the anchor to define a passageway through the shunt.
  • the shunt may transition from a contracted delivery state within the lumen of the sheath to an expanded state.
  • the system may include a delivery catheter movably disposed within the lumen of the sheath that may advance the shunt through the lumen of the sheath until the first region protrudes from the distal end of the sheath and transitions from the contracted delivery state to the expanded state within a first atrium.
  • the shunt and the sheath may be retracted towards the atrial septum until the first region in the expanded state engages with the atrial septum within the first atrium, and the sheath may further be retracted until the second region of the anchor is exposed from the distal end of the sheath and transitions from the contracted delivery state to the expanded state within a second atrium to implant the neck region at the atrial septum.
  • the force required to retract the sheath over the second region in the contracted delivery state is less than a force required to transition the first region from the expanded state to the contract delivery state. Moreover, the force required to retract the sheath over the second region in the contracted delivery state is less than a yield stress of the atrial septum.
  • the anchor may form a diabolo shape in the expanded state.
  • the first and second regions may be formed of a superelastic or a shape memory material.
  • the passageway may maintain a continuous opening across the atrial septum in the expanded state.
  • the delivery catheter may be detachably coupled to the shunt in the contracted delivery state within the lumen of the sheath.
  • the delivery catheter may advance the shunt through the lumen of the sheath until the delivery catheter reaches a stopping point such that the first region protrudes from the distal end of the sheath a predetermined distance. Additionally, the delivery catheter may be retracted from the stopping point such that the sheath causes the first region to transition from the expanded state to the contracted delivery state for retrieval of the shunt.
  • the system further may include a guidewire that may be positioned through the opening of the atrial septum of the patient, such that the sheath may be positioned through the opening of the atrial septum over the guidewire. Further, the system may include a dilator that may be advanced over the guidewire to dilate the opening of the atrial septum, and may be removed through the lumen of the sheath.
  • a method for redistributing blood across a patient’s interatrial septum may include: positioning the distal end of the sheath through an opening of the atrial septum; advancing the shunt through the lumen of the sheath via the delivery catheter until the first region of the anchor protrudes from the distal end of the sheath and transitions from the contracted delivery state within the lumen of the sheath to the expanded state within the first atrium; retracting the shunt and the sheath towards the atrial septum until the first region in the expanded state contacts the atrial septum within the first atrium; further retracting the sheath until the second region of the anchor is exposed from the distal end of the sheath and transitions from the contracted delivery state to the expanded state within the second atrium to thereby lock the shunt within the atrial septum; and shunting blood via the passageway of the conduit between the first and second atria.
  • advancing the shunt through the lumen of the sheath via the delivery catheter may include advancing the delivery catheter until the delivery catheter reaches a first stopping point wherein the shunt is within 1 to 5 cm from the distal end of the sheath, and advancing the delivery catheter to a second stopping point such that the first region protrudes from the distal end of the sheath a predetermined distance.
  • the method further may include verifying that the distal end of the sheath is positioned within 1 to 3 cm beyond the atrial septum prior to advancing the delivery catheter to the second stopping point.
  • retracting the shunt and the sheath may include retracting the shunt and the sheath towards the atrial septum until contact with the atrial septum is observed.
  • further retracting the sheath until the second region is exposed from the distal end of the sheath may include further retracting the sheath until a counterforce exerted by shunt tension on the atrial septum overcomes a friction of the second region in the contracted delivery state within the sheath.
  • the method further may include decoupling the delivery catheter from the shunt prior to further retracting the sheath until the second region is exposed from the distal end of the sheath.
  • the method may include injecting an agitated saline via the delivery catheter, and observing where microbubbles of the agitated saline exit the distal end of the sheath via ultrasonic imaging to confirm a position of the distal end of the sheath within the first atrium. Additionally or alternatively, the method may include injecting radiographic contrast material via the delivery catheter, and observing where the radiographic contrast material exits the distal end of the sheath via fluoroscopy to confirm a position of the distal end of the sheath within the first atrium.
  • FIGS. 1A to 1C are, respectively, perspective, end and side views of a preferred embodiment of a shunt constructed in accordance with the principles of the present disclosure.
  • FIG. 2 is a side view of an alternative embodiment of a shunt of the present disclosure having a cutout in its polymeric encapsulation to secure the shunt to a delivery system.
  • FIG. 3 is a perspective view of another alternative embodiment of a shunt of the present disclosure having an alternative cutout in its encapsulation.
  • FIGS 4A and 4B are, respectively, end and side views of a further alternative embodiment of a shunt constructed in accordance with the principles of the present disclosure having eyelets that engage a delivery system.
  • FIGS. 5A and 5B are plan views of further alternative embodiments of anchors suitable for use in the inventive shunt, cut along line 5 A — 5 A and 5B — 5B, and unrolled to a flat configuration.
  • FIG. 6 is a graph comparing theoretical flows through a shunt design having a Venturi contour with 5 mm and 6 mm diameter orifices compared to theoretical flows obtained using orifice plate-type devices.
  • FIGS. 7A and 7B are, respectively, a plan view of the right atrial side of the atrial septum, illustrating implantation of a shunt through a portion of the fossa ovalis, and a perspective view of an embodiment of the shunt of FIGS. 1A-1C positioned in the fossa ovalis of the atrial septum.
  • FIGS. 8 A and 8B schematically depict pannus formation on an hourglass-shaped embodiment of the shunt of the present disclosure positioned in the fossa ovalis orthogonal to the atrial septum wall, immediately after implantation and after pannus formation.
  • FIGS. 9A and 9B schematically depict pannus formation on an hourglass-shaped embodiment of the shunt of the present disclosure positioned in the fossa ovalis non-orthogonal to the atrial septum wall, immediately after implantation and after pannus formation.
  • FIGS. 10 through 15 depict various alternative embodiments of shunts constructed in accordance with the principles of the present disclosure.
  • FIGS. 16A and 16B are, respectively, side and end views of anchor suitable for a further alternative shunt embodiment having self-expanding flexible arms that form a filter over the right atrial side of the conduit.
  • FIG. 17 is a graph comparing theoretical flows through shunt designs constructed in accordance with the principles of the present disclosure compared to a previously known valved shunt design.
  • FIGS. 18A to 18D illustrate steps taken during an exemplary method of implanting an hourglass-shaped shunt of the present disclosure in accordance with the principles of the present disclosure.
  • FIG. 19 is a flow chart of steps in an alternative exemplary method of implanting an hourglass-shaped shunt of the present disclosure in accordance with the principles of the present disclosure.
  • FIGS. 20A to 20D schematically illustrate steps taken during the method of FIG. 19, in accordance with the principles of the present disclosure.
  • Interatrial shunts are provided for redistributing interatrial blood volumes and reducing left atrial pressure, which may be advantageous in treating subjects suffering from heart failure (HF) or other disorders associated with elevated left atrial pressure.
  • a preferred embodiment of the inventive device includes an anchor, which may be an hourglass or “diabolo” shaped stent or frame, and a conduit, formed by encapsulating the frame in a synthetic biocompatible material.
  • the shunt is configured to be lodged securely within a passage formed in the atrial septum, preferably the fossa ovalis, and provides one-way blood flow from the left atrium to the right atrium, when blood pressure in the left atrium exceeds that on the right.
  • Shunt 10 generally comprises anchor 12 having three regions: flared or funnel-shaped end region 14, flared or funnel-shaped end region 18, and neck region 16 disposed between end regions 14 and 18.
  • Neck region 16 is configured to lodge in a puncture formed in the atrial septum, preferably in the fossa ovalis.
  • Flared end regions 14 and 18 are configured to partially engage and protrude beyond the right and left sides, respectively, of the atrial septum when implanted.
  • Shunt 10 further comprises a conduit, illustratively formed by encapsulating anchor 12 with biocompatible material 20 that covers all or substantially all of anchor 12 to form a conduit defining a lumen or interior passageway 22.
  • Flared region 14 is configured to be disposed in the right atrium, while flared region 18 is configured to be disposed in the left atrium.
  • anchor 12 includes six longitudinal struts 24 interconnected by five circumferential struts 26a-26e. Longitudinal struts 24 prevent foreshortening of the anchor during expansion, while the sinusoidal or serpentine bends in circumferential struts 26a-26e permit the anchor to transition between a radially collapsed substantially cylindrical delivery state to an expanded, flared, deployed state as illustrated in FIGS. 1A to 1C.
  • a conduit is formed by biocompatible material 20 that encapsulates the entirety of neck 16, flared end region 18, and flared end region 14.
  • Biocompatible material 20 preferably is affixed to anchor 12 using a suitable biocompatible adhesive or by sandwiching the anchor between inner and outer layers of biocompatible material using sintering techniques.
  • anchor 12 comprises a self-expanding material, such as a shape memory alloy, and circumferential struts 26a-26e are treated to expand a predetermined amount when deployed, so that together with encapsulation 20, lumen 22 has a contour that permits substantially laminar flow between flared end section 18 (in the left atrium) and flared end section 14 (in the right atrium).
  • Sinusoidal or serpentine bends 28 in circumferential struts on flared end region 14 preferably are 180 degrees out of phase with the sinusoidal or serpentine bends 28 in neck region 16 and flared end region 18, so that the sinusoidal or serpentine bends do not extend beyond the ends of longitudinal struts 24 in either the collapsed delivery state or deployed state.
  • Anchor 12 may comprise a biocompatible metal framework or laser-cut solid metallic tube made from nitinol, titanium alloy, cobalt chromium alloy, MP35n, 316 stainless steel, L605, Phynox/Elgiloy, platinum chromium or other biocompatible metal such as are known to persons of skill in the art. While a preferred embodiment employs a shape memory self-expanding alloy, anchor 12 alternatively may comprise an elastically or plastically deformable material, e.g., balloon expandable, or may be a shape memory alloy that responds to temperature changes to transition between contracted delivery and expanded deployed states. The surface finish applied to the material of the anchor may be selected to control the distance, thickness, composition and/or growth pattern of pannus formation, e.g., the external surfaces of anchor 12 may be electro-polished.
  • the radial dimensions, axial lengths and contours of neck region 16 and flared end regions 14 and 18 preferably are selected to provide laminar flow through the interior of the shunt, to reduce the formation of eddy currents when implanted, and thus inhibit thrombus formation; to inhibit pannus formation that could obstruct the neck region; to promote tissue ingrowth around the exterior of the neck region to secure the shunt against migration; to provide a desired rate of blood flow between the left and right atria at physiological pressure differentials; and to prevent retrograde paradoxical embolization.
  • Biocompatible material 20 forming the conduit preferably is resistant to the transmural and translational ingrowth of pannus material having a tissue thickness greater than 0.6 mm.
  • tissue thickness greater than 0.6 mm.
  • ePTFE vascular grafts those with a 60-micron internodal distance showed rapid, transmural infiltration with proliferating smooth muscle cells and granulation tissue, whereas ePTFE grafts with a 30-micron internodal distance were observed to develop only a slow growing, thin sheet of endothelium that advanced only a few millimeters into the graft lumen from the adjacent artery.
  • shunt 10 comprises anchor 12 made of, for example, electro polished nitinol
  • biocompatible material 20 may be an inert polymer such as ePTFE with an internodal distance of 30 microns or less, or is PTFE, such that pannus will grow to a thickness no greater than about 0.6 mm after extending translationally a distance of 3 mm from the site of contact with the Foramen Ovalis (“FO”) tissue.
  • luminal narrowing shall be defined as a loss of minimal shunt lumen diameter of greater than 25% and the term “luminal obstruction” is defined as total (100% loss of lumen diameter) blockage of the lumen to the flow of blood.
  • anchor 12 has an hourglass shape formed of a shape memory metal, e.g., nitinol, or any other suitable material known in the art.
  • Circumferential struts 26a-26e and longitudinal struts 24 preferably comprise a unitary construction, that is, entire anchor 12 is laser cut from a tube of shape memory metal.
  • Biocompatible material 20 may comprise, for example, a sheet of a polymer such as expanded polytetrafluoroethylene (“ePTFE”), polytetrafluoroethylene (“PTFE”,) silicone, polycarbonate urethane, DACRON (polyethylene terephthalate), Ultra High Molecular Weight Polyethylene (UHMWPE), or polyurethane.
  • the biocompatible material may also be a metal, ceramic, carbon nanotube array or any other suitable biocompatible material.
  • biocompatible material 20 may comprise ePTFE with an up to 30-micron internodal distance, and may be applied as inner and outer layers sintered together to form a unitary conduit.
  • biocompatible material 20 may be applied to the inner lumen and the outside of the anchor using electrospinning techniques.
  • Bare metal regions of anchor 12, and any other regions of the anchor optionally may be electropolished or otherwise treated to inhibit thrombus formation using known methods.
  • neck 16 of shunt 10 preferably is configured for implantation through the fossa ovalis of the atrial septum, and more preferably near or at the central portion of the fossa ovalis.
  • the fossa ovalis is a thinned portion of the atrial septum formed during fetal development of the heart, which appears as an indent in the right side of the atrial septum and is surrounded by a thicker portion of the atrial septum. While the atrial septum itself may be several millimeters thick and muscular, the fossa ovalis may be only approximately one millimeter thick, and is formed primarily of fibrous tissue.
  • shunt 10 may be asymmetrically shaped to take advantage of the natural features of the atrial septum near the fossa ovalis, and to provide suitable flow characteristics.
  • the anchor comprises an hourglass or diabolo shape where a LA entry funnel resembles a conical-shaped nozzle and a RA exit funnel is “bell” shaped, with the wide mouth lumen of the bell at the RA exit port in the RA.
  • the narrow entrance to the bell-shaped exit funnel connected to the orifice of the neck region may be configured to approximate the curved surface of a parabola.
  • This type of convergent-divergent nozzle resembles the shape of a classical de Laval nozzle used in rocket engines. Left to right flow is largely governed by the smooth convergence of streamlines in the entry cone and the divergence of streamlines exiting the bell. Such a nozzle configuration is very efficient in the forward flow direction having a discharge coefficient resembling a classic venturi tube, e.g., 0.95-0.98.
  • points B and C are located on the leftmost circumferential strut 26e, which defines the LA entry port.
  • Points A and D are located on circumferential strut 26d along the LA entry funnel proximal to strut 26e.
  • Points H and E are located on circumferential strut 26b along the RA exit funnel, and points G and F are located on circumferential strut 26a, which defines the RA exit port.
  • the diameter of lumen 22 in the neck region of the shunt orifice ranges from 5 to 6.5 mm.
  • the portion of the shunt crossing the FO, bounded by points ADEH may be 3 mm in axial length but may be extended up to 10 mm in patients with a thicker FO.
  • the diagonal length between points AB, CD, EF, and/or GH is preferably >3 mm so that pannus cannot grow translationally inward from the ends of the shunt and thus obstruct neck region 16.
  • the horizontal component length between points AB, CD, EF, and/or GH is preferably ⁇ 15 mm, to avoid interference with existing cardiac structures when implanted.
  • Truncated funnel cones bounded by ABCD and/or EFGH may have volumes ⁇ 2 ml.
  • anchor 12 may be made of a self-expanding polymer.
  • the anchor need not be self-expanding, and may be made from a plastically deformable biocompatible metal such as 316 L stainless steel, cobalt chromium alloys, or any other such suitable materials known to those skilled in the art.
  • Such a deformable shunt anchor may be delivered by an expanding member, such as a balloon, that is configured to achieve the desired luminal geometry.
  • the deformable anchor may be designed to expand prismatically or at certain localized sites where ductile hinges are configured for more selected expansion as taught by U.S. Patent No. 6,242,762 to Shanley, the contents of which are incorporated by reference herein.
  • Shunt 30 includes anchor 31 is similar in construction to that described for the embodiment of FIGS 1A-1C, and has flared end regions 32 and 33 and neck region 34.
  • flared end region 32 When implanted in a patient’s interatrial septum, flared end region 32 is disposed in the patient’s right atrium, while flared end region 33 is disposed in the patient’s left atrium, with neck region 34 situated in a passage formed in the interatrial septum.
  • Anchor 31 includes longitudinal struts 35 and circumferential struts 36a-36e, and is encapsulated by biocompatible material 37.
  • Anchor 31 may comprise a self-expanding or plastically deformable material as described herein above.
  • Shunt 30 of FIG. 2 differs from the previous embodiment in that biocompatible material 37, for example ePTFE, includes cutout 38 adjacent to circumferential strut 36a.
  • biocompatible material 37 for example ePTFE
  • Cutout 38 may extend proximally from circumferential strut 36a for a distance of 0.5 mm to 2 mm, and more preferably about 1 mm, to permit circumferential strut 36a to be releasably engaged with a delivery system during deployment, for example, hooks, as described by Yacoby in U.S. Patent No. 9,713,696, the entire contents of which are incorporated herein by reference.
  • Biocompatible material 37 may be trimmed manually or mechanically from circumferential strut 36a to create cutout 38 or by laser-cutting. In this manner, shunt 30 may be positioned and repositioned in a passage formed in the interatrial septum until the clinician is satisfied with the device placement, before being released.
  • each of longitudinal struts 35 optionally may include one or more holes adjacent to circumferential strut 36a, e.g., to permit longitudinal struts 35 to be releasably engaged with a delivery system during deployment.
  • FIG. 2 illustrates each of longitudinal struts 35 having one or more holes, not every longitudinal strut may include the one or more.
  • six longitudinal struts 35 form anchor 31, only three longitudinal struts may include one or more holes adjacent to circumferential strut 36a. Accordingly, the longitudinal struts without one or more holes may be narrower.
  • the conduit formed by biocompatible material 37 extends a distance of at least 3 mm beyond neck region 34 into flared end region 32, to ensure that pannus cannot grow translationally along luminal wall far enough to partially occlude the flow area of neck region 34.
  • flared end region 32 extends a distance of at least 5 mm into the right atrium when implanted in the interatrial septum to ensure that the entry of flared end region 34 is generally not aligned with flow paths generated by blood entering the right atrium from the inferior vena cava, thereby reducing the risk that emboli carried from the lower extremities into the right atrium will cause paradoxical embolism by passing through shunt 30.
  • Shunt 40 includes anchor 41 having flared end regions 42 and 43 joined by neck region 44, as described for the preceding embodiments.
  • Anchor 41 includes longitudinal struts 45 joined by circumferential struts 46a-46e and biocompatible material 47, for example a thin layer of ePTFE or other suitable material as described above.
  • Shunt 40 differs from the embodiment of FIGS. 1A to 1C in that the polymeric encapsulation includes cutouts 48 on alternating peaks of the sinusoidal bends formed by circumferential strut 46a that permit a delivery device to releasably engage shunt 40.
  • Shunt 40 also includes skirt 49 of biocompatible material that extends beyond circumferential strut 46e.
  • cutouts 48 include circular sectors having angles in the range of 60° to 180°, more preferably 120°, such that largest distance between the edge of the polymeric encapsulation and circumferential strut 46a is in the range of 0.5 to 2 mm, and more preferably 1 mm.
  • the configuration of cutouts 48 of shunt 40 which may be laser cut, advantageously maximize the encapsulated area of the shunt while still enabling proper engagement to the delivery system hooking mechanism. As will be apparent to those skilled in the art, other possible cutting patterns or methods may be employed.
  • Shunt 50 includes anchor 51 having end regions 52 and 53 joined by neck region 54.
  • Anchor 51 has longitudinal struts 55 coupled to circumferential struts 56a-56e as described for preceding embodiments, and includes a conduit formed of biocompatible material 57 as also described hereinabove.
  • Shunt 50 differs from the embodiment of FIGS. 1A to 1C in that alternating longitudinal struts 55 include elongated portions 58 having eyelets 59 for engagement with a delivery system extending from right atrial end region 52.
  • Shunt 50 may have between 2 to 6, and preferably 3 elongated portions 58 and eyelets 59 left as bare-metal, i.e., without polymeric encapsulation.
  • Elongated portions 58 preferably are short, protruding a minimum additional distance into the right atrium or alternatively are constructed to bend into the right atrium RA exit port on release from the delivery system to serve as filter to block paradoxical emboli from passing into the lumen of the conduit at end region 52.
  • An alternative approach that also filters the size of emboli is to construct the shunt with a plurality of passageways or lumina that transport blood in parallel such that the total cross-sectional area of all the of the passageways conserves the flow characteristics needed for adequate shunting to achieve the redistribution of blood between the atria as desired.
  • Anchor 60 is similar in design to anchor 51 of the embodiment of FIGS. 4 A and 4B, and includes longitudinal struts 61 joined to circumferential struts 62a-62e, which include sinusoidal bends. Accordingly, anchor 60 when expanded includes flared end regions joined by a neck region to form a generally hourglass shape, while longitudinal struts 61 prevent, or otherwise minimize, foreshortening, i.e., axial shrinkage, during deployment. For purposes of illustration, anchor 60 as depicted in FIG.
  • anchor 60 includes a polymeric encapsulation that forms a conduit, omitted for clarity from FIG. 5A, that covers the anchor between circumferential struts 62a and 62e.
  • Anchor 60 includes elongated portions 63 and eyelets 64 that extend into the right atrium when the shunt is deployed.
  • alternating eyelets 64 include radiopaque markers 65, for example made of platinum iridium, gold, tantalum, or any other similar suitable material, which enhance visualization of the shunt under fluoroscopy. Eyelets 64 that do not accommodate radiopaque markers 65 permit the shunt to be releasable engaged by a delivery system for percutaneous transluminal delivery.
  • anchor 66 is similar in design to anchor 60 of the embodiment of FIG.
  • Anchor 66 additionally includes eyelets 69 that extend from alternating longitudinal struts 68 for use in releasably coupling the shunt to a percutaneous transluminal delivery system.
  • anchor 66 when expanded includes flared end regions joined by a neck region to form a generally hourglass shape, while longitudinal struts 68 prevent, or otherwise minimize, foreshortening during deployment.
  • anchor 66 as depicted in FIG. 5B is shown cut along one of longitudinal struts 68 (along line 5B — 5B) and flattened, although the anchor preferably is cut from a tubular material.
  • Anchor 66 further includes a conduit formed by encapsulating the anchor with a biocompatible material, omitted for clarity from FIG. 5B, that covers the anchor between struts 67a and 67e.
  • an interatrial hourglass shaped shunt with flow characteristics resembling a venturi tube and a discharge coefficient of approximately 0.96-0.97 may have a minimal neck orifice inner diameter ranging from 5 mm to approximately 6.5 mm. Having a somewhat larger orifice diameter, within this range, e.g. 6.0 mm, will support approximately 35% more flow for any given pressure gradient compared with a 5.1 mm shunt, as shown in FIG. 6. This may create improved hemodynamic conditions and may provide additional benefit in maintaining shunt flow should some shunt narrowing due to pannus ingrowth occur during device healing.
  • various nozzle geometries with high discharge coefficients relative to an orifice-plate geometry advantageously may be used to provide laminar flow through the shunt.
  • These include but are not limited to various variations of venturi tubes, conical convergent nozzles (with convergence angles from 20 to 80 degrees), cylindrical convergent nozzles, and the Addy type nozzle with a convergent curved entrance wall leading to a length of cylindrical tubing having a diameter equivalent to the orifice diameter.
  • the shunt lumen may be a cylindrical tube with no or minimal dilation at the entry or exit ports.
  • the cross-section of lumen 22 need not be circular and/or the lumen need not be coaxial with a straight horizontal line axis when viewed longitudinally. Although these latter geometries may be difficult to deliver through catheters with circular luminal cross- sections, they may be constrained to such catheter lumens and expand into non-circular cross- sectional or curved longitudinal geometries upon deployment.
  • Other preferred embodiments include any combination of entry, orifice, and exit geometries where the exiting jet vena contracta cross-sectional area is 70% or greater compared with the minimal orifice area, over the range of physiological interatrial pressure gradients, thereby having a higher discharge coefficient than an orifice-plate.
  • a shunt with a single LA conical entry funnel, with an hourglass-shaped lumen, or with a tubular lumen, having a discharge coefficient of 0.70 or larger generally has a longer tunnel of entrained flow by nature of its longer length, typically 6 to 30 mm long, versus an orifice-plate mesh type shunt, which may be defined by the thickness of the FO itself and is typically shorter than 6 mm, e.g., 3 mm or less.
  • the paradoxical embolization to occur, i.e., for a paradoxical embolus to embolize from the heart into the systemic arterial circulation, the paradoxical embolus must pass completely or nearly completely through the shunt.
  • Emboli may be propagated by their momentum against a left-to right gradient or when there is no gradient, or may be carried along when a reversed pressure gradient creates right to left bulk flow.
  • a longer lumen shunt will tend to pass fewer emboli compared to an orifice- plate shunt with a shorter lumen. This is likely to be the case in the presence of normal left to right bulk flow or when there is zero net flow. This is also likely to be true during very transient pressure gradient reversals, such as during coughing, sneezing, squatting, defecation, or micturition.
  • a shunt with a flow lumen length of 6 to 30 mm, or more typically 10 to 15 mm, by virtue of its increased lumen length, will have less tendency for paradoxical embolization than an orifice-plate mesh shunt.
  • FIG. 7 A is a plan view of the right atrial side of atrial septum 70, including implantation site 71 located at a central position of fossa ovalis 72.
  • implantation site 71 is selected so that the shunt may be implanted spaced apart from the surrounding limbus 73, inferior vena cava (IVC) 74, and atrial septum 75.
  • IVC inferior vena cava
  • flared end region 14 is configured to be implanted in right atrium 76 and may be tapered so as to have a more cylindrical shape than does flared end region 18, which is configured to be implanted in left atrium 77.
  • the more cylindrical shape of flared end region 14 may reduce or inhibit contact between flared end region 14 and limbus 73 of fossa ovalis 72, that is, between flared end region 14 and the prominent margin of the fossa ovalis, while still anchoring device 10 across atrial septum 75.
  • the more cylindrical shape of flared end region 14 further may reduce or inhibit contact between flared end region 14, and the right side of atrial septum 70, as well as ridge 77 separating the coronary sinus from the IVC 74 (shown in FIG. 7A but not FIG. 7B).
  • a preferred location for shunt implantation may be slightly anterior to the centerline of the long axis of the fossa ovalis, i.e., located on the right hand side of the ovale. This location leaves potential space in the upper left quadrant (posterior- superior) of the fossa, which has been found to be optimal for crossing the fossa to perform structural heart disease procedures on the mitral valve, including edge-to-edge repair with MitraClip® transcatheter mitral valve repair system offered by Abbott, Abbott Park, IL and mitral annuloplasty with Cardioband, offered by Valtech Cardio, Or Yehuda, Israel.
  • This preferred location also leaves potential space in the lower left quadrant (posterior-inferior) of the fossa, which has been found to be optimal for crossing the fossa to perform structural heart disease procedures to occlude the left atrial appendage.
  • shunt 10 preferably is configured so as to avoid imposing significant mechanical forces on atrial septum 75, thus allowing the septum to naturally deform as the heart beats.
  • the thicknesses of muscular areas of septum 75 may change by over 20% between systole and diastole. It is believed that any significant mechanical constraints on the motion of atrial septum 75 in such areas would lead to the development of relatively large forces acting on the septum and/or on atrial tissue that contacts shunt 10. Such forces could invoke an inflammatory response and/or hyperplasia in the atrial septum tissue, and possibly cause shunt 10 to eventually lose patency.
  • the hourglass shape of shunt 10 is expected to be sufficiently stable so as to be retained in the septum, while reducing mechanical loads on the surrounding atrial septum 75. Tissue ingrowth from atrial septum 75 in regions 78 may further enhance binding of shunt 10 to the septum.
  • neck region 16 of shunt 10 is significantly narrower than flared end regions 14 and 18, shunt 10 will “self-locate” in a puncture through atrial septum 75, particularly when implanted through the fossa ovalis, with a tendency to assume an orientation where its longitudinal axis is substantially orthogonal to the FO.
  • neck region 16 may have a diameter suitable for implantation in the fossa ovalis, e.g., that is smaller than the fossa ovalis, and that also is selected to inhibit blood flow rates exceeding a predetermined threshold.
  • Neck region 16 preferably provides a passage having a diameter between about 4 and about 7 mm, and more preferably between about 5 mm and about 6.5 mm.
  • diameters of less than about 4 mm may in some circumstances not allow sufficient blood flow through the shunt to decompress the left atrium, and may reduce long-term patency of the shunt.
  • diameters of greater than about 7 mm may allow too much blood flow, resulting in right ventricular volume overload and pulmonary hypertension.
  • the effective diameter at the narrowest point in shunt 10 is about 5 mm to 6.5 mm.
  • flared end regions 14 and 18 further may be selected to stabilize shunt 10 in the puncture through atrial septum 45, e.g., in the puncture through fossa ovalis 72.
  • flared end region 18 may have a diameter of 10 to 20 mm at its widest point, e.g., about 13 to 15 mm; and flared end region 14 may have a diameter of 9 to 15 mm at its widest point, e.g., about 9 to 13 mm.
  • the largest diameter of flared end region 14 may be selected so as to avoid mechanically loading the limbus of the fossa ovalis 72, which might otherwise cause inflammation.
  • the largest diameter of flared end region 18 may be selected so as to provide a sufficient angle between flared end regions 14 and 18 to stabilize shunt 10 in the atrial septum, while limiting the extent to which flared end region 18 protrudes into the left atrium (e.g., inhibiting interference with flow from the pulmonary veins), and providing sufficient blood flow from the left atrium through neck region 16.
  • the length of end region 14 is selected to protrude into the right atrium by a distance sufficient to inhibit tissue ingrowth that may otherwise interfere with the operation of shunt 10.
  • tissue ingrowth inwards along an impermeably membranes of specified biomaterials from the end that contacts tissue generally stops after about 3 mm.
  • the distance R between the narrowest portion of neck region 16 and the end of region 14 should be at least 3 mm plus half of the thickness of the septal region, i.e., fossa ovalis, contacting the exterior of shunt 10.
  • the minimum distance R should be about 4.5 mm, based on applicants’ observations.
  • end region 18 preferably does not significantly engage the left side of atrial septum 75, so that distance L also preferably is at least 4.5 mm.
  • each distances R and L preferably fall within a range of 3 to 6 mm. Accordingly, for some embodiments, the overall dimensions of shunt 10 may be about 9-12 mm long (L+R, in FIG.
  • FIGS. 8A and 8B the expected healing response invoked by implanting shunt 10 of FIGS. 1A-1C orthogonally across the FO is described, while FIGS. 9A and 9B correspond to implantation of the shunt non-orthogonally so that an outer surface of the LA entry cone contacts the atrial septal tissue.
  • FIGS. 8 A and 9 A depict positioning of the shunts immediately post implantation, while FIGS. 8B and 9B depict shunt positioning after the completion of the healing phase.
  • the FO is shown as bowed towards the RA and concave towards the LA.
  • the FO portion of the interatrial septum In patients with dilated cardiomyopathy or restrictive physiology, including most patients with left ventricular failure, regardless of etiology, the FO portion of the interatrial septum generally is bowed toward the right atrium. This gives the LA a generally concave or near hemispherical shape in the region centered on the FO.
  • the LA volume In measurements of more than 100 patients exhibiting heart failure with preserved ejection fraction (HFpEF), the LA volume generally averaged 85 ml with a minimum volume of 54 ml, while for a like number of patients exhibiting heart failure with reduced ejection fraction (HFrEF), the LA volume generally averaged 104 ml with a minimum volume of 71 ml.
  • HFpEF preserved ejection fraction
  • HFrEF reduced ejection fraction
  • the LA is often approximated by a sphere or an ellipsoid, there are frequently exceptions to this, for example, where the LA appears squashed when viewed in its anterior-posterior dimension.
  • the RA appeared to be similar in size to the LA.
  • RA bowing of septal anatomy occur, they generally do so in the presence of isolated right ventricular failure or severe pulmonary hypertension in the absence of left ventricular dysfunction or mitral valve disease, e.g. as occurs in pulmonary arterial hypertension (PAH).
  • PAH pulmonary arterial hypertension
  • RA pressure tends to exceed LA pressure causing the FO to bow in the opposite direction toward the LA.
  • Such patients generally would derive no clinical benefit from left-to-right interatrial shunting.
  • patients with severe pulmonary hypertension in the absence of left-sided heart failure may benefit from right-to-left shunting as a means to improve low systemic cardiac output.
  • Several of the embodiments described in this disclosure would provide improved performance compared to right-to-left shunts currently available to that population of patients.
  • Another geometrical constraint is the frequent presence or need to place transvenous endocardial electrical pacing or defibrillation leads in or through the RA of heart failure patients.
  • V-Wave Nitzan-type shunt 74% of patients had already been implanted with cardiac rhythm management devices prior to interatrial shunting. Most of these patients had 2 or 3 such electrical leads placed. Leads most often enter the RA from the superior vena cava (SVC).
  • SVC superior vena cava
  • Right atrial pacing leads usually loop up and terminate anterio-laterally in the RA appendage, but in some circumstances, they are attached to a muscular portion of the interatrial septum.
  • IVC inferior vena cava
  • Leads are usually left with enough slack so that they do not put tension on their terminal ends when the heart moves or changes position. Much of this slack results in a web of excess lead body material that is often concentrated in the RA.
  • a shunt protrudes into the LA chamber it preferably is placed so that it generally projects orthogonally with respect to the FO as shown in FIG. 8 A. Orthogonal placement is expected to minimize impingement on other adjacent or nearby critical cardiac structures, such as the aortic root, the mitral valve annulus, the roof and the posterior wall of the LA, and the pulmonary veins. Alternatively, if not placed substantially orthogonally, as shown in FIG. 9A, the shunt geometry should be selected to prevent the shunt from interacting with these structures.
  • the shunt should also occupy minimal space within the LA and only minimally disturb its normal flow pattern.
  • the LA fills from the pulmonary veins during ventricular systole and drains into the left ventricle when the mitral valve opens during diastole. Blood coming from the right superior pulmonary veins tends to course along and hug the interatrial septum preventing stasis near the FO.
  • the volume of blood displaced by the portion of the shunt protruding into the LA i.e., the volume of blood in the portion of the shunt lumen protruding into the LA, should be less than or equal to 5% of the LA diastolic volume expected in the patient population. This is typically 2.0 ml or less in adult patients with heart failure.
  • the shunt should not protrude into the LA by more than 15 mm, or more typically 3 to 10 mm.
  • the shunt should occupy a minimal volume and have only a small effect on normal flow patterns.
  • the same occupying volume and protrusion distance considerations apply to the RA side of the shunt, that is, the device and its lumen should occupy less than or equal to 5% of the RA diastolic volume, e.g., 2.0 ml or less in adult patients with heart failure, and protrude into the RA by no more than, for example, 15 mm, or more typically 3 to 10 mm.
  • These dimensional considerations can also be accomplished in conjunction with other shunt features that facilitate a substantially orthogonal orientation, such as RA exit funnel.
  • RA to LA shunting e.g., pulmonary arterial hypertension (PAH).
  • PAH pulmonary arterial hypertension
  • the shunt should protrude in the RA the least amount necessary so that it does not foul pacing leads or abrade their electrical insulation.
  • VTE venous thromboembolism
  • the path of flow in the adult RA is complex because blood enters the chamber from multiple sources which include the inferior vena cava (IVC), the superior vena cava (SVC), the coronary sinus and from the LA through the shunt.
  • IVC inferior vena cava
  • SVC superior vena cava
  • These flow paths include directional changes and asymmetries whose topology has been assessed by color flow Doppler imaging and more recently from magnetic resonance velocity mapping.
  • this flow pattern of blood downwards from the roof of the RA and along the interatrial septum reduces the risk of blood pooling in the vicinity of neck region 16 of the inventive shunt 10, thus reducing the risk of local thrombus formation due to blood stasis.
  • these flow pathway observations suggest that a thrombus originating from inferior vena cava will a have a trajectory that passes very close to the RA orifice of a naturally occurring secundum type atrial septal defect or an orifice-plate mesh type shunt.
  • any thrombus arriving from the inferior vena cava is essentially delivered to such a septal orifice by the flow path within the RA, so that even a small reversal of shunt flow could embolize the thrombus across the orifice into the LA.
  • a preferred embodiment of an inventive shunt includes an exit port (end region 14) that extends a distance into the RA, e.g., 3 to 15 mm, or more typically 5 to 10 mm, sufficient to place the orifice of the exit port out of the naturally occurring flow paths in the RA.
  • the exit port projects partially or completely through the stream of blood originating from the IVC that loops down across the interatrial septum.
  • shunt 80 of FIG. 10 includes anchor 81, which may be employed to register conduit 82 within the interatrial septum.
  • Conduit 82 may include a separate encapsulated tubular frame or may comprise a tube of solid material, and may include a variety of geometries to achieve specific characteristics as previously described.
  • Anchor 81 and conduit 82 may be physically affixed to each other prior to insertion in the body by mechanical interference, welding, adhesives, or other well-known means, and preferably includes a skirt that prevents bypass flow between anchor 81 and conduit 82.
  • anchor 81 may be delivered across the septum deployed, and then conduit 82 may be inserted through and deployed within anchor 81 and held in place by mechanical interference or expansion with a balloon.
  • the advantages of such a two-part design are two-fold. First, pannus will grow thick only on the outside surface of anchor 81 because the LA and RA ends of conduit 82 are offset from, and thus do not contact, adjacent cardiac structures.
  • the design creates a longest straight channel for high velocity flow, but limits the ability of paradoxical emboli to transit conduit 82 during a transient pressure gradient reversal.
  • the dimensional aspects noted above with respect to the description of shunt 10 of FIG. 1C above may be applied to shunt 80.
  • FIG. 11 illustrates another preferred embodiment with benefits similar to that of the shunt of FIG. 10.
  • shunt 90 may include anchor 91 as described above with the respect to frame 12 of the embodiment of FIGS. 1A-1C.
  • Conduit 92 may include flared end regions as described above, e.g., to form an hourglass shape in the deployed state.
  • the specific shape of the flared end regions may be conical, parabolic, or horned shaped, and may be present at either or both ends of the shunt device depending on the desired hydraulic properties.
  • the dimensional aspects noted above with respect to the description of shunt 10 of FIG. 1C above may be applied to shunt 90.
  • the shunt types depicted in FIG 10 and FIG 11, or shunts with similar characteristics that would be apparent to one of ordinary skill in the art, may be particularly applicable to the clinical situation where too large an aperture defect has been created in the FO and where interatrial shunting to treat heart failure is required.
  • a repair procedure on the mitral valve e.g. MitraClip® of mitral annuloplasty by the percutaneous transseptal approach, followed by interatrial shunt placement.
  • These mitral valve procedures currently use a 23Fr I.D. ( ⁇ 8 mm O.D) guiding catheter to cross the FO.
  • an anchor with an outer minimal diameter matching the larger aperture defect caused by the prior procedure may be implanted, wherein the conduit as a smaller diameter desirable for shunting (e.g. 5.0 to 6.5 mm).
  • a smaller diameter desirable for shunting e.g. 5.0 to 6.5 mm.
  • shunts advantageously may be used where, during the transseptal procedure, the fossa ovalis has been torn, thus creating a larger aperture defect than required for various shunt embodiments described with respect to FIGS. 1 to 5.
  • a shunt of the kind described with respect to FIGS. 10 or 11 could be used to address such a situation.
  • FIGS. 12-15 show further alternative shunt embodiments 95, 100, 110 and 120, respectively that use different shunt geometries in combination with anchors and anchoring tabs.
  • the conduits of these shunts may be cylindrical, conical or have other lumen geometries as previously described herein.
  • anchor 95 suitable for use in an inventive shunt includes flared region 96 configured for deployment in the left atrium and substantially cylindrical region 97 that extends through the atrial septum and into the right atrium.
  • Flexible struts 98 bend distally, i.e., towards the septum when the anchor is released from its delivery sheath, and preferably include U-shaped inverted ends that contact, but do not penetrate, the right atrial wall in the fully deployed position, as depicted in FIG. 12.
  • anchor 95, other than flexible struts 98 includes a conduit formed by encapsulating the anchor with polymeric material that prevents tissue ingrowth from obstructing the lumen of cylindrical region 97, and may be made of a biocompatible shape memory alloy, as described for preceding embodiments.
  • Shunt 100 of FIG. 13 may include a plurality of collapsible tab-like retention elements 101 disposed on the RA region of a cylindrical shunt. Retention elements 101 are designed to engage the FO to prevent migration/embolization of shunt 100 into the LA or beyond. With a much-thickened FO, retention elements 101 may become buried within the FO wall itself.
  • shunt 100 may include conical anchor 102 extending at an angle into the LA from the LA side 103 of shunt 100, similar in construction to flared end region 18 of frame 12 of the embodiment of FIGS. 1A-1C. The advantage of this configuration is that it may be deployed in an FO that has any wall thickness (typically up to 10 mm). The other dimensional aspects noted above with respect to the description of shunt 10 of FIG. 1C above may be applied to shunt 100.
  • shunt 110 is similar in construction to shunt 100 and includes retention elements 111 on the RA side, but omits conical anchor 102 on the LA side. Instead, shunt 110 may include plurality of collapsible tabs 112 on LA side 113 of the shunt designed to offset cylindrical shunt 110 from the FO or other cardiac structures.
  • An advantage of this configuration is that there is less structure occupying the free space in the LA.
  • the other dimensional aspects of shunt 10 of FIG. 1C above may be applied to shunt 110.
  • shunt 120 comprises an encapsulated expanded LA side 121, and a simple cylinder on RA side 122 that includes a plurality of retention elements 123.
  • An advantage of this configuration is that shunt 120 may be constructed from a singular tubular frame. The other dimensional aspects of shunt 10 of FIG. 1C above may be applied to shunt 120.
  • FIGS. 16A and 16B anchor 130 of an alternative embodiment of a shunt constructed in accordance with the principles of the present disclosure is described.
  • Anchor 100 is similar to anchor 12 of the embodiment of FIGS. 1A-1C, but further includes a plurality of flexible arms 131 attached to the circumferential strut nearest the exit port in the right atrium.
  • Flexible arms 131 self-expand when the shunt is deployed to form a meshwork or filter that partially obstructs the exit port of the shunt.
  • flexible arms 131 unfold to extend across the lumen in the vicinity of the lumen of the RA exit port, ideally near the location of its widest opening, to form a filter that prevents larger paradoxical emboli from passing into the left atrium.
  • Flexible arms 131 permit blood to pass in either direction with minimal resistance while excluding the passage of paradoxical emboli that are generally larger than the mesh size, e.g., venous thromboemboli above a certain size, which may be on a paradoxical trajectory.
  • the size of the emboli excluded is determined by the geometry of mesh. Prior to deployment, these arms may also serve as locations of attachment of the shunt to its delivery system.
  • flexible arms 131 comprise struts that fold across the exit port of anchor 130 upon deployment
  • flexible arms 130 may take any of a number of configurations, including a plurality or multiplicity of bars or arches that fold across the exit port to create a filter.
  • larger paradoxical emboli could be excluded by having a plurality of passageways or lumina through the shunt device.
  • FIG. 17 is a graph depicting the effects of orifice size on the flow characteristics, e.g., bench testing quantified flow vs. pressure relationships, of two types of V-Wave Nitzan-type shunts as described in the above-incorporated application. Measurements were made in saline at 37 degrees Celsius, under constant pressure gradient conditions over the expected range of left- to-right pressure gradients. Flow was measured for the V-Wave 5.1 mm inner diameter orifice Nitzan-type hourglass-shaped valveless shunt and for a 6-mm inner diameter orifice valveless version of the shunt built upon the same nitinol frame. As depicted in FIG.
  • the 6-mm shunt has about 35% more flow than the 5 mm valved shunt. Also shown in FIG. 17, is the simulated flow for venturi tubes with orifice inner diameters of 5.1 and 6 mm with discharge coefficients of 0.97 and 0.96 respectively. These data suggest that the performance of the valveless hourglass shunts is closely approximated by a classical venturi. Simulations of a conical convergent nozzle (not shown) with a convergence angle of 37 and 36 degrees and a discharge coefficient of 0.92 for the 5.1 and 6 mm orifice inner diameters, respectively, showed similar predictive accuracy with actual shunts.
  • FIG. 6 that figure depicts theoretical flows for a 5.1 mm and 6.0 mm venturi tube (discharge coefficient 0.97 and 0.96, respectively), as described above, along with flows through 6.4 mm and 7.5 mm orifice plates (discharge coefficient 0.61), respectively.
  • an orifice plate device requires an inner diameter of 7.5 mm to have flow characteristics similar to a 6 mm venturi tube.
  • an orifice plate device requires an inner diameter of about 6.4 mm to have flow characteristics similar to f a 5.1 mm venturi tube.
  • an hourglass-shaped shunt permits a smaller orifice than an orifice-plate shunt with similar bulk flow capacity (7-8 mm in diameter).
  • the smaller orifice prevents proportionally larger thrombi from passing retrograde through the shunt and into the systemic circulation. Since ischemic damage from the lodging of embolus is limited to the watershed organ territory supplied by the occluded vessel, larger emboli tend to cause more damage and have more associated dangerous consequences, especially when the occluding vessel supplies the brain.
  • paradoxical embolic strokes if they occur, are likely to be smaller than with an orifice-plate mesh type shunt.
  • a shunt having a discharge coefficient of 0.70 or greater will, by virtue of its smaller diameter or area orifice, have less tendency for paradoxical embolization than an orifice- plate mesh shunt with similar flow characteristics.
  • the self-expanding shunts described herein may be implanted using a variety of delivery methods.
  • the percutaneous placement of self-expanding devices across the atrial septum, or for that matter, across any cardiovascular structure that forms a barrier or wall with or without a pre-existing naturally occurring defect or orifice or a procedurally created defect dividing one hollow viscus from another requires device-specific delivery systems that may cross the dividing barrier or orifice while keeping the device constrained and which may control the expansion of the device in the correct location in a secure way so as to minimize the risk of device misplacement or free embolization of the device.
  • the desired barrier e.g., the fossa ovalis of the atrial septum
  • the transseptal catheterization procedure may be performed from any suitable venous access site and may be guided by echocardiographic and/or fluoroscopic imaging.
  • a guidewire may then be positioned to cross into the hollow viscus, e.g., the left atrium, distal to the barrier.
  • the transseptal system may then be exchanged over the guidewire and replaced with the device-specific delivery system.
  • an outer introducer sheath having a conical shaped dilator protruding distally therefrom may be delivered across the atrial septum to enlarge the defect created by the transseptal crossing.
  • the dilator may be withdrawn.
  • the dilator may be extended.
  • the guidewire may be withdrawn, or alternatively, the guidewire may remain positioned across the atrial septum.
  • the self-expanding shunt may be constrained and advanced through the lumen of the introducer sheath, e.g., a cylindrical sleeve, with a reduced diameter so that it may easily be advanced across the atrial septum.
  • the shunt may be pre-constrained within the sheath at the time of manufacture or may be loaded into the sheath at the time of the delivery/deployment procedure.
  • the shunt may be mechanically coupled to a delivery catheter, e.g., a flexible tether having an inner mandrel on which the shunt is concentrically constrained.
  • the mandrel/tether may be used either to advance the shunt or retract it, or both, depending on the deployment procedure or the need to recover a partially or fully expanded device.
  • the mechanical coupling apparatus preferably is reversible to allow for decoupling of the mandrel/tether from the shunt at the desired time.
  • coupling mechanisms may include screw type threaded couplings, ball and releasable socket couplings, moveable hook/eyelet couplings, or any other suitable type of mechanical interference couplings that may be controlled remotely to maintain the shunt in a constrained configuration within the outer introducer sheath.
  • the delivery catheter may be coupled at its proximal end to a control handle external to the patient that allows the operator to independently manipulate the sheath, mandrel/ tether, and coupling mechanism in the desired sequence needed for delivery.
  • an exemplary method for implanting an hourglass-shaped shunt e.g., shunt 10
  • a transseptal puncture may be created, e.g., via a transseptal needle, resulting in a procedurally created defect across atrial septum AS, e.g., at the location of fossa ovalis FO.
  • guidewire 1801 may be placed across the orifice into the left atrium.
  • the delivery apparatus may include outer catheter sleeve/introducer sheath 1802, delivery catheter 1804, e.g., a mandrel/tether combination apparatus having distal conical dilator tip 1806 and coupling mechanism 1808, slidably moveable within the lumen of sheath 1802, and shunt 10 removably coupled to coupling mechanism 1808 of delivery catheter 1804 in a collapsed delivery state.
  • shunt 10 may be coupled to coupling mechanism 1808 by interference fit, such that delivery catheter 1804 may advance and/or retract shunt 10 within the lumen of sheath 1802.
  • the delivery apparatus may be advanced from the site of venous access over guidewire 1801 until the distal end of sheath 1802 is disposed within the left atrium. Delivery catheter 1804 may then be advanced into the left atrium (in the direction of the arrow) while sheath 1802 is maintained in position relative to atrial septum AS, to create sufficient space between the proximal end of conical dilator tip 1806 and the distal end of sheath 1802, as shown in FIG. 18A.
  • delivery catheter 1804 may be further advanced into the left atrium (in the direction of the arrow) while sheath 1802 is maintained in position relative to atrial septum AS, by a specific displacement amount relative to sheath 1802.
  • this displacement amount advances shunt 10 within the lumen of sheath 1802 such that flared end region 18 of anchor 12 of shunt 10 is exposed beyond the distal end of sheath 1802 within the left atrium.
  • flared end region 18 self-expands from the collapsed delivery state to an expanded deployed state within the left atrium.
  • the specific displacement amount may be limited by a control mechanism in the region of the control handle (not shown).
  • shunt 10 may be retracted into the lumen of sheath 1802 via coupling mechanism 1808 of delivery catheter 1804 if delivery catheter 1804 is advanced too far relative to sheath 1802.
  • sheath 1802 and delivery catheter 1804 coupled to shunt 10 may be withdrawn as a unit (in the direction of the arrow) proximally until flared end region 18 contacts the left atrial side of fossa ovalis FO.
  • FIG. 18D illustrates the final stage of shunt deployment. While the operator maintains strict stationary positioning of guidewire 1801 and delivery catheter 1804 (indicated by the opposing arrows), sheath 1802 is retracted proximally (in the direction of the arrow) exposing flared end region 14 of anchor 12 of shunt 10. Once correct positioning of shunt 10 at atrial septum AS is confirmed via, e.g., echocardiographic or fluoroscopic imaging, coupling mechanism 1808 may be decoupled from flared end region 14, such that flared end region 14 self-expands from the collapsed delivery state to an expanded deployed state within the right atrium.
  • coupling mechanism 1808 may be decoupled from flared end region 14, such that flared end region 14 self-expands from the collapsed delivery state to an expanded deployed state within the right atrium.
  • neck region 16 of anchor 16 of shunt 10 will be lodged with the orifice of fossa ovalis FO.
  • Conical dilator tip 1806 of delivery catheter 1804 and guidewire 1801 may then be withdrawn towards the right atrium through the passageway of shunt 10, and sheath 1802, delivery catheter 1804, and guidewire 1801 may be removed from the patient’s body.
  • exemplary method 1900 for implanting an hourglass shaped shunt e.g., shunt 10.
  • a transseptal puncture may be created, e.g., via a transseptal needle, resulting in a procedurally created defect across atrial septum AS, e.g., at the location of fossa ovalis FO.
  • guidewire 2001 may be placed across the orifice into the left atrium.
  • the delivery apparatus may include outer catheter sleeve/introducer sheath 2002, delivery catheter 2004, e.g., a mandrel/tether combination apparatus having coupling mechanism 2006, slidably moveable within the lumen of sheath 2002, and shunt 10 removably coupled to coupling mechanism 2006 of delivery catheter 2004 in a collapsed delivery state.
  • shunt 10 may be coupled to coupling mechanism 2006 by interference fit, such that delivery catheter 2004 may advance and/or retract shunt 10 within the lumen of sheath 2002.
  • coupling mechanism 2006 may include a plurality of retractable hooks for releasably engaging with shunt 10, as described in, for example, U.S. Patent No. 9,713,696 to Yacoby and/or U.S. Patent Publication No. 2020/0315599 to Nae, the entire contents of each of which are incorporated herein by reference.
  • sheath 2002 may be advanced over guidewire 2001 across the orifice into the left atrium such that the distal end of sheath 2002 is disposed within the left atrium.
  • Sheath 2002 may be advanced across the orifice of fossa ovalis FO with a removable conical tip dilator (not shown) to dilate the orifice, and the dilator tip may be removed through the lumen of sheath 2002.
  • a loading apparatus may be used to constrain the diameter of shunt 10 within sheath 2002.
  • delivery catheter 2004 coupled to shunt 10 may be advanced through the lumen of sheath 2002, e.g., over guidewire 2001.
  • delivery catheter 2004 may be advanced to first stopping point A within the lumen of sheath 2002, as shown in FIG. 20A.
  • the distal end of shunt 10 may be within 1 to 5 cm proximal to the distal end of sheath 2002.
  • Correct positioning of delivery catheter 2004 at first stopping point A may be determined by the operator based on, e.g., fluoroscopic or echocardiographic visualization of shunt 10 relative to the distal end of sheath 10.
  • correct positioning of delivery catheter 2004 at first stopping point A may be determined by fiducial markings on delivery catheter 2004, or by some portion of delivery catheter 2004 reaching a mechanical stopper.
  • shunt 10 is fully constrained within sheath 2002 such that the distal end of shunt 10 is positioned within 1 to 5 cm, or preferably 1 to 3 cm, from the distal end of sheath 2002.
  • the operator may confirm that the distal end of sheath 2002 is positioned a predetermined distance, e.g., 1 to 3 cm, beyond the barrier, e.g., fossa ovalis FO within the left atrium, such that the distal end of sheath 2002 is not in proximity to more distal cardiac structures, e.g., the pulmonary veins, the left atrial appendage, the mitral valve or the left ventricular cavity. Moreover, the operator may further confirm that the distal end of sheath 2002 has not been inadvertently withdrawn back across fossa ovalis FO into the right atrium, or more proximally.
  • a predetermined distance e.g., 1 to 3 cm
  • this may be determined by injecting agitated saline through a proximal port of delivery catheter 2004 or of sheath 2002, and observing the location of microbubbles exiting the distal end of sheath 2002, e.g., via 2- dimensional ultrasonic imaging, or alternatively, by injecting radiographic contrast material through a proximal port of delivery catheter 2004 or of sheath 2002, and observing the location of radiographic contrast material exiting the distal end of sheath 2002, e.g., by fluoroscopy.
  • delivery catheter 2004 may be advanced to second stopping point B within the lumen of sheath 2002, as shown in FIG. 20B.
  • flared end region 18 of anchor 12 of shunt 10 protrudes beyond the distal end of sheath 2002.
  • flared end region 18 self-expands from the collapsed delivery state to an expanded deployed state within the left atrium.
  • the specific displacement amount may be limited by a control mechanism in the region of the control handle (not shown).
  • the operator may manually control the amount of displacement of the shunt, via coupling mechanism 2006 of delivery catheter 2004. Accordingly, shunt 10 may be retracted into the lumen of sheath 2002 via coupling mechanism 2006 of delivery catheter 2004 if delivery catheter 2004 is advanced too far relative to sheath 2002.
  • step 1910 while guidewire 2001 is maintained stationary relative to atrial septum AS, sheath 2002 and delivery catheter 2004 coupled to shunt 10, are withdrawn as a unit proximally, e.g., to third stopping point C, until flared end region 18 contacts the left atrial side of fossa ovalis FO, as shown in FIG. 20C.
  • Tension applied to the left atrial side of fossa ovalis FO by flared end region 18 of shunt 10 may be observed, e.g., by ultrasonic imaging, as bowing of fossa ovalis FO toward the right atrium, also known as “reverse tenting.”
  • coupling mechanism 2006 of delivery catheter 2004 may be decoupled from shunt 10.
  • FIG. 20D illustrates the final stage of shunt deployment.
  • sheath 2002 may be retracted (in the direction of the arrow) until the counterforce exerted by shunt tension on fossa ovalis OA and septal tissues overcomes the friction of neck region 16 and flared end region 14 of shunt 10 retained within sheath 10, effectively pulling the retained portions of shunt 10 out of sheath 2002.
  • only guidewire 2001 needs to be maintained in position (indicated by the opposing arrows), while sheath 2002 and delivery catheter 2004 may be moved relative to atrial septum AS.
  • the operator need not maintain the position of shunt 10 via delivery catheter 2004 during shunt deployment.
  • the force (FI) required to unsheathe neck region 16 and flared end region 14 of the shunt 10 must be less than the force (F2) required to retract and re-constrain flared end region 18 of shunt 10 within sheath 2002, e.g., cause flared end region 18 to transition from the expanded state to the contracted state.
  • F2 force required to retract and re-constrain flared end region 18 of shunt 10 within sheath 2002, e.g., cause flared end region 18 to transition from the expanded state to the contracted state.
  • F2 may range from 12 to 16 Newtons.
  • the yield stress of fossa ovalis FO and atrial septum AS must also exceed FI. Accordingly, the septal anatomy in close proximity to the orifice of fossa ovalis FO accurately registers the optimal positioning of flared end region 18 at all times during the deployment of flared end region 14 of shunt 10, thereby assuring safe and accurate shunt deployment.
  • flared end region 14 of shunt 10 will be exposed from the distal end of sheath 2002, such that flared end region 14 self-expands from the collapsed delivery state to an expanded deployed state within the right atrium. Accordingly, neck region 16 of shunt 10 will be lodged within the orifice of fossa ovalis FO.
  • This “drag-and-drop” delivery procedure provides reliable, repeatable shunt deployment.
  • guidewire 2001 may then be withdrawn towards the right atrium through the passageway of shunt 10, and sheath 2002, delivery catheter 2004, and guidewire 2001 may be removed from the patient’s body.
  • blood may be shunted via the passageway of shunt 10 between the left and right atria, e.g., responsive to a pressure differential across atrial septum AS.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Surgery (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Medical Informatics (AREA)
  • Molecular Biology (AREA)
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  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Prostheses (AREA)

Abstract

L'invention concerne des systèmes et des méthodes d'implantation d'une dérivation pour réguler la pression sanguine entre les oreillettes gauche et droite d'un patient. La dérivation comprend un ancrage ayant une région de col, des première et seconde régions d'extrémité, et un conduit fixé à l'ancrage formé d'un matériau biocompatible qui est résistant à la croissance tissulaire transmurale et de translation et qui réduit un risque d'embolie paradoxale. La dérivation peut être avancée à travers la gaine jusqu'à ce que la première région fasse saillie à partir de la gaine et s'auto-dilate à l'intérieur de l'oreillette gauche. La dérivation et la gaine peuvent ensuite être rétractées jusqu'à ce que la première région entre en contact avec le côté gauche du septum auriculaire. La gaine peut en outre être rétractée jusqu'à ce que la force antagoniste exercée par la tension de dérivation sur le septum auriculaire surmonte le frottement des parties retenues de la dérivation de telle sorte que la seconde région soit exposée à partir de la gaine et s'auto-dilate à l'intérieur de la seconde oreillette.
PCT/IB2022/051177 2021-02-12 2022-02-09 Dérivation pour redistribution du volume sanguin auriculaire WO2022172179A1 (fr)

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US17/175,549 US20210161637A1 (en) 2009-05-04 2021-02-12 Shunt for redistributing atrial blood volume
US17/175,549 2021-02-12

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US6120534A (en) 1997-10-29 2000-09-19 Ruiz; Carlos E. Endoluminal prosthesis having adjustable constriction
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