WO2004049957A2

WO2004049957A2 - Apparatus and methods for minimally invasive harvesting of a vascular conduit

Info

Publication number: WO2004049957A2
Application number: PCT/US2003/038618
Authority: WO
Inventors: Amir Belson; Scott C. Anderson; Christopher A. Julian; Kevin H. Van Bladel; Matt Ohline
Original assignee: Osiro Vascular
Priority date: 2002-12-04
Filing date: 2003-12-04
Publication date: 2004-06-17
Also published as: AU2003298905A1; WO2004049957A3

Abstract

The vessel harvesting apparatus includes a balloon catheter, a coaxial cannula with a vessel dissecting and sidebranch separating mechanism and a visualization subsystem. The balloon catheter is first inserted into the vessel to be removed and the balloon is inflated to hold the vessel. The cannula portion of the apparatus is positioned coaxially over the balloon catheter. The cannula is positioned around the outside of the vessel. The cannula is advanced to separate the main vessel from the surrounding tissue. Optionally, the cannula may include a dissecting mechanism to assist in separating main vessel from the surrounding tissue. Optionnally, the cannula may include a dissecting mechanism to assist in separating main vessel from the surrounding tissue. The cannula applies a metal clip, a ligating suture and/or electrocautery to the sidebranch and severs it from the harvest vessel.

Description

APPARATUS AND METHODS FOR MINIMALLY INVASIVE HARVESTING OF A VASCULAR CONDUIT

FIELD OF THE INVENTION The present invention relates to apparatus and methods for harvesting a vascular conduit, such as a vein or artery, or other elongate anatomical structures using minimally invasive surgical techniques. The harvested vascular conduit is particularly useful as a vascular graft.

BACKGROUND OF THE INVENTION The saphenous vein is the most commonly used vascular graft for coronary artery bypass grafting (CABG). The use of the saphenous vein is specifically preferred by some surgeons in emergency situations, in patients with poor ventricular function, and in aged patients. Because the saphenous vein is abundant, easy to handle, and has superior flow rates when compared to other available vessels, use of the saphenous vein graft has benefited many patients undergoing a coronary artery bypass procedure. The saphenous vein is often needed as a graft for performing multiple bypasses, even when a different vessel, such as the internal mammary artery, is used as a primary graft. Free or pedicled graft vessels may also be used for peripheral vascular bypass.

However, the surgical procedure used to harvest the saphenous vein prior to its use as a coronary artery bypass graft may be traumatic to the patient. The harvesting procedure also lengthens the overall time and increases the cost of a coronary bypass operation. A long continuous incision down the entire length of the inside of the leg is the standard method to expose and harvest the greater saphenous vein. Main complications of the large wound such as skin loss or infections result in significant morbidity for approximately 1% of patients and frequently cause prolonged hospitalization. Other complications, such as impaired wound healing, saphenous nerve damage, hematomas, prolonged lymphatic drainage, fat necrosis with cellulitis, and chronic edema, can occur at rates exceeding 20% and are particularly costly and traumatic for a patient who has also undergone cardiac surgery. Moreover, many patients who do not suffer main complications still experience lower extremity discomfort lasting 4-6 months after the harvesting procedure. Also, ischemic and/or mechanical injury to the saphenous vein during the harvesting procedure may lead to increased rates of occlusion in the vessel graft in the months and years after the procedure. The saphenous vein is also excised for other medical conditions such as reflux disease that causes varicose veins. There are several non-invasive ways to occlude the vein but the definitive treatment is to take the vein out.

To attempt to overcome those problems, less-invasive techniques for harvesting the vein have been developed that reduce the trauma to the patient. The use of a minimally invasive harvesting procedure and specially designed devices which minimize the trauma to the patient, reduces the chances for infection in the wound, maintains tissue perfusion in surrounding tissues, maintains body temperature and fluid volume during surgery, and reduces the overall length of the incision needed for the harvesting procedure. Most current less-invasive techniques for dissecting the vessel rely on blunt mechanical force to first create a working space in the tissue surrounding the vein, followed by introducing tools for harvesting the vein through a smaller number of discrete incisions. Additional vessel harvesting tools can be introduced through these smaller incision(s) to permit separating the vein from the surrounding tissue and to separate sidebranches of the vessel. However, even where these less-invasive techniques reduce the overall length of the incision, the trauma to the vessel, the surrounding tissue and the patient can be severe. In particular, the operative time of the harvesting procedure may actually be significantly lengthened and the trauma to the vessel potentially increased by the less invasive techniques, in part because a number of tools must be introduced through the incision(s) and frequently exchanged for cleaning or to provide different functions at the site of the harvesting procedure, and because of poor access and poor angle of attack to the worksite.

The increased operative time and the need for multiple steps requiring frequent and repetitive instrument exchanges has proven to be a barrier to adoption of prior minimally invasive vessel harvesting procedures.

The goal of the present invention is to further reduce the trauma to the patient by providing the capability to more rapidly and less traumatically harvest the vein by detaching the vein from surrounding tissue on all sides together with ligating sidebranches in a more expeditious procedure that reduces or eliminates the need to frequently exchange instruments during the procedure. The apparatus and methods of the present invention are also useful for harvesting of other vascular conduits that are used as bypass grafts, such as the internal mammary artery, the brachial artery and the gastroepiploic artery. In addition to graft vessel harvesting, the present invention will also find other applications for vein stripping and perforator vein ligation as a treatment for venous reflux disease, creating fistulas, internal mammary artery takedown, and for harvesting or removing elongate anatomical structures such as tendons, nerves, urethra, ureter, etc.

SUMMARY OF THE INVENTION

The vessel harvesting apparatus of the present invention optionally includes a balloon catheter, a coaxial cannula with a vessel dissecting and sidebranch separating mechanism and a visualization subsystem. The use of the balloon catheter is optional and the cannula could be used without it. The balloon catheter serves as a guide for the cannula to facilitate removal of the vessel. The balloon catheter is first inserted into the vessel to be removed and the balloon is inflated to hold and straighten the vessel. The cannula portion of the apparatus is positioned coaxially over the balloon catheter. The cannula is positioned around the outside of the vessel and can be independently rotated around the vessel. The cannula is advanced to separate the main vessel from the surrounding tissue. Optionally, the cannula may include a dissecting mechanism to assist in separating the main vessel from the surrounding tissue. The cannula rotates, trapping sidebranches within its cutting jaws as the cannula moves forward around the outside of the vessel. The visualization subsystem is preferably positioned to view the cutting jaws to assure the physician they are indeed cutting the correct part of the vessel. The cannula applies a metal clip, a ligating suture and/or electrocautery to the sidebranch and severs it from the harvest vessel. The cannula moves down the entire length of the vessel using the balloon catheter as a guide. Procedure time is reduced dramatically due to the ease in finding and removing sidebranches from the harvested vessel. The catheter could be used to deliver light to the tip. This light could indicate the location of the vein to the surgeon so only a tiny cut would need to be made to cut the distal part of the vein in order to free it.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG 1 is an exploded view illustrating the guidewire, balloon catheter, coaxial cannula and endoscope of the vessel harvesting apparatus.

FIG 2 shows an embodiment of the cannula that includes two endoscope lumens or two built-in imaging devices positioned 180 degrees apart at the distal tip of the cannula. FIG 3 shows an enlarged view of the distal tip of the cannula.

FIG 4 is a cross section of the distal tip of the cannula showing a bipolar coagulating cutter mechanism that uses a scissor action.

FIG 5 is a cross section of an alternate configuration of the distal tip of the cannula showing a bipolar coagulating cutter mechanism that uses a pair of rotating ring-shaped blades.

FIG 6 illustrates a clip applier insertable through an instrument lumen in the cannula.

FIG 7 shows the balloon catheter of the vessel harvesting apparatus inserted into a patient's saphenous vein and inflated to act as a vessel support member.

FIG 8 shows the coaxial cannula being advanced over the balloon catheter to separate the saphenous vein from the surrounding tissue.

FIGS 9-14 show alternative configurations of the cannula.

FIG 15 shows a first embodiment of an additional dissecting mechanism.

FIG 16 shows a second embodiment of an additional dissecting mechanism.

FIGS 17 A and 17B show a third embodiment of an additional dissecting mechanism.

FIG 18 shows an embodiment of the cannula that includes a flexible proximal portion of the shaft.

FIGS 19A-C show further details of the bipolar coagulating cutter mechanism shown in FIG 5.

FIG 20 shows an embodiment of a one shot clip applier insertable through an instrument lumen in the cannula. FIG 21 shows an embodiment of a clip applier built into the cannula shaft with a channel or cassette for holding multiple ligating clips.

FIG 22 shows an end view of an embodiment of the cannula with a trapdoor to facilitate placing the cannula around the vessel without the necessity of transecting it.

FIG 23 shows the cannula of FIG 22 with the trapdoor open to pass the cannula around a vessel.

DETAILED DESCRIPTION OF THE INVENTION Although the precise physiology may vary from patient to patient, the greater saphenous vein generally runs the length of the inner side of the leg in close association with the saphenous nerve and terminates at the groin, where it enters the femoral vein. Prior to harvesting the saphenous vein for a coronary artery bypass procedure, the right or left greater saphenous vein is chosen for removal following a preoperative examination of the legs of the patient. The first priority of the surgeon performing the saphenous vein harvesting procedure is to obtain an adequate length of saphenous vein for the particular bypass procedure to be performed. For example, the total vein length that is required is determined by the number of coronary artery bypasses to be performed and whether one or both internal mammary arteries will be used as grafts. A minimum length of 6 to 8 inches of saphenous vein is harvested for each bypass graft. When adequate segments of a greater saphenous vein cannot be found, the lesser saphenous vein may then be used if it proves of adequate diameter. On rare occasions, suitable segments of vein cannot be found in either leg and another vessel must be found. The cephalic vein can be taken from wrist to shoulder, but its walls are usually thinner than those of the leg veins. Ultimately, a target vessel is identified and the harvesting procedure is planned by selecting a segment or segments of a suitable vessel(s) of an appropriate length for removal. In the following description, the saphenous vein is used as the example with the understanding that other vessels may be harvested using the devices and procedures of the invention.

Preoperative venous mapping also facilitates a minimally invasive surgical dissection and reduces the incidence of wound complications. The initial incision may be made in the ankle or groin region or above or below the knee. The saphenous vein has a larger diameter in the groin region and is less fragile above the knee than below the knee. However, some surgeons prefer to make the initial incision at the ankle because of the ease in locating the vein, better exposure, less crowded workspace, and decreased chance of wound infection because of the distal location from the groin. The apparatus of this invention are introduced through one, or a small number of discrete incisions in any of these locations and are progressively advanced along the length of the vessel to be harvested.

As the instrument is advanced, the main trunk of the saphenous vein is dissected from the surrounding tissue while each side vessel is carefully located and separated from the main vessel. Sidebranches occurring within a segment of the vessel to be harvested are separated at a point close to their entry into the main trunk, typically by the application of a suture, staples or surgical clip to secure the vessel and by severing the side vessel. Pursuant to the invention, a sidebranch may also be separated in a single step by cauterization. The ends of the harvested vessel are identified and secured prior to removal. The vessel is then removed and placed in a basin of heparinized saline, or other preservative solution, until the coronary bypass anastomoses are performed.

FIG 1 is an exploded view illustrating the balloon catheter 200 and the coaxial cannula 300 of the vessel harvesting apparatus. The balloon catheter 200 includes an inflatable balloon 202 mounted on a flexible elongated catheter shaft 204. The catheter shaft 204 may be made of polyethylene, polyurethane, nylon copolymers (e.g. PEBAX) or other known catheter materials. A guidewire lumen, which is sized to fit a coaxial guidewire 100, extends through the catheter shaft 204 from a proximal luer fitting 206 to the distal end 208 of the catheter. The guidewire 100 will typically have a diameter of 0.035 or 0.038 inches. Alternatively, the guidewire lumen may extend through the catheter shaft 204 along the length of the inflatable balloon 202 and exit the catheter shaft 204 at a sideport in the shaft proximal to the balloon. A balloon inflation lumen extends through the catheter shaft 204 from an inflation port located within the inflatable balloon 202 to an inflation fitting 210 on the proximal end of the catheter shaft 204. The inflatable balloon 202 has an elongated cylindrical configuration with a diameter of approximately 5-9 mm and a length of approximately 1-50 cm. The overall length of the catheter shaft 204 is preferably in the range of 50-120 cm. The balloon 202 preferably has a thin- walled construction and may be made from polyethylene, polyurethane, nylon, polyester, latex, silicone or other known catheter balloon materials. The balloon 202 may be pressure compliant or noncompliant. The balloon 202 will preferably have a burst pressure of 5 atmospheres or greater. A range of balloons with different diameters and lengths may be provided for use in various veins. The cannula 300 has a shaft 314 with a generally cylindrical configuration with an outer diameter of approximately 10-16 mm and a length of approximately 40-50 cm. The cannula shaft 314 can be made of plastic or metal. A handle 324 is located at the proximal end of the cannula shaft 314. The cannula shaft 314 has an internal lumen 316 that extends the length of the cannula 300 and is configured to fit coaxially around the vessel to be harvested with the balloon 202 inflated within the vessel. Preferably, the internal lumen 316 has a diameter of approximately 6- 12 mm. The dimensions given are typical for use in saphenous vein harvesting, however, the internal and external dimensions of the cannula 300 may be varied for use on larger or smaller vessels. In addition, the cannula 300 has an endoscope lumen 318 configured to accept an endoscope 400. The endoscope 400 will preferably have a diameter of approximately 1-2 mm and a length of 40-50 cm. The endoscope 400 may utilize conventional fiber optics or rod optics or it may utilize a miniaturized electronic video camera (CCD). Alternatively, the cannula 300 may have a miniaturized electronic video camera, endoscope-type optics or other imaging device built directly into it. In an alternate configuration shown in FIG 2, the cannula 300 may include two endoscope lumens or two built-in imaging devices positioned 180 degrees apart at the distal tip of the cannula 300. Preferably, the endoscope 400 includes a fiber optic illumination device or, alternatively, an illumination device may be built into the cannula 300. Alternatively, the endoscope lumen may have an arcuate configuration so that the endoscope or other visualization device can be moved for selectively viewing structures encountered by the cannula. The illumination device could also be used to indicate the location of the vein to the surgeon so only a tiny cut would need to be made to cut the distal part of the vein in order to free it.

In an alternative embodiment, the cannula 300 may have a straight rod extending down the center of the lumen. The rod follows the guidewire lumen of the balloon catheter 200 to help center the cannula 300 around the inflated balloon 202.

FIG 3 shows an enlarged view of the distal tip of the cannula 300. The distal tip of the cannula 300 includes a dissecting mechanism (referred to generally by reference numeral 302) for separating the vessel from the surrounding tissue and a sidebranch separating mechanism

(referred to generally by reference numeral 304) for separating any sidebranches of the vessel that are encountered. In a preferred embodiment of the cannula 300, the dissecting mechanism 302 takes the form of a hollow, tapered nosecone 326 mounted on the distal end of the cannula shaft 314. The tapered nosecone 326 of the dissecting mechanism 302 is preferably made of an optically clear plastic, such as polycarbonate or polymethylmethacrylate, so that it does not limit the field of vision of the endoscope 400. In a preferred embodiment of the cannula 300, the sidebranch separating mechanism 304 takes the form of a slot 306 formed in the tapered distal nosecone 326 of the cannula 300 with a cutting 308 and/or coagulating mechanism 310 positioned within the slot 306. The slot 306 is preferably formed at an angle (preferably 0-75 degrees, most preferably approximately 45 degrees) with respect to the axis of the cannula 300. Optionally, one or more additional slots may be formed in the nosecone to reduce the amount of rotation necessary to capture a sidebranch. The cutting 308 and coagulating mechanisms 310 may be separate or they may be integrated together in the form of a bipolar coagulating cutter mechanism located within the slot 306. Preferably, the endoscope lumen is positioned such that the slot 306 and the cutting 308 and coagulating mechanisms 310 are in direct view of the endoscope 400. FIG 4 is a cross section of the distal tip of the cannula 300 showing a bipolar coagulating cutter mechanism that uses a scissor action. FIG 5 is a cross section of an alternate configuration of the distal tip of the cannula 300 showing a bipolar coagulating cutter mechanism that uses a pair of rotating ring-shaped blades 320 that can be actuated from the proximal end of the cannula 300. Preferably, the cutting 308 and coagulating mechanisms 310 are integrated into the cannula 300. Alternatively, the cutting 308 and coagulating mechanisms 310 can be separate instrument(s) insertable through an instrument lumen 322 provided in the cannula 300.

In one preferred embodiment, the cutting mechanism 308 has a stationary cutting blade and a blunt arm that moves the sidebranch across the blade to sever it.

Alternatively or in addition, the cannula 300 may include a clip applier 312 for applying ligating clips or the like to the sidebranches to be separated from the vessel being harvested. Preferably, the clip applier 312 is integrated into the cannula 300. Alternatively, the clip applier 312 can be a separate instrument insertable through the instrument lumen 322 in the cannula 300, as shown in FIG 6. Preferably, the clip applier 312 is capable of delivering multiple ligating clips without reloading or removal of the clip applier 312 from the cannula 300.

The guidewire 100, balloon catheter 200, cannula 300 and endoscope 400 provide an integrated vessel harvesting system that can be used in the following method for harvesting a vessel, such as a saphenous vein, for use as a bypass graft or for other purposes. The saphenous vein is accessed through a small incision in the patient's leg. The exposed portion of the vein is dissected away from the surrounding tissue and the vein is incised or transected to open the lumen of the vein. The guidewire 100 is inserted into the lumen of the vein, followed by the catheter 200 with the balloon 202 in a deflated condition. Once the catheter 200 has been inserted a sufficient distance, the balloon 202 is inflated with fluid or gas to support the vein from inside of the lumen, as shown in FIG 7. The cannula 300 may be preloaded coaxially over the proximal shaft 204 of the balloon catheter 200. The tapered distal nosecone 326 of the cannula 300 is inserted over the inflated balloon 202 and into the space between the vein and the surrounding tissue with the vein passing through the internal lumen 316 of the cannula 300. The inflated balloon 202 provides some grasping force for holding the vein from the inside as the cannula 300 is advanced to dissect the vein from the surrounding tissue using the tapered distal nosecone 326. In addition, the inflated balloon 202 may straighten the vein somewhat, which facilitates advancement of the cannula 300. The handle 324 is used to rotate the cannula 300 as it is advanced, which helps to separate the vein from the surrounding tissue. Alternatively, the cannula 300 may include an electric motor for automatically rotating the cannula shaft 314 and/or the nosecone 326. Alternatively, the cannula 300 may rotate back-and-forth while advancing, rather than a continuous rotation.

When a sidebranch of the vein is encountered, the cannula 300 is rotated so that the sidebranch enters the slot 306 in the nosecone 326, as shown in FIG 8. The cutting 308 and coagulating mechanisms 310 are used to cut and seal the sidebranch. In addition, the clip applier 312 may be used to apply one or more ligating clips to the sidebranch where it attaches to the main vessel and/or to the cut end of the sidebranch that remains in the tissue.

The method is continued by advancing the cannula 300 to dissect the main vessel from the surrounding tissue and separating any sidebranches encountered until a sufficient length of the vessel has been processed. A second incision can be made through the patient's skin just distal to where the nosecone 326 of the cannula 300 is positioned. The illumination device of the endoscope or the cannula 300 could be used to indicate the location of the vein to the surgeon so only a tiny cut would need to be made to cut the distal part of the vein in order to free it. Alternatively or in addition, the catheter may be configured with an illumination device to deliver light to the tip. A ligating clip is applied to the main vessel and the vessel is transected proximal to the clip. Alternatively, a clip can be applied with the integrated clip applier, which would obviate the need for a second incision. At this point, the cannula 300 can be withdrawn with the harvested vessel inside of the internal lumen 316. The method can be repeated if additional length of vessel is needed for multiple bypass grafts.

The apparatus and method of the present invention can be modified to include the following features and functions.

FIGS 9-14 show alternative configurations of the cannula 300 of the present invention. FIGS 9 and 10 show a cannula 300 with the nosecone 326 mounted on a closed cylindrical shaft 314. FIGS 11 and 12 show a cannula 300 with the nosecone 326 mounted on an open partially cylindrical shaft 314. The cannula 300 has a slot 328 that runs the length of the shaft 314. The partial cylinder 314 may encompass approximately 270 degrees, leaving a 90 degree slot 328 open for placing the cannula 300 around the vessel. The open shaft may also incorporate a trapdoor as illustrated in FIGS 22 and 23. FIGS 13 and 14 show a cannula 300 with the nosecone 326 mounted on an open shaft 314 that is made up of a plurality of rods 330 positioned to approximate a cylindrical configuration.

FIG 22 shows an end view of an embodiment of the cannula 300 with a trapdoor 332 to facilitate placing the cannula around the vessel without the necessity of transecting it. FIG 23 shows the cannula of FIG 22 with the trapdoor 332 open to pass the cannula around a vessel. In alternative embodiments, the trapdoor may be configured as a sliding door or pivoting door, rather than the swinging door configuration shown.

The vessel harvesting system may include an additional dissecting mechanism for separating the vessel from the surrounding tissue. The dissecting mechanism preferably produces an outward and rearward motion, with respect to the nosecone, that separates the tissue for the vessel and facilitates advancement of the cannula. The preferred motion has been likened to a swimmer's arm motions when performing the breaststroke. The additional dissecting mechanism may be integrated into the cannula 300 or it may be configured as a separate instrument insertable through the internal lumen of the cannula 300. FIG 15 shows one embodiment of such a dissecting mechanism 500. The dissecting mechanism 500 includes a plurality of duckbill expansion members 502 that are pivo tally mounted on the tapered nosecone 326 on the distal end of the cannula 300 or on a separate instrument shaft. The duckbill expansion members 502 may be made of plastic or metal. The duckbill expansion members 502 are actuated by actuation rods 504 that extend through the shaft 314 of the cannula 300. The duckbill expansion members 502 move from a contracted position, where they closely conform to the narrow, tapered shape of the nosecone 326, to an expanded position 502' to create a spreading action that helps to separate the surrounding tissue from the vein.

FIG 16 shows another embodiment of a dissecting mechanism 510. The dissecting mechanism 510 includes a plurality of expansion members 512 that are attached to the tapered nosecone 326 at the distal end of the cannula 300 or on a separate instrument shaft. The expansion members 512 have a living hinge 514 that connects two levers 516, 518 that are in turn connected to a tubular actuation member 520 that extends to the proximal end of the cannula 300. The expansion members 512 and the tubular actuation member 520 may be made of plastic or metal. When the tubular actuation member 520 is moved distally with respect to the cannula shaft 314, the expansion members 512 move from a contracted position, where they closely conform to the narrow, tapered shape of the nosecone 326, to an expanded position to create a spreading action that helps to separate the surrounding tissue from the vein. The expansion members 512 may be surrounded or connected to one another with an elastic webbing to avoid tissue pinching between the expansion members 512.

FIGS 17A and 17B show another possible embodiment of a dissecting mechanism 530. The dissecting mechanism 530 includes a plurality of spreader members 532 that are attached to the shaft 314 of the cannula 300 or on a separate instrument shaft. Typically, the dissecting mechanism 530 will include approximately 4 to 8 spreader members 532 arranged around the cannula shaft 314. A sliding collar 534, which is slidably mounted on the cannula shaft 314, restrains the spreader members 532 against the cannula shaft 314. The spreader members 532 are precurved or otherwise biased to spread radially outward when the sliding collar 534 is retracted, as shown in FIG 17B. Alternatively, the collar 534 can be stationary on the shaft 314 and the spreader members 532 can be slidably mounted. The spreader members 532 are preferably made of a superelastic NiTi alloy or other highly elastic material. The distal ends of the spreader members 532 preferably have sharp edges, ridges or teeth to grip the tissue as the spreader members 532 spread apart to help separate the surrounding tissue from the vein. Other dissecting mechanisms, such as an inflatable balloon or expandable dissecting member may also be incorporated into the cannula 300.

FIG 18 shows an alternative embodiment of the cannula 300 of the present invention wherein the cannula shaft 314 includes a flexible proximal portion 340 that is configured to transmit pushing force and rotation from the handle 324 to the nosecone 326 around a curve.

FIGS 19A-C show further details of the bipolar coagulating cutter mechanism that uses a pair of rotating ring-shaped blades 320 that can be actuated from the proximal end of the cannula 300 shown in FIG 5.

FIG 20 shows an embodiment of a one shot clip applier 312 insertable through an instrument lumen in the cannula.

FIG 21 shows an embodiment of a clip applier 312 built into the cannula shaft 314 with a channel or cassette 344 for holding multiple ligating clips.

While the present invention has been described herein with respect to the exemplary embodiments and the best mode for practicing the invention, it will be apparent to one of ordinary skill in the art that many modifications, improvements and subcombinations of the various embodiments, adaptations and variations can be made to the invention without departing from the spirit and scope thereof.

Claims

We claim:

1. A method of harvesting a vascular conduit, comprising: inserting an elongated expandable vessel support member into an internal lumen of the vascular conduit; expanding the expandable vessel support member within the internal lumen of the vascular conduit to support the vascular conduit; and advancing a dissecting cannula coaxially around the elongated expandable vessel support member and externally of the vascular conduit to separate the vascular conduit from surrounding tissue.

2. The method of harvesting a vascular conduit of claim 1, further comprising: rotating the dissecting cannula while advancing the dissecting cannula coaxially around the elongated expandable vessel support member.

3. The method of harvesting a vascular conduit of claim 1, further comprising: imaging the vascular conduit with an endoscope inserted through the dissecting cannula.

4. The method of harvesting a vascular conduit of claim 1, further comprising: imaging the vascular conduit with a camera mounted within the dissecting cannula.

5. The method of harvesting a vascular conduit of claim 1, further comprising: severing a sidebranch vessel from the vascular conduit.

6. The method of harvesting a vascular conduit of claim 1, further comprising: ligating a sidebranch vessel of the vascular conduit and severing the ligated sidebranch vessel from the vascular conduit.

7. The method of harvesting a vascular conduit of claim 1, further comprising: rotating the dissecting cannula while advancing the dissecting cannula to engage a sidebranch vessel of the vascular conduit in a slot located at a distal end of the dissecting cannula and severing the sidebranch vessel from the vascular conduit with a cutting mechanism positioned proximate to the slot.

8. Apparatus for harvesting a vascular conduit, comprising: an elongated expandable vessel support member; and a dissecting cannula configured to be advanced coaxially around the elongated expandable vessel support member and externally of the vascular conduit to separate the vascular conduit from surrounding tissue.

9. The apparatus for harvesting a vascular conduit of claim 1, wherein: the elongated expandable vessel support member comprises an elongated inflatable balloon.

10. The apparatus for harvesting a vascular conduit of claim 1, further comprising: means for rotating the dissecting cannula while advancing the dissecting cannula coaxially around the elongated expandable vessel support member.

11. The apparatus for harvesting a vascular conduit of claim 1 , further comprising: an endoscope insertable through the dissecting cannula.

12. The apparatus for harvesting a vascular conduit of claim 1, further comprising: a camera located within the dissecting cannula.

13. The apparatus for harvesting a vascular conduit of claim 1, further comprising: means for severing a sidebranch vessel from the vascular conduit.

14. The apparatus for harvesting a vascular conduit of claim 1, further comprising: means for ligating a sidebranch vessel of the vascular conduit and severing the ligated sidebranch vessel from the vascular conduit.

15. The apparatus for harvesting a vascular conduit of claim 1, further comprising: a slot located at a distal end of the dissecting cannula and a cutting mechanism positioned proximate to the slot for severing a sidebranch vessel from the vascular conduit.