Creation of a transrenal arteriovenous dialysis shunt: feasibility study in a swine model

Creation of an Extraluminal Arterial Bypass Graft Using a Commercially Available Self-Expanding Stent Graft: Feasibility Study in a Porcine Model

PURPOSE

The purpose of this study was to assess the technical feasibility of ultrasound-guided endovascular creation of a percutaneous extraluminal arterial bypass graft without a surgically created arterial anastomosis.

MATERIALS AND METHODS

Nine swine were utilized for this IACUC-approved study using a carotid bypass model in swine. Using sonographic guidance, percutaneous access was obtained to the proximal and distal common carotid artery. A self-expanding stent graft was advanced through the proximal carotid access site, tunneled subcutaneously, then advanced through the distal carotid access site, and deployed. The stent grafts were monitored weekly for patency using ultrasound. Angiography was performed at 4 weeks to evaluate for graft patency. Gross pathologic analysis was performed on the explanted stent grafts.

RESULTS

In eight out of the nine swine (89%), percutaneous extraluminal bypass graft creation was technically successful, with brisk flow through the stent graft to the distal circulation, complete exclusion of the bypassed segment of carotid artery, and no extravasation. The technical failure was due to stent graft maldeployment. Of the six swine evaluated for patency, four grafts were patent at the 4-week end point. Both occluded stent grafts were due to extraluminal extrusion of one end, likely related to neck movement and growth in neck length.

CONCLUSION

The percutaneous arterial bypass technique had a high technical success rate and a graft patency rate of 67% at 4 weeks, with early occlusions possibly related to limitations of the animal model.

Salvage of a Failing Dialysis Graft by Percutaneous Creation of a Jump Bypass Graft

Percutaneous salvage of failing arteriovenous grafts with diffuse disease or occlusion in the venous outflow remains an issue with no ideal solution. The present report describes a method of percutaneous creation of vascular bypasses in a patient with a failing graft. The patient had a long-segment stenosis in the venous outflow of a brachial-cephalic dialysis graft, and the graft was salvaged by conversion to a brachial-basilic graft. Notably, this method allowed the bypass to safely traverse a long distance (20 cm), and at 8 months, the graft remained functional and free of complications. In principle, this approach can be applied to different situations in which superficial bypass conduits are desired.

Simplified Technique for Percutaneous Transrenal Arteriovenous Dialysis Graft Creation in a Swine Model

PURPOSE

To investigate the experimental creation of a percutaneous arteriovenous graft via the renal vessels using a simplified technique and to report on its safety, complications, and 1-month follow-up.

MATERIALS AND METHODS

Transrenal arteriovenous grafts were created from the renal artery to the renal vein in six swine. Using a combined transfemoral and percutaneous approach, a 7 mm x 150 mm stent graft was deployed to create a renal vein limb, and a 6 mm x 150 mm stent graft was deployed to form the renal artery limb. The external portion of the arterial limb was telescoped into the venous limb to form one continuous loop and was placed into a subcutaneous pocket. The duration and technical success of the procedure were recorded. Shunt patency was assessed by auscultation and angiography, as well as by necropsy and histopathology.

RESULTS

Arteriovenous graft creation was technically successful in all six animals with rapid arteriovenous shunting documented with angiography at completion. The mean procedure duration was 84 minutes (range, 70-130 minutes). Auscultation and angiography revealed that four of the six shunts were occluded at 4 weeks. Moderate (50% to 75%) diffuse in-stent angiographic stenosis was present in the two remaining animals. No technical complications occurred. Midterm complications of localized and gradual concentric stenosis due to mural thrombosis occurred in three animals. Graft infection resulting in late abrupt thrombosis occurred in four animals.

CONCLUSIONS

Transrenal arteriovenous graft creation using the simplified technique can be performed safely in swine. Delayed complications including graft infection and in-stent stenosis must be addressed prior to use of the technique in clinical settings.

Percutaneous Vein Graft Reanastomosis with Use of a Covered Stent to Salvage a Thrombosed Hemodialysis Graft

Technical success rates for percutaneous restoration of thrombosed arteriovenous grafts are high. However, in thrombosed grafts without restorable original outflow veins, percutaneous salvage is usually not possible. In this situation, patients are referred for bypass grafting or recreation of their vascular access sites. This report describes a patient in whom the original outflow vein at the venous anastomosis was completely obliterated and in whom vascular access was successfully salvaged by percutaneously reanastomosing the venous stump of the thrombosed graft with an adjacent patent vein. This procedure is technically feasible for the salvage of a thrombosed graft.

Axillorenal arteriovenous graft: A new approach for dialysis access

As the population requiring hemodialysis grows, it becomes increasingly common to encounter patients with limited options for vascular access. Because inability to secure vascular access is a life-threatening problem, it is important to consider all possible options in each patient. We report a new arteriovenous grafting procedure in which the left renal vein is used for outflow in a patient with multiple venous occlusions. Patency of the graft continues 18 months after placement. This graft carries acceptable morbidity, and can be revised. Consideration of this graft is appropriate in selected patients.

Transrenal arteriovenous dialysis graft creation: survival and patency in a swine model

PURPOSE

To investigate transrenal arteriovenous graft creation in an animal model and to report survival and patency.

MATERIALS AND METHODS

Arteriovenous grafts were created from the renal artery to the renal vein in 10 swine. Renal access was accomplished with a combined percutaneous and transvascular approach. A reinforced 6-mm polytetrafluoroethylene conduit was tunneled between both flank access points, and stent-grafts were deployed from each of the renal origins into the conduit. Clopidogrel (10 mg per kilogram of body weight) was administered intravenously during the procedure, followed by a daily oral dose (75 mg) for up to 2 weeks. Animals were monitored with auscultation and angiography for up to 1 month; necropsy was performed in all animals.

RESULTS

Rapid arteriovenous flow at completion angiography was achieved in eight of 10 animals. Shunts were patent in five of six animals that were followed for 1 month. Diffuse pseudointimal hyperplasia was mild in three of six shunts and moderate in two (focal stenoses). Immediate thrombosis occurred in the first two animals when the clopidogrel bolus was administered after stent-graft deployment. These shunts were recanalized mechanically. Shunts were immediately patent in five of the six remaining shunts when the clopidogrel bolus was administered prior to stent-graft deployment. Complications occurred in four of 10 animals, three of which were euthanized within 1 week. The bowel was traversed in two animals, and renal vein laceration occurred during two procedures because of failure of the stent-graft delivery system.

CONCLUSION

Transrenal arteriovenous graft creation in swine is technically feasible, and long-term patency is possible with antiplatelet therapy.