Percutaneous creation of arteriovenous hemodialysis grafts: work in progress

Endovascular Arteriovenous Fistula Creation-Review of Current Experience

Functioning vascular access is an essential element for life-saving hemodialysis therapy. A surgically-created arteriovenous fistula has been considered the best option for many years. Recently, two manufacturers developed systems for percutaneous/endovascular creation of an arteriovenous fistula (WavelinQ and Ellipsys). We provide a review of the available experience with these systems and discuss advantages and disadvantages.

Advances in Endovascular Techniques to Treat Failing and Failed Hemodialysis Access

During the decade since JEVT was inaugurated, we have witnessed the growing application of endovascular techniques for arteriovenous (AV) access in parallel with the evolution of endovascular therapy for arterial pathology. To date, few if any technologies have compared with balloon angioplasty for treating venous anastomotic stenosis, the most common cause of access failure. Only one device, which incorporates the principles of access graft design and self-expanding stent technology, has been uniquely conceived for this pathology. The encapsulated polytetrafluoroethylene stent-graft has achieved reasonable preliminary results, but randomized data is forthcoming. Technology to clear the clot from a thrombosed graft continues to evolve, but will never be as cost-effective as simple balloon thrombectomy. However, the pressure placed on providers to perform all percutaneous interventions and move away from open techniques continues to fuel interest in this component of treatment. Finally, the pursuit of a completely percutaneous AV access continues. As with endovascular procedures in general, whether or not the procedure is cost-effective or time-consuming seems to take a back seat to the all-percutaneous approach that so many seem to converge upon. Moreover, as most autogenous fistulas and AV grafts can be created with minimal incisions under local anesthesia, the pursuit of a completely percutaneous access system seems more like an academic exercise than a practical application of technology. We must try and avoid the tendency to “minimize invasiveness” with technology that is maximally intensive (and expensive), such as limiting ourselves to only percutaneous methods. Given the increasing pressure to have an all autogenous access program, current techniques that apply well in prosthetic grafts will need to be modified to accommodate the different biology of a native fistula. Clearly, the enlarging end-stage renal disease population will continue to provide endovascular specialists with clinically challenging problems requiring new and revolutionary technology.

Promises for the Future: Minimally Invasive Fistula Creation

The surgical creation of an autogenous fistula is the vascular access of choice for delivery of hemodialysis. However, it is prone to relatively high rates of maturation failure, stenosis and thrombosis. Most of these problems can be attributed to the surgical creation itself. Percutaneous or endovascular creation of an autogenous fistula offers the possibility of overcoming some of these problems.

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.

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.

Advances in endovascular techniques to treat failing and failed hemodialysis access

During the decade since JEVT was inaugurated, we have witnessed the growing application of endovascular techniques for arteriovenous (AV) access in parallel with the evolution of endovascular therapy for arterial pathology. To date, few if any technologies have compared with balloon angioplasty for treating venous anastomotic stenosis, the most common cause of access failure. Only one device, which incorporates the principles of access graft design and self-expanding stent technology, has been uniquely conceived for this pathology. The encapsulated polytetrafluoroethylene stent-graft has achieved reasonable preliminary results, but randomized data is forthcoming. Technology to clear the clot from a thrombosed graft continues to evolve, but will never be as cost-effective as simple balloon thrombectomy. However, the pressure placed on providers to perform all percutaneous interventions and move away from open techniques continues to fuel interest in this component of treatment. Finally, the pursuit of a completely percutaneous AV access continues. As with endovascular procedures in general, whether or not the procedure is cost-effective or time-consuming seems to take a back seat to the all-percutaneous approach that so many seem to converge upon. Moreover, as most autogenous fistulas and AV grafts can be created with minimal incisions under local anesthesia, the pursuit of a completely percutaneous access system seems more like an academic exercise than a practical application of technology. We must try and avoid the tendency to "minimize invasiveness" with technology that is maximally intensive (and expensive), such as limiting ourselves to only percutaneous methods. Given the increasing pressure to have an all autogenous access program, current techniques that apply well in prosthetic grafts will need to be modified to accommodate the different biology of a native fistula. Clearly, the enlarging end-stage renal disease population will continue to provide endovascular specialists with clinically challenging problems requiring new and revolutionary technology.

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

PURPOSE

To investigate the feasibility of percutaneous renal artery and vein access for the creation of a transrenal arteriovenous hemodialysis graft.

MATERIALS AND METHODS

Renal-artery-to-ipsilateral-renal-vein conduits were constructed with use of entirely percutaneous techniques in seven swine. Renal artery and vein access was performed in six animals with use of a retrograde (inside-out) technique and in one animal with use of an antegrade (outside-in) technique. Modified 8-F sheaths were used in the first three animals and Wallgrafts were used in the final four animals to form the arterial and venous limbs of each shunt. The arterial and venous limbs were joined together by a subcutaneous segment of 6-mm reinforced polytetrafluoroethylene (PTFE) in five animals and by external conduits in two animals. Wallgrafts were deployed from the renal artery and vein into the segments of PTFE. The free ends of each conduit were tunneled and joined together to close the arteriovenous circuit. Post-shunt angiography was used in all animals to document successful shunt creation and demonstrate rapid arteriovenous shunting as a determinant of technical feasibility. Two of the seven animals received additional anticoagulation therapy and/or antiplatelet therapy to prevent shunt thrombosis during the follow-up period. The three initial animals were killed within 2 hours of shunt creation, and two of the remaining four animals returned for angiographic follow-up, one on day 2 and one on day 9. All animals underwent a complete necropsy to assess for potential complications including hemorrhage and vascular or bowel injury.

RESULTS

Retrograde renal arterial and venous access was successful in all six animals in which it was attempted. Five of six arterial accesses and four of six venous accesses traversed the peritoneum with two arterial accesses and one venous access penetrating a loop of large bowel. Antegrade access was performed and successfully accomplished in the final animal. Brisk arteriovenous shunting was demonstrated on completion angiography in all animals. Graft occlusion was present in the two animals that returned for follow-up and two animals died before follow-up as a result of graft leakage and subsequent hemorrhage. Minimal perinephric and intrarenal hemorrhage was demonstrated at necropsy after shunt insertion in the remaining five animals. Renal infarction was present in all kidneys used for transrenal access.

CONCLUSION

The transrenal approach for the creation of a percutaneous arteriovenous shunt is feasible after renal artery and vein access by either the retrograde or antegrade technique. Additional technical refinements of the procedure and the devices used will be necessary before follow-up studies are conducted.