The session on haemodialysis intervention and venous access at Charing Cross, chaired by Professor Jim Reekers, could so easily have become a US versus UK show-down on the best type of access for haemodialysis. However, despite obvious differences in dominant practice, both Drs Ziv Haskal and Kieran McBride agreed to fight “the common enemy of restenosis”, said McBride.
Speaking first, Haskal (New Jersey, USA) commented that as he was following the high-tech session on next-generation vascular devices, his talk must be something of a journey “from the exotic to the mundane. Stent grafts used to be as radical as any procedure could be, but now they’re common-place”.
However, synthetic stent-grafts are plagued by intimal hyperplasia. “Bare stents are not a durable answer,” he noted. Haskal presented data from a multi-center randomized study that assessed the safety and efficacy of the Bard ePTFE covered stent compared with percutaneous transluminal angioplasty (PTA) for the treatment of stenotic venous anastomoses in failing synthetic arteriovenous access grafts.
The six month prospective randomized multi-center trial covered 128 implanted devices with a delivery success rate of 99%. Results showed that the Bard ePTFE encapsulated stent-graft provides safe, clear six month primary patency superiority to balloon angioplasty for the treatment of venous anastomotic stenoses in failing prosthetic AV grafts. “It’s the first trial that has shown any benefit of stent-grafts over the gold standard of angioplasty,” he concluded.Fistula fight
However, while the Bard ePTFE graft is very impressive, it is “an American solution to an American problem”, commented McBride (Dunfermline, UK). McBride presented results of a different, but related study. “I envy Dr Haskal’s study, but it is only six months long. This one is three-and-a-half years.” AV fistulas, while preferable to prosthetic grafts in many ways, do have their own problems of veins thickening and closing down. McBride’s trial tested the ability of the Boston Scientific cutting balloon, first created for use in the coronary arteries, to treat fistula stenoses.
The trial started in March 2002. It took place in three centers in Scotland in 41 patients (26 male); 50 procedures (11 above wrist ; 30 above elbow). Twenty-five patients had primary stenosis or dysfunctional graft, and in 20 patients it was recurrent stenosis at the same site. Only one of the 50 procedures was not successful. However, two of the balloons burst at ten atmospheres and there were four leaks. In the follow-up, which lasted from two to 30 months (average 12.5), there were nine patient deaths, although all had working fistulas, and four transplants. At 12 months, 19 out of 34 patients (56%) had assisted patency. By comparison, the BEST trial had 57-67% at six months, said McBride.
The benefits of the balloon are that it is effective at around eight atmospheres of pressure and that it is “always painless. If nothing else we can justify the device on the grounds of patient comfort”, he commented. It works by ‘scoring’ the stenosis using the four hair-sized 130 micron blades, allowing the fistula to be more easily pushed open. McBride observed that while the trial was impressive, with “pretty damn good” patency rates, “it’s not science – we need more data, and that means a comparative trial. Then maybe we can convince the Americans to get over their fear of fistulas and use the device”.