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Title: Cryoplasty Treatment Beneficial for In-stent Restenosis in Lower Extremities: Presented at SIR

"Cryoplasty Treatment Beneficial for In-stent Restenosis in Lower Extremities: Presented at SIR"

By M. M. Pennell PHOENIX, AZ -- March 29, 2004 -- In a small single-centre series, cryoplasty for lower extremity in-stent restenosis (ISR) was associated with a 10-month post-procedure patency rate of 78%, according to results presented here on March 27th at the Society of Interventional Radiology 29th Annual Meeting. These initial results will be confirmed in larger studies predicted James D. Joye, DO, Director of Cardiac Catheterization, El Camino Hospital, Mountain View, California, United States. The long-term patency rate in de novo lesion is about 80%, he noted, and "I would expect the rate in ISR to be slightly lower because the lesions are more difficult." Dr. Joye noted that the device -- the PolarCath cryoplasty balloon by CryoVascular Systems, Los Gatos, California -- is approved by the United States Food and Drug Administration for treatment of de novo lesions. "But it is only a small step from de novo to ISR," he said. That observation was confirmed by at least 3 audience members at the session, all who said they are already using the device for ISR. The device uses a nitrous oxide-filled balloon to cool the vessel wall to about -10şC. The supercooled balloon is left on the vessel wall for about 10 seconds, said Dr. Joye. "The cold serves as a trigger to induce apoptosis in the vascular tissue, which prevents proliferation," he stated. Eight women and 10 men were included in the series. Thirty-nine percent of the patients had type 2 diabetes and 50% were current or former smokers. The mean lesion length was 14 cm, but the range was 4 to 40 cm. Acute angiographic success was defined as residual stenosis of 30% or less. "The acute angiographic success rate was 94.4%. We had one patient who had 50% residual stenosis," said Dr. Joye. Mean baseline ankle brachial index was 0.65, which improved to 0.89 at 3 months, 0.85 at 6 months and 0.83 at 9 months. When asked about the need to "touch-up" the lesion with additional balloons, Dr. Joye said: "Our belief is that the last therapy the vessel wall should see is cold therapy. If I were to find that I need to 'touch-up' the procedure, I would go back in with cold inflation again." He noted that earlier models of the cryoplasty balloon used "instant inflation to 8 atmospheres, but the latest model inflates sequentially in 2-atmosphere segments, which gives more control over the balloon." Dr. Joye added that he thinks lesions up to 15 cm "can be treated with stand-alone cryoplasty," but longer lesions may need atherectomy before cryoplasty. Interestingly, Dr. Joye noted that "there is no fall-off with cold therapy, no edge effect at all" -- unlike with brachytherapy, which has been associated with "edge effect" (rapid proliferation at either end of the treatment site). CryoVascular Systems Inc. funded this study. [Study Title: Initial Results Using CryoPlasty To Treat Lower Extremity In-Stent Restenosis. Abstract 71]

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