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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 27^th at the Society of Interventional Radiology 29^th 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 -10ºC. 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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