Clinical review: irradiation for lower extremity arterial occlusive disease

Benefits of external beam irradiation for peripheral arterial bypass: preliminary report on a phase I study

PURPOSE

To perform a Phase I study to determine the safety and feasibility of using external beam radiotherapy to prevent neointimal hyperplasia in patients after surgical bypass of occluded infrainguinal arteries.

METHODS AND MATERIALS

All patients undergoing operative infrainguinal bypass for chronic ischemia were eligible for enrollment, although those requiring a prosthetic graft were preferentially considered. Immediately after bypass, the distal anastomosis was marked with clips, and the baseline anatomy of the anastomosis was documented with an intraoperative angiogram. The distal anastomotic site and 2 cm of surrounding tissues were irradiated to a total dose of 30 Gy, delivered in 10 fractions. The first dose was given within 48 h of surgery.

RESULTS

Twenty-one patients were enrolled in this study. No anastomotic or wound problems or any other short-term complications of the treatment developed. However, at a mean follow-up of 10 months (range 3-18), 12 (57%) of the 21 grafts had occluded. Angiography was performed in 2 patients after successful thrombolysis and demonstrated normal anastomoses without residual stenosis. Evidence of stenosis at the irradiated anastomosis was seen in only 1 of the 21 patients by ongoing ultrasound surveillance.

CONCLUSION

Fractionated external irradiation to a total dose of 30 Gy delivered to the distal surgical anastomosis immediately after operative bypass has no short-term complications and was associated with an apparently low rate of intimal hyperplasia. However, any possible gains made by reducing the neointimal hyperplasia at the site of anastomosis were significantly diminished by the high frequency of thrombotic events.

Irradiation for intimal hyperplasia: implications for peripheral arterial bypass

Irradiation has been shown to inhibit postangioplasty intimal hyperplasia ("restenosis") in unbranched tubes. It seems likely that irradiation will similarly be able to inhibit intimal hyperplasia after a surgical anastomosis at a biochemical and cellular level, but whether it will produce a clinically relevant or even clinically detectable difference is unproved. One possibility is that no clinical effect may occur; the search for a "cure" for intimal hyperplasia has been long and, as yet, unsuccessful. On the other hand, if a strong effect without insurmountable logistical problems could be produced, one major cause of bypass graft failure would be preventable. Not only would the incidence of late graft occlusion, need for reoperation, and limb loss be reduced, but, if patency of prosthetics could be sufficiently improved, the initial operation could be made much easier, faster, and perhaps safer.