Carotid-subclavian bypass--a decade of experience. From August 1979 to August 1989, carotid-subclavian bypass or transposition procedures were performed on 18 women and 13 men ranging in age from 19 to 75 (mean, 58.2) years. Indications for surgery included symptoms of vertebrobasilar insufficiency in 16 (52%), upper extremity ischemia in six (19%), both vertebrobasilar insufficiency and extremity ischemia in four (13%), and stroke and/or hemispheric transient ischemic attacks in four (13%) patients. One patient (3%) had angina pectoris caused by "coronary-subclavian steal." Formal bypass grafts were performed in 28 (90%) cases by means of polyterafluoroethylene (24), Dacron (2), or saphenous vein (2), and carotid-subclavian transposition was performed in three (10%) cases. Synchronous procedures included carotid endarterectomy (4), carotid-carotid bypass (1), and axillobrachial bypass (1). There was no operative mortality. Thirty-day primary patency was 97%. Follow-up has ranged from 1 to 121 (mean, 42) months. Three grafts (polytetrafluoroethylene) have occluded during follow-up yielding long-term primary patency of 92% at 5 years and 83% at 8 years. Relief of symptoms was initially achieved in 30 (97%) patients. Recurrent symptoms have developed in six (20%) patients from 2 to 55 (mean, 26) months after surgery, including two with occluded and four with patent grafts. Symptom-free survival is 89% at 1 year, 84% at 2 years, and 71% at 7 years of follow-up. Six patients have died during follow-up yielding overall survival of 88% at 5 years, and 48% at 10 years. 