An autoperfusion balloon catheter was developed to allow passive myocardial perfusion during inflation through a central lumen and multiple side holes in the shaft proximal and distal to the balloon. We report its safety and efficacy in 11 patients undergoing elective angioplasty to a single coronary lesion. Each lesion was dilated three times with the autoperfusion inflation bracketed between two inflations by standard angioplasty catheters. Chest pain score, 12-lead electrocardiogram, heart rate, and mean aortic pressure were recorded before each inflation and at 1-minute intervals after inflation. Inflation duration during autoperfusion angioplasty (513+± 303 seconds) was longer than for the pre-(107+±-55 seconds, p=0.0004) and post-(139+± 71 seconds, p=0.0006) standard dilatations. The maximum ST-segment elevation and depression in any lead during autoperfusion angioplasty (0.3 0.5 and 0.6 0.8 mm) was significantly less than for the pre-(2.4± 1.7 mm, p=0.002 and 2.2± 1.3 mm, p=0.0004) or post-(1.9 + 1.3 mm, p = 0.002 and 1.6±+1.3 mm, p= 0.018) standard dilatations at the same point in time. Maximal chest pain score during autoperfusion (3.2-+ 3.5) was lower than for the pre-(6.1 2. 1, p=0.003) but not the post-(5.2 3.1, p=0.07) standard angioplasty. All 11 patients underwent successful, uncomplicated procedures. We conclude that this autoperfusion catheter significantly reduces ischemic symptoms and signs during coronary angioplasty, allowing prolonged periods of balloon inflation. (Circulation 1988;78:1128-1134 M a aximum duration of balloon inflation during conventional percutaneous transluminal coronary angioplasty is usually short (30-60 seconds) because it is limited by the development of symptoms and signs of myocardial ischemia. Theoretical advantages of more prolonged inflation periods, for which there is some experimental and clinical support, include improved initial angiographic results and lower restenosis rates.1-3 Autoperfusion balloon catheters, which allow continued passive myocardial perfusion during periods of balloon inflation, provide us with the means potentially to achieve this goal. Previous studies with similar catheters have demonstated adequate From the Interventional Cardiac Catheterization Program,