Balloon inflation following injection of contrast material through the distal lumen of the USCI balloon catheter.

We report on four patients in whom we observed inflation of the balloon following injection of contrast material into the distal lumen during percutaneous transluminal coronary angioplasty. This is a rare technical problem. However, inadvertent balloon inflation may cause transient occlusion of the proximal coronary artery and in one case was associated with acute occlusion of a vessel that had been dilated. Management involves prompt deflation of the balloon.