Cardiac arrest in the catheterization laboratory is fatal if unresponsive to advanced cardiac life support (ACLS). Seven patients not responding to ACLS following cardiac arrest in the catheterization laboratory underwent percutaneously instituted cardiopulmonary bypass support. Cardiac arrest occurred following abrupt closure postcoronary angioplasty in three patients, during cardiogenic shock in three patients, and during diagnostic angiography in one patient. Cardiopulmonary bypass was instituted 10-45 min (mean, 21 min) following the onset of cardiac arrest. Flows on bypass ranged from 4.0 to 5.2 liter/min. Mean blood pressure ranged from 70 to 110 mm Hg on bypass. Six of the seven patients regained consciousness after the institution of bypass. Acid-base balance was normalized in all patients. Coronary bypass surgery was subsequently performed in three patients and coronary angioplasty in two. Four patients survived. One patient died following coronary bypass surgery. Two patients, who were not suitable candidates for revascularization, expired. Total bypass time was 1.5-8.5 hr (mean, 2.7 hr). At a mean follow-up of 6 months, all four survivors are alive and asymptomatic or NYHA class 1. We conclude that cardiopulmonary bypass support 1) can stabilize patients following cardiac arrest in the catheterization laboratory, 2) can facilitate emergency coronary angioplasty or transfer to the operating room for coronary bypass surgery, and (3) can improve survival in patients unresponsive to ACLS when instituted early following cardiac arrest in the catheterization laboratory.