The abdominal aortic counterpulsation device is a round pumping chamber with a valveless opening which is implanted retroperitoneally on the abdominal aorta. The Utah driver is connected to the device through an air conduit and is synchronized on the electrocardiographic signal to provide diastolic aortic augmentation. For comparison an intraaortic balloon was also driven by the Utah driver system. The abdominal aortic counterpulsation device (stroke volume = 30, 40 and 60 ml) and the intraaortic balloon pump (balloon volume = 20 ml) were tested in dogs with acute left ventricular failure. The abdominal aortic counterpulsation device was also tested in normal animals. In acute left ventricular failure the abdominal aortic counterpulsation device at a stroke volume of 30, 40 or 60 ml decreased left ventricular end-diastolic pressure by an average of 28.56 (p less than 0.001), 39.56 (p less than 0.001) and 44.14% (p less than 0.005), respectively; aortic end-diastolic pressure by 24.11 (p less than 0.001), 26.67 (p less than 0.001) and 19.57% (p less than 0.01); and aortic systolic pressure by 18.56 (p less than 0.002), 26.0 (p less than 0.001) and 22.43% (p less than 0.005). It increased cardiac index by 27.58 (p less than 0.02), 35.59 (p less than 0.005) and 43.42% (p less than 0.001) and it provided peak aortic diastolic augmentation of 64.5 (p less than 0.001), 69.78 (p less than 0.001) and 74.43% (p less than 0.001), respectively, above the control aortic end-diastolic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)