Effect of synchronous and asynchronous pulsatile flow during left, right, and biventricular bypass

Ventricular assist devices augment aortic or pulmonary flow while the patient's heart recovers from surgery or infarction. Most are used in the asynchronous full-to-empty mode, but they also may be used in a synchronous counter-pulsation mode. This study examines which assist mode optimally reduces myocardial oxygen consumption (MVO2). Eighteen pigs were instrumented with pulmonary artery, carotid artery, and coronary sinus catheters for determination of MVO2. Pierce-Donachy Ventricular Assist Devices (VAD) were used in left, right, or biventricular assist mode. Fifteen minute periods each of control, synchronous, and asynchronous bypass were randomly instituted. The mid-left anterior descending coronary artery was then ligated, and the sequence repeated. At the end of each period, MVO2 was determined. In comparison with controls, MVO2 was statistically significant in the BIVAD asynchronous mode only. Synchronized counterpulsation did not decrease MVO2. When ventricular assist devices are used to aid in cardiac recovery postoperatively or postmyocardial infarction, biventricular assist should be used.