Experimental evaluation and clinical application of intraoperative counterpulsation without balloon pumping.
Cardiac assistance in the form of counterpulsation (CP), created by intraaortic balloon pumping (IABP), has recently been utilized to wean patients from cardiopulmonary bypass (CPB) after conventional modalities have failed. The use of IABP, however, is often delayed because it is not part of the standard CPB setup and requires an additional cutdown, an arterial graft, and the retrograde insertion of a foreign body into the arterial tree. To eliminate the disadvantages of IABP, an alternate technique for CP has been developed. A pneumatially actuated external blood reservoir connected via a "Y" connector to the standard arterial line of the CPB circuit can provide pulsatile flow, and when synchronized with the EKG, CP with or without CPB. Experimental evaluation with dogs comparing this technique with IABP has shown that the former can create comparable CP pressure curves to the latter. The technique was applied to 11 patients undergoing either aorto-coronary bypass surgery and/or valvular surgery. Two of the 11 patients could come off CPB only with the assistance of CP. Coronary bypass graft flow, when measured, increased by 25% due to CP in two out of seven patients. The arterial CP technique has proven to be easily adapted to clinical settings and provides immediate and effective CP when required.