Is flow really continuous in last generation continuous flow Ventricular Assist Devices? A comparison between HeartMate II and HeartWare HVAD

HSR Proceedings in Intensive Care and Cardiovascular Anesthesia 2011, Vol. 4 Corresponding author: Giulio Melisurgo Cardiovascular and Thoracic Department Università Vita-Salute San Raffaele Via Olgettina, 60 20132 Milan, Italy e-mail: [email protected] Continuous-flow ventricular assist devices (VADs) are the standard of care for implantable mechanical circulatory support (1). However, some doubts have been raised based on the experience with cardiopulmonary bypass about possible adverse effects of non-pulsatile flow on organ function (2). Pulsatile perfusion might have a beneficial effect on peripheral organs probably through an action on systemic vascular resistance and on microcirculation, as a result of less endothelial damage and normalization of nitric oxide (NO) release. However, long-term use of newer generation continuous-flow devices has resulted in similar improvements in organ function (3). Actually, blood flow through continuous-flow VADs is not really continuous, since it depends on the differential pressure between the left ventricle and the ascending aorta at a certain VAD speed (4). During support, the failing native heart continues to function and it generates a variation in intracardiac pressures along the cardiac cycle: during systole an increase in left ventricular pressure will be transmitted to the pump and will transiently increase the VAD flow, generating some degree of arterial pulsatility. Potapov et al. (5) first detected a pulsatile flow in patients Is flow really continuous in last generation continuous flow Ventricular Assist Devices? A comparison between HeartMate II and HeartWare HVAD