Creating adequate pulsatility with a continuous flow left ventricular assist device

Continuous flow left ventricular assist devices (LVADs) have revolutionized the treatment of advanced heart failure; however, as experience with these devices has grown, a number of unanticipated adverse events have emerged. In this study, we review the current literature associating a lack of pulsatility with these events.It is now evident that continuous flow LVAD physiology reflects a spectrum of 'low pulsatile' rather than a truly 'nonpulsatile' state. Thus, the detrimental consequences of nonpulsatile flow noted in early experimental setups may or may not occur in humans supported with continuous flow LVADs. Such studies have demonstrated not only alterations in vascular function and structure during continuous flow LVAD support, but also a clear association of the degree of alterations in vascular, baroreceptor, and sympathetic nervous system function with the degree of actual pulsatility. In addition, a number of clinical events have been linked to continuous flow LVAD physiology, including a decreased extent of ventricular unloading possibly impairing myocardial recovery, hemolysis and device thrombosis, development of aortic insufficiency, and mucosal bleeding.Many of the adverse effects of the current continuous flow LVADs are associated with low pulsatile flow. An evolved understanding of pulsatility as a continuous rather than a binary variable may allow us to incorporate appropriate degrees of pulsatility into the next generation pumps and mitigate these effects.