Why pulsatility still matters: a review of current knowledge

Continuous-flow left ventricular assist devices (LVAD) have become standard therapy option for patients with advanced heart failure. They offer several advantages over previously used pulsatile-flow LVADs, including improved durability, less surgical trauma, higher energy efficiency, and lower thrombogenicity. These benefits translate into better survival, lower frequency of adverse events, improved quality of life, and higher functional capacity of patients. However, mounting evidence shows unanticipated consequences of continuous-flow support, such as acquired aortic valve insufficiency and acquired von Willebrand syndrome. In this review article we discuss current evidence on differences between continuous and pulsatile mechanical circulatory support, with a focus on clinical implications and potential benefits of pulsatile flow.During the last few decades, mechanical circulatory support has evolved into a standard therapy for patients with advanced heart failure – as a bridge to cardiac transplantation (1-3), bridge to myocardial recovery (4-7), or as destination therapy (8-10). This success can in most part be attributed to the use of continuous-flow devices and their advantages over previously used pulsatile pumps: they offer improved durability, less surgical trauma due to their smaller size, higher energy efficiency, and lower thrombogenicity. These benefits translate into better survival, lower frequency of adverse events, improved quality of life, and higher functional capacity of patients (11-13).The debate on the importance of pulsatility began several decades ago with the research on the effects of nonpulsatile flow during the cardiopulmonary bypass (CPB) (14,15). It is still alive today, after nearly a decade of use of continuous-flow devices, especially after evidence has shown that this therapy is complicated by diminished pulsatility. In this review article we discuss current evidence on differences between continuous and pulsatile ventricular assist devices, with a focus on clinical implications and potential benefits of pulsatile flow.