Is pulsatile blood flow no longer essential?

The heart’s natural provision of pulsatile blood flow has been regarded as an essential requirement for normal organ function, especially critical organs such as the kidney, liver, and brain. However, in this issue of Circulation, Russell and colleagues1 have demonstrated that this tenet of medicine is no longer accurate. Their study examined the long-term impact of nonpulsatile blood flow as provided by a new generation of so-called continuous-flow left ventricular assist devices (LVADs), in this case the Heartmate II LVAD (Thoratec Corp, Pleasanton, Calif), on end-organ function in patients with refractory heart failure awaiting a heart transplant. These pumps draw blood from the left ventricle via a drainage cannula placed in the LV apex on a continuous basis and propel the blood by a rotary pump back into the circulation in a nonphasic flow pattern2 through a return cannula connected to the aorta. The major findings of the Heartmate II clinical trial, including both the primary cohort2 and a larger number of patients enrolled in the continuousaccess protocol,3 have previously been reported.