Restoring pulsatility and peakVO2 in the era of continuous flow, fixed pump speed, left ventricular assist devices: 'A hypothesis of pump's or patient's speed?'.

Despite significant improvement in survival and functional capacity after continuous flow left ventricular assist device implantation, the patient's quality of life may remain limited by complications such as aortic valve insufficiency, thromboembolic episodes and gastrointestinal bleeding attributed to high shear stress continuous flow with attenuated or absence of pulsatile flow and by a reduced peak oxygen consumption (peakVO2) primarily associated with a fixed pump speed operation. Revision of current evidence suggests that high technology pump speed algorithms, a 'hypothesis of decreasing pump's speed' to promote pulsatile flow and a 'hypothesis of increasing pump's speed' to increase peakVO2, may only partially reverse these barriers. A 'hypothesis of increasing patient's speed' is introduced, suggesting that exercise training may further contribute to the patient's recovery, enhancing peakVO2 and pulsatile flow by improving skeletal muscle oxidative capacity and strength, peripheral vasodilatory and ventilatory responses, favour changes in preload/afterload and facilitate native flow, formulating the rationale for further studies in the field.