Background: The current generation of left ventricular assist devices (LVADs) provide continuous flow and have the capacity to reduce aortic pulsatility, which may be related to a range of complications associated with these devices. Pulsed LVAD operation using speed modulation presents a mechanism to restore aortic pulsatility and potentially mitigate complications.
Objectives: We sought to investigate the interaction of axial and centrifugal LVADs with the left ventricle (LV) and quantify the effects of continuous and pulsed LVAD operation on LV generated wave patterns.
Methods: In 4 anesthetized pigs, pressure and flow were measured in the ascending aorta and wave intensity analysis was used to identify and quantify the energy of waves created by the LV. The peak wave intensity of each wave created by the heart and total wave energy provided by the LV were measured during continuous and pulsed LVAD operation, which was split into periods of co- and counter-pulsation during post-hoc analysis.
Results: The axial LVAD created greater wave intensity associated with left ventricular relaxation. In both LVADs, there were only minor and variable differences between the continuous and pulsed operation. The response to physiological stress was preserved with LVAD implantation as wave intensity increased marginally with volume loading and significantly with infusion of norepinephrine.
Conclusions: The axial pump design causes the LV to relax with more energy compared to the centrifugal design. Augmenting the ability of the LV to relax could encourage increased coronary blood flow and may help left ventricular recovery. The effects of pulsed LVAD operation appear to be minimal during acute observation of healthy hearts. Further study is necessary to uncover the effects of other modes of speed modulation with healthy and unhealthy hearts to determine if pulsed operation will benefit patients by reducing LVAD complications.