Preload sensitivity of the Jarvik 2000 and HeartMate II left ventricular assist devices.
The in vitro sensitivity of continuous flow pumps to preload and afterload pressure has been well characterized. We compared flow in the Jarvik 2000 and HeartMate II continuous flow left ventricular assist devices (LVADs) at different inflow and outflow pressures and different pump speeds. This allowed us to measure the impact of a changing inflow pressure on the pump flow rate at different speeds but against a constant afterload. The resulting preload sensitivity curves showed that, overall, both LVADs have a mean preload sensitivity of 0.07 L/min/mm Hg in the physiologic ranges of pressures and flows encountered during normal operation. The HeartMate II pump had an increased preload sensitivity (up to approximately 0.1 L/min/mm Hg) as the preload was increased. The preload sensitivity of the Jarvik 2000 LVAD was more variable, having several peaks and troughs as the preload was increased. In future LVADs, improved preload sensitivity may allow passive regulation of pump output, optimize ventricular unloading, and decrease the risk of ventricular suction by the pump.
Khalil
Hassan A
HA
Department of Cardiovascular Surgery, Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas 77225-0345, USA.
Cohn
William E
WE
Metcalfe
Ralph W
RW
Frazier
O H
OH
D001696:Biomechanical Phenomena; D001698:Biomedical Engineering; D001783:Blood Flow Velocity; D001794:Blood Pressure; D004867:Equipment Design; D006353:Heart-Assist Devices / Q000706:statistics & numerical data; D006439:Hemodynamics; D006801:Humans; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D012680:Sensitivity and Specificity