TY - JOUR
T1 - Continuous-Flow Cardiac Assistance: Effects on Aortic Valve Function in a Mock Loop
AU - Tuzun, Egemen
AU - Rutten, Marcel
AU - Dat, Marco
AU - van de Vosse, Frans
AU - Kadipasaoglu, Cihan
AU - de Mol, Bas
PY - 2011
Y1 - 2011
N2 - Background. As the use of left ventricular assist devices (LVADs) to treat end-stage heart failure has become more widespread, leaflet fusion-with resultant aortic regurgitation-has been observed more frequently. To quantitatively assess the effects of nonpulsatile flow on aortic valve function, we tested a continuous-flow LVAD in a mock circulatory system (MCS) with an interposed valve. Materials and Methods. To mimic the hemodynamic characteristics of LVAD patients, we utilized an MCS in which a Jarvik 2000 LVAD was positioned at the base of a servomotor-operated piston pump (left ventricular chamber). We operated the LVAD at 8000 to 12,000 rpm, changing the speed in 1000-rpm increments. At each speed, we first varied the outflow resistance at a constant stroke volume, then varied the stroke volume at a constant outflow resistance. We measured the left ventricular pressure, aortic pressure, pump flow, and total flow, and used these values to compute the change, if any, in the aortic duty cycle (aortic valve open time) and transvalvular aortic pressure loads. Results. Validation of the MCS was demonstrated by the simulation of physiologic pressure and flow waveforms. At increasing LVAD speeds, the mean aortic pressure load steadily increased, while the aortic duty cycle steadily decreased. Changes were consistent for each MCS experimental setting, despite variations in stroke volume and outflow resistance. Conclusions. Increased LVAD flow results in an impaired aortic valve-open time due to a pressure overload above the aortic valve. Such an overload may initiate structural changes, causing aortic leaflet fusion and/or regurgitation. (C) 2011 Elsevier Inc. All rights reserved
AB - Background. As the use of left ventricular assist devices (LVADs) to treat end-stage heart failure has become more widespread, leaflet fusion-with resultant aortic regurgitation-has been observed more frequently. To quantitatively assess the effects of nonpulsatile flow on aortic valve function, we tested a continuous-flow LVAD in a mock circulatory system (MCS) with an interposed valve. Materials and Methods. To mimic the hemodynamic characteristics of LVAD patients, we utilized an MCS in which a Jarvik 2000 LVAD was positioned at the base of a servomotor-operated piston pump (left ventricular chamber). We operated the LVAD at 8000 to 12,000 rpm, changing the speed in 1000-rpm increments. At each speed, we first varied the outflow resistance at a constant stroke volume, then varied the stroke volume at a constant outflow resistance. We measured the left ventricular pressure, aortic pressure, pump flow, and total flow, and used these values to compute the change, if any, in the aortic duty cycle (aortic valve open time) and transvalvular aortic pressure loads. Results. Validation of the MCS was demonstrated by the simulation of physiologic pressure and flow waveforms. At increasing LVAD speeds, the mean aortic pressure load steadily increased, while the aortic duty cycle steadily decreased. Changes were consistent for each MCS experimental setting, despite variations in stroke volume and outflow resistance. Conclusions. Increased LVAD flow results in an impaired aortic valve-open time due to a pressure overload above the aortic valve. Such an overload may initiate structural changes, causing aortic leaflet fusion and/or regurgitation. (C) 2011 Elsevier Inc. All rights reserved
U2 - https://doi.org/10.1016/j.jss.2010.05.040
DO - https://doi.org/10.1016/j.jss.2010.05.040
M3 - Article
C2 - 20828746
SN - 0022-4804
VL - 171
SP - 443
EP - 447
JO - Journal of Surgical Research
JF - Journal of Surgical Research
IS - 2
ER -