Key result
In vitro, LV drainage yields higher flow than LA drainage at equivalent pump speeds.
Why the study?
Centrifugal and axial continuous flow LVADs lack valves, creating a risk of back flow at low pump speeds, necessitating estimation of minimum pump speed to prevent regurgitation.
In an in vitro LVAD model, LV drainage provides higher flow than LA drainage at the same pump speed, and preventing regurgitation requires maintaining pump speeds that overcome aortic diastolic pressure for LV drainage and aortic systolic pressure for LA drainage.
LV drainage may yield higher flows than LA in LVAD models; leaves open optimal cannulation site pending clinical validation.
Due to the fact that centrifugal and axial pumps do not require valves, there is a possibility of back flow when the pump speed is low. To estimate the minimum required pump speed to prevent this regurgitation, an in vitro simulation test was conducted. A pulsatile pump simulated the natural heart while a centrifugal pump simulated the continuous flow left ventricular assist device (LVAD). The LVAD flow was attained from the left atrial (LA) drainage or left ventricular (LV) drainage. The minimum or regurgitate flow was observed in the systolic phase with LA drainage and in the diastolic phase with LV drainage. LV drainage always provided higher flow than LA drainage at the same pump speed. These differences are due to the various total pressure heads of the LVAD. To prevent the regurgitation, the LVAD should maintain a certain pump speed which can create positive flow against the aortic systolic pressure with LA drainage and against the aortic diastolic pressure with LV drainage. These required pump speeds can be identified by the LVAD flow-pressure curve.
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Tayama et al. (1997) studied Left ventricular assist device (LVAD) regurgitation. Left ventricular (LV) drainage vs. Left atrial (LA) drainage was evaluated on Minimum or regurgitate flow and required pump speed to prevent regurgitation. In an in vitro simulation, LV drainage consistently provided higher flow than LA drainage at the same pump speed, requiring different minimum pump speeds to prevent regurgitation.
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