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Abstracts: ASAIO Cardiac Abstracts

SIMULATION OF TAH CIRCUIT WITH TANDEM CONTINUOUS-FLOW VADS

Khalil, Hassan A1,2; Franchek, Matthew A2; Metcalfe, Ralph W2; Frazier, O H1; Kadipasaoglu, Kamuran A1,2

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Background:

If two continuous-flow pumps (CFP) are used in tandem to replace both ventricles, a small, durable and 100% pulseless TAH system is achieved. We characterized the hemodynamic effects of various flow disturbances on a pulseless TAH in vitro.

Methods:

Two centrifugal VADs (Levitronix, Waltham, MA) were connected each to atrial (preload) and systemic/pulmonary (afterload) reservoirs through tubing of variable diameter and compliance. Left and right pump speeds and vascular resistance levels were adjusted.

Results:

Mean aortic and pulmonary pressures (mmHg) were 80±20 and 25±10, respectively; and left pump and bronchial return flows (L/min) were 6±3 and 1±0.5, respectively. Pressures were successfully uncoupled in the left and right systems while respective flows remained interdependent. External manipulation of pump speed was necessary to restore AoP during exercise (elevated venous return, VR) and prevent LA suction during pulmonary hypertension (HTN).

Conclusions:

The circuit reliably simulated the hemodynamic responses of a comparable in vivo system. A feedback control algorithm is needed to automatically adjust pump speed(s) during physiologic disturbances that exceed the intrinsic autoregulatory capacity of the dual CFP system.

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Copyright © 2005 by the American Society for Artificial Internal Organs