INFLUENCE OF THE COMPLIANCE OF THE PUMP HOUSING AND CANNULAS OF A PARACORPOREAL PNEUMATIC VENTRICULAR ASSIST DEVICE ON TRANSIENT PRESSURE CHARACTERISTICS

The dependence of transient pressure characteristics of a ventricular assist device (VAD) on the compliance of its housing and cannulas was investigated in a mock circulation. The peak rate of change of pressur e (dP/dt(max)) values was greater in the cannulas than other compartme nts and was associated with valve closure-induced pressure oscillation s. When cannula compliance was increased from 0.0057 to 0.0129 cm(3)/m m Hg, these values decreased by similar to 20%, and outflow cannula pr essure oscillation frequency decreased from 17.5 Hz by 35%. This trend was also apparent in the inflow. A VAD housing compliance increase fr om 0.0162 to 0.0483 cm3lmm Hg caused a dP/dt(max) decrease of 30% in b oth the blood chamber and the outflow cannula. The effect of this chan ge on the inflow was weaker implying that housing absorbs the energy a ssociated with outflow deceleration more effectively than the inflow. These findings suggest that increasing VAD housing and cannulas compli ance can improve hydrodynamic performance.