Experimental Determination of Vascular Pulsatility During Continuous-Flow LVAD Assistance

Continuous flow ventricular assist devices (CF-VADs) are being used to treat of infant patients with acute heart failure. Because of their operation mode, these devices present an increase in gastrointestinal bleeding and vascular remodeling. To overcome these problems, newer pumps are developing control strategies with pulsatile flow, focusing in minimizing the very high pathological shear stress, which is known to cause platelet activation, hemolysis, and acquired von Willebrand syndrome. In this work, we used an automatic hydraulic simulator to study the interaction of the CF-VAD PedVad Incor prototype as a means to identify important parameters for the development of a control strategy algorithm. The simulator uses a 30 ml pneumatic pump to mimic the native heart, with pressure and flow data recorded digitally. Energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE) were calculated to quantify flow pulsatility. The simulator was set to operate in normal hemodynamic condition and two conditions of heart failures insufficient conditions at 70, 80 and 90 cycles per minute (cpm) with no assistance, partial and full assistance. The results demonstrated that assistance at 50% maximal cardiac output there is an increase in pulsatility. At full assistance there is no flow from the native heart and pulsatility drops to near zero. The application of the simulator for studies that attempt to increase the hemodynamic energy provided by continuous-flow devices is an important tool for the development of novel control strategies for pediatric mechanical circulatory devices.