Hemodynamic consequences of pressure-flow curve gradient variations in continuous-flow ventricular assist devices

Continuous-flow ventricular assist devices (VADs) have been widely adopted in clinical practice for the treatment of heart failure, but the effect of their non-pulsatile blood flow on microvascular circulation is still debated. Although VADs with a flatter H-Q curve are known to produce greater pulse pressure (PP), other hemodynamic performances have not been systematically compared and analyzed.

This study employed a lumped-parameter cardiopulmonary circulation numerical model to compare the hemodynamic responses of two continuous-flow centrifugal pumps: the Corheart 6 (flatter H-Q curve) and the HeartMate 3 (steeper H-Q curve). Comparisons were conducted across four distinct clinical scenarios: left heart failure, right heart failure, myocardial recovery and acute preload shifts. A quantitative assessment focused on arterial PP, peripheral organ perfusion, ventricular unloading, pump suction risk, and pump thrombosis risk.

At the same average pump flow, pumps with a flatter H-Q curve, because of their higher sensitivity to preload, generated higher pump flow pulsatility and greater arterial PP, thereby creating hemodynamic conditions that may theoretically reduce risks associated with flow stasis. However, their ventricular unloading and peripheral organ perfusion were slightly inferior. When pump speed was increased, these pumps achieved ventricular unloading and peripheral organ perfusion comparable to those with steeper H-Q curves while simultaneously yielding even higher arterial PP. In contrast to the static condition, during dynamic events such as acute preload reduction caused by postural changes, VADs with a flatter H-Q curve are better able to maintain systemic perfusion pressure. When applied in right heart failure, right atrium implantation yields superior right ventricular unloading but lower pump flow pulsatility of both pumps.

The findings provide references for VAD developers and clinicians for the optimal design and utilization of blood pumps with different H-Q characteristics.