Response of a physiological controller for ventricular assist devices during acute patho-physiological events: an in vitro study.

The current paper analyzes the performance of a physiological controller for turbodynamic ventricular assist devices (tVADs) during acute patho-physiological events. The numerical model of the human blood circulation implemented on our hybrid mock circulation was extended in order to simulate the Valsalva maneuver (VM) and premature ventricular contractions (PVCs). The performance of an end-diastolic volume (EDV)-based physiological controller for VADs, named preload responsive speed (PRS) controller was evaluated under VM and PVCs. A slow and a fast response of the PRS controller were implemented by using a 3 s moving window, and a beat-to-beat method, respectively, to extract the EDV index. The hemodynamics of a pathological circulation, assisted by a tVAD controlled by the PRS controller were analyzed and compared with a constant speed support case. The results show that the PRS controller prevented suction during the VM with both methods, while with constant speed, this was not the case. On the other hand, the pump flow reduction with the PRS controller led to low aortic pressure, while it remained physiological with the constant speed control. Pump backflow was increased when the moving window was used but it avoided sudden undesirable speed changes, which occurred during PVCs with the beat-to-beat method. In a possible clinical implementation of any physiological controller, the desired performance during frequent clinical acute scenarios should be considered.