Estimation of Filling and Afterload Conditions by Pump Intrinsic Parameters in a Pulsatile Total Artificial Heart

Abstract

A physiological control algorithm is being developed to ensure an optimal physiological interaction between the ReinHeart total artificial heart (TAH) and the circulatory system. A key factor for that is the long-term, accurate determination of the hemodynamic state of the cardiovascular system. This study presents a method to determine estimation models for predicting hemodynamic parameters (pump chamber filling and afterload) from both left and right cardiovascular circulations. The estimation models are based on linear regression models that correlate filling and afterload values with pump intrinsic parameters derived from measured values of motor current and piston position. Predictions for filling lie in average within 5% from actual values, predictions for systemic afterload (AoPmean , AoPsys ) and mean pulmonary afterload (PAPmean ) lie in average within 9% from actual values. Predictions for systolic pulmonary afterload (PAPsys ) present an average deviation of 14%. The estimation models show satisfactory prediction and confidence intervals and are thus suitable to estimate hemodynamic parameters. This method and derived estimation models are a valuable alternative to implanted sensors and are an essential step for the development of a physiological control algorithm for a fully implantable TAH.

Experimental investigation of right‐left flow balance concepts for a total artificial heart

“…For that purpose, the membrane is deflected by the pusher plates into the pumping chamber displacing the blood during the respective systole. During the diastole, the membrane separates from the pusher plate (passive filling) and returns to its rest position by the elastic restoring force and due to a pressure difference (related to atrial blood pressure) over the membrane 7,9 . Due to the elastic properties of the membrane, the ejected stroke volume is slightly dependent on the afterload.…”

“…During the diastole, the membrane separates from the pusher plate (passive filling) and returns to its rest position by the elastic restoring force and due to a pressure difference (related to atrial blood pressure) over the membrane. 7,9 Due to the elastic properties of the membrane, the ejected stroke volume is slightly dependent on the afterload. This results in a reduced systemic stroke volume (caused by high outlet pressures) compared to the pulmonary side and has a slight negative influence on the flow balance.…”

Detection of physiological control inputs preload and afterload from intrinsic pump parameters in total artificial heart

“…afterload, cardiovascular system, intrinsic parameters, physiological control, preload, total artificial heart and depends on the piston's position. 12 Cumulatively, however, they reflect the force required for emptying the chambers in a timely manner as planned with the preset reference position.…”

“…It has been shown conceptually in the past that preload and afterload can be detected from the electrical currents in one of the piston's driving coils in a limited range of cardiovascular system states. 12 To develop a practical and robust solution for preload and afterload detection, the data from all four coils need to be fused. Data fusion can be achieved by assembling the force that the piston exerts on the chambers.…”

A review of implantable pulsatile blood pumps: Engineering perspectives

“…Furthermore, a control algorithm in response to preload and afterload was developed to address the imbalance between pulmonary circulation and system circulation. 79 Therefore, the ReinHeart device could provide customized assist for different physiological conditions.…”