Resonantly Coupled High-Efficiency Sensors for Assessment of Ventricular Chamber Size for Autonomous Control of Left Ventricular Assist Device

Abstract

Current left ventricular assist devices (LVADs) are set to a fixed rpm and are unable to adjust to physiological demands irrespective of preload or afterload. Autonomous control of LVADs has the potential to reduce septal shift, preserve right ventricle function, and meet physiological demands. A highly innovative resonantly coupled regimen is presented which can achieve this goal. We introduce sensors based on a highly sensitive relationship between transmission coefficient and spatial separation in a resonantly coupled regimen. This relationship represents a polynomial regression. A regimen of an apical sensor and multiple outflow sensors is investigated. A range of separations varying from 50-200 mm was systematically investigated. These ranges consider anatomical & physiological variation(s) in cardiac chamber size. Validation was obtained in porcine heart preparation.The polynomial regression model predicted distance between the sensors with a mean absolute percentage error of 0.77%, 1.07%, and 5.75% for the three putative positions of the outflow sensors and apical sensor when compared with experimental results. A high degree of accuracy (95%) between the predicted and observed distance was obtained. Continuous measurements were done over 90 days to examine drift, with no statistically detectable change in measurements over million sampling cycles.We have demonstrated a reliable sensor methodology without drift for assessing ventricular chamber size in an LVAD setup. This has the potential to allow autonomous control of LVAD based on ventricular chamber size to address some of the adverse events.

Toward a Self-Actuating Continuous Flow Ventricular Assist Device: The Pudding Is in the Proof

“…In this issue of the Journal , Palagani et al present an important step toward the clinical reality of Smart Pump technology. 10 These investigators developed and tested a series of sensors that could be easily integrated into current LVAD technology that would allow real-time assessment of left ventricular size and inform adjustments in pump speed based upon changes in left ventricular volumes. The authors integrated a transmitter in the apical sewing ring and placed a series of detectors in the outflow graft of a ventricular assist device to enable determination of left ventricular volumes.…”