The Circumferential Loading of a Direct Cardiac Compression Assist Device

Abstract

Heart disease is the developed world's largest killer. Transplantation of the failing heart remains the most effective treatment currently employed, but demand far exceeds donor supply. In a bid to address this imbalance, the use of mechanical circulatory support has been explored since the mid-1960s. This paper utilizes one such device, which achieves assistance by mechanically compressing the epicardial surface of the failing heart. The circumferential normal loading of the device is investigated, showing how frictional effects inherent to the device's operation affect localized surface pressure. Results showed that as distance from the device's actuator increased, assistive systolic force reduced, whilst device constriction to ventricular filling detrimentally increased. Active device relaxation was shown to limit the diastolic effect outlined above, providing the simulated diseased heart with an improved cardiac output. The results also raise questions concerning device in-vivo positioning and short-comings with the current heart simulator.

Introducing a hardware-in-the-loop simulation of the cardiovascular system

“…This reflects the importance of these pressure transducer for different type of assistance which was not considered in previous HiL study [27]. Keeling et al has reported how frictional effects inherent to the DMVA device's operation affect localized surface pressure [33]. Adapting from these studies, type of the DMVA and its position relative to the physical heart is configurable in our proposed HiL simulation.…”

“…Preliminary in-vitro experiments were carried out in an attempt to investigate into the effect that the DMVA system similar to [33], has on PV loop, cardiac output, and overall hemodynamics under different physiological conditions. The hemodynamic parameters, collected from an ovine at 87bpm, were used to tune the numerical CV model ran on the proposed HiL simulation.…”