Development of a cardiac loading device to monitor cardiac function during ex vivo graft perfusion.

Abstract

Ex vivo heart perfusion systems, allowing continuous perfusion of the coronary vasculature, have recently been introduced to limit ischemic time of donor hearts prior to transplantation. Hearts are, however, perfused in an unloaded manner (via the aorta) and therefore, cardiac contractile function cannot be reliably evaluated. We aim to develop a ventricular loading device that enables monitoring of myocardial function in an ex vivo perfusion system. In this initial study, was to develop a prototype for rat experimentation. We designed a device consisting of a ventricular balloon and a reservoir balloon, connected through an electronic check valve, which opens and closes in coordination with changes in ventricular pressure. All balloons were produced in our laboratory and their properties, particularly pressure-volume relationships, were characterized. We developed a mock ventricle in vitro test system to evaluate the device, which was ultimately tested in ex vivo perfused rat hearts. Balloon production was consistent and balloon properties were maintained over time and with use on the device. Results from in vitro and ex vivo experiments show that the device functions appropriately; hemodynamic function can be measured and compares well to measurements made in an isolated, working (loaded) rat heart preparation. Our cardiac loading device appears to reliably allow measurement of several left ventricular hemodynamic parameters and provides the opportunity to control ventricular load.