In this study we used Visible Heart® methodologies featuring cyclic temperature modulation of porcine hearts in order to establish characteristic temperature responses. This isolated and perfused model is a more predictable and modifiable analog for human heart preservation and isolates the response of the cardiac tissue. We comprehensively monitored isolated porcine hearts undergoing temperature change and demonstrated optimization of isolated cardiac function under mild hypothermia. We tracked metrics of cardiac function as continuous variables during temperature changes (~ 31 to 39 °C), eliciting a well-defined reduction in metabolic demand and in heart rate modulation. Optimization of function appeared to occur around 34.7 ± 0.9 °C (n = 13). Cardiac response was further investigated in the presence of active pacing in order to assess pacing capture and the heart's functional response without a means of regulating rate. Our results may have direct clinical implications for emerging heart preservation methods prior to transplantation, as well as benefits for investigators using isolated heart models for preclinical device testing. Clinically, this porcine model is a basis for finding new ways to extend the window of viability for transplantable organs, thereby restoring or improving graft function and potentially enhancing recipient outcomes.
Keywords: Hemodynamic responses; Isolated heart; Mild hypothermia; Pacing; Transplantation.