Contractility versus Metabolic Cardiac Assessment during Ex Situ Heart Perfusion: A Pre-Clinical Transplant Study

Abstract

Purpose Assessment of DCD hearts during ex situ perfusion (ESP) is required to determine suitability of these organs for transplant. To date, metabolic and contractility parameters have not been compared using a full transplant model. We aimed to identify which parameters measured during ESP could predict myocardial performance post-transplantation Methods Porcine hearts were procured from beating-heart donations (n=6) or following hypoxic circulatory arrest and 15min of warm ischemia (n=6). They underwent 4h of ESP, transplantation, and reperfusion for 3h. Cardiac function was assessed during ESP using left (LV) and right (RV) ventricular pressure-volume loops, and metabolic parameters. We performed linear regressions to identify significant correlations Results Several parameters correlated with recovery of cardiac function (Table 1). LV developed pressure was the best predictor of LV Max dP/dt (R2=0.523; p=0.018) while myocardial oxygen consumption (MVO2) at 30min of ESP better predicted LV stroke work (R2=0.625; p=0.006). RV Tau during ESP was the best predictor of post-transplant RV function (R2=0.615; p=0.021). Several metabolic parameters predicted cardiac index. LV Preload Recruitable Stroke Work was the only contractile measurement to predict cardiac index (R2=0.467; p=0.021), while MVO2 at 30min was the best predictor (R2=0.578; p=0.007) Conclusion Both contractility and metabolic markers measured during ESP were able to predict myocardial performance following transplantation. Assessment of metabolic parameters demonstrated a more significant number of correlations and provided a better evaluation of cardiac index. This is contradictory with previous reports showing contractile evaluation would provide a more accurate estimation of early transplant function. However, contractility parameters were better to evaluate isolated LV and RV function post-transplant. Further studies are needed to clarify this question.