The Evaluation of Coronary Artery Function during Normothermic Ex Situ Heart Perfusion

Abstract

Purpose Ex situ heart perfusion (ESHP) allows continuous functional and metabolic assessment of donor hearts before transplantation. The coronary artery autoregulation is essential to maintain normal cardiac function during ESHP. Our objective is to investigate coronary autoregulation during normothermic ESHP and find ways to protect myocardial function during heart preservation. Methods The procured hearts (n=12) were perfused in ex situ working heart system at 37°C for 12 hours (with whole blood based perfusate). Cardiac functional parameters was monitored in the entire interval. Coronary vascular resistance (CVR) was calculated as an indicator of coronary artery function. At 1 and 5 hours of perfusion, loading of the heart will be varied by increasing or decreasing left atrial pressure to observe the corresponding response in coronary artery flow. Results During 12 hours normothermic perfusion, myocardial function declined over time as indicated by the cardiac index change at 5 and 11 hours compared with its baseline (p˂0.05); myocardial oxygen consumption was decreased significantly (p˂0.01, Fig. A). The coronary blood flow increased over time and coronary vascular resistance decreased, with significantly difference at T5 and T11 compared with T1 respectively (p˂0.01, Fig. B). At T1 of perfusion, coronary artery flow shows strong correlation with left ventricle stroke work (p˂0.01, R2=0.79, Fig. C); however, at T5, the regression line is significantly different (p˂0.01), with relative lower slope (R2=0.36, Fig. D). Conclusion There is uncoupling between cardiac function and coronary artery flow. Our data reveals a poor correlation between hemodynamic stress and coronary blood flow after 5 during ESHP, indicating that the coronary autoregulation phenomenon is disturbed, which lead to excessive coronary blood flow overtime. Whether the loss of coronary artery regulation cause the decline of heart function need to be further investigated.