Initial Reperfusion of DCD Hearts Under Hypothermic Conditions Impairs Myocardial Functional Recovery During Ex Vivo Heart Perfusion.

Abstract

Objective: Initial reperfusion (IR) of donor hearts following circulatory death (DCD) with cardioplegia may facilitate restoration of ion homeostasis prior to myocardial contraction, minimize ischemia-reperfusion injury, and optimize functional recovery. We investigated the impact of IR temperature on the recovery of myocardial function during ex vivo heart perfusion. Methods: Eighteen pigs were anesthetized, mechanical ventilation was discontinued, and cardiac arrest ensued. A 15-minute standoff period was observed and then hearts were procured and reperfused with a normokalemic adenosine-lidocaine crystalloid cardioplegia for 3 minutes at 3 different temperatures (5°C; N=6, 25°C; N=5, and 35°C; N=7). Hearts were then perfused ex vivo in a normothermic beating state and transitioned into working mode (left atrial pressure: 8 mmHg) at 1, 3, and 5 hours for assessment of myocardial function using a conductance catheter. Results: Hearts sustained an equivalent period of warm ischemia (5°C=28±1, 25°C=29±1, 35°C=27±1 minutes, p=0.50) prior to IR. IR coronary blood flow (5°C=483±53, 25°C=722±60, 35°C=906±36 mL/min, p<0.01) and coronary sinus lactate concentration (5°C=0.73±0.06, 25°C=1.33±0.03, 35°C=1.75±0.15 umol/L, p<0.01) differed among treatment groups. IR under hypothermic conditions impaired systolic (dP/dt max) and diastolic (dP/dt min) functional recovery (Figure 1). Electron microscopy revealed greater preservation of endothelial cell integrity in hearts reperfused at warmer temperatures (injury score 5°C=3.2±0.5, 25°C=1.8±0.2, 35°C=1.7±0.3 minutes, p=0.01). Conclusions:Avoidance of profound hypothermia during IR with an adenosine-lidocaine cardioplegia preserves endothelial integrity and improves the functional recovery of DCD hearts.Figure: No Caption available.