Normothermic Regional Perfusion of Circulatory Dead Donor Hearts: Quick and Dirty or Slow and Steady?

Purpose We sought to compare two strategies for cardiac reanimation in normothermic regional perfusion (NRP) in a clinically relevant porcine model of donation after circulatory death (DCD). To this day, many different protocols for NRP have been described. Methods For NRP-strategy 1(30mProp), pigs (n=16) were anaesthetized with intravenous Propofol (3.5 mg/kg/h) and subjected to hypoxic circulatory arrest (CA) by halting mechanical ventilation. After an 8-minute warm ischemia period, donor hearts were reanimated by a 30-minute NRP-period with Propofol suspended. For NRP-strategy 2(60mSevo), pigs (n=10) were anaesthetized with inhaled Sevoflurane (3.5%) before institution of hypoxia induced CA. A 10-minute warm ischemia followed before 60 minutes NRP with Sevoflurane continued. Both groups were reperfused via central cannulation with the aortic arch vessels and infrarenal aorta occluded. NRP flow, oxygenation, and weaning were standardized between groups. We assessed hemodynamic function with invasive blood pressure and bi-ventricular pressure-volume recordings 30 minutes post-NRP. Results All hearts were successfully reanimated during NRP in both groups. During NRP, a significantly higher mean arterial blood pressure and a minor need for pressor support with norepinephrine were observed in the 60mSevo group compared to the 30mProp group. Cardiac output remained on baseline levels in both groups post-NRP. Arterial lactate was significantly lower in the 60mSevo group post-NRP compared to the 30-minProp group. Left ventricular end-systole elastance as a measure of contractility increased significantly from baseline to post-NRP by 0.5 mmHg/mL (95%CI 0.09 : 1.0) in the 60-minSevo group and increased non-significantly by 0.3 mmHg/mL (95%CI -0.04 : 0.7) in the 30minProp group, while right ventricular contractility increased non-significantly in both groups. Conclusion Hearts reperfused for 60 minutes combined with inhaled Sevoflurane showed superior contractile function compared to hearts subjected to 30-minute NRP and Propofol anaesthesia. The results indicate that longer NRP is beneficial in DCD heart donation.