Synergistic effects of remote perconditioning with terminal blood cardioplegia in an in vivo piglet model

OBJECTIVES: This study tested the hypothesis that remote perconditioning offers effective and synergistic cardioprotection to terminal warm blood cardioplegia for prompt ventricular recovery after prolonged cardioplegic arrest in an in vivo piglet model. METHODS: Twenty-four piglets were subjected to 120 min of single-dose cardioplegic arrest and were divided into 4 groups according to the mode of reperfusion: control (simple aortic unclamp), remote perconditioning, terminal warm blood cardioplegia or remote perconditioning + terminal warm blood cardioplegia; remote perconditioning (4 cycles of 5-min ischaemia-reperfusion of the lower limb) was applied prior to aortic unclamping. Left ventricular systolic and diastolic functions were assessed by pressure-volume loop analysis at baseline and after 60 min of reperfusion. Biochemical injury was evaluated by plasma troponin T level. RESULTS: The control group showed decreased end-systolic elastance, preload recruitable stroke work and inverse of end-diastolic pressure-volume relationship of 51.3 ± 14.0%, 46.1 ± 22.5% and 34.8 ± 14.9%, respectively. Percentage recovery of end-systolic elastance and preload recruitable stroke work were significantly better with terminal warm blood cardioplegia (with or without remote perconditioning) (end-systolic elastance: 95% confidence interval, 38.6-84.1; preload recruitable stroke work: 95% confidence interval, 0.4-54.3). Percentage recovery of inverse of end-diastolic pressure-volume relationship was significantly better in the remote perconditioning groups (with or without terminal warm blood cardioplegia) (95% confidence interval, 1.6-41.6). No synergistic effects of remote perconditioning and terminal warm blood cardioplegia on troponin T release were noted. CONCLUSIONS: Remote perconditioning offers promising synergistic cardioprotection to terminal warm blood cardioplegia, implicating potential clinical benefit by contributing to prompt left ventricular functional recovery during paediatric open-heart surgery.