[Adaptation of perfusion flow during reperfusion to protect ischemic myocardium from calcium loading]

The aim of this study was (i) to evaluate calcium exchanges occurring during the first stage of reperfusion, and (ii) to investigate the effect of reperfusion flow applied on safe and ischemic hearts. Pig hearts (n = 20) were arrested with cardioplegia and randomly assigned into 2 groups: an ischemic group (1 hour in vitro ischemia at 38 degrees C) versus control group, before being subjected to aortic reperfusion (using 1 and 0.1 ml min-1 g-1 perfusion flow). Both oedema and arterio-venous differences in calcium were analysed during reperfusion. The data showed myocardial Ca++ loading in control hearts reperfused at low flow (p < 0.01) and in ischemic hearts reperfused at high flow (p < 0.01), whereas a low flow reperfusion appeared to protect ischemic hearts. In all groups, reperfusion oedema was greater than 20%. In conclusion, the data suggest that reperfusion flow of arrested hearts should be adapted to the state of the heart: a high flow, necessary for a safe heart, can be deleterious for ischemic heart, whereas a low flow, protective for ischemic hearts, can be deleterious for safe heart.