Reperfusion strategy after regional ischaemia: simulation of emergency revascularization and effects of integrated cardioplegia on myocardial resuscitation.

We induced ischaemia in the left anterior descending artery of 16 dogs while the heart was beating, followed by cardiopulmonary bypass (CPB), aortic cross clamping and blood cardioplegia. Half of the dogs received integrated blood cardioplegia and sudden uncontrolled reperfusion (group A) while the others received the same cardioplegia followed by pressure-controlled tepid initial reperfusion (group B). The effects on myocardial cell metabolism, oxidative stress and ultrastructure were recorded. The recovery period was significantly longer and cardiac output levels after CPB significantly lower in group A compared with group B. Group A showed a failure to uptake and utilize oxygen during the recovery period and significant lipid peroxidation. Marked tissue oedema was seen in group A but mitochondrial and organelle integrity was almost normal in both groups. We conclude that integrated cardioplegia could partially resuscitate the myocardium in this model, and pressure controlled reperfusion during the first 2 min is needed as an adjunct procedure.