Monophasic action potentials, electrocardiograms and mechanical performance in normal and ischaemic epicardial segments of the pig ventricle in situ.

Few studies report simultaneous electrical and mechanical recordings from the epicardium of intact beating hearts in situ during ischaemia. We use suction to apply transducers and electrodes to areas of the epicardium. This interferes little with its behaviour and allows: i) free mobility over the surface; ii) simultaneous tridirectional length changes to be recorded and summed for an overall impression of mechanical behaviour, iii) detection of changes in direction of movement; iv) simultaneous recordings of monophasic action potential and epicardial ECG. During ischaemia we can detect impaired contraction with dyskinesis and a change in direction of epicardial forces. The action potential duration shortens and we have noted impaired conduction, inexitability and recordings consistent with re-entry leading to ventricular fibrillation.