Criteria for the multiple use of isolated perfused hearts in electrophysiological and metabolic experiments.

Both ethical and economic restrictions limit the availability of porcine hearts for in vitro perfusion experiments. Therefore, we tested the feasibility of multiple use of in vitro perfused working hearts for electrophysiological and metabolic investigations. Pig hearts (n=7) rejected for originally planned haemodynamic measurements because of exclusion criteria were perfused in a four-chamber working heart mode. All hearts were kept in steady-state conditions on a low haemodynamic level over 2 h during 75-channel ECG recordings and NADH fluorescence measurements before and after norepinephrine (NE) was administered. QRS and QT interval durations were in a range comparable to in vitro studies and, like QRS and T amplitudes, were found to be sensitive markers of the changing condition of the isolated heart preparation, as myocardial oedema leads to prolonged QRS and QT intervals and declining ECG voltage amplitudes. A change in NADH fluorescence following NE administration was observed in the first 150 min of perfusion, but not later. Considering a time frame of 120 min, multiple use of isolated perfused porcine hearts with low-level haemodynamics may allow a broad spectrum of investigations and could therefore represent a possibility of overcoming the restricted availability of porcine hearts.