Computer support for experiments on isolated hearts.

The left ventricular pressure (LVP) and ECG signals that appear during and after ischaemia tend to be very irregular (fibrillation, arrhythmia). Computer based data acquisition system, that we developed to support experiments on isolated Langendorff's rat heart, enabled the usage of methods derived from non-linear dynamics. To classify the irregularity of heart action, ECG and LVP time series have been used to calculate correlation dimension (D2) and largest Lyapunov exponent. We compared the results of signals derived from isolated heart at standard conditions and hearts rendered ischaemic for 60 minutes. Our results show that the level of irregularity can be classified efficiently using the quoted approach.