On-line analysis of intracellular electrophysiological data using a microcomputer system

Automated analysis of intracellular action potentials from cardiac Purkinje fibers was implemented using a microcomputer system. A dual sampling rate was used during analog-to-digital conversion of action potentials recorded from stimulated fibers. The rapid phase of depolarization was sampled at 42.55 kHz. The repolarization and the diastolic phases were sampled at 1 kHz. The resting potential, action potential amplitude, conduction time, action potential duration measured at 50% and at 90% of repolarization, and the maximum upstroke velocity were obtained on-line. The digital form of the action potential was stored on cassette tape and a table containing the various measurements was assembled during the experiment. In unstimulated fibers, the time interval between consecutive action potentials was measured on-line along with the maximum diastolic potential, the action potential overshoot, and the slope of the diastolic depolarization.