Energy consumption for cardiac stimulation as a function of pulse duration

Abstract

Studies were performed of the threshold of cardiac stimulation as a function of impulse duration in dogs, acutely, and in humans acutely and chronically. Impulse durations from 0.1 to 5.0 msec. were utilized. o.1.Myocardial impedance does not vary as a function of impulse duration, within the measured range. 2.Voltage needed at threshold falls progressively from the shortest to the longest impulse durations. 3.Current utilized falls progressively from shortest to longest impulse durations. 4.Energy consumed at thresholds, acute and chronic, is highest at short impulse durations, falls progressively to a minimum at impulse durations of 0.2 to 1.0 msec., then rises at longer impulse durations. 5.Total charge consumed remains low until impulse durations of 0.2 and 0.5 msec. are reached. With lengthening of impulse, total charge consumed rises. An impulse duration of 0.5 to 0.75 msec. is more economical for production of ventricular systole. Studies were performed of the threshold of cardiac stimulation as a function of impulse duration in dogs, acutely, and in humans acutely and chronically. Impulse durations from 0.1 to 5.0 msec. were utilized. o.1.Myocardial impedance does not vary as a function of impulse duration, within the measured range. 2.Voltage needed at threshold falls progressively from the shortest to the longest impulse durations. 3.Current utilized falls progressively from shortest to longest impulse durations. 4.Energy consumed at thresholds, acute and chronic, is highest at short impulse durations, falls progressively to a minimum at impulse durations of 0.2 to 1.0 msec., then rises at longer impulse durations. 5.Total charge consumed remains low until impulse durations of 0.2 and 0.5 msec. are reached. With lengthening of impulse, total charge consumed rises. An impulse duration of 0.5 to 0.75 msec. is more economical for production of ventricular systole.