EFFECTS OF STIMULUS WAVE-FORMS ON THE MAGNETIC STIMULATION OF CARDIAC-MUSCLE

We analytically and experimentally studied how the stimulation thresho ld depended on the waveforms ui magnetic fields for magnetic heart sti mulation. The stimulation threshold was calculated for the magnetic fi elds of rectangular, damped sinusoidal and crowbar pulses on the basis of a cell membrane model for the ventricular muscle. In the experimen t, premature contractions of canine hearts mere induced by pulsed magn etic fields with different waveforms. The observed stimulation thresho ld for single pulses did not show the systematic waveform dependence w hich was obtained in the analysis. Applying double crowbar poises to t he canine hearts resulted in a lowering in the stimulation threshold, which corresponded to the analytical result.