心臓ペースメーカ電極と刺激閾値に関する研究

抄録

Studies were made, to elucidate problems concerned with pacemaker electrodes and stimulation threshold.
1) Electrolysis of electrodes was compared among various stimulation waveforms used for cardiac pacemaking by using gelatinized physiological saline solution. The degree of electrolysis was judged by the degree of metal ion tincture to the gelatinized solution around the electrodes. Less electrolysis was observed with a symmetrical biphasic pulse, a condenser blocked pulse and a monophasic rectangular pulse in the descending order, when they were used as pacemaking pulses. The direct induction pacemaker was employed for generating the symmetrical biphasic pulse.
2) There was an optimal surface area of an electrode for the heart to be paced with a minimum electricity. Electrical threshold was not affected significantly by the distance between bipolar electrodes or their locality on the heart. Monopolar stimulation had lower threshold than bipolar stimulation.
3) A Hunter-Roth electrode, a coiled electrode, a cored coil electrode, a screw-in electrode and a catheter electrode were examined in regards to electrical threshold, tissue reaction and structual strength. The coil type electrodes and catheter electrode were satisfactory in all respects during long term observation, while the Hunter-Roth electrode failed of functioning in a relatively short period of time.
4) Stimulation threshold was changed to some degree by physiological conditions such as myocardial anoxia or autonomic nervous disturbances, but not significantly from the practical viewpoint of cardiac pacemaking.
5) Clinical experiences have shown that the elevation of threshold encounterd was brought about mostly by infection around the electrodes. The infectious granulous tissue or scar formation around the electrodes separated them from normal myocardial tissue, thus reducing transmembraneous current density of myocardial cells.