Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Patent
1992-04-09
1994-11-22
Kamm, William E.
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
A61N 139
Patent
active
053664841
ABSTRACT:
The present invention determines mathematically the optimum pulse duration, d, for a truncated capacitor-discharge waveform employed for cardioversion. The present invention comprehends the system time constant, RC, where R is tissue resistance and C is the value of the capacitor being discharged, and also the cardioversion chronaxie, d.sub.c, defined by Lapicque, which is a characteristic time associated with the stimulation of heart tissue. The present invention determines the optimum pulse duration to be roughly the average of RC and d.sub.c, appreciably smaller than the value employed in the prior art. The optimized-pulse of the present invention can be applied to a monophasic waveform, or to the first phases of biphasic waveforms. The second phase can be specified to have equal or lesser duration than the first. The process of the present invention can also be applied to the first phases of multiphasic waveforms. Pulse duration can be controlled by sensing duration directly, or by sensing tilt. When energy delivered to the heart is taken to be constant, and the waveform is optimized on that basis, then the waveform has a very short duration, approximating the chronaxie of the myocardial tissue, and the waveform approximates a rectangular pulse.
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Angeion Corporation
Kamm William E.
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