Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Patent
1999-07-06
2000-10-17
Getzow, Scott M.
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
A61N 1362
Patent
active
061344699
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to an implantable cardioverter-defibrillator and/or cardiac pacemaker for stimulating the cardiac muscle (cardiac stimulation device), with at least one electrode for connection to the heart muscle, a programmable electrical circuit for producing series of stimulation impulses with impinge upon the electrode, and with an electronic memory connected to said circuit, with which over several periods of the heart beat the electrical phenomena inherent in the heart-beat, in particular systoles and their characteristic frequency f.sub.c, can be recorded and stored, the electrical circuit evaluating the stored electrical phenomena and emitting corresponding series of anti-tachycardiac and anti-bradycardiac stimulation impulses.
The two most important types of cardiac stimulation devices, cardioverter-defibrillators and so-called pacemakers, conventionally operate using types of stimulation which begin after the onset of cardiac tachyarrhythmias.
Cardiac stimulation devices of this type, in the form of cardioverter-defibrillators and or pacemakers with anti-tachycardiac or anti-bradycardiac modes of stimulation are known, for example according to U.S. Pat. No. 4,052,991 and U.S. Pat. No. 3,857,399. However, the stimulation devices according to the state of art emit stimulation impulses which, during anti-tachycardiac function, begin with a 1-s time delay after the onset of the tachycardia.
They operate in correspondence, that is, the period duration of the stimulation impulses is shorter than the duration of the systoles in tachycardia. This shortened impulses series is intended to "intercept" the extrasystoles, which become present in tachycardia. On perception of the systole frequencies arising during tachycardia, the delay time is followed by a continuous stimulation at a frequency f.sub.s, which is higher than the characteristic frequency, f.sub.e. This frequency f.sub.s is for the most part held constant.
The aim is to provide a cardiac-stimulation device, which is capable of preventing the occurrence of tachycardia at an early stage.
The aim is achieved by a cardiac-stimulation device, namely a cardioverter-defibrillator or a pacemaker of the type named in the preamble, characterized in that the electrical circuit is able, on detection of one or more of successive extrasystole(s) not of the characteristic frequency f.sub.e, to produce a series of stimulation impulses of frequency f.sub.g (t) which, after the appearance of extrasystole(s), begin after a programmable time interval (between 50 and 100% of t.sub.mean) at a frequency f.sub.gi higher than the detected previous frequency f.sub.g and are then steadily retarded, i.e. they steadily decrease in frequency f.sub.g until the frequency f.sub.g (t) essentially corresponds to the characteristic frequency f.sub.e, in particular that the frequency f.sub.g (t) falls below the characteristic frequency f.sub.g to a frequency f.sub.sub or ends with the frequency f.sub.c.
This type of production of a series of stimulation impulses is embodied in a cardiac stimulation device, which is itself known, as characterized in generic term in claim 1.
Following an extrasystole, the cardiac-stimulation device according to the invention produces an initially more rapid series of stimulation impulses at a higher frequency f.sub.gi than frequency f.sub.c (characteristic or natural frequency). A steady slowing then follows, until the frequency f*(t) corresponds to the characteristic frequency f.sub.c. The frequency f.sub.g preferably ends on attaining the characteristic frequency f.sub.c.
The cardiac-stimulation device according to the invention is therefore capable of producing, in addition to the known and still available modes of stimulation, another mode of stimulation setting in after each extrasystole, which is followed by a longer "compensatory" pause, without a prior delay of the order of 1 s for the first stimulation impulse, as in the state of art. It is therefore proposed that the time interval t.sub.i betw
REFERENCES:
patent: 4467810 (1984-08-01), Vollmann
patent: 5312451 (1994-05-01), Limousin et al.
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