Table of Contents
See Also: Biography of Barouh Berkovits
The D.C. Defibrillator
The United States Patent Office 3,236,239 DEFIBRILLATOR
Barouh V. Berkovits, Buffalo, N.Y., assignor
to American Optical Company, Southbridge Mass.
Filed July 17, 1962, Ser. No. 210,5947 Claims (Cl. 128-419)
This invention relates to electronic equipment for the treatment of cardiac disorders.
Classic treatment of most cardiac arrythmias involves the use of various drugs, such as quinidine, procainamide, digitalis, and the like. It has been known, also that electrical depolarizing impulses of rather high voltage and amperage can be effective in reverting certain arrythmias to normal sinus rhythm. However, due to the rather high mortality incident to the use of such depolarizing technique, it has heretofore been limited to use in conjunction with terminal events, for example ventricular fibrillation, and even here, usually only in those cases where the classic treatment, open chest cardiac resuscitation, is not indicated. In accord with the present invention, a therapeutic electrical stimulus derived from a charged capacitance is applied in controlled, timed relation to the cardiac cycle, it having been found that the high mortality previously associated with electrical depolarizing is due to application of the depolarizing impulse during one or both of two critical periods during the cardiac cycle. Of primary concern in connection with the present invention, then, is the provision of means enabling a physician to apply a capacitance discharge depolarizing impulse at a selected and precise point during the cardiac cycle which lies outside the above mentioned known critical areas. To achieve this effect, the present invention employs means for detecting the electrical activity of successive cardiac cycles and electrical depolarizing means controllable in timed relation to a known reference point occurring during a cardiac cycle as established from the means for detecting so as to intelligently apply the depolarizing impulse as aforesaid.
| In general, this invention envisages equipment capable of providing electrical stimuli either directly or indirectly to a patient’s heart for the purpose of reverting cardiac arrythmias. FIG. 5 is a waveform showing normal sinus rhythm; FIG. 6 is a waveform showing the output of the trigger synchronized with the R waves of FIG. 5; FIG.7 is a waveform showing the output of the trigger synchronized with the R waveform of FIG. 6. FIG. 8 is a waveform showing the output of the delay means; and FIG. 9 is a waveform showing the output of the defibrillator. |  |
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Demand Pacer
United States Patent Office 3,345,990
Heart-Beat Pacing Apparatus
Barouh V. Berkovits, Tonawanda, N.Y., assignor to
American Optical Company, Southbridge, Mass. a voluntary association of Massachusetts
Filed June 19, 1964, Ser. No. 376,489
9 Claims. (Cl. 128-419)
A heart pacing apparatus which provides electrical heart-stimulating impulses to the patient's heart only in the absence of natural heartbeats. If only a single natural heartbeat is absent only a single electrical impulse will be provided. If more than one natural heartbeat is missing, an equal number of electrical impulses will be provided. No matter how many electrical stimuli are generated, they occur at essentially the same time spacing from each other and from the last natural heartbeat as would be the case if they were all natural heartbeats. The apparatus is arranged normally to generate electrical impulses at pre-determined time intervals approximately the rate of the heartbeat. Upon detection of the natural heartbeat the next electrical stimulus which would otherwise be generated is inhibited. At the same time, the apparatus restarts its timing cycle so that the next electrical impulse will be generated (if needed) after the predetermined time interval has elapsed, starting with the heartbeat just detected. The result is an overall "integrated" operation, i.e., a mutually exclusive cooperation of the natural heartbeats and stimulating pulses.
3,528,428
Heart-Beat Pacing Apparatus
Barouh V. Berkovits, Newton Highlands, Mass.,
assignor to American Optical Company, Southbridge, Mass., a corporation of Delaware
Filed Sept. 15, 1970, Ser. No. 727,129
42 Claims. (Cl. 128-419)
A demand pacer which provides electrical heart-stimulating impulses in the absence of natural heart-beats. In a pacer of this type, if the natural heartbeat detector is erroneously triggered, it is possible for impulses to be inhibited when they are actually needed. Erroneous operation of the detector in the invention is partially prevented by tuning it to the dominant frequencies in the electrical signal which is generated as a result of a localized ventricular depolarization. These frequencies, however, are relatively close to 60 Hz, and thus 60 Hz stray signals might erroneously cut off the generation of impulses. For this reason, a capacitor charging circuit is provided in the detecting circuit. All input signals are processed so that the capacitor is fed by unipolar pulses. Pulses occurring at a 120 Hz rate (from the processing of stray 60 Hz signals) occur so rapidly compared to the discharge time constant of the capacitor circuit that the voltage across the capacitor does not change appreciably. Heartbeat signals, on the other hand, occurring at the much slower rate of approximately 72 per minute, allow the capacitor to discharge sufficiently after each charging pulse such that a large pulsating signal is developed across the capacitor. It is each pulsating signal which shuts off the generation of an impulse. In the presence of 60 Hz stray signals, the pacer functions in its continuous mode.
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Repetitive Firing During Synchronized Electrical Stimulation
Repetitive firing induced by artificial stimuli delivered by commercial (portable or implanted) pacemakers has been considered to be rare in the past. Recent reports suggest that the occurrence of this phenomenon in the human heart is more frequent than previously thought. This potential hazard of synchronized electrical stimulation has been emphasized. The study of other variables, such as the supernormal phase, as well as the analysis of the effects of "strong" driving impulses (15 to 20 times above the threshold) on previously subthreshold responses will be presented in a separate communication. The duration of the absolute refractory period, measured with testing stimulus with an intensity of five times above the threshold, ranged from 265 to 310 msec., for cycle lengths varying between 920 and 1,000 msec. In 6 patients there were spontaneous fluctuations in the length of the refractory period, amounting up to 25 msec. These unexpected effects could not be attributed to variations in the driving rate as happens with those methods of studying excitability which take advantage of the co-action of natural (sino-atrial) and an artificial pacemaker. On the contrary, they could be explained by the movement of the catheter electrode away from the endocardium, although similar variations in refractoriness have also been recorded in experimental studies employing intramyocardial electrodes. The threshold values ranged between 0.6 and 1.5 volts. There were 3 patients in whom repetitive firing occurred in response to impulses falling close to the peak of the T wave.
Castellanos A, Lemberg L, Jude JR, Berkovits BV. Repetitive firing occurring during synchronized electrical stimulation of the heart. J Thorac Cardiovasc Surg 1966; 51: 334-340.
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Demand Pacing
Demand pacemakers function as an artificial automatic fiber with an electronically controlled escape. They stimulate with a preset interval after the preceding ventricular depolarization. This depolarization may be spontaneous or pacemaker induced. When the intrinsic R-R interval is shorter than the escape interval of the pacemaker, the artificial pacemaker remains dormant; similar to an automatic fiber, it continues to be dormant until the interval after a ventricular depolarization is long enough to permit pacemaker escape with resulting stimulation. This stimulation continues with the same escape interval until a spontaneous beat occurs. Thus.in patients with intermittent block, such instruments provide stimulation to the myocardium only when such stimulation is needed, and may even compensate for a single missing beat.
Berkovits B. Ann NY Acad Sci 1969; 167:891-894
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Clinical Application of Demand Pacing
With early reliability, the use of demand pacing was extended to all indications for permanent pacing. Support for demand pacing for presumed permanent block is derived from the fact that three patients with such blich had return of normal sinus rhythm after pacemaker implantation. Two patients had recurrent syncope that defied etiological diagnosis. Following demand pacemaker implantation, they had no further difficulty. This successful therapeutic trial lends support to the occasional empirical use of demand pacing. Transvenous implantation has been utilized with but four exceptions. Proper electrode position is essential for proper sensing. Fluoroscopic control is used initially for positioning of the electrode in the apex of the right ventricle. Constant capture should occur with less than 1.5 volts. An endocardial tracing is then taken with a battery-powered or properly grounded electrocardiographic machine. The endocardial tracing shows a characteristic rapid depolarization signal followed by a slow repolarization wave. The unit requires a depolarization signal of 1.5-2.0 millivolts for proper sensing. A deflection of 8-10 millivolts is usually obtained. To provide an adequate safety margin, less than 6 millivolts should not be accepted. Depolarization signals of variable amplitude are indicative of a floating catheter electrode and should not be accepted. Improper electrode position is also diagnosed if the tracing resembles a peripheral electrocardiogram.
Zuckerman W, Matloff JM, Harken DE, Berkovits BV. Clinical Applications on Demand Pacing. Ann NY Acad Sci 1969; 167:1055-1059.
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Pacemaker-induced Cardiac Rhythm Disturbances
Continuous stimulation of the heart has been used successfully in the treatment of symptomatic atrioventricular conduction disturbances. Recent reports have stressed the possible occurrence of pacemaker-induced repetitive firing during coaction of natural and artificial rhythms. Repetitive firing (more than one response to a single stimulus falling in the preceding T-wave) has been observed fourteen times in our department: (a) during intermittent paired electrical stimulation, three cases, one requiring countershock; (b) at the onset of pacing during complete atrioventricular block, five cases; (c) during coaction of sinus rhythm and continuous asynchronized pacers (chronic block, three [unreported] cases, in two of which the spikes that triggered repetitive firing fell on an extrasystolic T-wave); (d) in acute myocardial infarction during coaction of supraventricular and continuous pacemakers,three cases, one requiring countershock. Stimuli fell on the T-waves of supraventricular complexes. It is for precisely this purpose that other forms of pacing have been developed.
Castellanos A, Maytin 0, Lemberg L, Berkovits BV Part VIII. Rhythm Disturbances and Pacing: Pacemaker induced cardiac rhythm disturbances. Ann NY Acad Sci 1969; 903-910
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Bifocal Demand Pacing
Transient pervenous bifocal (sequential atrioventricular) demand pacing was performed in ten patients. Six had chronic conducting system disease and four acute myocardial infarction. The control electrocardiograms showed different degrees of coexisting, alternating or intermittent sinoatrial slowing and AV block. This modality of electrical stimulation was achieved by the combination of QRS-inhibited ventricular demand pacing with QRS-inhibited atrial demand stimulation. In the presence of atrial bradycardia and normal AV conduction only the atria were stimulated. When sinus slowing was associated with AV block, both atria and ventricles were paced. A double electrode system was required for the restoration of AV synchronization. Consistent atrial capture was achieved by means of a J-shaped endocardial bipolar electrode. Permanent bifocal demand pacing has also been used in three patients with satisfactory results. Further studies are required to assess the optimal AV sequential interval as well as the long-term electrical reliability and hemodynamics benefits.
Castillo CA, Berkovits BV, Castellanos A, Lemberg L, Callard G, Jude JR. Bifocal Demand Pacing. Chest 1971; 59:360-364.
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Overdrive Pacing in the WPW syndrome
In all patients with either spontaneous or induced SVT every episode could be rapidly (<60 seconds) terminated by high right atrial, coronary sinus or right ventricular overdrive pacing. The overdrive rate was > 10% above the basal tachycardia rate. Implantable. The above results prompted the design of an implantable pacemaker for use in WPW patients with medically uncontrollable SVT. A bipolar J-shaped electrode is implanted in the right atrial appendage by the transvenous route. The unit, magnetically activated by the patient during a tachycardia, delivers stimuli at a progressively increasing frequency (150-300 beats/min) over a maximum period of 2 minutes. It can be prematurely deactivated by removing the magnet. This unit has been implanted in a 25-year-old female WPW patient with intractable SVT. The unit has functioned successfully over a 9-month period and has been used as many as 5 times/day. The presence of recurrent SVT in the WPW syndrome unresponsive to medical management has, in the recent past, been managed only by surgical approaches. The ability to rapidly terminate SVT with overdrive, utilize permanent transvenous atrial pacing and design new pacemaker circuitry has led to the development of the implantable unit described in this report. The potential benefits of this method are clear in that a limited surgical procedure with low morbidity may be realized for successful management of a previously unmanageable patient. A noncontinuous record showing the onset of supraventricular tachycardia and its termination by the implanted atrial scanning pacemaker unit. In the first strip, sinus rhythm with prominent delta waves is noted. Subsequently, supraventricular tachycardia is initiated by a premature atrial systole. The second strip shows the initiation of artificial atrial pacing at progressively increasing heart rates.The third strip shows the termination of the tachycardia followed by 1:1 anterograde conduction across the bypass tract. With termination of the atrial pacing, restoration of sinus rhythm is observed.
Mandel WJ,Yamaguchi I, Laks M, Berkovits BV. The use of overdrive pacing for termination of tachycardia episodes in the Wolff-Parkinson-White (WPW) syndrome.Cardiac Pacing:ProcV International Symposium.Tokyo,1976.YoshioWatanabe,Ed.Excerpta Medica, 1977; 162-165.
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Effect of Multiple Simultaneous Activation Sites (Biventricular Pacing) on Ventricular Depolarization and Ventricular Arrhythmias
In 1976 Barouh V. Berkovits developed a VVT pacemaker capable of sending the earliest ventricular depolarization from 2 to 10 epicardial sites and simultaneously stimulating all ventricular sites. Studies in the infarcted ventricular dog heart proved that all ventricular sites could be simultaneously activated but ventricular tachycardia could not be terminated (Figure 8). In this experiment simultaneous activation of both right and left ventricular sites corrected the conduction delay between RV and LV sites (compare the left and right hand portions of the strip) but failed to shorten the QRS duration of the ventricular arrhythmia. Local conduction delay in the region of the region of the infarcted myocardium probably led to microreentry and the continuation of ventricular tachycardia. Reexamination of the figures from this study revealed a flaw in the method of sensing the earliest sire of ventricular polarization at the onset of a ventricular arrhythmia. Notably, the surface ECG should have been used to sense the initial depolarization rather than a local epicardial site. Further studies are now in progress to investigate the use of biventricular pacing to terminate ventricular arrhythmias.
Dreifus LS, Ogawa S, Watanabe Y, Dreifus HN, Berkovits BV. In: Cardiac Pacing. Proceedings of the Vth International Symposium Tokyo, March 14-18, 1976. Ed. by Watanabe, Y. Amsterdam. Excerpta Medica, 1977. pp. 33-39.
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Biventricular Pacing
Programmed stimulation was alternatively performed exclusively from the right ventricular endocardium, exclusively from the left ventricular epicardium and simultaneously from both ventricles in 8 patients who did not have coronary artery disease or bundle branch block. The latter had no untoward effects and was not more dangerous than exclusive right ventricular, or exclusive left ventricular, stimulation. In 3 patients, pacemaker-induced repetitive firing occurred during right and left ventricular pacing. Persistence of this phenomenon (in these 3 patients) during simultaneous biventricular stimulation is in keeping either with a microreentry occurring in the vicinity of the electrodes or with a macroreentry involving the bundle branches. This study suggests that simultaneous atrial and ventricular activation (or pacing) can be achieved by connecting one pacemaker pole to an atrial electrode and the other pole to a ventricular electrode. This modality of stimulation can be effective in preventing or abolishing some types of reciprocating atrioventricular tachycardias.
Befeler B, Berkovits BV, Aranda JM, Sung RJ, Moleiro F, Castellanos A. Programmed simultaneous biventricular stimulation in men, with special reference to its use in the evaluation of intraventricular reentry. Eur J Cardiol 1979; 9:369-378.
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Self Adapting Autodecremental Overdrive Pacing
We have developed and tested an external beat-by-beat self-adapting autodecremental overdrive pacing system for termination of ventricular tachycardia (VT) in patients with recurring symptomatic VT undergoing programmed ventricular stimulation and serial drug testing. With this device, we sought to test the hypothesis that this beat-by-beat autodecremental overdrive pacing method may be more effective and theoretically safer for the termination of VT. We compared this method to previously described antitachycardia pacing methods, in particular those used in commercially available implantable antitachycardia pacemakers. The graphic displays termination of VT by self-adapting autodecremental overdrive pacing. The arrows denote pacer stimuli in the decremental overdrive pacing train. A train of seven decremental pacing stimuli are delivered, each of which is decremented by a value of 3.5% of the VT cycle length. Transient entrainment of the reentry circuit is observed with persistence of the VT upon cessation of pacing. Persistence of tachycardia is detected by the Dysrhythmia Research Instrument and a subsequent train of eight decremental stimuli is delivered. Termination of the VT results. RVA = right ventricular apical electrogram; HBE = His bundle electrogram.
Charos GS, Haffajee CI, Gold RL, Bishop RL, Berkovits BV, Alpert JS. A theoretical and practically more effective method for interruption of ventricular tachycardia: self-adapting autodecremental overdrive pacing. Circulation 1986; 73:309-315.
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Studies with an Implantable Multimodal A-V Pacemaker for Reciprocating Atrioventricular Tachycardias
The efficacy of a recently developed programmable implantable pacemaker which can be used in the management of supraventricular tachycardias (with or without, associated brady-arrhythmias) was evaluated. Although this pacemaker functions primarily in a DVI-DVO mode, it was also made to operate in a DOO mode. The study was performed in six patients with reciprocating atrioventricular tachycardias (four of the long P-R - short R-P type and two of the short P-R - long R-P type). Both DVI-DVO and DOO pacing abolished all episodes of tachycardia in five of the patients. However, DOO pacing was also capable of initiating episodes of tachycardia in two of the six patients. The events observed in two of the patients raise the possibility that ventriculoatrial sequential pacing may be required in some tachycardias of the short P-R - long R-P type.
Castellanos A, Waxman HL, Moleiro F, Berkovits BV, Sung RJ. Preliminary studies with an implantable multimodal A-V pacemaker for reciprocating atrioventricular tachycardia. PACE 1980;3:257-265
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The Wedensky Effect in the Human Heart
Artificial electrical stimulation has proved to be of great value in understanding electrophysiological events occurring in the human heart. Progress in the clinical arrhythmias had been made either by interpolation from animal experiments or by careful analysis of certain tracings in which the various parameters could not be controlled at will. Several authors have shown the presence of a supernormal phase and of a vulnerable phase under controlled conditions in man. One mechanism that has been implicated in the origin of arrhythmias is the Wedensky effect, first described in neuromuscular studies as a prolonged lowered threshold of excitability induced by strong stimulus; that under certain conditions one impulse could trigger a second impulse without invoking vulnerability or supernormality. And that such a phenomenon, and not a re-entry mechanism, could adequately explain the origin of extrasystoles occurring late in the cardiac cycle. Extrasystoles were due primarily to a disturbance of cardiac excitability, not of conductivity. 
FIGURE 3.
Exposure of the Wedensky effect in the human heart during intermittent paired electrical stimulation. Numbers indicate interspike (S†-S†) intervals in hundredths of a second. The first step in this process consists in identifying the supernormal phase. The driving rate was around 60 per minute. Numbers in the top strips indicate the distance between driving and testing stimulus artifacts. The latter did not stimulate the ventricles when occurring at intervals shorter than 0.425 sec or longer than 0.615 sec. Hence, testing stimuli produced a propagated response only during the supernormal phase, that is, towards the end of the T wave and slightly afterwards. In a second step, the intensity of the testing stimuli was lowered below the level required to detect super-normality. Note that when the intensity of the driving stimuli was increased from twice to 15 times above diastolic threshold, the second (previously subthreshold) impulse is now able to produce a propagated response. This is a classic Wedensky effect.
Castellanos A, Lemberg L, Johnson D, Berkovits BV. The Wedensky Effect in the Human Heart. Brit Heart J 1966:28:276-283 Back to Top
Atrial Synchronized Pacemaker Arrhythmias: Revisited
Synchronized pacemakers have been used successfully in the treatment of Stokes-Adams attacks. Their major advantage lies in the correction of the A-V block by artificially restoring physiological atrioventricular conduction. Several complex arrhythmias have appeared after its implantation, during its normal behavior as well as during its malfunction. In some cases, the ectopic rhythms were iatrogenically created with the purpose of studying the response of the pacemaker. Four possible mechanisms by which synchronized stimulus artefact could appear during an antecedent T wave were presented. Differences between true and false escapes were stressed. One tracing showed a rare form of pacemaker capture by a high A-V nodal rhythm. In another patient, the synchronized pacer was captured by a continuous unit. An increase in rate of the latter led to a previously undescribed arrhythmia, hereby labeled pacemaker-to-pacemaker block. In this case, there were two different centers competing to capture the synchronized pacemaker. 
FIGURE 6.
Three different mechanisms by which the stimulus artefacts can follow the extrasystolic R waves: (a) V-P synchronization (Ex.1); (b) A-P synchronization by a sinoatrial contraction preceding or merging with the ectopic ventricular contraction (Ex.2); (c) A-P synchronization by the retrograde atrial activation produced by an ectopic ventricular contraction (Ex. 3). The numbers below the extrasystoles indicate their order of appearance in the strip. "A" represents atrial contractions of sinoatrial origin except for A-, which is produced by the retrograde conduction of one of the extrasystoles.
Castellanos A, Lemberg L, Rodriguez-Tocker L, Berkovits BV. Atrial Synchronized Pacemaker Arrhythmias: Revisited. Amer Heart J 1968; 76:199-208 Back to Top
Pacemaker Vectorcardiography
The spatial vectorcardiograms of 20 patients with implanted pacemakers were studied. Ten had left ventricular and 10 right ventricular units. The orientation of the stimulus artifacts did not prove to be an important parameter in the distinction between each type of instrument. The spikes appeared as a sharp deflection which lasted more than the accepted value of 2.5 msec. Initial delays, attributed to conduction through ordinary cardiac muscle, was seen in all patients with left ventricular and in 8 of the patients with right ventricular pacemakers. The morphology of the loops elicited by left ventricular stimulation resembled vectorcardiograms considered diagnostic of right bundle branch block with or without right ventricular hypertrophy. Beats originating in the right ventricle yielded vectorcardiograms similar to those seen in cases of left bundle branch block. 
FIGURE 3.
Right ventricular endocardial pacemaker. In the vectorcardiogram the stimulus artefacts are oriented to the left, superiorly and slightly anteriorly. The QRS loop shows an initial delay associated with a spatial (two plane) mid delay or plateau. Similar types of loops have been described in patients with W-P-W coexisting with left bundle branch block. There is left axis deviation in the electrocardiogram.
Castellanos A, Lemberg L, Salhanick L, Berkovits BV. Pacemaker Vectorcardiography. Amer Heart J 1968;75:6-18. Back to Top
Munk-Gaskell Phenomenon
Induction of repetitive responses originating in an area other than the one subjected to artificial stimulation was reported by Munk in 1878. This author observed that after placement of the second ligature of Stannius in the heart of the frog, one single mechanical stimulus applied to the upper border of the ventricles produced a series of contractions which initially were rapid, but later became slower. In 1900 Gaskell showed that the secondary responses originated in the A-V junction.
The Munk-Gaskell phenomenon can be produced easily in the amphibian and reptile heart. Figure 1 was recorded after the ventricles had stopped following application of the second ligature of Stannius. The small, upwards-directed atrial deflections are seen most clearly at the beginning of the strip. Thereafter, five mechanically induced ventricular extrasystoles are followed by five spontaneous extrasystoles originating in another center. Note that the rate of the latter rhythm diminishes gradually.
Castellanos A, Johnson D, Berkovits BV. Significance of multiple responses produced by electrical depolarization of the heart. Acta Cardiologica 1966;21:157-166.
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