Low-Energy Direct Defibrillation of the Human Heart

Rubio, Pedro A.; Farrell, Edward M.

doi:10.1016/s0003-4975(10)62967-0

Cited by 14 publications

(4 citation statements)

References 4 publications

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“…They abandoned the use of contoured electrodes in humans, however, because of the difficulty in achieving a good fit. 4 Although large electrodes have been found to reduce defibrillation energy requirements, there are possible disadvantages that must be considered before such electrodes may be used clinically. The use of large electrodes may not be possible in patients with an aneurysmectomy or coronary artery bypass grafts to marginal branches of the left circumflex artery or to distal portions of diagonal branches of the left anterior descending artery.…”

Section: Discussionmentioning

confidence: 99%

Improved defibrillation thresholds with large contoured epicardial electrodes and biphasic waveforms.

et al. 1987

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A reduction in the shock strength required for defibrillation would allow use of a smaller automatic implantable cardioverter-defibrillator and would reduce the possibility of myocardial damage by the shock. Most internal defibrillation electrodes require 5 to 25 J for successful defibrillation in human beings and in dogs. In an attempt to lower the shock strength needed for defibrillation, we designed two large titanium defibrillation patch electrodes that were contoured to fit over the right and left ventricles of the dog heart, covering areas of approximately 33 and 39 cm2, respectively. In six anesthetized open-chest dogs, the electrodes were secured directly to the epicardium and ventricular fibrillation was induced by 60 Hz alternating current. Truncated exponential monophasic and biphasic shocks were given 10 sec later and defibrillation thresholds (DFTs) were determined. The DFT was 159 48 V, 3.2 + 1.9 J (mean + SD) for 10 msec monophasic shocks and 106 + 22 V, 1.3 + 0.4 J, for biphasic shocks with both phase durations equal to 5 msec (5-5 msec). The experiment was repeated in another six dogs in which the electrodes were secured to the pericardium. The mean DFT was not significantly higher than that for the electrodes on the epicardium: 165 + 27 V, 3.1 + 1.2 J for 10 msec monophasic shocks and 116 ± 19 V, 1.6 + 0.5 J for 5-5 msec biphasic shocks. Low DFTs were also obtained with biphasic shocks in which the duration of the first phase was longer than that of the second. In a third group of six dogs, DFTs were determined for the large contoured electrodes as well as for 10 cm2 flat patch electrodes on the right and left ventricular epicardium. The mean DFT was significantly lower for the 5-5 msec biphasic waveform than for the 10 msec monophasic waveform for both types of electrodes, and the mean DFT for the large contoured electrodes was significantly lower than that for the flat patch electrodes for both types of waveforms. We conclude that the shock strength required for defibrillation can be markedly lowered by means of biphasic shocks and large contoured patch electrodes. A CLINICAL advantage would be gained if the shock strength required for direct defibrillation with the automatic implantable cardioverter-defibrillator (AICD) could be reduced. Since the size of the unit is largely determined by the sizes of the battery and capacitor, a reduction in required shock strength would permit the implantable device to be smaller.' 2 A decrease in defibrillation shock strength might also reduce the myo-cardial damage 1 34 and cardiac arrhythmias5-7 caused by high-intensity defibrillation shocks. Increasing the size of AICD electrodes has been shown to decrease the defibrillation threshold (DFT).8 1 We designed a pair of large titanium defibrillation patch electrodes that were contoured to fit the right and left ventricles of the canine heart. The purpose of this study was to determine whether the DFT was low for these large electrodes. Since recent studies have indicated that biphasic waveforms decrease re...

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Section: Discussionmentioning

confidence: 99%

Improved defibrillation thresholds with large contoured epicardial electrodes and biphasic waveforms.

et al. 1987

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“…The authors suggest that other factors such as left ventricular venting, retrograde coronary sinus perfusion and revascularization strategies may alter the pattern of reperfusion ventricular fibrillation and CK-MB balance. Other potential deleterious consequences of the triad of ventricular fibrillation, internal cardiac massage and electrical cardioversion in coronary bypass operations are listed in Table 7 and include thermal myocardial injury due to the electrical current of cardioversion and mechanical disruption of distal anastamosis integrity by the trauma of internal cardiac massage and cumbersome and bulky cardioversion paddles, especially in patients with hearts that are difficult to access (6,7,8).…”

Section: Results-mentioning

confidence: 99%

Predictable Spontaneous Beating in 96% of Coronary Bypass Operations

Brenner

1990

J Extra Corpor Technol

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To determine the incidence of spontaneous beating in isolated coronary bypass operations, one cardiac surgeon's experience with 677 consecutive cases over an 8 1/2 year period (1980-1988) was studied. Myocardial protection included hypothermic (4°C) blood cardioplegia containing procaine and papaverine, topical cooling (4°C) and systemic hypothermia (25°C). During warming, 100 mg of lidocaine was administered when body temperature reached 30°C. Six hundred fifty-one patients (96%) had spontaneous beating after removal of the aortic cross-clamp following completion of distal anastamoses. Electrical cardioversion was required immediately in 26 of these 677 patients (4%) and in an additional 32 (5%) later in the operation, usually when ventricular fibrillation was induced by manipulation of the beating heart to inspect the distal anastamoses. Therefore, 619 of these 677 coronary bypass patients (91 %) were spared intraoperative electrical cardioversion and its potential for myocardial damage.

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“…Several previous studies have explored the energy requirements for open‐chest epicardial defibrillation during cardiac surgery 16–22 . All these studies used monophasic damped sinusoidal waveform shocks, not biphasic shocks, and only limited energy levels were studied.…”

Section: Discussionmentioning

confidence: 99%

“…All these studies used monophasic damped sinusoidal waveform shocks, not biphasic shocks, and only limited energy levels were studied. Tacker et al 17 and Rubio and Farrell 18 demonstrated that shock energies of 5–10 J were sufficient to terminate VF in most patients during cardiac surgery. The authors prospectively studied open‐chest defibrillation in 202 patients; 10–20 J were the optimal initial energy doses for open‐chest defibrillation 19 …”

Section: Discussionmentioning

confidence: 99%

Open‐Chest Epicardial “Surgical” Defibrillation:

Zhang

Davies

Coddington

et al. 2003

Pacing Clinical Electrophis

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The aim of the study was to compare biphasic versus monophasic shocks for open-chest epicardial defibrillation. Transthoracic biphasic waveform shocks require less energy to terminate ventricular fibrillation compared to monophasic waveform shocks. However, if biphasic shocks are effective for open-chest epicardial ("surgical") defibrillation has not been established. Twenty-eight anesthetized adult swine (15-25 kg) underwent a midline sternotomy. Ventricular fibrillation was electrically induced. After 15 seconds of ventricular fibrillation, each pig in group 1 (n = 16) randomly received damped sinusoidal monophasic epicardial shocks and truncated exponential biphasic epicardial shocks from large (44.2 cm2) paddle electrodes at eight energy levels (2-50 J). Pigs in group 2 (n = 12) received monophasic and truncated exponential biphasic shocks from small (15.9 cm2) paddle electrodes. In group 1 (large paddle electrodes), the overall percent shock success rose from 15 +/- 9% at 2 J to 97 +/- 3% at 50 J. In this group there was no significant difference in percent of shock success between damped sinusoidal monophasic and biphasic waveform shocks. In group 2 (small paddle electrodes), biphasic shocks yielded a significantly higher percent of shock success than monophasic shocks at mid-energy levels from 7 to 20 J (all P < 0.01). With small surgical paddle electrodes, biphasic waveform shocks demonstrated a significantly higher percent of shock success rate compared to monophasic waveform shocks. With large paddle electrodes, the two waveforms were equally effective.

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Low-Energy Direct Defibrillation of the Human Heart

Cited by 14 publications

References 4 publications

Improved defibrillation thresholds with large contoured epicardial electrodes and biphasic waveforms.

Improved defibrillation thresholds with large contoured epicardial electrodes and biphasic waveforms.

Predictable Spontaneous Beating in 96% of Coronary Bypass Operations

Open‐Chest Epicardial “Surgical” Defibrillation:

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