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PubMed1983

Determinants of defibrillation: prospective analysis of 183 patients.

Previous studies have suggested that a number of factors may influence the ability to defibrillate: the transthoracic resistance and resultant current flow, the paddle electrode size, the duration of preshock ventricular fibrillation (VF) and cardiopulmonary resuscitation, metabolic abnormalities, body weight, the shock energy selected, and whether the patient is receiving lidocaine. To examine the effect of these variables, a prospective study was conducted of 183 patients who received direct-current shocks for VF. Overall defibrillation rates approached 90%, even in patients with secondary VF, but rates of successful resuscitation and survival were much lower. Patients who never defibrillated despite multiple shocks had a prolonged duration of cardiopulmonary resuscitation preceding the first shock (21 +/- 14 minutes) and systemic hypoxia and acidosis. These conditions tended to occur in patients who initially had cardiac arrest from causes other than VF: asystole, severe bradycardia and electromechanical dissociation. In such patients, VF developed only as a late event, which was then often unresponsive to attempted defibrillation. The other factors examined were not major determinants of defibrillation.

Body Weight↗
PubMed1991

Late results of the left subcostal approach for automatic implantable cardioverter defibrillator implantation.

A left subcostal surgical approach was used to implant an automatic implantable cardioverter defibrillator (AICD) in 48 patients with a history of nonfatal cardiac arrest or documented ventricular tachycardia/fibrillation. Electrophysiologic studies before surgery yielded induction of monomorphic or polymorphic ventricular tachycardia in 40 patients, whereas 8 were noninducible. Mean (+/- standard deviation) age was 58 +/- 12 years. Mean ejection fraction was 33 +/- 16%. Thirty patients (63%) had documented coronary artery disease; 14 patients (29%) had previous coronary bypass surgery. The mean intraoperative defibrillation threshold was 13.8 +/- 6.6 J. In 6 patients, an adjunctive right minithoracotomy was used to position 1 patch over the right atrium and thus optimize the defibrillation threshold. Patients with prior exposure to amiodarone and previous coronary bypass surgery had higher defibrillation thresholds at implantation. Two perioperative deaths occurred. There were no infections. Long-term follow-up yielded a 1- and 5-year survival of 0.88 and 0.58, respectively, and a freedom from sudden cardiac death of 1.0 and 0.97, respectively. The nonthoracotomy, left subcostal surgical approach is safe and effective, provides adequate defibrillation thresholds in most patients, and yields long-term survival comparable to other implantation techniques.

Cardiac Pacing, Artificial↗
PubMed1992

Prospective comparison of biphasic and monophasic shocks for implantable cardioverter-defibrillators using endocardial leads.

Bidirectional shocks using 2 current pathways have been used in endocardial lead systems for implantable cardioverter-defibrillators, but the optimal shock waveform for endocardial defibrillation is unknown. The clinical efficacy and electrical characteristics of bidirectional monophasic and biphasic shocks for endocardial cardioversion-defibrillation of fast monomorphic or polymorphic ventricular tachycardia (VT), or ventricular fibrillation (VF) were evaluated. Thirty-three patients (mean age 60 +/- 12 years, and mean left ventricular ejection fraction 34 +/- 13%) were studied. Defibrillation catheter electrodes were located in the right ventricular apex and superior vena cava/right atrial junction. A triple-electrode configuration including the 2 catheter electrodes and a left thoracic patch was used to deliver bidirectional shocks from the right ventricular cathode to an atrial anode (pathway 1) and the thoracic patch (pathway 2). The shock waveforms examined were sequential and simultaneous monophasic, and simultaneous biphasic. The efficacy of 580 V (20 J) shocks for fast monomorphic VT were comparable for the 3 waveforms (73% for sequential monophasic, 73% for simultaneous monophasic, and 100% for simultaneous biphasic). However, for polymorphic VT and VF, 580 V sequential monophasic shocks had a significantly lower efficacy (25%) than did simultaneous monophasic (75%; p = 0.01) or biphasic (89%; p less than 0.001) shocks. Single-shock defibrillation thresholds with simultaneous biphasic shocks were significantly lower (9 +/- 5 J) than were those with simultaneous monophasic shocks (15 +/- 4 J; p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Electric Countershock↗
PubMed1992

Implantation of cardioverter defibrillators in the post-sternotomy patient.

In an attempt to minimize the hazards of redo sternotomy or thoracotomy in patients who have undergone previous cardiac procedures, a technique has been developed for cardioverter defibrillator implantation that involves dissection through a left subcostal incision and placement of extrapericardial defibrillation patches. This approach was used in 22 consecutive patients who required an implantable cardioverter defibrillator 4 to 156 months after previous median sternotomy. Defibrillation threshold energy was less than or equal to 20 J in every patient. Ninety-one percent of patients were extubated during the first 24 hours and were transferred out of the intensive care unit by the second postoperative day. One patient died of an acute myocardial infarction 3 days postoperatively (1/22, 4.5%). It was necessary to replace one lead for mechanical failure of an adapter, one patch required repositioning, and 1 patient needed drainage of a persistent pleural effusion (3/22, 13.6%). No further complications occurred during 3 to 27 months of follow-up. Advantages of the subcostal approach included prompt extubation, a single incision, and minimal morbidity. This approach is safe and effective, and is the method of choice for implantation of a cardioverter defibrillator in patients who have undergone prior sternotomy.

Adult↗
PubMed1994

Training St John Ambulance volunteers to use an automated external defibrillator.

The key to improving survival from pre-hospital cardiac arrest lies in reducing the time interval between onset of cardiac arrest and defibrillation. Placing automated external defibrillators at strategic points in the community could potentially reduce this time interval, but would necessitate widespread training in defibrillation for lay people in addition to health care workers. There are unanswered questions regarding the ability of lay people to acquire and retain this skill when the training programme is, by necessity, very brief, (otherwise it would not be possible to train large enough numbers of people) and the skill is used infrequently. In this study, nurse and lay volunteer first-aiders were taught to use an automated external defibrillator, either by a 2-h, or a 4-h course, and their skills were assessed at training, and at 3 and 6 months afterwards. Using stringent assessment criteria, 54% of volunteers passed the assessment at every session. Little difference in acquisition or retention of skills between the nurse and lay volunteers, and the 2- and 4-h course groups was found. It is concluded that brief training in defibrillation for volunteer first-aiders is feasible.

Ambulances↗
PubMed1990

Automatic implantable cardioverter-defibrillator: is early implantation cost-effective?

The evaluation of survivors of sudden cardiac death with serial electrophysiologic studies involves a lengthy and expensive hospitalization, especially when an automatic implantable cardioverter-defibrillator is ultimately necessary. The cost efficacy of this conventional approach was therefore compared with direct implantation of a cardioverter-defibrillator after the first electrophysiologic study. Thirty-two survivors of sudden death who had inducible ventricular tachycardia during their initial electrophysiologic study underwent serial drug trials. At discharge 12 (37%) were taking an antiarrhythmic drug found to prevent induction of ventricular tachycardia and 20 underwent cardioverter-defibrillator implantation after serial drug trials proved ineffective. The average length of hospitalization for this group that had undergone serial drug testing was 20.2 +/- 9.3 days at an average cost of $48,900 +/- $31,600. Seven survivors of sudden death had no inducible ventricular tachycardia during their initial electrophysiologic study and underwent direct cardioverter-defibrillator implantation. Their average length of hospitalization was 12.6 +/- 6.2 days at an average cost of $40,400 +/- $8,300. It is concluded that automatic implantable cardioverter-defibrillator implantation as an early intervention is not more costly and indeed may be cost-effective compared with therapy guided by serial electrophysiologic testing. As antitachycardia devices become more versatile, long lived and easier to implant, earlier implantation is likely to compare even more favorably with drug therapy.

Anti-Arrhythmia Agents↗
PubMed1993

External cardiac pacing using low impedance electrodes suitable for defibrillation: a comparative blinded study.

OBJECTIVES: The objective of this study was to determine whether the threshold for successful cardiac pacing is affected by electrode impedance and whether this procedure can be successfully carried out through low impedance electrodes that are also suitable for defibrillation. BACKGROUND: Reintroduced in the early 1980s, external cardiac pacing utilizes large externally placed electrodes with a high impedance, in conjunction with a stimulator capable of producing an impulse of 20 to 40 ms in duration. On the basis of empiric observation, high impedance electrodes (> 500 omega) are believed to be optimal for external cardiac pacing. Such electrodes are unsuitable for defibrillation, a technique that is most successful when impedance is low. In view of the absence of controlled data to support this recommendation, as well as the desirability of using one set of electrodes for both pacing and defibrillation, we undertook the following study. METHODS: Thirty-two normal subjects underwent a total of 110 attempts at external cardiac pacing with either (or both) high or low impedance electrodes in combination with one or two commercially available external cardiac pacemakers. Each subject underwent pacing at least twice in a randomized double-blind fashion to determine the pacing threshold and level of discomfort. RESULTS: Individual subjects had a wide range of pacing thresholds but did not experience any greater discomfort with one pacemaker-electrode combination than with any other. Similarly, no pacemaker-electrode combination was superior to another in terms of pacing thresholds. The mean pacing threshold was 72.5 +/- 6 mA for the 40-ms impulse/high impedance electrode combination, 78.7 +/- 6 mA for the 40-ms impulse/low impedance electrode, 73.8 +/- 7 mA for the 20-ms impulse/high impedance electrode and 77.5 +/- 7 mA for the 20-ms impulse/low impedance electrode (p = NS for all comparisons). CONCLUSIONS: Contrary to previous belief, a high impedance electrode offers no advantage for external pacing in terms of either pacing threshold or discomfort level during pacing. This study demonstrates that it is feasible to perform external pacing through an electrode that is also suitable for defibrillation and suggests that a single external pacing-defibrillation electrode is all that is needed to perform these two procedures.

Adult↗
PubMed1985

Effect of epinephrine on defibrillation in ischemic ventricular fibrillation.

Epinephrine is thought to improve the success of defibrillation with countershock therapy. However, a recent study failed to show any effect of epinephrine in dogs with normal coronary arteries undergoing electrically-induced ventricular fibrillation (VF). In the current study, the effects of epinephrine were examined in dogs with coronary occlusion undergoing both spontaneous and electrically-induced fibrillation. Forty pentobarbital-anesthetized dogs were prepared by placing snares around the circumflex and left anterior descending coronary arteries. Fibrillation and subsequent resuscitation were carried out with one coronary artery occluded. Dogs were randomly allocated so that half of the animals underwent spontaneous fibrillation and half were electrically fibrillated. In addition, half received epinephrine (1 mg) during resuscitation and half received normal saline solution (1 ml). After 3 minutes of cardiac arrest, cardiopulmonary resuscitation (CPR) was begun, and 30 seconds later epinephrine or saline were injected. One minute later defibrillation was attempted using successive stored energy doses of 1, 2, 4, 8, 16, and 32 J/kg. Delivered energy and transthoracic impedance were measured for each countershock. Successful defibrillation was defined as conversion to any rhythm other than VF or ventricular tachycardia that degenerated in VF within 10 seconds. No other drugs were given during resuscitation. Neither the type of fibrillation (electrically-induced versus spontaneous) or drug therapy (epinephrine versus placebo) had a significant effect on the incidence of defibrillation or the energy necessary for successful defibrillation. Epinephrine did significantly increase the incidence of resuscitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Cost-effectiveness of defibrillation by emergency medical technicians.

Effective emergency systems using emergency medical technicians (EMTs) trained to defibrillate or paramedics can save more lives from out-of-hospital cardiac arrest due to ventricular fibrillation than can emergency systems staffed with basic EMTs who cannot defibrillate. This article focuses on the cost-effectiveness of systems staffed with each type of EMT. Data were collected from all 50 states and from the District of Columbia to determine the number of hours and estimated cost of initial training for the three types of EMTs in the United States in 1986. The median initial training hours for basic EMTs, EMTs trained in defibrillation, and paramedics were 110, 129, and 700, respectively. Median costs for initial training at each EMT level were +123, +150, and +1580/student. According to published survival data for emergency medical systems staffed with EMTs at each level, the total initial training personnel and equipment cost per life saved from ventricular fibrillation was +7687, +2126, and +2289 for systems staffed by the respective EMTs. The initial cost per life saved from ventricular fibrillation is more than three times greater in systems staffed by basic EMTs than in systems staffed by EMTs trained in defibrillation or paramedics. From a medical and a cost-effective standpoint, all communities served by basic EMTs should consider upgrading them to at least the defibrillation-trained EMT level.

Allied Health Personnel↗
PubMed2004

Myocardial injury, neurohormonal activation and inflammation after internal atrial defibrillation.

BACKGROUND: The effects of patient-activated atrial defibrillation on subclinical myocardial injury are unknown. Using biochemical markers, this study assessed the effect of a single internal atrial shock delivered by the implantable atrial defibrillator on myocardial damage, neurohormonal activation and inflammation. METHODS: Twelve patients were implanted with a dual chamber defibrillator for the sole indication of drug refractory symptomatic persistent atrial fibrillation (AF). All had maximum defibrillation energy programmed to maximise the first shock success rate. Creatine kinase isoenzyme, troponin T, cortisol, catecholamines, C-reactive protein and brain natriuretic peptide were measured (i) during sinus rhythm, (ii) 8 h after onset of spontaneously occurring AF (before cardioversion) and (iii) 8 h following successful patient activated cardioversion. RESULTS: There was no change in creatine kinase, troponin T, cortisol or C-reactive protein during AF or following internal cardioversion. Brain natriuretic peptide levels rose from a median value of 56 pg/ml during sinus rhythm (inter-quartile range 14-92 pg/ml) to 133 pg/ml during AF (30-262 pg/ml), p=0.002. There was a decrease 8 h after cardioversion to baseline (52 and 40-189 pg/ml), p=0.01. There were increases in serum adrenaline and noradrenaline levels during AF from 0.43 (0.12-0.61) to 0.58 pg/ml (0.39-0.80 pg/ml), p=0.002 and from 2.06 (1.61-2.59) to 2.83 nmol/l (2.43-3.46 nmol/l), p=0.02, respectively. These figures reverted to baseline levels 8 h post-cardioversion. CONCLUSIONS: Internal atrial defibrillation does not result in myocardial injury. The onset of AF results in sympathetic activation and increased brain natriuretic peptide levels, which resolve following restoration of sinus rhythm.

Adult↗
PubMedDate not supplied

Defibrillation threshold computed from normal and supernormal excitable cardiac tissue.

The applicability of the 'upper limit of vulnerability' defibrillation theory was evaluated in models of cardiac tissue in which spatial changes within cells are retained. Defibrillation thresholds were computed from two models of cardiac tissue: one with, and one without, a supernormal period, and compared with those predicted by the theory. In the cardiac virtual tissue with a monotonic recovery of excitation - a normal refractory period, the computed defibrillation threshold is consistent with the prediction of the 'upper limit of vulnerability' defibrillation theory. However, in cardiac tissue with non-monotonic recovery of excitation - a supernormal period, the computed defibrillation threshold is significantly less than the theory prediction.

Animals↗
PubMed2005

Effect of hypothermia on transthoracic defibrillation in a swine model.

BACKGROUND: Induced hypothermia (H) appears a promising intervention to protect the heart and brain after resuscitation from cardiac arrest. However, the influence of H on transthoracic defibrillation energy requirements is not well documented. METHODS: In 39 swine (21.4+/-1.3(S.E.) kg) hypothermia was induced by surrounding the head, thorax and abdomen with ice. The swine were divided into four groups: (1) normothermia (N) followed by severe H (30 degrees C) (n=10), (2) severe H followed by N (n=10), (3) N followed by moderate H (33 degrees C) (n=10) and (4) moderate H followed by N (n=9). After 30s of electrically induced ventricular fibrillation (VF), the swine were defibrillated (biphasic waveform) at energies of 20J, 30J, 50J and 100J in random order in both N and H conditions. RESULTS: For pigs in Group 1 (N followed by severe H), shock success in terminating VF was higher during hypothermia (odds ratio 4.09 (95% CI: 2.21, 5.58; p<0.0001), despite the fact that impedance rose from 39+/-3Omega (N) to 42+/-3Omega (H) (p<0.001) and current fell from 22+/-8 (N) to 21+/-7A (H) (p<0.001). There were no significant differences in the shock success between N and H for the other groups. Post-defibrillation ventricular asystole occurred less often during hypothermia compared to normothermia (p=0.0002). CONCLUSION: Severe H facilitated transthoracic defibrillation in this swine model. Since impedance rose and current fell during H, the improved shock success must be due to a hypothermia-induced change in the mechanical or electrophysiologic properties of the myocardium. Moderate hypothermia did not alter the energy requirement for defibrillation.

Animals↗
PubMed1977

Effectiveness of direct current defibrillation: role of paddle electrode size.

Myocardial necrosis from repeated direct current defibrillation discharges is less when the same stored energy is delivered by paddle electrodes that are larger than those presently available on the majority of commercial defibrillators. The present study was undertaken to determine if the larger 12.8 cm. diameter paddle electrodes are as effective as the standard 8.0 cm. diameter paddle electrodes in defibrillation. Ventricular fibrillation (VF) was induced in 45 dogs and each was allowed to remain in ventricular fibrillation for progressively longer time intervals before defibrillation was attempted. With the 12.8 cm. diameter paddle electrodes, the longest duration of VF sucessfully terminated was 1.22+/-1.05 minutes when the 8.0 cm. paddle electrodes were used (p less than 0.02). Ventricular fibrillation was terminated during the first minute with the 12.8 cm. diameter electrode in 88 per cent of trials as compared with a 71 per cent success rate with 8.0 cm. diameter paddle electrodes (p less than 0.04). When the success rates during the first minute of VF for both sizes of paddle electrodes were ploted against the measure transthoracic impedance, a high correlation cofficient (r=-0.94) was found. This study suggest that 12.8 cm. diameter paddle electrodes are more effective for defibrillation of subjects in the 13.5 kilogram (29 to 69 pound) weight range than are paddle electrodes that are only 8.0 cm. in diameter.

Animals↗
PubMed1996

Truncated exponential versus damped sinusoidal waveform shocks for transthoracic defibrillation.

Currently available transthoracic defibrillators use either a damped sinusoidal or truncated exponential (TE) waveform. Truncated exponential waveforms deliver a long pulse if the transthoracic impedance is high; it has been suggested that such a long pulse may be less effective for defibrillation. Our objective was to compare the ability of damped sinusoidal (DS) waveform shocks versus TE waveform shocks to terminate ventricular fibrillation (VF) and achieve survival from witnessed cardiac arrest. We retrospectively reviewed field-recorded electrocardiograms from 86 patients with witnessed VF, treated by prehospital personnel equipped with DS or TE waveform defibrillators. Forty-four patients received 130 shocks from TE defibrillators; 42 patients received 108 shocks from DS defibrillators. There were no significant differences in time from arrest to first shock (8.0 vs 8.1 minutes), nor were there any differences in the size of the communities involved. The shocks resulted in the following rhythms: organized rhythm: TE: 15 of 130 (12%), DS: 24 of 108 (22%), p = 0.10 (NS); persistent VF: TE: 85 of 130 (65%), DS: 45 of 108 (42%), p <0.01; asystole: TE: 30 of 130 (23%), DS: 39 of 108 (36%), p = NS; and survival to hospital discharge: TE: 5 of 44 (11%), DS: 8 of 42 (19%), p = NS. We conclude that DS waveforms terminated VF more frequently than TE, but there was no significant difference in resumption of an organized rhythm or survival. A prospective comparison of these 2 waveforms is needed.

Aged↗
PubMed1983

Alterations induced by a single defibrillating shock applied through a chronically implanted catheter electrode.

In ten beagles ranging in weight from 7.4 to 13.0 kg, a defibrillating shock of 10 A (three dogs), 20 A (four dogs), or 30 A (three dogs) intensity was applied through a chronically implanted right ventricular catheter electrode. Ten-lead ECG, right ventricular electrogram, and right ventricular impedance were recorded prior to, immediately following, and 48 hours post-shock. A single shock of 10 A, 20 A, and 30 A intensity succeeded in defibrillating nine of ten dogs. One dog required two 20 A shocks to defibrillate. No shock was fatal. Post-shock arrhythmias increased in duration and severity as the shock strength increased. ECG vector analysis suggested damage to the right ventricle in eight of ten dogs. The impedance signal amplitude increased directly after the shock, but dropped below control level by 200 seconds post-shock and remained below control by 48 hours post-shock. Pale areas of shock-induced myocardial necrosis were concentrated in the right ventricular walls adjacent to the distal electrode. The mean weight of necrotic myocardium was 0.043 + 0.006 grams at 10 A, 1.203 + 0.268 grams at 20 A, and 1.397 + 1.218 grams at 30 A (mean + sd). Defibrillation was effective after long-term implantation. The alterations sustained from defibrillation were minimized by using a low intensity shock.

Animals↗
PubMed1998

Right atrial potential profiles during atrial fibrillation predict the success of atrial defibrillation.

The right atrial electric potential was measured in 29 patients with chronic atrial fibrillation, and the clinical utility of these measurements in predicting the success of atrial defibrillation was investigated. The endocardial electric potential was recorded at 12 sites within the right atrium (high, middle, and low loci of anterior, posterior, lateral, and medial sites of the right atrium) with an electrode catheter. The duration and polar displacement of the atrial waves were measured at the one site that showed the maximum atrial electric potential among the 12 sites. The ratio of the maximum to the minimum atrial electric potential (atrial wave ratio) was calculated. Patients were classified into two groups according to the success (n = 6) or failure (n = 23) of atrial defibrillation. Electrophysiologic data were compared between the two groups, and correlations were evaluated between the data and the maximal left atrial diameter obtained from M-mode echocardiography. The two groups did not differ in the duration and polar displacement of the atrial waves. However, the atrial wave ratio was significantly lower in the success group than in the failure group, and the success rate of atrial defibrillation was also significantly greater in the patients with an atrial wave ratio of 10 or lower. This ratio showed a positive correlation with the maximal left atrial diameter; it became more difficult to achieve atrial defibrillation as the atrial wave ratio increased. Thus, the right atrial electric potential profile of patients with atrial fibrillation is a useful predictor of the success of atrial defibrillation.

Adolescent↗
PubMed1984

High-energy versus low-energy defibrillation: experience in patients (excluding those in the intensive care unit) at Mayo Clinic-affiliated hospitals.

/he purpose of this study was to determine whether electric shocks of low (200 to 240 J), intermediate (300 to 320 J), or high (400 to 440 J) delivered energy were most successful in defibrillating hospitalized patients (excluding those in intensive care units) in whom resuscitation was attempted by a code emergency team. From January 1980 through December 1982, 101 cases of ventricular fibrillation in 100 patients were treated by Mayo Clinic code emergency teams. Many of the patients in this trial had secondary or agonal ventricular Defibrillation. Most patients (64%) were defibrillated by one to eight shocks. For the first shock, intermediate and high energy seemed to be more effective than low energy. Patient weight, time of delivery of shock 1 after onset of the code emergency, blood pH, acute and chronic medical diagnoses, and pharmacotherapy before the onset of ventricular fibrillation were not clearly related to the response to shock 1. Nine of 16 patients who did not initially respond to shocks of low or intermediate energy were defibrillated when higher energy was subsequently used. Only 14 patients ultimately survived and were dismissed from the hospital. These results suggest that in this patient population, high levels of delivered energy are preferable to low energy for the first shocks administered; we recommend that 400 J of delivered energy be used initially. The 360-J maximal energy dose available in most currently manufactured defibrillators should be sufficiently close to this recommendation to justify use of that dose with the initial shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

External defibrillation: new technologies.

Recent technological advances have enhanced our ability to diagnose and treat ventricular fibrillation (VF). Self-adhesive electrode pads for external defibrillation are as effective as standard hand-held paddle electrodes, and have substantial advantages for monitoring during transportation and in the emergency department/intensive care unit/critical care unit. These electrode pads work equally well whether placed in apex-anterior or apex-posterior positions. Preapplication in calm, prearrest circumstances assures accurate placement and enhances shock success. Transthoracic impedance is a critical determinant of the success of low-energy shocks. Prediction of transthoracic impedance in advance of the first shock is now feasible. First-shock energy can then be based on impedance, and inappropriate low energies for high-impedance patients may be avoided. Automatic external defibrillation by minimally trained rescuers extends our ability to treat out-of-hospital ventricular fibrillation. A vertical defibrillation pathway, using the tongue as one electrode site, allows rapid, automated detection of VF. Animal defibrillation studies and preliminary human studies (during elective cardioversion) have demonstrated the efficacy of the pathway and defined the impedance and energy requirements. Clinical trials of the device for out-of-hospital defibrillation are now in progress.

Cardiography, Impedance↗