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Biomedical subjects

M M Scheinman

Publications and source records attributed to M M Scheinman.

At least 91 records · Page 5Linked to original sources
PubMed1994

Electrophysiological laboratory, electrophysiologist-implanted, nonthoracotomy-implantable cardioverter/defibrillators.

BACKGROUND: Implantable cardioverter/defibrillators (ICDs) have conventionally been implanted in the operating room by surgeons. However, technological developments have reduced size and increased simplicity, bringing the procedure into the realm of the electrophysiologist. The purpose of this study was to evaluate the safety and efficacy of implantation of the entire ICD system by electrophysiologists in an electrophysiology laboratory. METHODS AND RESULTS: Between July 1993 and February 1994, 23 patients (21 men; age, 64 +/- 11 years) underwent transvenous ICD implantation by electrophysiologists working alone, entirely in the electrophysiology laboratory. Indications for ICD were sudden death in 10 patients, uncontrolled life-threatening ventricular tachycardia in 12, and syncope with cardiomyopathy and familial sudden death in 1. Seventeen patients had coronary artery disease and a past history of acute myocardial infarction. Four patients had idiopathic dilated cardiomyopathy, 1 had coronary ectasia and poor left ventricular function, and another had poor left ventricular function related to valvular dysfunction. The mean left ventricular ejection fraction was 34 +/- 10% (range, 20% to 50%). General anesthesia was administered in 22 cases, and deep sedation was used in 1 elderly patient. After positioning of transvenous leads and subcutaneous patch/array lead positioning, defibrillation testing was performed. After transvenous and subcutaneous lead tunneling, all generators were placed subcutaneously in an abdominal pocket. The mean total time in the electrophysiology laboratory was 254 +/- 68 minutes (range, 150 to 375 minutes), with 104 +/- 42 minutes for anesthetic and other preparation, 159 +/- 45 minutes for implantation, and 8.7 +/- 5 minutes (range, 3 to 25 minutes) of fluoroscopy required for positioning of transvenous and subcutaneous lead systems. Implant times showed a significant improvement when the first 10 cases (188 +/- 44 minutes) were compared with the last 10 in the series (124 +/- 44 minutes, P < .01). The mean defibrillation threshold was 17 +/- 5 J (range, 5 to 25 J). There were 5 complications (22%): 1 patch-site hematoma, 1 pneumothorax related to subclavian venous puncture, 1 pulmonary embolism, and 2 patients requiring overnight ventilation after hemodynamic deterioration following defibrillation testing. There were no deaths, and there were no infections. The mean time to hospital discharge after the implant was 5.1 +/- 3.5 days. After 11.6 +/- 9 weeks of follow-up, all devices were functioning satisfactorily, all patients had successfully defibrillated at postimplant predischarge checkup with 29 +/- 5 J, and there had been no late complications. CONCLUSIONS: This is the first report to show that nonthoracotomy ICD implantation may be successfully carried out by electrophysiologists working alone in the electrophysiology laboratory, with a high rate of success and few complications, even in high-risk patients. This high rate of success and safety probably relates to the availability of high-quality fluoroscopy and familiarity with electrophysiology laboratory equipment and personnel.

Adult↗
PubMed1994

Radiofrequency catheter ablation of atriofascicular and nodoventricular Mahaim tracts.

BACKGROUND: Several mechanisms have been proposed to explain the pathogenesis of tachycardia in patients with Mahaim tracts. The tachycardia may involve antegrade conduction over an atriofascicular pathway with decremental properties or a nodofascicular pathway. METHODS AND RESULTS: We report six patients with recurrent episodes of preexcited tachycardia with findings consistent with "Mahaim tract" conduction. All patients exhibited decremental antegrade preexcited conduction with atrial pacing and a preexcited tachycardia with initial activation of the proximal right bundle branch. In four patients (group 1), atrial premature complexes (APCs) induced at the tricuspid annulus just after the inscription of the septal atrial electrogram and during left bundle branch block preexcited tachycardia advanced the next preexcited ventricular complex. In these patients, discrete Mahaim potentials were inscribed over the right anterolateral or lateral tricuspid annulus. Two patients (group 2) had evidence of dual atrioventricular nodal conduction. APCs during left bundle branch block tachycardia just after inscription of the septal atrial electrogram failed to advance the next ventricular complex with similar preexcited morphology, and no Mahaim potentials could be recorded from the tricuspid annulus. In group 1 patients, application of radiofrequency energy to sites recording the Mahaim potentials resulted in tachycardia cure. For patients in group 2, selective slow atrioventricular nodal pathway ablation in the midseptal region resulted in complete ablation of both the slow atrioventricular nodal pathway and Mahaim conduction in two patients. CONCLUSIONS: Mahaim tachycardia can be due to atriofascicular pathways, which may be ablated over the right tricuspid annulus, or to septal pathways, which may arise from the slow atrioventricular nodal pathway in patients with dual atrioventricular nodal physiology. In the latter circumstance, successful ablation is achieved by placing the lesion in the midseptal region.

Adult↗
PubMed1994

MR features of arrhythmogenic right ventricular dysplasia.

Arrhythmogenic right ventricular dysplasia is defined as a primary disorder of the right ventricle characterized by partial or total replacement of muscle by adipose or fibrous tissue. Its diagnosis currently rests on techniques that accurately identify specific anatomic and functional abnormalities of the right ventricle. To date, none of these methods (except for autopsy) are specific for right ventricular dysplasia although angiography of the right ventricle is considered to be the current gold standard. MR imaging shows promise in clarifying the diagnosis of right ventricular dysplasia. This pictorial essay describes our current technique for examining the right ventricular myocardium in patients thought to have this disease and illustrates the spectrum of abnormalities encountered in these patients.

Adipose Tissue↗
PubMed1993

Ventricular septal summit stimulation in atrioventricular nodal reentrant tachycardia.

In all, 18 consecutive patients with atrioventricular nodal reentry tachycardia (AVNRT) underwent right ventricular (RV) stimulation during AVNRT from either the RV apex or summit. Stimulation from the RV apex advanced the tachycardia with the same atrial sequence in 6 of 18 patients (33%), but never conclusively excluded the presence of a low atrial tachycardia. RV summit stimulation resulted in direct stimulation of the low septal right atrium in 6 patients. RV summit stimulation advanced the tachycardia in 4 patients, delayed it in 2 and terminated it in 3 without an atrial electrogram. The latter 2 findings exclude the presence of a low atrial tachycardia. Thus, in patients with AVNRT, application of extrastimuli closer to the putative reentrant site enables greater efficacy in tachycardia resetting and in excluding a low septal atrial tachycardia.

Cardiac Pacing, Artificial↗
PubMed1993

Comparison of high energy direct current and radiofrequency catheter ablation of the atrioventricular junction.

OBJECTIVES: The goal of the study was to determine short- and long-term success and complications of radiofrequency atrioventricular (AV) junction catheter ablation and to compare these with those of high energy direct current catheter ablation. BACKGROUND: Catheter ablation of the AV junction with radiofrequency or direct current energy is an accepted treatment for drug-refractory supraventricular tachycardias. Few data are available on the long-term success and effects of radiofrequency ablation or its comparison with direct current ablation. METHODS: Fifty-four patients who underwent attempted AV junction ablation with radiofrequency energy were followed up for a mean of 24 +/- 8.4 months. These patients were retrospectively compared with 49 patients who underwent attempted AV junction ablation with direct current energy and were followed up for a mean of 41 +/- 23 months. RESULTS: The early success rate at the time of discharge for radiofrequency ablation was 81.5%, which was not statistically different from that for direct current ablation (85.7%). Fewer sessions were required to achieve complete AV block in the radiofrequency group (1.05 +/- 0.23) (mean +/- SD) compared with the direct current group (1.21 +/- 0.41) (p = 0.02). Although overall complication rates were similar for both groups (9.3% in the radiofrequency group and 8.2% in the direct current group), there was a trend toward more life-threatening early complications in those patients who received direct-current shocks (6.8%) than in those who underwent radiofrequency ablation alone (2.3%) (p = 0.1). Early sudden death (one patient), early ventricular tachycardia (two patients) and cardiac tamponade (one patient) were seen only in those patients who underwent ablation with direct current energy, whereas pulmonary embolism (one patient) was the only early life-threatening complication in the radiofrequency group. During follow-up, the rate of recurrence of AV conduction was the same (5%) for both the direct current and radiofrequency groups. In the direct current group, one patient died suddenly 2 weeks after the procedure and another had a cardiac arrest due to ventricular tachycardia 6 h after the procedure. In the radiofrequency group, two patients died suddenly at 11 and 7 months, respectively. Two patients, one who had unsuccessful radiofrequency ablation and required direct current ablation, were resuscitated from ventricular tachycardia. CONCLUSIONS: Radiofrequency energy appears to be as efficacious as and perhaps safer than direct current energy for AV junction ablation.

Atrioventricular Node↗
PubMed1993

Effects of canine myocardial infarction on sympathetic efferent neuronal function: scintigraphic and electrophysiologic correlates.

We studied the effects of nondecentralized left stellate ganglion stimulation on regional epicardial monophasic action potential duration at 50% (APD50) and 90% (APD90) repolarization from 104 sites in 10 surviving dogs with a chronic myocardial infarction model. These effects were correlated with thallium-201 and iodine-123 metiodobenzylguanidine (MIBG) imaging to identify areas of viable but denervated myocardium. Mean infarct size was 5.2% +/- 0.8% total heart weight, and the planimetered areas of denervation were always larger (18% +/- 4% total heart area). During constant ventricular pacing, stellate stimulation tended to shorten the APD90 only in normally innervated areas (364 +/- 5 to 358 +/- 5 msec) and to increase in denervated areas (358 +/- 5 to 362 +/- 5 msec), (p value not significant (NS) for prestellate and poststellate stimulation; p < 0.05 for difference between denervated vs innervated). The APD50 significantly shortened in innervated areas from 287 +/- 5 to 270 +/- 3 msec (p < 0.05) compared with denervated areas (283 +/- 4 to 274 +/- 5 msec, p = NS). We conclude that MIBG imaging demonstration of denervation identifies areas with impaired shortening of the epicardial APD50 in response to stellate stimulation and that nontransmural myocardial infarction produces areas of denervation larger than areas of necrosis.

Action Potentials↗
PubMed1993

Comparison of the retrograde and transseptal methods for ablation of left free wall accessory pathways.

OBJECTIVES: The purpose of this study was to compare success rates, procedure and fluoroscopy times and complications for the transseptal and retrograde aortic approaches in a consecutive series of patients undergoing catheter ablation of left free wall accessory pathways. BACKGROUND: Radiofrequency catheter ablation of left-sided accessory pathways can be performed either by a retrograde, transaortic approach or by means of a transseptal puncture. METHODS: A total of 106 patients (mean age 33 years, range 4 to 79) underwent attempted catheter ablation of a single left-sided accessory pathway by either the retrograde or the transseptal approach, or both. In the first 65 patients, the retrograde aortic approach was the preferred initial method. In the most recent 51 patients, we first attempted the transseptal approach whenever a physician trained in the technique was available. Ultimately, 102 (96.2%) of 106 patients had successful ablation. RESULTS: Of 89 retrograde procedures, 85% resulted in elimination of accessory pathway conduction. Four retrograde procedures performed after failure of the transseptal approach were successful. Of the 13 patients with a failed retrograde procedure, 11 later underwent ablation using the transseptal approach. Twenty-six (85%) of 33 transseptal procedures were successful. All four patients with unsuccessful initial transseptal attempts were successfully treated with the retrograde method during the same session in the electrophysiology laboratory. Ten of 11 transseptal procedures after unsuccessful retrograde procedures were successful. Crossover from the retrograde to the transseptal approach was performed during a separate session in 9 of these 11. There was no difference in total procedure time (220 +/- 12.8 vs. 205 +/- 12.5 min) (mean +/- SEM) or fluoroscopy time (44.1 +/- 4.4 vs. 44.7 +/- 5.1 min) between the retrograde and transseptal methods. Ablation time was longer for the retrograde method (69.2 +/- 10.5 vs. 43.4 +/- 9.3 min) (p < 0.01). Of patients > or = 65 or < or = 16 years old, technical factors requiring crossover to the other technique or complications occurred in 7 (42%) of 17 patients undergoing the retrograde and 1 (11%) of 9 patients undergoing the transseptal approach (p < 0.01). The overall rate of complications was the same for both (6.7% for retrograde and 6.1% for transseptal). The most serious complication involved dissection of the left coronary artery with myocardial infarction during a retrograde procedure. CONCLUSIONS: The retrograde and transseptal approaches are complementary; if one method fails, the other should be attempted, yielding an overall success rate close to 100%. Because patients undergo heparinization immediately after the arterial system is entered during a retrograde procedure, failure of that approach requires crossover to the transseptal method during a separate session or reversal of heparin; if the transseptal method is tried first, crossover to the retrograde approach can be accomplished easily during the same session. To avoid complications related to access, the transseptal method should be the first used in children, the elderly and those with arterial disease or hypertrophic ventricles.

Adolescent↗
PubMed1993

Safety and efficacy of central intravenous bolus administration of adenosine for termination of supraventricular tachycardia.

OBJECTIVES: This study was done to quantify the dosing differences between central and peripheral adenosine administration for treatment of supraventricular tachycardia. BACKGROUND: Earlier studies that evaluated the safety and efficacy of adenosine primarily utilized a peripheral site of administration. Although it has been recommended that lower doses should be given centrally, dosing recommendations have not been provided. METHODS: Thirty adults with supraventricular tachycardia underwent invasive electrophysiologic study and were treated with central and peripheral intravenous administration of adenosine. Peripheral injections were administered through a venous catheter in an upper extremity and central infusions were accomplished by means of a catheter positioned in or near the right atrium. The site of administration was randomized and each subject received adenosine by both routes. Adenosine was administered every minute in increasing increments of 3, 6, 9 and 12 mg until the tachycardia terminated. Peripheral responses were compared with those obtained centrally. RESULTS: The minimal effective peripheral dose was distributed among the four doses: Tachycardia was terminated in 11 patients with 3 mg (37%), in 10 (33%) with 6 mg, in 4 (13%) with 9 mg and in 5 (17%) with 12 mg. In contrast, after central administration, 23 episodes of tachycardia (77%) were terminated with 3 mg, 6 (20%) with 6 mg and 1 (3%) with 9 mg; none required 12 mg. Lower doses of adenosine were more effective after central than after peripheral administration, with 63% of the subjects requiring a lesser dose. There was no difference between the two routes of drug administration in the incidence of side effects or transient arrhythmias at the time of tachycardia termination. CONCLUSIONS: Adenosine can be safely given centrally for termination of supraventricular tachycardia. The initial dose should be 3 mg.

Adenosine↗
PubMed1993

Atrioventricular nodal conduction and refractoriness.

The AV node is ideally suited to act as a weigh station between atrium and ventricle. It is believed that the latter function is achieved by virtue of nodal conduction being dependent on slow channel conduction probably carried by calcium currents. The AV nodal structure allows for encouragement of decremental conduction but also allows for two or more pathways or collection of cells which may trigger reentrant arrhythmias.

Arrhythmias, Cardiac↗
PubMed1993

Head-up tilt testing with and without isoproterenol infusion in healthy subjects of different ages.

Passive head-up tilt testing with or without infusion of isoproterenol is used in the investigation and management of patients with syncope. Twenty-five healthy asymptomatic volunteers prospectively grouped according to age (young [28 +/- 1.7 years]: n = 9; middle [51 +/- 3.3 years]: n = 11; elderly [81 +/- 2.4 years]: n = 5; mean +/- SE) were studied during: (1) supine carotid sinus massage; (2) 60 degrees head-up tilt alone; and (3) infusion of isoproterenol to raise the heart rate 20% above supine baseline, prior to 10-minute repeat tilt. Symptoms occurred in three subjects (12%) and only occurred with passive tilting alone. Two young subjects had syncope with sinus pauses greater than 10 seconds. One elderly subject developed atrial flutter. No subject had symptoms or hypotension during tilt plus isoproterenol or a pause greater than 3 seconds with carotid sinus massage. With passive tilt, mean heart rate increased by 16 +/- 6 beats/min and 18 +/- 7.8 beats/min in the young and middle aged subjects (P < 0.05), but only by 6 +/- 5 beats/min in the elderly (P = NS, supine vs 60 degrees in each group). With head-up tilt plus isoproterenol infusion, the mean heart rate elevation in response to tilt was 17 +/- 9 beats/min, 8 +/- 3 beats/min, and 12 +/- 4 beats/min for the young, middle, and elderly subjects, respectively (P < 0.05, supine vs 60 degrees in each group).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Transesophageal defibrillation: animal studies and preliminary clinical observations.

Ventricular fibrillation (VF) that fails to respond to transthoracic defibrillation leaves the clinician with few alternatives. The purpose of this study was to develop a technique of rescue defibrillation by use of transesophageal electrodes. Fourteen anesthetized dogs (20-30 kg) were investigated in this study. Two electrodes (300 mm2) were mounted 8 cm apart on an esophageal probe and inserted approximately 40 cm from the mouth. VF was induced using AC current delivered to the myocardium. Defibrillation was then performed between the distal electrode (anode) and anterior skin patch (cathode). After 15 seconds of induced VF, transesophageal and transthoracic defibrillation thresholds (DFTs) were determined in random order. The esophageal DFT (90 +/- 15 joules) tended to be lower than the transthoracic DFT (115 +/- 35 joules), though this difference was not statistically significant. One dog could not be defibrillated by transthoracic defibrillation but responded to transesophageal defibrillation. Esophageal electrodes were also useful for arrhythmia discrimination and ventricular pacing (pacing threshold of 38 +/- 5 mA at a pulse duration of 2.5 msec). Following transesophageal DFT determination, in ten dogs (total energy of 600 +/- 150 joules), acute esophageal histopathology demonstrated mild to severe focal injury to the mucosa and/or muscular layers. However, esophagi in four chronic dogs (total energy of 470 +/- 110 joules) showed no gross evidence of mucosal damage, perforation, or stricture 4 weeks following defibrillation. Histopathology showed only focal myocyte atrophy and repair. As a last resort, transesophageal defibrillation was performed in the emergency room on four patients with out-of-hospital refractory VF who failed > 6 high energy transthoracic shocks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Electrocardiographic and electrophysiologic characteristics of anterior, midseptal and right anterior free wall accessory pathways.

OBJECTIVES: The objective of this study was to define the electrocardiographic (ECG) and electrophysiologic characteristics of midseptal, anteroseptal and right anterior free wall accessory pathways. METHODS: The fully pre-excited 12-lead surface ECGs and ECGs during orthodromic atrioventricular (AV) reentrant tachycardia were compared for 13 patients with an anteroseptal, 7 with a midseptal and 7 with a right free wall accessory pathway. Routine electrophysiologic studies were performed in all and stimulation of the right ventricular summit during tachycardia was accomplished in 10 patients. RESULTS: Differences in the surface ECGs were not sufficiently sensitive to distinguish among accessory pathway locations. Premature ventricular complexes induced from the right ventricular septal summit during ventricular activation either advanced the succeeding atrial depolarization or terminated the tachycardia in three of six patients with a septal pathway and in none of the four with a right anterior pathway. The change in ventriculoatrial (VA) interval with the development of right bundle branch block during orthodromic AV tachycardia proved most helpful in distinguishing these pathways. Patients with a right anterior free wall pathway showed a change in VA interval > or = 40 ms, whereas those with an anteroseptal pathway showed changes of 20 to 30 ms and those with a midseptal pathway showed no change. CONCLUSIONS: Anteroseptal, midseptal and right anterior free wall pathways may be distinguished by using programmed stimulation of the summit of the right ventricular septum and especially with changes in the VA interval with development of right bundle branch block during orthodromic AV reentrant tachycardia.

Adolescent↗
PubMed1992

Active compression-decompression. A new method of cardiopulmonary resuscitation. Cardiopulmonary Resuscitation Working Group.

OBJECTIVE: To describe and compare with standard cardiopulmonary resuscitation (CPR) in humans a new form of CPR that involves both active compression and active decompression of the chest. DESIGN: Patients in cardiac arrest in whom standard advanced cardiac life support failed were randomized to receive 2 minutes of either standard or active compression-decompression (ACD) CPR using a custom, hand-held suction device, followed by 2 minutes of the alternate technique. The ACD device was applied midsternum and used to perform CPR according to the guidelines of the American Heart Association: 80 compressions per minute, compression depth of 3.8 to 5 cm, 50% duty cycle, and constant-volume ventilation. Mechanical Thumper CPR was also compared in five patients. End-tidal carbon dioxide (ETCO2) concentrations and hemodynamic variables were measured. Transesophageal Doppler echocardiography was used to assess contractility, the velocity time integral (an analogue of cardiac output), and diastolic myocardial filling times. RESULTS: Ten patients were enrolled. The mean +/- SD ETCO2 was 4.3 +/- 3.8 mm Hg with standard CPR and 9.0 +/- 3.9 mm Hg with ACD CPR (P less than .0001). Systolic arterial pressure with standard CPR was 52.5 +/- 14.0 mm Hg and with ACD CPR, 88.9 +/- 24.7 mm Hg (P less than .003). The velocity time integral increased from 7.3 +/- 2.6 cm with standard CPR to 17.5 +/- 5.6 cm with ACD CPR (P less than .0001), and diastolic filling times increased from 0.23 +/- .09 seconds with standard CPR to 0.37 +/- .12 seconds with ACD CPR (P less than .004). Mechanical Thumper CPR consistently underperformed both standard and ACD CPR. Minute ventilation obtained in four patients during ACD CPR without endotracheal ventilation was 6.6 +/- 0.9 L/min. After 1 hour of standard CPR failed, three of 10 patients randomized to ACD CPR rapidly converted to a hemodynamically stable rhythm following 2 minutes of ACD CPR. CONCLUSION: ACD CPR is a simple manual technique that improved cardiopulmonary circulation in 10 patients during cardiac arrest. Although ACD CPR may have produced a return of spontaneous circulation in three patients refractory to standard measures, its impact on survival when used early in cardiac arrest remains to be determined.

Adult↗
PubMed1992

Usefulness of adenosine in augmenting ventricular preexcitation for noninvasive localization of accessory pathways.

Adenosine was administered to test the hypothesis that it would maximize preexcitation and facilitate noninvasive localization of accessory pathways in 22 patients with suspected accessory pathway-mediated tachycardias. Twelve-lead electrocardiograms and 2-dimensional echocardiograms were recorded at baseline and during adenosine-augmented ventricular preexcitation to localize the accessory pathway. Phase analysis was performed on digitized 4-chamber and short-axis views using a first harmonic Fourier transformation. At baseline, 15 patients had manifest preexcitation. In 14 of these patients (93.3%), preexcitation became more prominent after adenosine. Four patients without preexcitation at baseline clearly had it after adenosine. In patients who had preexcitation in response to adenosine, the electrocardiogram correctly identified the accessory pathway locations in 18 of 19 patients at a regional level and was incorrect in 1 of 19 patients. Echocardiographic phase analysis correctly identified the accessory pathway location in all 17 patients, who had technically adequate studies, at a regional level. In conclusion, administration of adenosine accentuates preexcitation, allowing for more accurate electrocardiographic and echocardiographic accessory pathway localization.

Adenosine↗
PubMed1992

Survival after implantation of the cardioverter defibrillator.

The actuarial survival of 60 consecutive recipients of the implanted cardioverter defibrillator (ICD) were compared with 120 matched concurrent medically treated patients using a case-control design. All ICD patients and controls presented with either sustained ventricular tachycardia or ventricular fibrillation. Controls were matched to ICD recipients according to 5 variables: age, left ventricular ejection fraction, arrhythmia at presentation, underlying heart disease and drug therapy status. Mean ages were 58 and 59 years in ICD patients and controls, and the average ejection fractions were 36 and 35%. Coronary artery disease was present in 75 and 79% of ICD patients and controls, respectively. During follow-up, sudden deaths were fewer in ICD recipients than in controls (5 vs 10%, p less than 0.01). At 1 and 3 years, actuarial survival was 0.89 vs 0.72 and 0.65 vs 0.49 for ICD recipients and controls. The 5-year actuarial survival curves were significantly different by the Cox proportional hazards model (p less than 0.05). It is concluded that in this retrospective case-control study, the use of the ICD in the management of patients at risk for sudden death results in improved probability of survival.

Actuarial Analysis↗
PubMed1992

Comparison of a vectorcardiographically derived 12-lead electrocardiogram with the conventional electrocardiogram during wide QRS complex tachycardia, and its potential application for continuous bedside monitoring.

Previous investigators published conflicting reports comparing a vectorcardiographically derived electrocardiogram (ECGD) with the conventional 12-lead one (ECG). Prior comparisons were obtained in adults during sinus rhythm, but never in patients with wide QRS complex tachycardia. The ECGD was evaluated during baseline rhythms in patients with varying cardiac diagnoses, and the diagnostic accuracy of the 2 methods was compared during 64 episodes of wide QRS complex tachycardia in 49 patients during cardiac electrophysiologic study. All leads of the 12-lead ECGD closely resembled the conventional ECG in baseline and tachycardia tracings, except leads V3 and V4. QRS voltages were less in the ECGD, resulting in an inability to detect left ventricular hypertrophy in one third of patients with that diagnosis. There was excellent agreement between the ECGD and ECG in diagnosing prior myocardial infarction (92%), ventricular preexcitation patterns (100%), bundle branch and fascicular blocks (100%), and axis deviation. The ECGD was equally as valuable as the ECG in the diagnosis of wide QRS complex tachycardia. There was perfect agreement between the 2 lead systems in application of the morphologic criteria differentiating supraventricular tachycardia with aberration from ventricular tachycardia in leads V1, V2 and V6, and for criteria requiring axis determination and measurement of RS intervals in the precordial leads. The ECGD tracings contained less muscle artifact during body movements (e.g., after direct-current defibrillation). In conclusion, the ECGD's close correlation with the ECG, and its technical superiority and simple 5 torso-positioned electrode configuration make it worth pursuing as an option for continuous bedside monitoring.

Adult↗