Experimental Study of the Pathogenesis of Ventricular Extrasystolia

Baschieri, L; Palagi, L; Puletti, M

doi:10.1159/000169218

Cited by 9 publications

(1 citation statement)

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“…Although not all of the activation recorded in the ischemic zone showed marked delay, in four cases the onset of the lethal arrhythmia provided a sequence of events like that depicted in Figures 1 and 2. Delay of activation as great as 200 msec has been noted by others (20,21) in ischemic and infarcted myocardial tissue. However, the present data consistently demonstrated a progressive delay of ventricular activation at local epicardial sites within minutes of coronary artery occlusion leading to ventricular arrhythmias.…”

Section: Underlying Automaticity Revealed By Vagally Induced Sinus Armentioning

confidence: 54%

Characterization and Localization of Ventricular Arrhythmias Resulting from Myocardial Ischemia and Infarction

Scherlag

El‐Sherif

Hope

et al. 1974

Circulation Research

369

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Electrocardiograms and electrograms were recorded in 18 dogs anesthetized with sodium pentobarbital. Using endocardial and epicardial plunge wire electrodes in normal and ischemic or infarcted areas, activation of Purkinje and regular muscle tissue was studied within the first 20-30 minutes and 24 hours after anterior descending coronary artery ligation. The ventricular arrhythmias in the first 20 minutes were abolished during vagally induced atrial arrest, but ventricular automaticity was unchanged from that during the control period. These rate-related arrhythmias were uniformly associated with marked diminution and delay of epicardial activation in the ischemic zone. Slowing of the heart rate caused recovery of the timing, form, and duration of these epicardial potentials with the coincident disappearance of ventricular arrhythmias. The ventricular arrhythmias of the early phase spontaneously subsided with time 20-30 minutes after ligation; concurrently, epicardial activation in the ischemic zone improved. The ventricular arrhythmias noted 24 hours after coronary artery ligation were revealed by vagally induced atrial slowing and suppressed by rapid atrial pacing, indicating the existence of enhanced ventricular automaticity. There was a loss of endocardial muscle activation; Purkinje tissue was depressed but viable in the infarcted zone. The sequence of firing during many of the multifocal ventricular ectopic beats showed that the earliest activation arose from Purkinje tissue in the infarcted zone. However, other ectopic beats appeared to arise from infarcted epicardial muscle. KEY WORDS ventricular automaticity ventricular electrograms atrial pacing anesthetized dogs Purkinje fibers reentry vagal stimulation• Harris and Rojas in 1943 (1) described two distinct phases of ventricular arrhythmias after major coronary artery ligation in the dog. Sudden one-stage occlusion of the left anterior descending coronary artery close to its origin in the dog results in a high incidence of rapid paroxysmal ventricular tachycardia which usually degenerates into ventricular fibrillation within the first 20 minutes (1). If the dog survives the early arrhythmic episodes, a relatively quiescent period ensues followed by another prolonged interval of rapid ventricular ectopic activity. This later arrhythmic period starts MethodsEighteen adult mongrel dogs were anesthetized with sodium pentobarbital (30 mg/kg, iv). Under controlled ventilation, the thorax was opened at the fourth intercostal space, and the heart was exposed via a pericardiotomy. The left atrial appendage was reflected, and the left anterior descending coronary artery was exposed within 1 or 2 cm of its origin. Silk ligatures were then placed 3 7 2

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Section: Underlying Automaticity Revealed By Vagally Induced Sinus Armentioning

confidence: 54%

Characterization and Localization of Ventricular Arrhythmias Resulting from Myocardial Ischemia and Infarction

Scherlag

El‐Sherif

Hope

et al. 1974

Circulation Research

369

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The applicability of the signal averaging technique in clinical cardiology

Hombach

Braun

Höpp

et al. 1982

Clinical Cardiology

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Summary:Since 1963 the signal averaging technique has been applied to improve the signal to noise ratio in highly amplified EKG registrations. Based on the experiences from the literature and the authors own laboratory, the applications of the signal averaging technique in clinical cardiology are reviewed: extraction and analysis of the fetal EKG and P-wave variations, His bundle electrograms from the body surface (recovery rate 33-100% of cases), ventricular delayed depolarizations within the ST segment of the surface EKG (recovery rate, 40-90% of cases, depending on patient groups investigated), preatrial activity (sinus nodal potentials) from intracardiac (recovery rate, 80-90% of individuals), or surface EKGs (recovery rate, 60% of patients), analysis of frequency components of surface EKG-QRS complexes in patients with previous myocardial infarctions, and detection of low amplitude diastolic signals from surface phonocardiogram (recovery rate, 80% of cases). At present, advantages and limitations of the signal averaging technique may be appraised as follows: ( 1 ) sinus nodal potentials: S-A conduction times may be more reliable than those obtained by the extra-stimulus technique, since with averaging they are recorded during undisturbed sinus rhythm; direct recordings of changing S-A blocks may be impossible due to the summation process; validation of sinus nodal potentials in man necessary, (2) A-V nodal potentials: demonstration of true A-V nodal rhythm rather than His bundle rhythm; possibly direct identification of abnormal pathways in A-V nodal tachycardias; direct recordings of single A-V nodal blocks impossible due to summation process; (3) surface His bundle potentials: follow-up or screening of patients with A-V nodal and particularly His-Purkinje-system blocks; monitoring of antiarrhythmic drug therapy; atrial overlap in one-third of cases; direct identification of higher degree A-V nodal blocks impossible due to summation process (future developments may overcome this problem); (4) ventricular delayed depolarizations: possible identification of patients at high risk of sudden cardiac death; follow-up of therapeutic measures like antiarrhythmic drug therapy or cardiac surgery (bypass grafting, aneurysmectomy); validation of delayed depolarizations from body surface by direct intracardiac and/or epicardial mapping necessary.

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Die Bedeutung der Signalmittlungstechnik in der Kardiologie

Hombach¹,

Hilger²,

Braun³

et al. 1982

Klin Wochenschr

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This paper gives a survey on the principles, methodology, and clinical applications of the signal-averaging technique. Bioelectric signals of the heart at the microvolt level are overwhelmed by basal noise in high-gain amplified EKG registrations. By summation and averaging of several hundreds of cardiac cycles, basal noise can be minimized and the signal of interest accumulates. This improvement of the signal-noise ratio primarily depends on the number of cycles averaged, e.g., by 10:1 when 100 cycles are averaged (approximately, the square root of the number of averaged cycles). At present, signal-averaging computers in use are rather variable with respect to data acquisition, filter settings, trigger mechanism/stability, and data processing. These properties have to be taken into account when the results of different groups using different types of averaging computers have to be compared. At present, several applications of the signal-averaging technique in clinical cardiology have been proposed: (1) Surface EKG--registrations of pre-P potentials, of His bundle potentials, and of ventricular late potentials, as well as analysis of the frequency spectrum of the QRS complex in patients with myocardial infarction; (2) intracardiac EKG--recordings of pre-P potentials and of A-V nodal potentials; (3) surface phonocardiogram--detection of low-amplitude, late diastolic signals; (4) Intracardiac pressure analysis--recording of average phasic pressure changes. The most promising and clinically proven application of the signal-averaging technique, at present, seems to be the registration of His bundle potentials as well as of ventricular late potentials from the body surface. Future efforts will need to be made to record cardiac microvolt potentials beat by beat from the body surface by means of specially designed EKG recorders.

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Experimental Study of the Pathogenesis of Ventricular Extrasystolia

Cited by 9 publications

References 0 publications

Characterization and Localization of Ventricular Arrhythmias Resulting from Myocardial Ischemia and Infarction

Characterization and Localization of Ventricular Arrhythmias Resulting from Myocardial Ischemia and Infarction

The applicability of the signal averaging technique in clinical cardiology

Die Bedeutung der Signalmittlungstechnik in der Kardiologie

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