ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

Electrically induced ventricular and atrial tachycardias were observed in 12 cases, and ventriculoatrial (V-A) and atrioventricular (A-V) relationships were studied. It was noted that retrograde V-A conduction is a common phenomenon and that A-V dissociation is not a prerequisite for diagnosis of ventricular tachycardia. Conduction through the A-V node occurred readily in both antegrade and retrograde directions; and, all grades of block from first to complete and including the Wenckebach phenomenon were observed in both directions. The intensity of the first heart sound and the amplitude of the jugularawave were governed directly by the temporal relationship between the P and the QRS regardless of whether conduction was antegrade, atrioventricular, or retrograde, ventriculoatrial.It is concluded that at present no electrocardiographic or bedside criteria are available for an unequivocal diagnosis of ventricular tachycardia and that further studies are needed.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

Recurrent tachycardia in a 10-year-old child with acute rheumatic carditis was interpreted as being produced by a reciprocating (circus) mechanism involving either the normal atrioventricular pathway or the anomalous pathway of the Wolff-Parkinson-White syndrome. The tachycardia could be stopped by appropriately timed, electrically induced, atrial premature systoles, which apparently interrupted the circus movement.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

In four patients with WPW syndrome atrial and ventricular premature beats were induced and the changes in form of the ventricular and atrial complexes were studied. Results indicate that, depending upon the timing of the premature atrial beat and the state of refractoriness of the His and Kent bundles, excitation of the ventricles occurs predominantly through the atrioventricular nodal system, predominantly through the Kent bundle or exclusively through one or both conduction systems. With short delays conduction through the Kent bundle may be blocked and only normal excitation of the ventricles occurs. In one patient with a history of attacks of tachycardia these normal QRS complexes were followed by retrograde activation of the atria by the Kent bundle, and attacks of supraventricular tachycardia of shorter or larger duration occurred. They stopped spontaneously, sometimes by delay or block, either of retrograde Kent conduction or of antegrade A-V nodal conduction, making it possible for the sinus node to capture the ventricles. They also could be terminated by induced atrial premature beats.In two patients tachycardias could be induced by appropriately timed ventricular premature beats during regular driving of the right ventricle. In one of these patients a circus movement, involving the Kent bundle, is probably present. By appropriate stimulation of the atria or ventricles during an attack of supraventricular tachycardia in this patient, one cycle length could be shortened without changing those of the following beats. These results suggest that a circus movement involving the atria, the normal atrioventricular conduction system and the Kent bundle is present. In the other patient, not fulfilling the WPW criteria, ventricular or atrial premature beats did not interfere with the basic rhythm of the tachycardia. Two hypotheses for this tachycardia are given: nodal tachycardia caused by rapid firing of the A-V node or a nodal tachycardia caused by a reciprocal mechanism in the A-V junction. The attacks could be blocked too by appropriately timed atrial and ventricular premature beats. No ventricular type of tachycardia could be demonstrated.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

A patient with an atrial septal defect, paroxysmal tachycardia, and the Wolff-Parkinson-White syndrome (type B) had epicardial exploration to determine the nature of the excitation anomaly. Right bundle-branch block in association with the WPW syndrome (type B) was evidenced by the late activation (0.12 sec) of the epicardium over the outflow tract of the right ventricle. Early activation of the base of the right ventricle (near the atrioventricular groove at the right border of the heart) was interpreted as indicating an actively conducting atrioventricular muscle bridge (bundle of Kent) in this region. During paroxysms of tachycardia, the ventricular area excited much later than when sinus mechanism was present, and the adjacent right atrium was excited in sequence. This sequence supported the concept of a circus movement, that is, movement from atrium to ventricle via atrioventricular bundle (His) and ventricle to atrium via a muscle bridge (Kent). Injection of procaine into the base of the right ventricle abolished the pre-excitation of the ventricle.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

Aberrant ventricular conduction (AbC) was produced in 17 of 18 subjects, including six normal persons, by the introduction of electric stimuli via a transvenous catheter situated in the right atrium.Analysis of electrophysiological determinants indicated that AbC was favored by a long cycle preceding the short cycle which terminated in the aberrant complex, a short R to stimulus coupling interval, and fast atrioventricular conduction time.Electrocardiographic analysis of AbC revealed that all patients had right bundle-branch block (RBBB). In addition, incomplete right bundle-branch block was present in eight patients and was transformed to RBBB in all cases by shortening the coupling interval. Ten patients had slight but distinct variations of their RBBB pattern. There were two instances each of left bundle-branch block and intraventricular conduction disturbance. Hence, any patient may have the potential to produce a variety of AbC patterns. AbC was produced in six normal subjects and must be considered a physiological event which does not require covert pathology of the specialized conduction system.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

The effects of intravenous diphenylhydantoin (5 mg/kg) on atrioventricular conduction in man at controlled heart rates in the digitalized and undigitalized state were studied. In undigitalized subjects, diphenylhydantoin administration consistently decreased A-V conduction time in each individual subject when identical heart rates were compared. Ouabain infusion produced an increase in A-V conduction time and this prolongation was always reversed by diphenylhydantoin. In two patients with atrial flutter and in two with atrial fibrillation, diphenylhydantoin caused a decrease in ventricular rate without affecting the atrial arrhythmias.These findings are of clinical importance, especially in the therapy of digitalis toxicity. When digitalis excess is manifested by both ectopic beats and incomplete A-V block, diphenylhydantoin would have special utility since, in contrast with the commonly used antiarrhythmic agents, it decreases A-V conduction time in addition to suppressing ectopic beats. Diphenylhydantoin-induced depression of the ventricular rate in atrial flutter or fibrillation may also be useful clinically. However, since diphenylhydantoin markedly decreases ventricular automaticity, its use in patients with complete heart block is contraindicated.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

The effect of 250 mg of diphenylhydantoin, administered intravenously, on left ventricular function was determined during cardiac catheterization in nine patients with heart disease.Five minutes after drug administration, left ventricular end-diastolic pressure rose in each patient from an average of 6.0 mm Hg to 10.0 mm Hg. Concurrently, stroke work and stroke power indices decreased in each patient by an average of 22.0% and 22.2%, respectively. Stroke volume index decreased in seven patients and maximum left ventricular dp/dt fell in eight patients. Over the next 25 minutes, all parameters returned to control values. Cardiac index was unchanged, whereas generally small and insignificant changes were observed in heart rate and systemic arterial pressure throughout the study.Although this study has demonstrated that diphenylhydantoin depresses myocardial function, the effect may have limited clinical significance since it was relatively short-lived and did not reduce cardiac output or greatly elevate ventricular end-diastolic pressure. Furthermore, the absence of a significant systemic hypotensive effect is of distinct clinical importance.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

Following the taking of 12-lead routine electrocardiograms, three precordial leads were recorded before, during, and after 10 to 15 seconds of voluntary hyperventilation in 296 students, ranging in age from 8 to 17 years.Fifteen per cent of the total group, comprising 212 Caucasians and 84 Negroes, inverted one or more previously upright precordial T waves following hyperventilation. The incidence of T-wave inversion in children 12 years of age and under was nearly four times greater in Caucasians than in Negroes. There was no significant difference when the older Negro and Caucasian students were similarly compared. Sinus tachycardia, T-wave flattening, and “tucking,” short of frank inversion, as well as junctional depression of the ST segment, were commonly seen following hyperventilation.The similarity of the hyperventilation-induced T-wave inversion in children to those previously documented in adults is noted, and the clinical implication of this study requires continued cognizance of the occurrence of “nonpathological” T-wave inversion in adults, so as to avoid iatrogenic heart disease.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID

摘要:

One hundred ten cases of T waves more than 10 mm in height in the precordial leads were studied. The T waves were wide in ischemic heart disease and thin and peaked in uremia. Marked changes in the ventricular gradient were observed in ischemic heart disease and in uremia with hyperkalemia. In other conditions, the changes in the ventricular gradient were of a lesser degree. In cases of left ventricular hypertrophy, the T waves were tall from V1to V4in systolic (pressure) overloading, from V4to V6in diastolic (volume) overloading, and from V2to V6in combined types of overloading.The appearance of tall T waves was the earliest electrocardiographic sign encountered in clinical and experimental cases of acute myocardial infarction. In anterior myocardial infarction they disappeared within 24 hours indicating initial transient ischemia, while in angina pectoris and posterior myocardial infarction they lasted for a longer time probably due to persistent subendocardial ischemia.

ISSN:0009-7322    

出版商:OVID    

年代:1967

数据来源: OVID