Aberrant ventricular conduction (AbC) was produced in 52 subjects, including 14 normal volunteers, by the introduction of atrial premature beats through a transvenous catheter electrode. Simultaneous standard electrocardiograms and vectorcardiogams permitted detailed analysis of configuration. Multiple patterns of AbC were produced in 29 of 52 subjects. The general categories and their frequency were as follows: right bundle-branch block without significant axis shift from control, 31; right bundle-branch block with left axis deviation, 27; left axis deviation, 14; inferior axis deviation, six; right bundle-branch block with inferior axis deviation, seven; and complete left bundle-branch block, six. These patterns were believed to depend on the location of isolated or combined functional block in the major pathways of the specialized conduction system, which include the right bundle branch, common left bundle branch, anterior division of the left bundle branch, and posterior division of the left bundle branch. The present study has documented the general varieties of AbC, their relevance to clinical cardiology, and the varieties most likely to cause diagnostic difficulty.
SUMMARYThis study was undertaken with a consideration of the physiological relationship between myocardial oxygen consumption and heart rate. Atrial pacing was performed in 63 resting subjects, 36 Standardized stress test Coronary artery disease physiological considerations, which will adequately and safely test the coronary reserve of subjects suspected of having coronary artery disease.Most investigators agree that the heart rate varies with the relative intensity of exercise according to the age and physical fitness of the subject.3 This response, coupled with available evidence that myocardial oxygen consumption per minute increases with heart rate6 and the finding that S-T segment depression may occur during induced tachycardia,7 suggests that heart rate alone may play a significant role in uncovering inadequacies of coronary reserve.In this study the effects of increasing heart rate alone, by means of right atrial pacing, on the electrocardiograms of normal and hypertensive subjects and of patients with angina pectoris were evaluated. This report represents an extension of our observations which we previously reported in abstract
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