Biomedical subjects
Publications and source records attributed to L Schamroth.
The electrical axis of the heart is an important parameter in electrocardiographic assessment. Slight degrees of left axis deviation have been attributed to a horizontal heart position resulting from the mechanical effects of abdominal distension, such as the physiological event of pregnancy. This study was undertaken to establish the validity of this concept.
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Two cases of transient hemiblock occurring during the course of acute myocardial infarction are reported. The transient manifestation permits the accurate evaluation of the diagnostic features of the hemiblocks as modified by acute infarction. One case reflects the development of left bundle branch block due to bilateral post-divisional block which inter alia permits the study of left bundle branch block in the presence of acute myocardial infarction.
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A patient with idionodal rhythm with alternation of retrograde conduction times is described. The idionodal escape rhythm is associated with alternating slow and relatively fast retrograde conduction times to the atria. The mechanisms underlying this phenomenon are discussed.
A case is described where the basic sinus rhythms is associated with an advanced degree of left anterior hemiblock. The rhythm is complicated by atrial extrasystoles, associated with a lesser degree of left anterior hemiblock. This paradox of 'supernormality' is explained on a critical interplay of differential refractoriness within the divisions of the left bundle-branch.
Two cases which exhibited a Wenckebach form of exit conduction between an electrical pacemaker and the ventricular myocardium are presented. This manifests with increasing latency (stimulus to QRS intervals) and ultimate stimulus failure (block). The cycle then repeats itself. The QRS duration also increases progressively within each cycle. The phenomenon connotes an adverse prognosis. Several postulates regarding the mechanism are discussed.
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The electrocardiographic manifestations of left bundle-branch block associated with acute inferior wall myocardial infarction are presented. The classic features of uncomplicated left bundle-branch block are modified in the following manner. The QRS complex is diminished in amplitude, and the S-T segment and T wave reflect primary changes: a coved, elevated S-T segment and an inverted, symmetrical T wave. These changes occur in leads orientated to the infarcted surface.
The electrocardiographic features and genesis of so-called masquerading' bundle-branch block are presented. The phenomenon is essentially a right bundle-branch block with left anterior hemiblock, with further modifications of the initial and terminal QRS vectors, so that the standard leads, and at times the left precordial leads, resemble left bundle-branch block.
A patient presented in the coronary care unit with acute chest pain and in shock. The electrocardiographic features suggested an acute high lateral myocardial infarction. Certain features were, however, paradoxical, and suggested reversed arm electrodes. A repeat electrocardiogram reflected the classic features of acute pulmonary embolism. It is evident that the "mirror image' of the classic S1Q3T3 presentation of acute pulmonary embolism mimics an acute high lateral infarction.
Three cases of acute inferior wall myocardial infarction associated with complete atrioventricular block and junctional escape rhythm showing left posterior hemiblock are presented. The triad appears to consitiute a distinct syndrome. It is postuated that the subsidiary pacemaker is situated either in the bundle of His or the proximal part of the anterior division of the left bundle-branch.
A further mechanism of escape-capture bigeminy is described, viz, blocked atrial extrasystoles.
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