Characteristic intraeavitary electrocardiographic conmplexes at various sites within the heart in normal individuals have been described previously. The intracardiac tracings in 150 eatheterizations, 129 of which were abnormal hearts, predominantly congenital defects, were studied in relationship to the position within the heart as determined fluoroscopically. In our experience, the tracings remain sufficiently unchanged in abnormal hearts so that the intracavitary electrocardiogram may be used successfully as a guide, making it possible to decrease total x-ray exposure time considerably. In addition, the significance of an intraeavitary injury current became apparent. A few diagnostically useful variants were found and are described. DURING the last 2 years, intracavitaryelectrocardiography combined with cardiac catheterization has become an increasingly useful procedure in our hands. Reports are available describing the rather characteristic complexes obtained at various sites in the normal heart,1-7 and others indicate the possible value of such tracings in specific cardiac abnormalities.8-" In our studies in 150 cases, 129 of which were abnormal, it has become apparent that, as a rule, the characteristic tracings at the various sites within the heart," 2, 5 continue to be present.The intracavitary electrocardiogram refers to the tracing that is recorded as a V lead through an electrode ring affixed to the distal tip of the cardiac catheter. The advantages resulting from its use may be described in terms of increased safety to the patient and the additional information gained. electrocardiographically, we have observed additional variants that are diagnostically useful and that do not obscure the basic chamber patterns. Several of the more useful ones are cited.The intracavity tracing obtained from the left atrium resembles that of the right except that atrial depolarization occurs later. The right atrial P wave is written during the ascending limb of the lead II P wave, whereas the left artial complex is inscribed during the descending limb ( fig. 3). This occurrence is useful diagnostically when all abrupt increase in oxygen saturation is detected in the atrium. Ordinarily, such an increase indicates a left-to-right shunt through an atrial septal defect and the atrial pattern will be as expected. It has been our repeated observation that when such occurs in the presence of ostium secundum, the recorded pattern is that of the proximal right atrium. In ostium primum, the abrupt increase in oxygen saturation occurs at a level where the right atrial P wave is diphasic.It is of additional note that with the catheter tip within the silhouette of a prominent right atrium, abrupt increases in oxygen saturation can occur with 3 less frequent conditions. If the oxygen content becomes that of full saturation, the tip of the catheter may have passed INTRACAVITARY ELECTROCARDIOGRAPHunimportant foramen ovale or into an acutely angled anomalous pulmonary vein. In the latter instance, a right atrial tracing will be recor...

During the past decade, beta-adrenoreceptor blocking agents have proved to be valuable assets in our therapeutic armamentarium for management of both angina pectoris and essential hypertension. In ischemic heart disease, these agents reduce myocardial oxygen requirements by decreasing the force of myocardial contraction and by reducing heart rate. Consequently, decreased blood supply to portions of the myocardium is tolerated better. The beta-blockers are effective in reducing the frequency and severity of episodes of angina pectoris and in extending exercise tolerance. If needed, additional benefit may be gained by adding long-acting nitrates, or calcium-channel blockers or both.

No abstract