Although the therapeutic action of digitalis is generally agreed to result largely from its ability to stimulate the contraction of the myocardium, there has been considerable suspicion that cardiac glycosides may also act directly upon the systemic vascular bed. Excised arterial and venous strips contract when exposed to digitalis glycosides (1-4), and generalized systemic arteriolar and venous constriction has been induced by digitalis in-anesthetized open-chest dogs on cardiopulmonary bypass (5, 6). In normal human subjects digitalis glycosides elevate arterial pressure and either have little effect on or diminish cardiac output, thus augmenting the calculated systemic vascular resistance (7). More direct evidence that digitalis acts upon vascular smiiooth muscle was provided by the observation that the drug elevated systemic vascular resistance in patients on total cardiopulmonary bypass, in whom the systemic perfusion rate was held constant, and in whom the cardiac effects of the drug could not influence arterial pressure directly (8). Little information is available, however, concerning the extracardiac actions of digitalis glycosides when given in the usual clinical doses to intact human subjects. The present investigation was undertaken to characterize the effects of ouabain on a specific vascular bed, that of the forearm. The effects of the drug on both the resistance and capacitance vessels were examined in normal subjects and in patients with congestive heart failure. Materials and MethodsThe effects of ouabain were determined in 12 normal subjects, between 18 and 49 years of age, and in 6 patients with congestive heart failure, between 34 and 52 years in age. Four of these patients had rheumatic mitral

In contrast to previous opinions, recent investigations have suggested that increasing heart rate (HR) with atropine when moderate sinus bradycardia accompanies acute myocardial infarction is not necessarily beneficial. To further characterize the influence of vagally mediated changes in HR during ischemia, we evaluated the effects of atropine and of electric stimulation of the vagus nerves on the incidence of ventricular arrhythmias during acute coronary occlusion in closed-chest dogs. Protection from occlusion-induced arrhythmia was not observed when 28 dogs receiving atropine were compared with 27 control dogs. Rather, the total incidence of ventricular arrhythmias was significantly higher ( P < 0.05) and ventricular fibrillation tended to occur more frequently in the atropine-treated group. Moreover, fewer ventricular arrhythmias (and total absence of ventricular fibrillation or close-coupled premature beats) were noted in 12 control animals with spontaneous bradycardia (HR<60 beats/min) compared with 15 nonbradycardic animals. When vagal stimulation produced bradycardia (HR = 40-60 beats/min) during coronary occlusion, occurrence and character of ventricular arrhythmias were the same as in dogs with normal rates (HR = 80-100 beats/min). Although these results may not necessarily apply to man, further studies are needed before it can be assumed that all individuals with moderate bradycardia during acute myocardial infarction should receive vagolytic agents.

The purpose of this study was to determine if there were consistent differentiating patterns in body surface potential maps in children with normal hearts and in those with ostium primum versus ostium secundum atrial septal defects. A second purpose was to interpret the isopotential surface maps in terms of the position of intracardiac electrical wave fronts.Body surface activity throughout QRS demonstrated three major intervals: developing, transitional, and declining potentials. Patients with both types of atrial septal defects demonstrated complex distributions (multiple maxima) during the transitional interval which were not encountered in normal subjects. In the primum group, the distribution of positive and negative potentials sequentially changed in an inverted pattern as compared to the pattern in those patients with secundum defects. Furthermore, during the transitional interval the potential distribution was considerably more complex in the primum group. In two additional patients, body surface maps were helpful in clarifying misleading and atypical conventional electrocardiograms.The presence of simultaneous multiple maxima could only be accounted for by the existence of multiple wave fronts simultaneously present within the heart. In particular the emergence of two widely separated anterior chest maxima in patients with secundum atrial defect indicated the simultaneous presence of prominent left and right ventricular wave fronts. Also, the marked differences in the relative positions of the major body surface maximum and minimum could be accounted for only by considerable differences in the position and extent of intracardiac wave fronts. For example, the target distribution, consisting of an isolated minimum surrounded by multiple maxima and positive potentials over the upper body, in the ostium primum patients, indicated epicardial breakthrough in a wave front positioned in the anterosuperior portion of the heart. In contrast, normal subjects and patients with secundum defect had distributions indicating antero-inferior wave front position at the time of right ventricular epicardial breakthrough. Additional Indexing Words: Intracardiac electrical wave fronts PRESENTATION of body surface potential distributions (body surface maps) provides a picture of cardiac electrical events as projected on the body surface. Surface maps differ from selective scalar leads by providing Body surface activity an integrated picture containing more information for predictions concerning single or multiple intracardiac wave fronts than is available from viewing scalar leads alone. From an electrophysiologic point of view, an From the

Since the initial report of the 49,XXXXY karyotype nearly 15 years ago, 86 cases have been reported in the world literature. The major features of the syndrome have been noted to be a triad of skeletal anomalies, hypogenitalism, and moderate-to-severe mental retardation. Among the less commonly associated abnormalities has been congenital heart disease, reported to have been seen in no more than 14 cases. The most frequently described lesion has been patent ductus arteriosus (PDA). We have recently seen two patients with the 49,XXXXY syndrome with associated congenital heart disease. This communication describes these two patients and reviews the literature to attempt to determine the actual frequency and types of congenital heart disease seen in this syndrome.