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Quinidine syncope is an unpredictable side effect of quinidine administrateion which has a mortality rate of 11.5 per cent when managed with conventional drugs and direct-current countershock. In 2 patients with quindine syncope, the arrhythmias were effectively controlled within 30 minutes following the slow infusion of 150 mg. of bretylium tosylate. This control is contrasted with 2 cases managed in the conventional manner. Bretylium tosylate is a quaternary amine with unique antifibrillatory properties and appears to have a significant role in the management of these arrhylmias.

Digitalis accelerated the rate in atrial flutter resulting in atrial fibrillation, whereas the addition of quinidine slowed the atrial rate producing either asystole or interference dissociation. In some patients receiving both digitalis and quinidine, the atrial rate showed less of a tendency to slow or actually increased, resulting in atrial fibrillation followed by normal sinus rhythm. This suggests an overriding effect of digitalis. Since the spontaneous termination of atrial flutter occurred in unknown circumstances that usually slowed the atrial rate and asystole was observed, this suggests that asystole is not a toxic effect of quinidine. Atrial flutter, fibrillation, and atrial premature beats began more commonly in the P-T cycle than in the T-P cycle. Since atrial recovery is more likely incomplete during the P-T cycle, this favors reentry as the underlying mechanism in the patient studied. Atrial and nodal tachycardia begin with an irregular sequence of premature beats before a stable tachycardia is established. There is usually a significant slowing of the rate prior to termination of the abnormal rhythm. Sinus arrest with ventricular escape is the usual method of termination, regardless of the form of therapy used. Bursts of rapid ventricular rhythm resembling ventricular tachycardia were seen only after the use of pressor agents. Atrial tachycardia with block treated with digitalis shows an initial atrial slowing but, as the dose of digitalis was raised in one patient, abrupt increases in atrial rate occurred until the rhythm terminated. This is a mechanism similar to that seen in the digitalis-induced termination of atrial flutter.

The acceptable zeros of the potential of the electrical fields produced by certain dipole distributions in homogeneous volume conductors is discussed. A bridge circuit is described by which a solution of the three-arm and the four-arm central terminals of Wilson may be solved for a zero of potential of the field produced by an arbitrary distribution of dipoles in a homogeneous volume conductor. An acceptable zero of potential for evaluation of the potentials in a locus on the "body" surface distant from the heart is described.

Expanding the frequency response of the electrocardiogram and its derivative to 1,000 cps revealed notching in certain parts of the QRS complex which correlates with the presence of primary myocardial disease. Chi-square analysis of data from 169 patients with myocardial involvement indicated that notching on the downstroke of leads X, V 4 , and V 6 separated abnormal from normal patients at the 1% level of significance, whereas fine and coarse slurring showed reverse correlation at the 1% level of significance. This suggests that notching and not slurring is the important evidence of disease. Neither notching nor slurring was significant at the peak of the R wave in any lead. Study of individual cases revealed that complete right and left bundle-branch blocks do not mask high-frequency components caused by myocardial disease nor do they produce high-frequency components. Conclusions regarding specific diagnostic nostic criteria, however, should serve only as guidelines.

The transmyocardial temperature gradient was measured in both right and left ventricles and in the septum of the dog by percutaneous ventricular puncture, using a no. 21 thin-wall needle fitted with a thermocouple stylus. The outer half of the left ventricular myocardium was invariably warmer than the endocardium. The peak temperature of the right ventricle was located midway between the endocardium and epicardium. The midseptal region was found to have a higher temperature than either its right or left endocardial aspects. The left ventricular cavity was cooler than the right ventricular cavity by a mean of 0.1°C. The transmyocardial temperature gradient was measured successfully in the left ventricle of two patients with cardiac disease. As in the dog, the outer layers of the myocardium were warmer than either the endocardium or cavity in these two patients. In one patient the T waves in the left precordial leads were negative and in the other the T waves were upright in the same lead. The location of peak temperature consistently in the outer half of the left ventricular wall may partly explain the normal upright T wave and may contribute to a more rapid recovery in the outer layers of the ventricle compared with the inner layers. However, reversal of the T wave must be explained by other factors and it is apparent that the polarity of the T wave is not governed exclusively by the transmyocardial temperature gradient. The transmyocardial temperature gradient may be explained partly on the basis of differences in heat removal by blood flow in the coronary system as well as in the ventricular cavity. The latter was found to be an important factor, because during ventricular fibrillation the transmyocardial temperature gradient was abolished.

Antazoline is a comparatively safe and effective antiarrhythmic drug in many situations, for both the conversion and prevention of arrhythmias. It appeared to be most effective in the abolition of ventricular tachycardia, possibly helpful in 2 cases of cardiac arrest due to ventricular fibrillation and beneficial in the prevention of atrial and ventricular premature beats. It was useful and deserves further trial in the prevention of paroxysmal ventricular tachycardia. It was almost ineffective in the conversion and prophylaxis of atrial flutter and atrial fibrillation but appeared to be of value in the prevention of paroxysmal atrial tachycardia. There was a high incidence of mild side effects, mostly of the gastrointestinal type, some of which were prevented by taking the drug with meals or with an antacid preparation. No irreversible or serious side actions were encountered, but diarrhea, central nervous system symptoms and chills and fever necessitated stopping the drug in a small percentage of patients.

The histopathology of the sinus node, the atrioventricular node, and the atrioventricular bundle of the heart from a child dying of diphtheria is presented. The terminal illness included atrial arrhythmias and heart block. [see figure in the PDF file] [see figure in the PDF file] The possible importance of the neuropathology of the diphtheritic heart is indicated.