Muhtar Yildiz

The effect of diphenylhydantoin (Dilantin) sodium on atrial flutter and fibrillation provoked by focal application of aconitine or delphinine

Abstract In dogs anesthetized with Nembutal and morphine the heart was exposed, and aconitine or delphinine crystals were applied to the surface of the right atrium in order to create flutter or fibrillation. The effect of the intravenous administration of diphenylhydantoin sodium (Dilantin) on these arrhythmias was studied. In 14 experiments with aconitine and 8 with delphinine, sinus rhythm was obtained quickly, and in 20 of the 22 experiments it was obtained abruptly by the intravenous injection of 5 mg. per kilogram of diphenylhydantoin. This effect was transient, since the atrial arrhythmias reappeared within a few minutes. Repetition of the injection (up to five injections in a single experiment) had the same effect as that of the first injection. Ventricular tachycardias provoked by the topical application of aconitine crystals on the right ventricle responded in the same way as did the atrial flutter and fibrillation. Special characteristics of atrial and ventricular arrhythmias caused by diphenylhydantoin are described. The experimental and clinical literature dealing with the action of diphenylhydantoin on cardiac arrhythmias is discussed.

Blood pressure measurements in obese persons

Abstract 1. 1. Simultaneous direct intra-arterial blood pressure measurements and indirect measurements with the auscultatory method were made in 100 subjects. The subjects were grouped according to their Ponderal Index W/H, weight per inch of height. Sixty-one subjects were obese, thirty-nine were nonobese. 2. 2. Nine out of the ten stoutest subjects were hypertensive, whereas only one of the ten leanest subjects was hypertensive. 3. 3. The indirect method generally underestimates systolic and overestimates diastolic pressure. This holds for lean persons as well as for moderately obese persons. 4. 4. The discrepancies between the direct and indirect methods were usually minor among the lean and the moderately obese subjects and went in both directions. Falsely high blood pressure readings in lean and moderately obese persons are not common. 5. 5. In extremely obese persons the indirect method is subject to considerable error. In eight out of ten such persons the systolic pressure was overestimated, and in nine out of ten such persons the diastolic pressure was overestimated. 6. 6. Overestimation of systolic pressure in very obese persons can be much greater than was heretofore known; it amounted to 44, 50 and 51 mm. in three of our stoutest subjects. 7. 7. Falsely high readings in extremely obese subjects are caused by the large size of their arms. If this possibility is borne in mind, an unwarranted diagnosis of hypertension is not likely to be made. In dubious cases, intraarterial measurement should be resorted to. 8. 8. Many factors other than arm size may cause inaccuracies of the indirect method, and the large arm does not regularly cause falsely high readings. It is not feasible to apply a correction to an individual reading.

Experimental study on ventricular extrasystoles provoked by vagal stimulation.

Abstract Ventricular extrasystolic tachycardias were provoked by focal application of a hypertonic solution of sodium chloride on the exposed heart of the dog. After these extrasystoles subsided, faradic stimulation of the right vagus nerve made them reappear. This effect was reproducible. The extrasystoles which were observed during vagal stimulation were identical with those which appeared after the application of sodium chloride. A characteristic feature of these extrasystoles was their unusually high rate.

A-V Nodal parasystole

Abstract Four instances of parasystole with the ectopic center in the upper portion of the A-V node are described, and several similar observations were collected from the literature. The astonishing fact is stressed that the automaticity of the ectopic center is slow in most of these observations. Unlike ventricular parasystole this form seems to appear in persons with healthy hearts.

Paroxysmal tachycardia precipitated by atrial or ventricular extrasystoles

Abstract In 4 patients, attacks of supraventricular tachycardia (3 cases of A–V nodal and 1 of atrial or A–V nodal tachycardia) were observed. In 3 of them the attack was initiated by an atrial and in 1 by a ventricular extrasystole. A reentry mechanism could be ruled out. It was assumed that these tachycardias are caused by rapid firing of an A–V nodal center triggered by an extrasystolic impulse reaching it early in diastole during the “vulnerable phase.”

Extrasystoles and parasystole

Abstract Ventricular ectopic tachycardias were created by the focal injection of 0.05 c.c. of a 30 per cent solution of sodium chloride, or a 3.8 per cent solution of sodium citrate or oxalate into the subepicardial layers of the ventricular myocardium. These tachycardias were often followed by a parasystolic rhythm. The experiments show that a rapidly firing center is protected from the normal impulses which spread over the heart, and, thus, the hypothesis of entrance (protection) block is not necessary. These parasystoles provide an opportunity for study of the distance between ectopic beats and preceding normal beats (coupling). It was found that this distance varies little if normal and ectopic rhythms are rapid and have an almost equal rate. Marked variations in the coupling occur if the rates differ. Little variation in the coupling may occur if the impulses of a rapid parasystolic center become effective only shortly after a conducted beat.

Cardiac Arrhythmias Provoked by Focal Application of Delphinine

SummaryDelphinine, focally applied on the atria of the exposed heart of the dog, elicits atrial flutter persisting long enough to permit studies of this arrhythmia. Vagus stimulation increased the rate of the flutter. In some experiments when the flutter subsided or before it started, tachycardias were observed which were terminated suddenly by vagus stimulation and re-appeared also suddenly and must therefore be termed paroxysmal tachycardias.Mechanical pressure exerted on the focus on which delphinine had been applied caused atrial fibrillation which disappeared quickly after pressure was discontinued.Ligation across any possible pathway around the venae cavae did not influence existing flutter and fibrillation. Cooling of the focus of application or clamping it from the rest of the atria stopped the flutter immediately.Delphinine is an excellent means to create experimentally atrial flutter or ventricular paroxysmal tachycardia orginating in a focus of rapid impulse formation.

Focal application of hypertonic solutions of sodium chloride on impulse formation in the heart of the dog.

Abstract Focal application of a hypertonic solution of sodium chloride to the atria or ventricles of the exposed heart of the dog leads to the appearance of coupled extrasystoles or short bouts of ectopic paroxysmal tachycardia 5 . When 0.05 c.c. of a 20 per cent solution of sodium chloride is injected into the taenia terminalis, in which the sinus node is situated, and one of the vagus nerves is stimulated in the neck with a faradic current, atrial flutter, atrial fibrillation, or a paroxysmal atrial tachycardia appears 11 . These effects are fleeting, and are observed for 4 to 5 minutes immediately following the injection. This investigation was continued and the effect of injections of the hypertonic solution in two other areas was studied: these areas were the atrioventricular node and the appendix of the left atrium, which is supposedly devoid of specialized automatic fibers.

Effect of epinephrine on experimental ectopic ventricular tachycardias.

Summary Intravenous injection in the dog of epinephrine in the amount of 0.01 cc kg in presence of a ventricular ectopic tachycardia, did not elicit ventricular fibrillation in 54 attempts. The tachycardia was moderately increased in most experiments or slowed down. Only in 4 experiments did the rate rise for more than 50 beats/minute.