Moderate Bradycardia Research Articles

Hypoglycaemia after propranolol in children.

Abstract Propranolol‐induced hypoglycaemia was seen in two healthy siblings, a boy aged 20 months and a 3‐year‐old girl. Treatment with carbohydrate had an immediate effect on the symptoms. There were no cardiac complications apart from moderate bradycardia, which may obscure the diagnosis.

The influence of sodium amidotrizoate and of methylglucamine amidotrizoate on electrocardiographic changes and subjective side-effects in angiocardiography. A comparative study in patients.

Urografin 76 per cent2 has a low toxicity and is usually suitable for angiocardiographic examinations. Its relatively high viscosity, however, makes it less suitable as a contrast medium in cases in which only small catheters can be used and in those in which a low injection pressure is desirable. A new preparation, Urovison,3 contains mainly sodium amidotrizoate and has a considerably lower viscosity than Urografin 76 per cent. Since there is need for a less viscous medium and since the use of Urovison in angiocardiography had been reported with favorable results (Weissleder and Kiefer, 1966), it was thought of interest to compare some of the side-effects of Urografin 76 per cent with those of Urovison in patients. The electrocardiographic changes following angiocardiography with Urografin 76 per cent were studied, as were those when Urovison was the contrast medium. In addition, the subjective side-effects were compared. In questioning the patients for their side-effects, care was taken not to influence the answers. In 10 nonselected cardiac patients identical injections of Urografin 76 per cent and Urovison were made as part of a routine preoperative study. In 5 patients the injections were made in the left ventricle through a transseptal catheter or through a catheter introduced retrograde from the femoral artery, and in 5 the injections were made in the ascending aorta with a percutaneously introduced catheter. Every second time Urografin 76 per cent was injected first and every second time Urovison. The patient and the tip of the catheter remained in the same position for both injections. Similar quantities of the two contrast media were employed, and the pressure in the injector was adjusted so that the speed of the injection was similar with both contrast media. An interval of fifteen minutes between the injections permitted heart rate and blood pressure to return to normal before the second injection. Biplane angiocardiography or cineangiocardiography was performed. The roentgen exposures, the electrocardiogram (lead 2), the arterial pressure, and usually one intracardiac pressure were recorded before, during, and after the injections. The recording was usually stopped one minute after the injection, but when electrocardiographic changes persisted, the recordings lasted longer. The electrocardiographic changes in heart rate were recorded, as were the occurrence of extrasystole and changes in the S-T interval or in the T-wave. Results The diagnostic value of the angiocardiograms or cineangiocardiograms obtained with the two different media was similar. Changes in Heart Rate: With both contrast media, a moderate bradycardia was followed by a slight tachycardia in all patients. There was no obvious difference between the two agents in this respect. Extrasystole occurred in 3 patients after injection of Urovison, whereas similar injections of Urografin 76 per cent gave no extrasystole.

Effects of maternal glucose loading upon induced fetal distress

1.1. The effect of maternal glucose administration upon the normal and stressed fetal heart has been studied.2.2. Twenty-five grams of glucose administered to the mother, both at the beginning and at 45 minutes in the experimental period, was effective in maintaining an elevated maternal blood glucose level.3.3. Changes in maternal blood pressure and fetal tissue oxygen “tension” were comparable in both glucose treated and untreated animals when Neosynephrine was administered to the mother.4.4. In the normal treated fetus, bradycardia was absent following the maternal administration of 0.9 to 24.0 gamma per kilogram of Neosynephrine. In contrast, tachycardia of 5 beats per minute was produced with 1.5 to 3.0 gamma per kilogram of Neosynephrine in the stressed fetus.5.5. The administration of from 3.0 to 24.0 gamma per kilogram of Neosynephrine produced only moderate bradycardia in the stressed and treated fetus.6.6. It was concluded that maternal glucose loading results in a significant increase in placental glucose transport and can prevent the marked bradycardia which is characteristic of severe fetal hypoxia.

STIMULATION OF THE VAGUS NERVE AND CAROTID SINUS IN MAN

The results of mechanical stimulation of the exposed vagus nerve and carotid sinus of man in a series of twenty cases have been recorded electrocardiographically.Of thirteen cases under ether anæsthesia, none showed any response to sinus stimulation, while one responded to vagal stimulation. Two cases under chloroform yielded responses to sinus stimulation, and one to vagal stimulation also. Of five cases under gas and oxygen, three gave responses to sinus or vagal stimulation, or to both.The response to sinus stimulation was usually moderate bradycardia, with or without diminution of the P‐waves. A different response was elicited under chloroform, consisting of the appearance of ventricular extrasystoles. Responses to vagal stimulation were similar in nature, but were characterised by a longer latent period and longer after‐effect.It has been demonstrated that the human vagus is in some cases excitable by mechanical means. The relation of this to Czermak's “vagal pressure” and to the “caroto‐vagal” pressure of Hering is discussed.The expenses of this research have been met by grants from the Moray Endowment Fund and from the Trustees of the Clinical Medicine Research Laboratory, Edinburgh Royal Infirmary.