Black and Stephenson (1962) reported the results of betaadrenergic-receptor blockade in animals, using pronethalol. They found that the drug induced bradycardia and they indicated the possibility of using it in certain arrhythmias. Stock and Dale (1963) reported its use on patients with various arrhythmias. They found it useful in controlling the ventricular rate in atrial fibrillation and in the treatment of digitalisinduced arrhythmias, and they studied its effect in supraventricular tachycardias and upon various types of ectopic beat. After the production of evidence that the drug is carcinogenic to mice (Paget, 1963) the makers advised that its use should be restricted to those conditions that directly threaten life or to those patients whose life-expectation is short. The development of propranolol (Inderal), which is free from carcinogenic activity in mice (Black, Crowther, Shanks, Smith, and Dornhorst, 1964) and has a therapeutic ratio ten to twenty times greater than pronethalol, has renewed interest in the clinical application of beta-receptor blockade. The present paper reports experiences using propranolol in selected cases of atrial fibrillation, in atrial flutter and tachycardia, and in ventricular arrhythmias.
Atrial FibrillationEleven patients were studied. Of these, five had rheumatic heart disease, four had thyrotoxicosis, one had mitral stenosis and thyrotoxicosis, and one had no underlying cardiac disorder. The patients with rheumatic heart disease were selected because of failure to control the ventricular rate at rest or on exercise with maximum tolerated doses of digitalis. The patient with idiopathic atrial fibrillation was studied both before and after digitalization. Those patients with thyrotoxicosis had been given digitalis to the maximum tolerated dose.Seven patients were studied before and during steady-state exercise on the cycle ergometer in the supine position. The patients were exercised for four minutes and the heart rate was measured during the last half-minute of exercise. The work load was kept constant for each individual patient. The propranolol was given intravenously in a standard dose of 10 mg. The resting rate after the drug was given was taken as the mean of readings at five-minute intervals between 15 and 25 minutes after the injection.
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