ABSTRACT
The excitatory influence on heart rate is generally considered by beta-adrenergic neuroreceptors of Ahlquist's classificantion. Blockade of the beta adrenergic system would therefore be expected to alter heart rate and consequently to have an effect of patients with a variety of cardiac arrhythmias. In 1964 a clinically useable agent was produced by the name of propranolol which would effectively block beta action of adrenergic system and safe from side effects. The purpose of this study is to determine and estimate the immediate therapeutic effects of propranolol on 29 cases with various cardiac arrhythmias, administered intravenously. The following results were obtained: 1. It is apparent that propranolol by the intravenous route offers a rapid means of inducing A-V block and hence a reduction of the ventricular response in atrial fibrillation and atrial flutter. 2. Propranolol may be of value in improving digitalis-resistant atrial tachyarrhythmias with the therapeutic supplement. 3. Propranolol diminishes the automaticity of ectopic pacemakers because this is evident in the slowing of atrial rate or conversion of paroxysmal atrial tachycardia to sinus rhythm and the abolition or diminution of ventricular extrasystoles. 4. Digitalis-induced ventricular arrhythmias respond to propranolol well, and propranolol may well be the drug of choice in treating digitalis-induced ventricular arrhythmias. 5. Ventricular arrhythmias not related to digitalis were not satisfactorily treated with propranolol in our series. 6. Side effects associated with propranolol treatment were not remarkable except for development of transient hypertension in 2 cases.