The excitatory influence on heart rate is generally considered by beta-adrenergic neuroreceptors of Ahlquist's classification. Blockade of the beta adrenergic system would therefore be expected to alter heart rate and consequently to have an effect
on 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 agents 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 caridac arrhythmias, administered intravenously.
The following results were obtained:
1. It was apparent that propranolol by the intravenous route offered 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 pacemarkers because this was evident in the slowing of atrial rate or conversion of paroxysmal atrial tachycarida to sinus rhythm, and the abolition or diminution of ventricular extrasystoles.
4. Digitalis-induced ventricular arrhythmias responded to propranolol well, and propranolol may well be the drug of choice in treating digitalisinduced 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 hypotension in 2 cases.