USE OF A BETA ADRENERGIC RECEPTOR BLOCKING AGENT (PROPRANOLOL) IN THE TREATMENT OF CARDIAC ARRHYTHMIAS

Abstract

Abstract The beta adrenergic blocking agent, propranolol, was given intravenously to fifty consecutive patients on fifty-four separate occasions for a variety of cardiac rhythm disturbances. The drug consistently slowed sinus tachycardias and reduced the ventricular rate in atrial flutter and atrial fibrillation. Digitalis-induced rhythm disturbances, especially paroxysmal atrial tachycardia with block and ectopic ventricular contractions, were particularly responsive to propranolol. Ectopic ventricular contractions due to other causes and ventricular tachycardias were much less responsive. Ectopic atrial and nodal tachycardias were occasionally converted to a sinus mechanism. Pre-existing atrioventricular block may be increased. Although no serious side effects were encountered in our series, the drug should not be administered intravenously to patients suffering from serious myocardial disease, particularly those manifesting hypotension and/or congestive failure, or to asthmatic patients. Nor should patients who display any degree of atrioventricular nodal block be given propranolol intravenously; an exception to this rule is digitalis-induced paroxysmal atrial tachycardia with block, in which case beta adrenergic blockade frequently re-establishes a sinus mechanism with only a transient increase in the degree of atrioventricular block. Propranolol may offer considerable differential diagnostic help in the evaluation of rapid regular tachycardias when there is no response to carotid sinus stimulation. Careful monitoring of blood pressure, apical rate and rhythm mechanism by electrocardiography during the intravenous administration of propranolol is mandatory.