BETA-ADRENERGIC RECEPTOR BLOCKADE IN CARDIAC ARRHYTHMIAS

Cardioversion and digitalis. IV. Effect of beta adrenergic blockade

Experiments were performed in anesthetized dogs to study some effects of propranolol, dextro-propranolol and ICI50,172 on digitalis-induced arrhythmias and digitalis-induced sensitization to electrical shock. When given in beta-blocking doses, propranolol did not abbreviate ouabain-induced ventricular tachycardia (VT) or decrease ouabain-induced sensitization to electrical shock. In larger doses, propranolol first controlled the arrhythmia without affecting shock sensitivity and then abolished both arrhythmia and shock sensitivity. Dextro-propranolol, a compound with nonspecific antiarrhythmic action equal to that of propranolol but with virtually no beta-blocking effect, abolished shock sensitivity, whereas ICI50,172, a pure beta-blocking agent, did not. Beta-blocking doses of propranolol given to dogs bordering on digitalis toxicity but in normal sinus rhythm caused recurrence of sustained ventricular tachycardia. Reappearance of toxicity appeared to be related to a propranolol-induced decrease in heart rate, since it was averted during continuous electrical pacing of the atrium and reversed by isoproterenol administration.

Cardio-circulatory effects of beta-adrenergic blockade in organic heart disease. Comparison between propranolol and CIBA 39,089-Ba

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The electrophysiologic effects of beta-adrenergic blockade and cardiac denervation

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Self-poisoning with digoxin: successful treatment with atropine

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Conversion of atrial fibrillation and flutter by propranolol

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Acute and chronic effects of an adrenergic beta-receptor blocking agent (propranolol) in treatment of cardiac arrhythmias

The effects of intravenous and oral administration of propranolol, an adrenergic beta-receptor blocking agent, have been studied in 29 patients with various cardiac arrhythmias. The ventricular responses in chronic or paroxysmal ectopic supraventricular arrhythmias were decreased at rest or during exercise. Sinus tachycardias were regularly slowed. Two supraventricular tachycardias and one ventricular tachycardia, all consistently precipitated by exogenous stimuli, were prevented. Six instances of digitalis-induced arrhythmias were responsive to treatment.

Propranolol, especially when given orally, is of definite value in selected disturbances of cardiac rhythm. Reasonable caution should be exercised, however, because of the risk of precipitation of congestive heart failure or hypotension in patients with limited cardiac reserves.