Treatment of cardiac arrhythmias with beta-adrenergic blocking agents. Clinical and experimental studies

Twenty-seven subjects with various cardiac rhythms were treated with intravenous pronethalol or propranolol. Slowed sinus rhythmicity, decreased A-V node conduction, and decreased ventricular premature contractions (particularly if caused by digitalis) were observed. One death occurred in a patient with A-V dissociation, severe pulmonary hypertension, and congestive heart failure. No other significant side effects were seen. These two drugs are considered to be quite useful in controlling ventricular responses to atrial flutter or fibrillation, and in certain cases of ventricular irritability. They are rapid acting and potent. Their use may be hazardous when bradycardia or A-V dissociation is present, or if the arrhythmia is complicated by severe congestive heart failure or bronchospastic pulmonary disease. Data in animals confirm the reversal of digitalis toxicity and suggest a mechanism of action in addition to beta-adrenergic blockade.