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March 1975

Ventricular Fibrillation Threshold: Its Physiological and Pharmacological Importance

Author Affiliations

From the Comparative Cardiovascular Studies Unit, School of Veterinary Medicine and Department of Medicine, School of Medicine, University of Pennsylvania, Philadelphia.

Arch Intern Med. 1975;135(3):446-453. doi:10.1001/archinte.1975.00330030096010

Ventricular fibrillation is one of the primary causes of early sudden death after myocardial infarction.1 Ventricular fibrillation is usually initiated by either a rapid ventricular tachyarrhythmia or a premature ventricular contraction falling within the vulnerable phase of the preceding beat (R-on-T phenomenon).2 The initiation and maintenance of the tachyarrhythmia or premature ventricular contraction can be due to either a reentrant mechanism or abnormal ectopic activity.3 If a patient with myocardial infarction survives until admittance into a modern coronary care unit and is not in cardiogenic shock, the dysrhythmias and ventricular fibrillation can usually be controlled by electrical and pharmacological means.

The present report deals primarily with recent studies using the experimental technique of measuring the ventricular fibrillation threshold by applying electrical current to the heart. Particular emphasis is placed on some of the recent findings regarding the electrophysiology and electropharmacology of initiation and prevention of ventricular fibrillation.