The Journal of Thoracic and Cardiovascular Surgery, Vol 75, 224-226, Copyright © 1978 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
The electrical dose for direct ventricular defibrillation in man
WA Tacker Jr, GA Guinn, LA Geddes, JD Bourland, FL Korompai and PA Rubio
The threshold electrical energy for direct ventricular defibrillation was
measured in 100 patients whose hypothermic hearts were fibrillated for
cardiac operations. In 93 cases 10 joules or less was sufficient, and in 48
of these cases 5 joules or less defibrillated the ventricles. Because a
shock of 10 joules defibrillated the heart of most of our patients, we
recommend an initial shock of 5 to 10 joules rather than the 20 joules used
more commonly. Until the safety margin between defibrillation threshold and
damage threshold is established for direct defibrillation, use of shocks
with adequate but not excessive strength may avoid unnecessary damage to
the myocardium. When hearts refibrillate after defibrillation, it is
unnecessary to use higher energy settings for subsequent defibrillation
attempts. Instead, an antiarrhythmic drug should be administered and
another shock of the same intensity that defibrillated the first time
should be applied.
