The Annals of Thoracic Surgery, Vol 35, 361-366, Copyright © 1983 by The Society of Thoracic Surgeons
The effects of cardiovascular drugs on the defibrillation threshold and the pathological effects on the heart using an automatic implantable defibrillator
GM Deeb, RL Hardesty, BP Griffith, ME Thompson, MS Heilman and RL Myerowitz
Internal defibrillating leads were implanted in 6 dogs through a left
thoracotomy and in 6 pigs through a subxiphoid approach. The effects of
digoxin (0.04 mg per kilogram of body weight), procainamide (15 mg per
kilogram), and propranolol (0.2 mg per kilogram) on the defibrillation
threshold was determined 30 to 60 minutes following intravenous
administration. Resultant blood levels were equal to or greater than
therapeutic levels. Individually these drugs resulted in no appreciable
change in the defibrillation threshold from baseline. Pathological study of
the myocardium obtained from 6 dogs that underwent more than two hundred
shocks each did not demonstrate any abnormality. The 6 pigs were reliably
defibrillated, this indicating that thoracotomy is not required for
successful implantation. The automatic implantable defibrillator is not the
definitive treatment for recurrent ventricular arrhythmias, but is a
practical regimen of therapy for a select group of high-risk,
out-of-hospital patients. These observations advance our knowledge of the
use of this device and give more assurance for future implantation in this
select group of patients.
