Setting of relatively low energy outputs may permit implantation of a nonthoracotomy automatic cardioverter defibrillator system when high energy outputs prove ineffective.
At intraoperative testing of defibrillation thresholds during implantation of internal cardioverter defibrillators, standard step-down approaches of energy outputs are used. If relatively high energy outputs are not successful at defibrillating the heart, the electrodes are frequently reconfigured. When attempting implantation of a nonthoracotomy lead system, high defibrillation thresholds may warrant opening of the chest cavity to place one or more epicardial electrodes. A case is presented where a nonthoracotomy system was able to be implanted using relatively low energy outputs which were reproducibly successful at terminating ventricular fibrillation when higher energy outputs were unsuccessful. Mechanisms for this phenomenon and alternate recommendations for defibrillation testing are presented.
Section of Cardiology, Morristown Memorial Hospital, New Jersey 07962-1956, USA.
S L
SL
Winters
A S
AS
Casale
T V
TV
Inglesby
J H
JH
Curwin
D000368:Aged; D017147:Defibrillators, Implantable; D004554:Electric Countershock / Q000379:methods*; D004567:Electrodes, Implanted; D006801:Humans; D008297:Male; D014693:Ventricular Fibrillation / Q000628:therapy