Effect of ischemia on implantable defibrillator intracardiac shock electrograms.
BACKGROUND
Few attempts have been made to extract information from the ventricular electrogram (EGM) recorded by implantable cardioverter defibrillators (ICD) aside from the discrimination of supraventricular tachycardia and ventricular tachycardia. The current study aims to examine the effect of ischemia in the major coronary artery distributions on the shock EGM from ICDs.


METHODS
Domestic crossbred pigs (n = 10, 20-40 kg) were implanted with a dual-coil right ventricular defibrillation system. Through the femoral approach, percutaneous balloon occlusion of the major coronary arteries was performed. The left anterior descending (LAD), left circumflex (LCx), and right coronary (RCA) arteries were occluded in random order for 3-5 minutes with 30-minute periods of reperfusion in between and the shock EGMs were recorded and analyzed.


RESULTS
During peak ischemia, R wave amplitude increased by a mean of 204.3% (P = 0.003), increased by a mean of 73.8% (P = 0.0009), and decreased by a mean of 28.0% (P = 0.109) in the LAD, LCx, and RCA territories, respectively. During peak ischemia ST segments elevated by a mean of 105.3% (P = 0.041), elevated by a mean of 114.9% (P = 0.064), and decreased by a mean of 584.5% (P = 0.006) in the LAD, LCx, and RCA territories, respectively.


CONCLUSIONS
Ischemia affects ICD shock EGMs in a manner that appears to vary depending on the culprit vessel. Our data demonstrate the feasibility of ischemia detection from ICD shock EGMs.
Williams
Jeffrey L
JL
Cardiovascular Institute of the University of Pittsburgh, Pittsburgh, Pennsylvania, USA. williamsjl4@upmc.edu
Mendenhall
G Stuart
GS
Saba
Samir
S
D000818:Animals; D047548:Defibrillators; D004562:Electrocardiography / Q000295:instrumentation / Q000379:methods*; D005240:Feasibility Studies; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000517:prevention & control*; D013552:Swine; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000517:prevention & control*; D016896:Treatment Outcome