Key result
Coronary artery occlusion in pigs significantly altered ICD shock EGM R wave amplitude (e.g., +204.3% for LAD, P=0.003) and ST segments, varying by culprit vessel.
Why the study?
Does ischemia in major coronary artery distributions affect the shock EGM from ICDs in a pig model?
Does ischemia in major coronary artery distributions affect the shock EGM from ICDs in a pig model?
Ischemia affects ICD shock EGMs differently depending on the culprit vessel, demonstrating the feasibility of ischemia detection from ICDs.
Answers are grounded in this paper and cite their sources.
Supports ischemia detection feasibility via ICD shock EGMs in pigs; leaves open human translation and prospective validation.
INTRODUCTION: 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.
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Williams et al. (2007) studied Myocardial Ischemia (n=10). Percutaneous balloon occlusion of major coronary arteries was evaluated on R wave amplitude and ST segment changes on shock EGM. Coronary artery occlusion in pigs significantly altered ICD shock EGM R wave amplitude (e.g., +204.3% for LAD, P=0.003) and ST segments, varying by culprit vessel.
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