The circumflex coronary artery occlusion canine model of sudden death: methodology and electrocardiographic observations.

This study deals with a left circumflex coronary artery occlusion-reperfusion canine model of sudden death using multiple electrocardiographic leads to define a subgroup of animals at high risk of ventricular fibrillation. Occlusion was followed by ventricular fibrillation in 15 of 30 animals (50\%). In the 15 dogs surviving 60 min postocclusion, reperfusion gave rise to ten cases of ventricular fibrillation (66.7\%). Thus, the total incidence of occlusion-reperfusion ventricular fibrillation was 25 of 30 (83.3\%). Electrocardiographic delta R\% changes greater than or equal to 25\% in leads 2 and 3 at both 3 and 5 min postocclusion predicted the occurrence of postocclusion ventricular fibrillation with 80\% specificity and 56\% sensitivity. However, ST segment elevation greater than or equal to 0.5 mV in the same leads at the same times predicted postocclusion ventricular fibrillation with 67\% specificity and 100\% sensitivity. When only dogs with ST segment elevation greater than or equal to 0.5 mV in leads 2 and 3 at both 3 and 5 min postocclusion were considered, ventricular fibrillation postocclusion was seen in 15 of 20 dogs (75\%) and ventricular fibrillation after reperfusion occurred in four of the remaining five animals (80\%). Thus, in the subgroup of animals presenting with ST segment elevation greater than or equal to 0.5 mV in leads 2 and 3 at both 3 and 5 min postocclusion, the overall incidence of occlusion-reperfusion ventricular fibrillation was 19 of 20 (95\%). These data may be useful in studies aimed at testing the effectiveness of drugs or other interventions in a canine model of sudden death.