Effects of different LAD-blocked sites on the development of acute myocardial infarction and malignant arrhythmia in a swine model.

To explore the effects of various left anterior descending (LAD) artery-blocked sites on the development of acute myocardial infarction (AMI) and malignant arrhythmia in a swine model.Twenty-two pigs underwent occlusion of the coronary artery with balloon angioplasty were randomly divided into three groups according to the blocked site of the balloon: middle-site-blocked LAD group, bottom-third-blocked LAD group and control group. Then, the development of AMI and malignant arrhythmia, including ventricular tachycardia and ventricular fibrillation during the process of model creation, were recorded. Changes of the hemodynamics, blood gas analysis, electrocardiography, and myocardial enzymes were analyzed in each group before and after occlusion.Middle-site-LAD blockage resulted in a larger infarction size and the corresponding incidence of ventricular fibrillation was significantly higher than that of the bottom-third-blocked group (P<0.05). After the occlusion, the QTc interval of the Middle-site-blocked LAD group was significantly longer than that in the other groups (P<0.01). Moreover, mean arterial blood pressure (MAP), left ventricular ejection fraction (LVEF), and partial pressure of oxygen (PaO2) were significantly lower, but partial pressure of carbon dioxide (PaCO2) increased, in the Middle-site-blocked-LAD group compared with that in the bottom-third-blocked group (P<0.01). Compared with the control group, the two LAD-blocked groups showed significantly higher levels of Mb, CK-MB, LDH, AST and cTnT (P<0.01) four hours after the artery occlusion. However, these indexes were not significantly different between the two LAD-blocked groups (P>0.05).Location of LAD blockages in swine models may affect the development of AMI and malignant arrhythmia.