A minimally invasive method for induction of myocardial infarction in an animal model using tungsten spirals

Most animal models use surgical thoracotomy with ligation of a coronary artery to induce myocardial infarction. Incision of the chest wall and myocardium affect remodeling after myocardial infarction. The aim of our study was to evaluate a new minimally invasive technique for inducing acute myocardial infarction in pigs. To this end, coronary angiography using a 6-F cardiac catheter was performed in 20 pigs. The cardiac catheter was advanced into the left circumflex artery (LCX) under electrocardiographic monitoring and small tungsten spirals were deployed in the vessel. LCX occlusion was verified by coronary angiography. Two days later, magnetic resonance imaging (MRI) was performed to estimate the extent of infarction. Thereafter, all animals were euthanized and the hearts stained with 2,3,5-triphenyltetrazolium chloride for histologic measurement of infarct size. Tungsten spirals were successfully placed in the LCX in all 20 pigs. About 13 of the 20 animals survived until the end of the experiment. The mean infarct size in the area supplied by the LCX was 4.4 ± 2.3 cm³ at MRI and 4.3 ± 2.2 cm³ at histology (r = 0.99, P < 0.001). No other myocardial regions showed infarction in any of the 13 pigs. Five of nine pigs requiring defibrillation due to ventricular fibrillation died because defibrillation was unsuccessful. One animal each died from pericarditis and pneumonia. Our results show that the minimally invasive method presented here enables reliable induction of myocardial infarction in a fairly straightforward manner. The 25% mortality rate associated with induction of myocardial infarction in our study is comparable to that reported by other investigators.