Minimally invasive close-chest method for creating reperfused or occlusive myocardial infarction in swine

We sought to evaluate a closed-chest model for reperfused and occlusive myocardial infarction (MI) in pigs and to report experiences and pitfalls.In 44 pigs, a balloon catheter was advanced into the left descending coronary artery (LAD) under fluoroscopic guidance. The balloon was inflated and occlusion of the vessel angiographically confirmed while ECG was continuously monitored. In case of ventricular fibrillation, direct current defibrillation was performed. In 6 animals, the balloon was left inflated during the following experiments, to obtain occlusive MI. In all other cases, the balloon was deflated after 45 minutes. After the experiments were finished, the hearts were stained with 2,3,5-triphenyltetrazolium chloride for assessment of infarct size.MI was successfully induced in 34 animals (28 reperfused and 6 occlusive). Mean size of MI was 15.8 +/- 5.1% of left ventricular surface area for reperfused and 21.5 +/- 8.7% for occlusive infarcts. In one pig, 2,3,5-triphenyltetrazolium chloride did not confirm infarction. In 26 pigs, ventricular fibrillation occurred. Defibrillation was successful in 17 pigs. Failure rate because of ventricular fibrillation decreased from 42% (6) in the first 14 to 10% (3) in the next 30 animals. One animal died due to technical failure of the ventilator. After initial experiences, we used balloon catheters with a diameter of 2-3 mm, instead of 4 mm. The smaller balloon sizes were used so as to decrease the incidence of fibrillation.The described technique of LAD occlusion presents a less invasive alternative to open chest models. The major pitfall, causing fatal arrhythmia in our series, was over-dilatation of the LAD with the balloon catheter.