Ventricular Aneurysm Animal Model Establishment by Plugging the Left Anterior Descending Branch

BACKGROUND: Biological characteristics of porcine cardiovascular system are similar to that of human. The metabolism, immune system, mechanism of disease have 99% homology between pig and human. OBJECTIVE: To develop ventricular aneurysm animal models by plugging left anterior descending branch. DESIGN, TIME AND SETTING: The animal observational study was performed at the Laboratory of Functional Material and Animal Experimental Center, Tongji Hospital Affiliated to Tongji University from December 2005 to July 2007. MATERIALS: A total of 13 pigs, of both genders, weighing 30-40 kg, were used in this study. METHODS: After abdominal cavity and intravenous anesthesia, balloon with ”WYW” stent was put into 13 pig left anterior descending coronary artery following No. 7 artery sheathing canal was implanted. The balloon was dilated and the stent was positioned into the distal point of the first diagonal branch to obstruct the artery under digital subtraction angiography. During and after the operation, electrocardiogram was monitored and recorded to maintain stable vital sign. MAIN OUTCOME MEASURES: Electrocardiogram, serum myocardial enzymes, myocardial radionuclide imaging, echocardiography and angiography and pathological changes were observed. RESULTS: One rat died of anesthetic accident before surgery. Six rats died from ventricular fibrillation during plugging, and the other 6 rats were survival. 4 weeks following surgery, coronary angiography showed blood flow at distal end was blocked 100%. Left ventricle angiography demonstrated that wall motion at apex of the heart and the left ventricle disappeared. Before embolism, electrocardio-monitoring displayed electrocardiogram was normal. After plugging, ST segment was raised continuously; amplitude of R wave was decreased; T wave was erected; ST-T fusion wave appeared; precordial leads were obvious. ST segment was reduced to basic level 2 week later, and pathological Q wave appeared 4 weeks later. Serum treponin was increased at 12 hours following surgery compared with before surgery (P＜0.01). Radioactive nuclide myocardial imaging revealed that cardiac apex and left ventricle anterior wall showed radioactive nuclide perfusion filling defect, thin ventricular wall and ventricular aneurysm. Cardiac ultrasonic showed six pigs suffered from weaken segmentation contraction motor of local ventricular wall, especially at anterior wall of the left ventricle and cardiac apex. After hematoxylin-eosin staining, optical microscope exhibited that cardiac muscle fiber disappeared, which was replaced by collagen fiber, with the presence of some capillary at the infarct of cardiac apex. Pyknosis and lysis of residual cardiac muscle fiber were visible in infarct region of anterior wall of the right ventricle. Many inflammatory cells and capillary infiltration were detected besides collagen fiber filling. CONCLUSION: The new approach of ”WYW” intervention embolization is able to develop the ventricular aneurysm animal model, which is similar to clinical pathophysiological variation. The outcome is precise and reliable.