A novel minimal-invasive model of chronic myocardial infariction in swine

Background Most animal studies on myocardial infarction (MI) have used open-chest models with direct surgical coronary artery ligation, which imply local as well as generalized side effects of major surgery. Some closed-chest models of MI have been established, mainly using catheterization techniques with coronary artery embolization, balloon occlusion, and intracoronary injection of thrombogenic agents. The aim of this study was to develop a closed-chest technique of chronic coronary artery occlusion at a selected location with subsequent thrombus formation without use of balloon inflation or thrombotic chemical agents. Methods and results A coronary angiography via the carotid artery was performed using a 7 F guiding catheter in 21 pigs. After insertion of a percutaneous transluminal coronary angioplasty (PTCA) guide wire into the distal coronary artery, a vessel-size adapted flexible foreign body comprising an open-cell sponge was advanced into the coronary artery via the guide wire by a non-inflated PTCA balloon. Five min after removal of the guide wire and the balloon catheter, total coronary artery occlusion was documented by angiography. Retrograde thrombosis of the coronary artery occurred in three animals. After one week, total vessel occlusion at the previously selected location was visualized by coronary angiography in animals that had survived. Macroscopic analysis demonstrated the foreign body with subsequent thrombus formation in the coronary artery and distal MI. Post-mortem histological analysis revealed myocardial necrosis and granulocyte infiltration at the margin of the infarction, without damage to remote myocardium. Conclusions This new easy-to-perform closed-chest technique provides reproducible chronic coronary artery occlusion at a selected location with subsequent MI. It avoids major surgery and thoracotomy and does not require balloon inflation or intracoronary injection of thrombotic or chemical agents.