Percutaneous microembolization of the left coronary artery to model ischemic heart disease in rats

Small animal models of myocardial infarction are used for a wide variety of research purposes, but common techniques for generating such models require thoracic surgeries that increase mortality risk and damage important structures, such as the pericardial sac. Here, we describe a technique for modeling myocardial infarction in rats by selective coronary microembolization, which has hitherto been described only in large animals. This technique selectively catheterizes the left coronary artery using a custom-made catheter that is introduced and precisely placed under fluoroscopic guidance. Microspheres are then injected through the catheter to cause embolization. This process creates multiple simultaneous micro-infarcts that resemble those from clinical embolization after a percutaneous coronary intervention. As this technique does not require thoracic surgery, a low attrition rate was expected and once it was optimized, this technique had a low mortality rate of just 14% during experimental application. This technique creates infarcts that appear small but are associated with transient ECG changes and a persistently lower ejection fraction after embolization. Microspheres are retained in the myocardial tissue and are visible by epifluorescent microscopy after histological staining and recognizable as a distinct speckle pattern in ultrasound images.