Observation of transient perfusion defects in a mouse heart using contrast ultrasound

There is a significant interest in noninvasive approaches for tracking anatomical and physiological changes resulting from myocardial infarction in the mouse heart. We assessed perfusion before, during and after an induced closed chest coronary ischemia. Ultrasound contrast agent, in a saline suspension, was injected via jugular cannulation in a bolus. This gave rise to contrast agent related echogenic enhancement in the right ventricle (RV), left ventricle (LV) and finally the myocardium (muscle tissue of the heart) in acquired short axis views. Image sequences were transferred from the scanner to a computer for analysis. Regions of interest were manually defined in septal and anterior segments of the myocardium. During the ischemic event, which degraded perfusion in the anterior segment, mean video intensity in the affected segment was reduced by approximately one half. However, following the removal of ischemia, hyperemia (enhanced blood flow) was observed. Specifically, the mean video intensity in the affected segment was increased by approximately 50% over the original baseline level prior to ischemia. In this way it may be possible to quantify myocardial blood flow in perfusion deficient regions of a mouse heart using computer automated analysis of contrast image sequences.