Subendocardial burn injury causes ST segment depression in bullfrog heart mimicking electrocardiographic change in subendocardial myocardial infarction.

Non-ST segment elevation myocardial infarction (NSTEMI) is caused by partial occlusion of a coronary artery due to atherosclerotic plaque disruption and superimposed thrombus formation. Common electrocardiographic findings in NSTEMI include permanent ST segment depression, indicative of subendocardial myocardial infarction. In our earlier research, we simulated the ST segment elevation observed in human ischemic heart disease by inducing subepicardial burn injuries in the bullfrog heart ventricle. In the present study, we successfully replicated ST segment depression, similar to that observed in patients with subendocardial myocardial infarction, by inducing burn injuries on the subendocardial surface of the frog heart ventricle, as confirmed by histological examination. The currents of injury generated by the damaged endocardium were thought to be responsible for this electrocardiographic change.