The current flows from the more positive subepicardium to the less positive subendocardium during phase 2 of the fast fiber type depolarization, which on ECG occurs during ST segment. Because the subepicardial region is more depolarized (more positive) compared to the endomyocardial cells, the current in the left ventricle flows toward the endomyocardial cells. A systolic injury current results from a greater depolarization in healthier cells. inferior wall MI) E - Encephalon hemorrhage S - Subendocardial infarct S - Subendocardial ischemia E - Embolism (pulmonary) D - Dilated cardiomyopathy S - Shock T - Toxicity ( digitalis/ quinidine)įor non-transmural ischemia (subendocardial ischemia) injured cells are closer to the inside of heart wall, resulting in a systolic injury current.
Central nervous system disease, such as stroke Ī mnemonic can be used for some causes of ST depression, namely DEPRESSED ST: ĭ - Drooping valve ( mitral valve prolapse) E - Enlargement of the left ventricle P - Potassium loss R - Reciprocal ST depression (e.g. Intraventricular conduction abnormalities (e.g., right or left bundle branch block, WPW, etc.). Right or left ventricular hypertrophy. Horizontal ST depression in V4, V5, V6 leads during a cardiac stress ECG Physiologic J-junctional depression with sinus tachycardia. Pseudo-ST-depression, which is a wandering baseline due to poor skin contact of the electrode. ST segment depression and T-wave changes may be seen in patients with unstable anginaĭepressed but upsloping ST segment generally rules out ischemia as a cause.Īlso, it can be a normal variant or artifacts, such as:. Reciprocal changes in acute Q-wave myocardial infarction (e.g., ST depression in leads I & aVL with acute inferior myocardial infarction). In contrast, ST elevation is transmural (or full thickness) ischemia Subendocardial means non full thickness ischemia. 
Subendocardial ischemia or even infarction.Other ischemic heart diseases causing ST depression include: It is often a sign of myocardial ischemia, of which coronary insufficiency is a major cause.
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