What indicates myocardial ischemia?

Horizontal or downsloping ST depression ≥ 0.5 mm at the J-point in ≥ 2 contiguous leads indicates myocardial ischaemia (according to the 2007 Task Force Criteria). ST depression ≥ 1 mm is more specific and conveys a worse prognosis.

What is ischemia in ECG?

Myocardial ischemia occurs when blood flow to the heart muscle (myocardium) is obstructed by a partial or complete blockage of a coronary artery by a buildup of plaques (atherosclerosis). If the plaques rupture, you can have a heart attack (myocardial infarction).

How does ischemia affect ECG?

The more intensive the ischemia, the greater the ST segment elevation. Similarly, the larger the affected area, the more ECG leads will display ST segment elevation. Although ST-segment elevations are the hallmark of transmural ischemia, they are actually preceded by hyperacute T-waves.

What does MI look like on ECG?

The ECG findings of an acute anterior myocardial infarction wall include: ST segment elevation in the anterior leads (V3 and V4) at the J point and sometimes in the septal or lateral leads, depending on the extent of the MI. This ST segment elevation is concave downward and frequently overwhelms the T wave.

What happens to the ECG during a myocardial infarction?

In the first hours and days after the onset of a myocardial infarction, several changes can be observed on the ECG. First, large peaked T waves (or hyperacute T waves), then ST elevation, then negative T waves and finally pathologic Q waves develop.

What is anterior ischemia on ECG?

The anterior wall ischaemia/infarction involving the left anterior descending artery (LAD) is usually represented on the ECG with ST-T changes in the precordial leads and in leads I and aVL while those of the inferior wall classically involve leads II, III and aVF.

Why does T wave invert in myocardial infarction?

T wave inversion T waves that are deep and symmetrically inverted (arrowhead) strongly suggest myocardial ischaemia. In some patients with partial thickness ischaemia the T waves show a biphasic pattern. This occurs particularly in the anterior chest leads and is an acute phenomenon.