Anterior myocardial infarction electrocardiograms, or ECGs, may contain convex patterns reminiscent of a row of tombstones, or simply exhibit particular J point, T-wave or ST-segment patterns that may be accompanied by inchoate tombstone forms with lateral and septal aspects, explains Healio. Where the tombstone forms are present, ST elevations reach heights of between 4 millimeters and 6 millimeters.
The ECG changes that accompany acute infarction include inverted T-waves, elevation and depression of the ST segment, variations in the QRS complex, and cresting of the T waves, behavior alternately known as hyperacute T-wave change, reports the American Heart Association. Several factors cause these patterns. For instance, voltage gradients at the boundary separating ischemic and nonischemic sections of the myocardium precipitate ST-segment variations, while changes in the QRS complex come from variations in electrical activation within the infarcted area.
When the ST segment peaks, the change is known as the ST-segment elevation myocardial infarction, or STEMI, notes the American Heart Association. In contrast, ST segment patterns that exhibit ST segment inversion, minimal ST segment elevation, T-wave inversion or unusual ST-segment elevations in less than two adjacent leads are known as non-STEMI, or NSTEMI.
Correct interpretation of these patterns is extremely important as ECGs form the most important first-line tools in the diagnosis of myocardial infarction and ischemia, according to the American Heart Association. Subsequent tests and therapeutic interventions depend on the initial interpretation of these tests.