Current is directed away from the normal myocardium(negative deflection) toward the ischemic myocardium(more positive deflection) during systole.
As a result the leads facing the ischemic myocardium represent upward or more positive deflection or ST-segment Elevation and sometimes Tall (hyperacute) T wave due to Myocardial ischemia. In normal myocardium, ST-segment is isoelectric or baseline.
Non-ischemic Causes of ST-segment elevation are following:
- Acute pericarditis
- Early repolarization pattern
- Left Ventricular Hypertrophy (V1-V3)
- Left Bundle Branch Block (V1-V3only)
- Hypothermia (Osborn wave)
- Brugada pattern
- Intracranial hemorrhage and
- After DC cardioversion.
Non-ischemic Causes of prominent T wave inversion include:
- Juvenile T wave pattern
- Early repolarization
- Cerebrovascular accidents
- Ventricular hypertrophy
- Bundle Branch Block
- Apical Hypertrophic cardiomyopathy
- Wolf-Perkinson-White Syndrome
- Post-tachycardia T wave pattern
- Idiopathic global T wave inversion syndrome and
- Memory T Wave.(intermittent bundle branch block, Ventricular pacing or Ventricular pre-excitation).