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Since PR and PT interval are regarded as baseline, ST segment elevation is regarded as a sign of myocardial ischemia. The opposing leads (such as V3 and V4 versus posterior leads V7–V9) always show reciprocal ST segment changes (ST elevation in one lead is followed by ST depression in the opposing lead).
I, aVL, V5, V6 correspond to the lateral wall; V3-V4 correspond to the anterior wall ; V1-V2 correspond to the septal wall; II, III, aVF correspond to the inferior wall.) This criterion is problematic, however, as acute myocardial infarction is not the most common cause of ST segment elevation in chest pain patients. [6]
Pseudo-ST-depression, which is a wandering baseline due to poor skin contact of the electrode [3] Physiologic J-junctional depression with sinus tachycardia [3] Hyperventilation [3] Horizontal ST depression in V4, V5, V6 leads during a cardiac stress ECG. Other, non-ischemic, causes include: Side effect of digoxin [4] [3] Hypokalemia [4] [3]
Highest amplitude of T wave is found at V2 and V3 leads. The shape of the T wave is usually asymmetrical with a rounded peak. T wave inversions from V2 to V4 leads are frequently found and normal in children. In normal adults, T wave inversions from V2 to V3 are less commonly found but can be normal. [4]
at least one lead of V1-V3 with concordant ST depression (Sgarbossa criterion 2) or; proportionally excessively discordant ST elevation in V1-V4, as defined by an ST/S ratio of equal to or more than 0.20 and at least 2 mm of STE. (this replaces Sgarbossa criterion 3 which uses an absolute of 5mm)
ST elevation may indicate transmural myocardial infarction. An elevation of >1mm and longer than 80 milliseconds following the J-point . This measure has a false positive rate of 15-20% (which is slightly higher in women than men) and a false negative rate of 20–30%.
It is diagnosed based on an elevated J-point / ST elevation with an end-QRS notch or end-QRS slur and where the ST segment concave up. It is believed to be a normal variant. [2] Benign early repolarization that occurs as some patterns is associated with ventricular fibrillation. The association, revealed by research performed in the late 2000s ...
S amplitude in V1 + R amplitude in V5 < 3.5 millivolt (mV) [4] R+S in a precordial lead < 4.5 mV [4] R in V5 or V6 < 2.6 mV; Increased amplitude indicates cardiac hypertrophy: Ventricular activation time (VAT) < 50 ms in V5 or V6 [4] < 30 ms in V1 [4] Measured in increased QRS amplitude [4] Q wave: Duration up to 40 ms in leads other than III ...