![]() T-wave inversions that are secondary to these conditions are typically symmetric and there is simultaneous ST-segment depression. Secondary T-wave inversions – similar to secondary ST-segment depressions – are caused by bundle branch block, pre-excitation, hypertrophy and ventricular pacemaker stimulation. Normalization of T-wave inversion after myocardial infarction is a good prognostic indicator. T-wave inversions may actually become chronic after myocardial infarction. Negative U-waves my occur when post-ischemic T-wave inversions are present. They may be gigantic (10 mm or more) or less than 1 mm. These T-wave inversions are symmetric with varying depth. Post-ischemic T-wave inversion is caused by abnormal repolarization. Such T-waves are seen after periods of ischemia, after infarction and after successful reperfusion (PCI). This is explained by the fact that T-wave inversions do occur after an ischemic episode, and these T-wave inversions are referred to as post-ischemic T-waves. ![]() Then one might wonder why T-wave inversions are included as criteria for myocardial infarction. T-wave inversions without simultaneous ST-segment deviation are not ischemic! However, T-wave inversions that are accompanied by ST-segment deviation (either depression or elevation) is representative of ischemia (but in that scenario, it is actually the ST-segment deviation that signals that the ischemia is ongoing). It is a general misunderstanding that T-wave inversions, without simultaneous ST-segment deviation, indicate acute (ongoing) myocardial ischemia. Ischemia never causes isolated T-wave inversions. In any instance, one must verify whether the inversion is isolated, because if there is T-wave inversion in two anatomically contiguous leads, then it is pathological. Isolated T-wave inversions also occur in leads V2, III or aVL. It is generally concordant with the QRS complex (which is negative in lead V1). Normal T-wave inversionĪn isolated (single) T-wave inversion in lead V1 is common and normal. T-wave inversions are frequently misunderstood, particularly in the setting of ischemia. The T-wave is negative if its terminal portion is below the baseline, regardless of whether its other parts are above the baseline. T-wave inversion means that the T-wave is negative. T-wave inversion (inverted / negative T-waves) Their duration is short they typically disappear within minutes after a total occlusion in a coronary artery occurs (then of course, the ST segment will be elevated). Hyperacute T-waves are broad based, high and symmetric. These must be differentiated from hyperacute T-waves seen in the very early phase of myocardial ischemia. A common cause of abnormally large T-waves is hyperkalemia, which results in high, pointed and asymmetric T-waves. T-waves that are higher than 10 mm and 8 mm, in men and women, respectively, should be considered abnormal. Usually, though, the amplitude in V2–V3 is around 6 mm and 3 mm in men and women, respectively. In the chest leads the amplitude is highest in V2–V3, where it may occasionally reach 10 mm in men and 8 mm in women. Positive T-waves are rarely higher than 6 mm in the limb leads (typically highest in lead II). All T-waves are illustrated in Figure 18. Below follows a discussion which aims to clarify some of the common misunderstandings. T-wave changes are notoriously misinterpreted, particularly inverted T-waves. Discordance and concordance between QRS and ST-T. A negative T-wave is also called an inverted T-wave. Otherwise there is discordance (opposite directions of QRS and T) which might be due to pathology. The T-wave should be concordant with the QRS complex, meaning that a net positive QRS complex should be followed by a positive T-wave, and vice versa ( Figure 17). Women have a more symmetrical T-wave, a more distinct transition from ST segment to T-wave and lower T-wave amplitude. The T-wave is normally slightly asymmetric since its downslope (second half) is steeper than its upslope (first half). As noted above, the transition from the ST segment to the T-wave should be smooth. The amplitude diminishes with increasing age. The T-wave amplitude is highest in V2–V3. ![]() The normal T-wave in adults is positive in most precordial and limb leads. Assessment of the T-wave represents a difficult but fundamental part of ECG interpretation. ![]()
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