Fig. 6.1
Normal T wave
Above all, when analyzing T wave, the judgment should be based on the patients’ history and clinical manifestation, not only the ECG, because various factors can change the morphology of T wave and T wave change lacks specificity for diagnosis.
6.2 Useful Methods for Analyzing T Wave
Method 1: analyze T wave according to its morphology (peaked, flat or inverted) (Fig. 6.2).
Fig. 6.2
Algorithm for T wave morphology analysis
Method 2: analyze the changes of both T wave and ST segment to draw a comprehensive conclusion (Fig. 6.3).
Fig. 6.3
Algorithm for T wave analysis with ST segment
6.3 Analysis of Abnormal T Wave
6.3.1 Inverted T Wave
Common Causes
1.
In leads I, II, and V4 to V6, inverted T wave is usually abnormal.
2.
If T wave is inverted with apparent change in ST segment (horizontal or downsloping ST segment depression >1 mm, Fig. 6.3), then you can consider myocardial ischemia. Inverted T wave with ST segment depression <1 mm or downsloping depression is nonspecific, which can be caused by cardiac disease and noncardiac disease.
3.
Simple T wave inversion without apparent ST segment changes is nonspecific under most circumstances (Fig. 6.4), but the prospect for myocardial ischemia cannot be totally eliminated.
Fig. 6.4
Female patient, aged 53, unstable coronary syndrome onset 1 week before. Notable deep inverted T wave with convex ST segment in leads V2 to V6. ECG indicates myocardial infarction
4.
Widespread deep inverted T wave without apparent ST segment elevation or depression is not specific for diagnosis and can be attributed to the following causes: myocardial ischemia, dynamic evolution of myocardial infarction, Adams-Stokes syndrome attack, ventricular and supraventricular tachycardia attack, myocarditis, pericarditis, cardiomyopathy, pulmonary embolism, medications (cocaine, tricyclic antidepressants, etc.), alcoholism, electrolyte disturbances, subarachnoid hemorrhage, acute pancreatitis, gallbladder disease, pheochromocytoma, etc. (Figs. 6.5 and 6.6).
Fig. 6.5
Male patient, aged 35, ECG in conventional health check. Notable inverted T wave with nonspecific ST change in leads V4 to V6
Fig. 6.6
Male patient, aged 48, severe brain hemorrhage in trauma. Notable inverted T wave in most leads
5.
Symmetrical inverted T wave: the proportion of female to male is 4:1, and the common cause is myocardial ischemia, but the causes mentioned above should also be taken into consideration.
6.
Slightly inverted T wave without ST segment change can be caused by the following factors, apart from abovementioned conditions: hyperventilation, feeding or cold drinks (fasting ECG is normal), mitral valve prolapse, ventricular block, and pneumothorax. Besides, slight changes in T wave, without apparent ST segment changes, can still be normal variant.
6.3.2 Peaked T wave
Normally, the height of T wave in limb leads is usually <5 and <10 mm in any chest leads. If the height of T wave is >5 mm in limb leads and >10 mm in chest leads, it is defined as peaked T wave. This ECG variant is always seen under the following circumstances:
1.
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In V2 to V5 leads, the base of normal peaked T wave is not narrow. And if T wave is peaked, occasionally with slight ST segment elevation, it is also a normal variant (Fig. 6.7, early repolarization).
Fig. 6.7
Healthy male, aged 30, ECG in health check, notable peaked T wave in leads V2 to V5, and prominent ST elevation in chest leads
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