<P> Normally, T waves are upright in all leads, except aVR, aVL, III and V1 leads . 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 V1 to V4 leads are frequently found and normal in children . In normal adults, T wave inversions are less commonly found, but can be normal from V1 to V3 . The depth of the T wave also becomes progressively shallow from one to the next lead . The height of the T wave should not exceed 5 mm in limb leads and more than 10 mm in precordial leads . </P> <P> Both the abnormalities of the ST segment and T wave represents the abnormalities of the ventricular repolarisation or secondary to abnormalities in ventricular depolarisation . </P> <P> Inverted T wave is considered abnormal if inversion is deeper than 1.0 mm . Inverted T waves found in other leads other than the V1 to V4 leads is associated with increased cardiac deaths . Inverted T waves associated with cardiac signs and symptoms (chest pain and cardiac murmur) are highly suggestive of myocardial ischaemia . Other ECG changes associated with myocardial ischaemia are: ST segment depression with an upright T wave; ST segment depression with biphasic T wave or inverted T wave with negative QRS complex; T wave symmetrically inverted with a pointed apex, while the ST segment is either bowed upwards or horizontally depressed, or not deviated; and ST segment depression progressing to abnormal T wave during ischaemia free intervals . However, ST segment depression is not suggestive of ischaemic location of the heart . ST segment depression in eight or more leads, associated with ST segment elevation in aVR and V1 are associated with left main coronary artery disease or three - vessel disease (blockage of all three major branches of coronary arteries). ST segment depression most prominent from V1 to V3 is suggestive of posterior infarction . Furthermore, tall or wide QRS complex with an upright T wave is further suggestive of the posterior infarction . </P> <P> Wellens' syndrome is caused by the injury or blockage of the left anterior descending artery, therefore resulting in symmetrical T wave inversions from V2 to V4 with depth more than 5 mm in 75% of the cases . Meanwhile, the remaining 25% of the cases shows biphasic T wave morphology . ST segments remains neutral in this syndrome . Those who were treated without angiography will develop anterior wall myocardial infarction in a mean period of 9 days . An episode of chest pain in Wellens' syndrome is associated with ST eleveation or depression and later progressed to T wave abnormality after chest pain subsided . T wave inversion less than 5 mm may still represents myocardial ischaemia, but is less severe than Wellens' syndrome . </P>

What does t wave inversion on ekg mean
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