|nextname=Step 7+1: Compare with previous ECG
|mainauthor= [[user:Drj|J.S.S.G. de Jong, MD]]
[[Image:changing_ST.png|thumb|ST changes occur when the endocardial and epicardial actionpotentials cesse to counterbalance each other]]
The '''ST segment''' represents ventricular repolarisation. Repolarisation follows upon contraction and depolarisation. During repolarisation the cardiomyocytes elongate and prepare for the next heartbeat. This process takes much more time than the depolarisation. Repolarisation is not passive elongation by stretch, it is an active process during which energy is consumed. On the ECG, the repolarisation phase starts at the junction, or ''j point'', and continues until the ''T wave''. The ST segment is normally at or near the baseline.
The T wave angle is the result of small differences in the duration of the repolarisation between the endocardial and epicardial layers of the left ventricle. The endocardial myocytes need a little more time to repolarise (about 22 msec). This difference causes an electrical current from the endocardium to the epicardium, which reads as a positive signal on the ECG.<cite>braunwald</cite>
[[Image:stelevatie_en.png|thumb|ST elevatie is measured 1,5 or 2mm (=60ms or 80ms) after the junctional or j-poin.<cite>Gibbons</cite>]]
*Right and left [[Chamber_Hypertrophy_and_Enlargment|ventricular hypertrophy]] with strain