ST Morphology: Difference between revisions
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[[Image:changing_ST.png|thumb|right|300px|ST changes occur when the endocardial and epicardial action potentials cease to counterbalance each other]] | [[Image:changing_ST.png|thumb|right|300px|ST changes occur when the endocardial and epicardial action potentials cease to counterbalance each other]] | ||
The '''ST segment''' represents ventricular repolarization. Repolarization follows upon contraction and depolarization. During repolarization the cardiomyocytes elongate and prepare for the next heartbeat. This process takes much more time than the depolarization. The elongation that takes place during repolarization is not passive; it is an active process during which energy is consumed. On the ECG, the repolarization 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 '''ST segment''' represents ventricular repolarization. Repolarization follows upon contraction and depolarization. During repolarization the cardiomyocytes elongate and prepare for the next heartbeat. This process takes much more time than the depolarization. The elongation that takes place during repolarization is not passive; it is an active process during which energy is consumed. On the ECG, the repolarization phase starts at the junction, or ''j point'', and continues until the ''T wave''. The ST segment is normally at or near the baseline. Minor STT changes are not necessarily associated with cardiac ischemia<cite>Lloyd</cite>. | ||
The '''T wave''' is usually concordant with the QRS complex. Thus if the QRS complex is positive in a certain lead (the area under the curve above the baseline is greater than the area under the curve below the baseline) than the T wave usually is positive too in that lead. Accordingly the T wave is normally upright or positive in leads I, II, AVL, AVF and V3-V6. The T wave is negative in V1 and AVR. The T wave flips around V2, but there is likely some genetic influence in this as in Blacks the T wave usually flips around V3. | The '''T wave''' is usually concordant with the QRS complex. Thus if the QRS complex is positive in a certain lead (the area under the curve above the baseline is greater than the area under the curve below the baseline) than the T wave usually is positive too in that lead. Accordingly the T wave is normally upright or positive in leads I, II, AVL, AVF and V3-V6. The T wave is negative in V1 and AVR. The T wave flips around V2, but there is likely some genetic influence in this as in Blacks the T wave usually flips around V3. | ||
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#Kambara pmid=133604 | #Kambara pmid=133604 | ||
#Tikkanen pmid=19917913 | #Tikkanen pmid=19917913 | ||
#Lloyd pmid=19801030 | |||
</biblio> | </biblio> | ||
}} | }} | ||
[[Category:ECG Course]] | [[Category:ECG Course]] | ||