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ST Morphology: Difference between revisions
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[[Image:changing_ST.svg|thumb|right| | [[Image:changing_ST.svg|thumb|right|240px|ST changes occur when the action potential in the ischemic area changes, resulting in an electric injury current from the healthy cardiomyocytes towards the ischemic area during the repolarization fase.]] | ||
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 '''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>. | ||
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==ST elevation== | ==ST elevation== | ||
{{multiple image | |||
| align = right | |||
| direction = vertical | |||
| width = 300 | |||
| image1 = stelevatie_en.png | |||
| caption1 = ST elevatie is measured at the junctional or j-point.<cite>Gibbons</cite> | |||
| image2 = STshift.svg | |||
| caption2 = common causes of ST shift | |||
| image3 = normal_ST_elevation.png | |||
| caption3 = Examples of normal ST elevation. Adapted from <cite>Wang</cite> | |||
| image4 = Pathologic ST elevation.png | |||
| caption4 = Examples of pathologic ST elevation. [[LVH]], [[LBBB]], [[Pericarditis]], [[Hyperkalemia]], [[Anterior AMI]]. Adapted from <cite>Wang</cite> | |||
| image5 = Semantic_confusion_early_repolarization.svg | |||
| caption5 = Unfortunately the term early repolarization is used to describe different phenomenons with differing clinical impact. Image adapted from Froelicher et al.<cite>Froelicher</cite> | |||
}} | |||
The most important cause of '''ST segment elevation''' is '''acute [[Ischemia]]'''. Other causes are <cite>Wang</cite><cite>Werf</cite>: | The most important cause of '''ST segment elevation''' is '''acute [[Ischemia]]'''. Other causes are <cite>Wang</cite><cite>Werf</cite>: | ||
*Early repolarization | *[[Early repolarization]] | ||
*[[Clinical Disorders#Pericarditis|Acute pericarditis]]: ST elevation in all leads except aVR | *[[Clinical Disorders#Pericarditis|Acute pericarditis]]: ST elevation in all leads except aVR | ||
*[[Pulmonary_Embolism|Pulmonary embolism]]: ST elevation in V1 and aVR | *[[Pulmonary_Embolism|Pulmonary embolism]]: ST elevation in V1 and aVR | ||
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[[Image:early_repol.png|thumb|none|Characteristics of early repolarization]] | [[Image:early_repol.png|thumb|none|Characteristics of early repolarization]] | ||
'''Early repolarization''' is a term used for ST segment elevation without underlying disease. It probably has nothing to do with actual early repolarization. It is commonly seen in young men. It is important to discern early repolarization from ST segment elevation from other causes such as [[ischemia]]. Characteristics of early repolarization are:<cite>Kambara</cite> | |||
'''[[Early repolarization]]''' is a term used for ST segment elevation without underlying disease. It probably has nothing to do with actual early repolarization. It is commonly seen in young men. It is important to discern early repolarization from ST segment elevation from other causes such as [[ischemia]]. Characteristics of early repolarization are:<cite>Kambara</cite> | |||
* an upward concave elevation of the RS-T segment with distinct or "embryonic" J waves | * an upward concave elevation of the RS-T segment with distinct or "embryonic" J waves | ||
* slurred downstroke of R waves or distinct J points or both | * slurred downstroke of R waves or distinct J points or both | ||
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* absence of reciprocal ST depression | * absence of reciprocal ST depression | ||
* large symmetrical T waves | * large symmetrical T waves | ||
Recently early repolarization has also been used to describe late QRS notching or J wave slurring. When defined as such in the inferior leads (II, III en AVF) it has been found to be associated with an increased risk of cardiac death (1 mm of ST elevation carried an OR of 1.3 and 2 mm an OR of 3.0 )<cite>Tikkanen</cite> | |||
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==T wave changes== | ==T wave changes== | ||
[[image:t_wave_morphology.png|thumb|300px|Different forms of T wave morphology]] | [[image:t_wave_morphology.png|thumb|300px|Different forms of T wave morphology]] | ||
[[File:E0003192.png|thumb|Negative T waves in III, AVR and V1 as in this example are normal. An upright T wave in III is more common.]] | |||
The T wave is quite 'labile' and long lists of possible causes of T wave changes exist. A changing T wave can be a sign that 'something' is abnormal, but it doesn't say much about the severity. T waves can be peaked, normal, flat, or negative. Flat and negative T waves are defined as: | The T wave is quite 'labile' and long lists of possible causes of T wave changes exist. A changing T wave can be a sign that 'something' is abnormal, but it doesn't say much about the severity. T waves can be peaked, normal, flat, or negative. Flat and negative T waves are defined as: | ||
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#Tikkanen pmid=19917913 | #Tikkanen pmid=19917913 | ||
#Lloyd pmid=19801030 | #Lloyd pmid=19801030 | ||
#Froelicher pmid=22340816 | |||
</biblio> | </biblio> | ||
}} | }} | ||
[[Category:ECG Course]] | [[Category:ECG Course]] | ||