ST elevation

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List of terms related to ST elevation

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Synonyms and keywords: ST segment elevation; J point elevation; vaulting of the ST segments; current of injury

Overview

ST elevations refers to a finding on an electrocardiogram that often reflects injury to the heart muscle or myocardium.

Pathophysiology

ST segment corresponds to a period of ventrical systolic depolarization, when the cardiac muscle is contracted. Subsequent relaxation occurs during the diastolic repolarization phase. The normal course of ST segment reflects a certain sequence of muscular layers undergoing repolarization and certain timing of this activity. When the cardiac muscle is damaged or undergoes a pathological process (e.g. inflammation), its contractile and electrical properties change. Usually, this leads to early repolarization, or premature ending of the systole.

The exact topology and distribution of the affected areas depend on the underlying condition. Thus, ST elevation may be present on all or some leads of ECG.

Causes

Common Cuases

Causes in Alphabetical Order

Acute MI or heart attack
Brugada syndrome
Coronary vasospasm
Early repolarization
Hyperkalemia and this is known as a dialyzable current of injury
Intracranial hemorrhage
Left bundle branch block
Left ventricular aneurysm
Pericardiocentesis with contact of the needle with the myocardium creating a current of injury
Pericarditis^[1]^[2]
Prinzmetal's angina
Pulmonary embolism
Short QT syndrome (some variants)
Vasospastic angina

Differentiating the Causes of ST Segment Elevation

Myocardial Injury

The ST elevation is usually localized to an anatomic distribution that follows the coronary arteries (e.g. leads II,III, aVF).
In the setting of myocardial injury, "reciprocal changes" representing ischemia in other leads or a mirror like effect of the ST elevation presenting as ST depression in other leads, may be present. For example, ST elevation in the anterior leads in acute MI may be accompanied by ST depression in the inferior leads.
Prinzmetal's angina can cause transient ST elevation during chest pain.
Contact of the needle can cause a "current of injury" and ST segment elevation during pericardiocentesis.

Pericarditis

There is diffuse ST segment elevation (usually flat or concave up) together with PR segment depression. ST elevation reflects inflammation of the ventricular subepicardial layer and PR segment depression reflects inflammation of the atrial subepicardial layer.
T wave inversion can be seen in pericarditis but usually not until the ST elevation has resolved, so *T wave inversion accompanying ST elevation is probably not due to pericarditis

Hyperkalemia

Hyperkalemia may not affect all leads.

Ventricular Aneurysm

Ventricular aneurysm should be suspected if the ST segment elevation persists > 6 weeks after acute MI and if there is a wall motion abnormality on echocardiography.

Early Repolarization

"J point" elevation aka "early repolarization" is a concave-upward ST segment deflection.
It is a normal variant
Vaulting ST segment or J point elevation is a normal variant in leads V₁-V₃

Differentiating the Causes of ST Segment Elevation EKG Examples

Shown below is an example of EKG illustrating ST elevation in various pathological states.

Shown below is an example of an EKG showing early repolarization ST elevation and normal ST elevation variants.

Related Chapters

References

↑ ^1.0 ^1.1 Tingle LE, Molina D, Calvert CW (2007). "Acute pericarditis". Am Fam Physician. 76 (10): 1509–14. PMID 18052017. Unknown parameter |month= ignored (help)
↑ ^2.0 ^2.1 Chew HC, Lim SH (2005). "Electrocardiographical case. ST elevation: is this an infarct? Pericarditis" (PDF). Singapore Med J. 46 (11): 656–60. PMID 16228101. Unknown parameter |month= ignored (help)

[pmid18052017-1] 1.0 ^1.1 Tingle LE, Molina D, Calvert CW (2007). "Acute pericarditis". Am Fam Physician. 76 (10): 1509–14. PMID 18052017. Unknown parameter |month= ignored (help)

[pmid16228101-2] 2.0 ^2.1 Chew HC, Lim SH (2005). "Electrocardiographical case. ST elevation: is this an infarct? Pericarditis" (PDF). Singapore Med J. 46 (11): 656–60. PMID 16228101. Unknown parameter |month= ignored (help)

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