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2025-05-20T23:58:26Z

Causes

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{{Short description|Depression of the ST segment on an electrocardiogram}}
[[File:ST depression illustration.jpg|alt=|thumb|Illustration of upsloping ST segment depression]]
'''ST depression''' refers to a finding on an [[electrocardiogram]],<ref name="pmid11333167">{{cite journal | vauthors = Okin PM, Devereux RB, Kors JA, van Herpen G, Crow RS, Fabsitz RR, Howard BV | title = Computerized ST depression analysis improves prediction of all-cause and cardiovascular mortality: the strong heart study | journal = Annals of Noninvasive Electrocardiology | volume = 6 | issue = 2 | pages = 107–16 | date = April 2001 | pmid = 11333167 | doi = 10.1111/j.1542-474X.2001.tb00094.x | pmc = 7027664 }}</ref><ref name="pmid14769809">{{cite journal | vauthors = Okin PM, Roman MJ, Lee ET, Galloway JM, Howard BV, Devereux RB | title = Combined echocardiographic left ventricular hypertrophy and electrocardiographic ST depression improve prediction of mortality in American Indians: the Strong Heart Study | journal = Hypertension | volume = 43 | issue = 4 | pages = 769–74 | date = April 2004 | pmid = 14769809 | doi = 10.1161/01.HYP.0000118585.73688.c6 | url = http://hyper.ahajournals.org/cgi/pmidlookup?view=long&pmid=14769809 | doi-access = free }}</ref> wherein the trace in the [[ST segment]] is abnormally low below the baseline.

==Causes==
It is often a sign of myocardial [[ischemia]], of which [[Coronary artery disease|coronary insufficiency]] is a major cause. Other [[ischemic heart disease]]s causing ST depression include:
* Subendocardial ischemia<ref name=Yanowitz/> or even infarction.<ref name=madscientist/> Subendocardial means non full thickness ischemia. In contrast, [[ST elevation]] is transmural (or full thickness) ischemia
* Non Q-wave [[myocardial infarction]]<ref name=Yanowitz/>
* Reciprocal changes in acute Q-wave myocardial infarction (e.g., ST depression in leads I & aVL with [[Myocardial infarction|acute inferior myocardial infarction]])<ref name=Yanowitz/>
* ST segment depression and T-wave changes may be seen in patients with unstable angina

Depressed but ''upsloping'' ST segment generally rules out ischemia as a cause.

Also, it can be a normal variant or [[visual artifact|artifacts]], such as:
* Pseudo-ST-depression, which is a wandering [[isoelectric line|baseline]] due to poor skin contact of the electrode<ref name=Yanowitz>[http://ecg.utah.edu/lesson/10#ST_up X. ST Segment Abnormalities] Frank G. Yanowitz, MD. University of Utah School of Medicine</ref>
* Physiologic [[Junctional rhythm|J-junctional]] depression with sinus tachycardia<ref name=Yanowitz/>
* Hyperventilation<ref name=Yanowitz/>
[[File:StressECG STDepression.jpg|thumb|Horizontal ST depression in V4, V5, V6 leads during a cardiac [[Cardiac stress test|stress ECG]]]]
Other, non-ischemic, causes include:
* Side effect of [[digoxin]]<ref name=madscientist/><ref name=Yanowitz/>
* [[Hypokalemia]]<ref name=madscientist/><ref name=Yanowitz/>
* Right or left [[ventricular hypertrophy]]<ref name=Yanowitz/>
* Intraventricular conduction abnormalities (e.g., [[Right bundle branch block|right]] or [[Left bundle branch block|left]] [[bundle branch block]], WPW, etc.)<ref name=Yanowitz/>
* [[Hypothermia]]<ref name=madscientist/>
* [[Tachycardia]]<ref name=madscientist/>
* Reciprocal ST elevation<ref name=madscientist/>
* [[Mitral valve prolapse]]<ref name=Yanowitz/>
* [[Central nervous system disease]],<ref name=Yanowitz/> such as [[stroke]]<ref>{{cite journal | vauthors = Togha M, Sharifpour A, Ashraf H, Moghadam M, Sahraian MA | title = Electrocardiographic abnormalities in acute cerebrovascular events in patients with/without cardiovascular disease | journal = Annals of Indian Academy of Neurology | volume = 16 | issue = 1 | pages = 66–71 | date = January 2013 | pmid = 23661966 | pmc = 3644785 | doi = 10.4103/0972-2327.107710 | doi-access = free }}</ref>

===Mnemonic===
A [[mnemonic]] can be used for some causes of ST depression, namely ''DEPRESSED ST'':{{cn|date=February 2021}}

'''D''' - Drooping valve ([[mitral valve prolapse]]) '''E''' - Enlargement of the left ventricle '''P''' - Potassium loss '''R''' - Reciprocal ST depression (e.g. inferior wall MI) '''E''' - Encephalon hemorrhage '''S''' - Subendocardial infarct '''S''' - Subendocardial ischemia '''E''' - [[Pulmonary embolism|Embolism (pulmonary)]] '''D''' - [[Dilated cardiomyopathy]] '''S''' - Shock '''T''' - Toxicity ([[Digoxin|digitalis]]/[[quinidine]])

==Physiology==

For non-transmural ischemia (subendocardial ischemia) injured cells are closer to the inside of heart wall, resulting in a systolic injury current. A systolic injury current results from a greater depolarization in healthier cells. Because the subepicardial region is more depolarized (more positive) compared to the endomyocardial cells, the current in the left ventricle flows toward the endomyocardial cells. The current flows from the more positive subepicardium to the less positive subendocardium during phase 2 of the fast fiber type depolarization, which on ECG occurs during ST segment. The positive electrodes on the anterior chest wall detect the movement of positive charge away from the electrode and record it as a downward deflection on the ECG paper.{{cn|date=February 2021}}

==Measurement==
ST segment depression may be determined by measuring the vertical distance between the patient's trace and the [[isoelectric line]] at a location 2<ref name=madscientist>[http://www.madsci.com/manu/ekg_st-t.htm madscientist software > MicroEKG Manual] Retrieved September 2010</ref>-3 millimeters from the [[QRS complex]].{{cn|date=February 2021}}

It is significant if it is more than 1 mm in V5-V6, or 1.5 mm in AVF or III.{{cn|date=February 2021}}

In a [[cardiac stress test]], an ST depression of at least 1 mm after [[adenosine]] administration indicates a reversible ischaemia, while an exercise stress test requires an ST depression of at least 2 mm to significantly indicate reversible ischaemia.<ref>{{cite journal | vauthors = Yap LB, Arshad W, Jain A, Kurbaan AS, Garvie NW | title = Significance of ST depression during exercise treadmill stress and adenosine infusion myocardial perfusion imaging | journal = The International Journal of Cardiovascular Imaging | volume = 21 | issue = 2–3 | pages = 253–8; discussion 259–60 | year = 2005 | pmid = 16015437 | doi = 10.1007/s10554-004-2458-y | s2cid = 23204152 }}</ref>

== See also ==
* [[ST segment]]
* [[ST elevation]]

== References ==
{{Reflist}}

{{Heart diseases}}

[[Category:Cardiac arrhythmia]]
[[Category:Medical mnemonics]]

ST depression - Revision history

imported>Jimw338: /* Causes */