ST depression - wikipedia ST depression ST depression refers to a finding on an electrocardiogram, wherein the trace in the ST segment is abnormally low below the baseline. Contents 1 Measurement 2 Physiology 3 Causes 3.1 Mnemonic 4 See also 5 References 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 - 3 millimeters from the QRS complex. It is significant if it is more than 1 mm in V5 - V6, or 1.5 mm in AVF or III. 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. 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. Causes It is often a sign of myocardial ischemia, of which coronary insufficiency is a major cause. Other ischemic heart diseases causing ST depression include : Subendocardial ischemia or even infarction. Subendocardial means non full thickness ischemia. In contrast, ST elevation is transmural ( or full thickness ) ischemia Non Q - wave myocardial infarction Reciprocal changes in acute Q - wave myocardial infarction ( e.g., ST depression in leads I & aVL with acute inferior myocardial infarction ) 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 artifacts, such as : Pseudo-ST - depression, which is a wandering baseline due to poor skin contact of the electrode Physiologic J - junctional depression with sinus tachycardia Hyperventilation Other, non-ischemic, causes include : Side effect of digoxin Hypokalemia Right or left ventricular hypertrophy Intraventricular conduction abnormalities ( e.g., right or left bundle branch block, WPW, etc. ) Hypothermia Tachycardia Reciprocal ST elevation Mitral valve prolapse Central nervous system disease, such as stroke Mnemonic A mnemonic can be used for some causes of ST depression, namely DEPRESSED ST : D - Drooping valve ( MV Prolapse ) E - Enlargement of the left ventricle P - Potassium loss R - Reciprocal ST depression ( e.g. inferior MI ) E - Encephalon hemorrhage S - Subendocardial infarct S - Subendocardial ischemia E - Embolism ( pulmonary ) D - Dilated cardiomyopathy S - Shock T - Toxicity ( digitalis / quinidine ) See also ST segment ST elevation References Jump up ^ Okin PM, Devereux RB, Kors JA, van Herpen G, Crow RS, Fabsitz RR, Howard BV ( April 2001 ). `` Computerized ST depression analysis improves prediction of all - cause and cardiovascular mortality : the strong heart study ''. Annals of Noninvasive Electrocardiology. 6 ( 2 ) : 107 -- 16. doi : 10.1111 / j. 1542 - 474X. 2001. tb00094. x. PMID 11333167. Jump up ^ Okin PM, Roman MJ, Lee ET, Galloway JM, Howard BV, Devereux RB ( April 2004 ). `` Combined echocardiographic left ventricular hypertrophy and electrocardiographic ST depression improve prediction of mortality in American Indians : the Strong Heart Study ''. Hypertension. 43 ( 4 ) : 769 -- 74. doi : 10.1161 / 01. HYP. 0000118585.73688. c6. PMID 14769809. ^ Jump up to : madscientist software > MicroEKG Manual Retrieved September 2010 Jump up ^ Yap LB, Arshad W, Jain A, Kurbaan AS, Garvie NW ( 2005 ). `` Significance of ST depression during exercise treadmill stress and adenosine infusion myocardial perfusion imaging ''. The International Journal of Cardiovascular Imaging. 21 ( 2 - 3 ) : 253 -- 8 ; discussion 259 -- 60. doi : 10.1007 / s10554 - 004 - 2458 - y. PMID 16015437. ^ Jump up to : X. ST Segment Abnormalities Frank G. Yanowitz, MD. University of Utah School of Medicine Jump up ^ Togha M, Sharifpour A, Ashraf H, Moghadam M, Sahraian MA ( January 2013 ). `` Electrocardiographic abnormalities in acute cerebrovascular events in patients with / without cardiovascular disease ''. Annals of Indian Academy of Neurology. 16 ( 1 ) : 66 -- 71. doi : 10.4103 / 0972 - 2327.107710. PMC 3644785. PMID 23661966. Cardiovascular disease ( heart ) ( I00 -- I52, 390 -- 429 ) Ischaemic Coronary disease Coronary artery disease ( CAD ) Coronary artery aneurysm Spontaneous coronary artery dissection ( SCAD ) Coronary thrombosis Coronary vasospasm Myocardial bridge Active ischemia Angina pectoris Prinzmetal 's angina Stable angina Acute coronary syndrome Myocardial infarction Unstable angina Sequelae hours Hibernating myocardium Myocardial stunning days Myocardial rupture weeks Aneurysm of heart / Ventricular aneurysm Dressler syndrome Layers Pericardium Pericarditis Acute Chronic / Constrictive Pericardial effusion Cardiac tamponade Hemopericardium Myocardium Myocarditis Chagas disease Cardiomyopathy Dilated Alcoholic Hypertrophic Restrictive Loeffler endocarditis Cardiac amyloidosis Endocardial fibroelastosis Arrhythmogenic right ventricular dysplasia Endocardium / valves Endocarditis infective endocarditis Subacute bacterial endocarditis non-infective endocarditis Libman -- Sacks endocarditis Nonbacterial thrombotic endocarditis Valves mitral regurgitation prolapse stenosis aortic stenosis insufficiency tricuspid stenosis insufficiency pulmonary stenosis insufficiency Conduction / arrhythmia Bradycardia Sinus bradycardia Sick sinus syndrome Heart block : Sinoatrial AV 1 ° 2 ° 3 ° Intraventricular Bundle branch block Right Left Left anterior fascicle Left posterior fascicle Bifascicular Trifascicular Adams -- Stokes syndrome Tachycardia ( paroxysmal and sinus ) Supraventricular Atrial Multifocal Junctional AV nodal reentrant Junctional ectopic Ventricular Accelerated idioventricular rhythm Catecholaminergic polymorphic Torsades de pointes Premature contraction Atrial Junctional Ventricular Pre-excitation syndrome Lown -- Ganong -- Levine Wolff -- Parkinson -- White Flutter / fibrillation Atrial flutter Ventricular flutter Atrial fibrillation Familial Ventricular fibrillation Pacemaker Ectopic pacemaker / Ectopic beat Multifocal atrial tachycardia Pacemaker syndrome Parasystole Wandering pacemaker Long QT syndrome Andersen -- Tawil Jervell and Lange - Nielsen Romano -- Ward Cardiac arrest Sudden cardiac death Asystole Pulseless electrical activity Sinoatrial arrest Other / ungrouped hexaxial reference system Right axis deviation Left axis deviation QT Short QT syndrome T wave alternans ST Osborn wave ST elevation ST depression Strain pattern Cardiomegaly Ventricular hypertrophy Left Right / Cor pulmonale Atrial enlargement Left Right Other Cardiac fibrosis Heart failure Diastolic heart failure Cardiac asthma Rheumatic fever Retrieved from `` https://en.wikipedia.org/w/index.php?title=ST_depression&oldid=839123743 '' Categories : Cardiac arrhythmia Talk Contents About Wikipedia Italiano Edit links This page was last edited on 1 May 2018, at 12 : 12 ( UTC ). 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Question: what does st depression on an ekg mean
Answer: the trace in the ST segment is abnormally low below the baseline