Descriptions: ST depression, reverse T wave.
ST depression refers to a finding on an electrocardiogram
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]-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, the pathophysiological cause of ST depression is a slightly elevated resting potential in myocardial cells, but with the ST segment less affected, as it represents a depolarized state. Still, the resting potential is the reference line in ECG, making it display an apparent ST depression rather than an elevation of the other segments.
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[5] or even infarction[3].
Non Q-wave myocardial infarction[5]
Reciprocal changes in acute Q-wave myocardial infarction (e.g., ST depression in leads I & aVL with acute inferior myocardial infarction)[5]
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[5]
Physiologic J-junctional depression with sinus tachycardia[5]
Hyperventilation[5]
Other, non-ischemic, causes include:
Side effect of digoxin[3][5]
Hypokalemia[3][5]
Right or left ventricular hypertrophy[5]
Intraventricular conduction abnormalities (e.g., right or left bundle branch block, WPW, etc.)[5]
Hypothermia[3]
Tachycardia[3]
Reciprocal ST elevation[3]
Mitral valve prolapse[5]
CNS disease[5]
Reference: https://en.wikipedia.org/wiki/ST_depression
Post by: Harvey Chen , 帕金森氏症的抗病心路歷程
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