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However, since it is usually difficult to determine exactly where the ST segment ends and the T wave begins, the relationship between the ST segment and T wave should be examined together. The typical ST segment duration is usually around 0.08 sec (80 ms). It should be essentially level with the PR and TP segments.
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 [3]
The ST segment is the plateau phase, in which the majority of the myocardial cells had gone through depolarization but not repolarization. The ST segment is the isoelectric line because there is no voltage difference across cardiac muscle cell membrane during this state. Any distortion in the shape, duration, or height of the cardiac action ...
Duke Treadmill Score is a tool for predicting the risk of ischemia or infarction in the heart muscle. [1] The score is a function of data from an exercise test: [citation needed] [1] [exercise duration in minutes, by Bruce protocol] – [ 5 × (maximal ST elevation or depression, in millimeters)] – [4 × (treadmill angina index)]
Myocardial infarction; Other names: Acute myocardial infarction (AMI), heart attack: A myocardial infarction occurs when an atherosclerotic plaque slowly builds up in the inner lining of a coronary artery and then suddenly ruptures, causing catastrophic thrombus formation, totally occluding the artery and preventing blood flow downstream to the heart muscle.
The TIMI risk score can identify high risk patients in ST-elevation and non-ST segment elevation MI ACS [30] [31] and has been independently validated. [ 32 ] [ 33 ] Based on a global registry of 102,341 patients, the GRACE risk score estimates in-hospital, 6 months, 1 year, and 3-year mortality risk after a heart attack. [ 34 ]
Other ECG changes associate with myocardial ischaemia are: ST segment depression with an upright T wave; ST segment depression with biphasic T wave or inverted T wave with negative QRS complex; [5] T wave symmetrically inverted with a pointed apex, while the ST segment is either bowed upwards or horizontally depressed, or not deviated; and ST ...
Research in the late 2000s has linked this finding to ventricular fibrillation, particularly in those who have fainted or have a family history of sudden cardiac death. [5] [6] [7] Although there is a significant relationship between ventricular fibrillation and some early repolarization's patterns, the overall lifetime occurrence of idiopathic ventricular fibrillation is exceptionally rare. [8]