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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]
Illustration of ST segment elevation and depression The normal ST segment has a slight upward concavity. Flat, downsloping, or depressed ST segments may indicate coronary ischemia. ST elevation may indicate transmural myocardial infarction. An elevation of >1mm and longer than 80 milliseconds following the J-point.
12-lead electrocardiogram showing ST-segment elevation (orange) in I, aVL and V1–V5 with reciprocal changes (blue) in the inferior leads, indicative of an anterior wall myocardial infarction. When there is a blockage of the coronary artery , there will be lack of oxygen supply to all three layers of cardiac muscle (transmural ischemia).
ST segments remains neutral in this syndrome. Those who were treated without angiography will develop anterior wall myocardial infarction in a mean period of 9 days. [4] An episode of chest pain in Wellens' syndrome is associated with ST elevation or depression and later progressed to T wave abnormality after chest pain subsided.
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 ]
Chronic hypertension, congenital heart disease with intracardiac shunting, and valvular heart disease may also lead to remodeling. After the insult occurs, a series of histopathological and structural changes occur in the left ventricular myocardium that lead to progressive decline in left ventricular performance.
Diagnosis is based on an ECG showing ST-segment depression at the J-point of 1 to 3 mm in leads V1 to V6, with tall and symmetrical T waves. [1] The ST-segment is upsloping and there is also often ST-segment elevation of 0.5 to 2 mm in lead aVR. [1] [2] The QRS complex is either normal or slightly wide. [1]
The mass size can obstruct blood flow or interfere with cardiac valve function and produce symptoms of heart failure. A tumor that invades the heart walls may cause arrhythmias, heart block, or pericardial effusion with or without tamponade. Tumors that invade adjacent lung tissue may cause pulmonary symptoms that mimic bronchogenic carcinoma. [6]