ECG Changes in Acute Myocardial Infarction Myocardial Ischemia –Symmetrical T wave inversion or elevation and ST segment elevation or depression.
Post on 24-Dec-2015
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ECG Changes in Acute Myocardial Infarction
• Myocardial Ischemia– Symmetrical T wave inversion or elevation and
ST segment elevation or depression
• Myocardial Injury– ST segment elevation or depression
• Myocardial Necrosis– Abnormal Q waves
Abnormal T Wave
• Repolarization begins at the epicardium and progresses toward the endocardium producing a + T-wave.
• Abnormal T waves indicate myocardial ischemia and appear within seconds of the onset of an acute MI. These are caused by a delay or change in direction of repolarization.
• Abnormal T waves are associated with depression or elevation of the ST segment.
Abnormal ST Segments
• Abnormal ST segments are present in myocardial infarction, indicating myocardial ischemia and injury, and in noninfarction-related myocardial ischemia from any cause
• ST Segment Elevation
• ST Segment Depression
ST Segment Elevation• ST elevation is an ECG sign of severe, extensive,
usually transmural, myocardial ischemia and injury in the evolution of an acute Q-wave MI.
• ST elevation is considered > 1 mm above baseline and measure .04 second after the J point.
• ST elevation usually appears within minutes after the onset of infarction, initially indicating extensive myocardial ischemia and a progression to Myocardial injury within 20 to 40 minutes.
• Then to Myocardial Necrosis in about 2 hours and the development of abnormal Q waves.
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