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T wave is considered flat when the wave varies from -1.0 mm to + 1.0 mm in height. Hypokalemia or digitalis therapy can cause flattened T wave with a prominent U wave. As hypokalemia progressively worsens, the T wave becomes more flattened while the U wave becomes more prominent, with progressively deeper ST segment depression.
R wave in most cases will be unaltered. In two weeks after pericarditis, there will be upward concave ST elevation, positive T wave, and PR depression. After several more weeks, PR and ST segments normalised with flattened T wave. At last, there will be T wave inversion which will take weeks or months to vanish. [1]
Inverted T waves can be a sign of myocardial ischemia, left ventricular hypertrophy, high intracranial pressure, or metabolic abnormalities. Peaked T waves can be a sign of hyperkalemia or very early myocardial infarction. 160 ms Corrected QT interval (QTc) The QT interval is measured from the beginning of the QRS complex to the end of the T wave.
Wellens' syndrome is an electrocardiographic manifestation of critical proximal left anterior descending (LAD) coronary artery stenosis in people with unstable angina. Originally thought of as two separate types, A and B, it is now considered an evolving wave form, initially of biphasic T wave inversions and later becoming symmetrical, often ...
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 [3] or even infarction. [4] Subendocardial means non full thickness ischemia. In contrast, ST elevation is transmural (or full thickness) ischemia.
In electrocardiography, the ST segment connects the QRS complex and the T wave and has a duration of 0.005 to 0.150 sec (5 to 150 ms). It starts at the J point (junction between the QRS complex and ST segment) and ends at the beginning of the T wave. However, since it is usually difficult to determine exactly where the ST segment ends and the T ...
QRS complex. Schematic representation of a normal sinus rhythm ECG wave. Diagram showing how the polarity of the QRS complex in leads I, II, and III can be used to estimate the heart's electrical axis in the frontal plane. The QRS complex is the combination of three of the graphical deflections seen on a typical electrocardiogram (ECG or EKG).
In cardiology, T wave alternans (TWA) is a periodic beat-to-beat variation in the amplitude or shape of the T wave in an electrocardiogram (ECG or EKG). TWA was first described in 1908. At that time, only large variations ("macroscopic" TWA) could be detected. Those large TWAs were associated with increased susceptibility to lethal ventricular ...