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The T wave can be described by its symmetry, skewness, slope of ascending and descending limbs, amplitude and subintervals like the T peak –T end interval. [1] In most leads, the T wave is positive. This is due to the repolarization of the membrane. During ventricle contraction (QRS complex), the heart depolarizes.
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. Acceptable ranges vary with heart rate, so it must be corrected to the QTc by dividing by the square root of the RR interval.
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 ...
Rate dependence of the action potential is a fundamental property of cardiac cells and alterations can lead to severe cardiac diseases including cardiac arrhythmia and sometimes sudden death. [3] Action potential activity within the heart can be recorded to produce an electrocardiogram (ECG). This is a series of upward and downward spikes ...
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).
The Pan–Tompkins algorithm[1] is commonly used to detect QRS complexes in electrocardiographic signals (ECG). The QRS complex represents the ventricular depolarization and the main spike visible in an ECG signal (see figure). This feature makes it particularly suitable for measuring heart rate, the first way to assess the heart health state.
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 ...
The 2018 European Society of Cardiology/American College of Cardiology Foundation/American Heart Association/World Health Federation Universal Definition of Myocardial Infarction for the ECG diagnosis of the ST segment elevation type of acute myocardial infarction require new ST elevation at J point of at least 1mm (0.1 mV) in two contiguous leads with the cut-points: ≥1 mm in all leads ...