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The last half of the T wave is referred to as the relative refractory period or vulnerable period. The T wave contains more information than the QT interval. 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 ...
The TWA test uses an ECG measurement of the heart's electrical conduction using electrodes attached to one's torso. It takes approximately a half-hour to perform on an outpatient basis. The test looks for the presence of repolarization alternans (T-wave alternans), which is variation in the vector and amplitude of the T wave component of the ...
Animation of a normal ECG wave Schematic representation of a normal ECG. All of the waves on an ECG tracing and the intervals between them have a predictable time duration, a range of acceptable amplitudes , and a typical morphology. Any deviation from the normal tracing is potentially pathological and therefore of clinical significance.
Electrical alternans is an electrocardiographic phenomenon of alternation of QRS complex amplitude or axis between beats and a possible wandering base-line. It can be seen in cardiac tamponade and severe pericardial effusion and is thought to be related to changes in the ventricular electrical axis due to fluid in the pericardium, as the heart essentially wobbles in the fluid filled ...
Only chest impacts occurring on a narrow band of the ECG during the upslope of the T wave (40 milliseconds (ms) before the peak of the T wave to the instant of the actual peak) will cause the ventricular fibrillation of commotio cordis, with an increased probability occurring when an impact happens from 30 to 10 ms before the peak of the T wave ...
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). It is usually ...
Long QT intervals predispose the patient to an R-on-T phenomenon, wherein the R-wave, representing ventricular depolarization, occurs during the relative refractory period at the end of repolarization (represented by the latter half of the T-wave). An R-on-T can initiate torsades. Sometimes, pathologic T-U waves may be seen in the ECG before ...
In electrocardiography, a strain pattern is a well-recognized marker for the presence of anatomic left ventricular hypertrophy (LVH) in the form of ST depression and T wave inversion on a resting ECG. [1] It is an abnormality of repolarization and it has been associated with an adverse prognosis in a variety heart disease patients.