A wave that follows the T waveThe wave that arrives after the QRS; is a graphical presentation of ventricular repolarization. Expect a T wave to follow every QRS complex. The T wave is a graphic representation of the repolarization of the ventricle. The T wave is... and precedes the P waveA wave generated from the depolarization of the atria; the P wave is upright when originating from the SA node. The P wave represents the depolarization of the right and left atria. The P wave begins with the first deviation...; its significance remains somewhat unknown, but it may be the repolarizationFollows depolarization, involving the return to a pre-depolarization state; the myocardial cell’s electrical potential returns from +30 mV to its polarized state of –90 mV; the ions potassium, calcium and sodium are largely involved; note that contraction of the myocardial... of the Purkinje fibres; a U wave taller than 2 mm may suggest hypokalemiaBlood potassium level lower than normal limits. Table 6.5 Normal and Abnormal Characteristics of ECG Waveforms Table 6.5 provides a non-exhaustive list of cardiac conditions that are associated with a variety of abnormal ECG waveforms. Arriving at a useful interpretation... or that the person is on digoxin or quinidine.
Occasionally, another wave – the U wave – is recorded immediately following the T wave and before the P wave. The U wave remains rather mysterious but is thought to represent a final stage of repolarization of unique ventricular cells in the midmyocardium. The U wave will most often orient in the same direction as the T wave with an amplitudeThe height or depth of waves and complexes of an ECG in millimetres; represents millivolts where 10 mm is 1 millivolt with a properly calibrated monitor. 1. Six Second ECG Guidebook (2012), T Barill, p. 190 less than 2 mm.
An abnormal U wave is inverted or tall with an amplitude of 2 mm or more. An abnormally tall U wave is associated with conditions such as hypokalemia, diabetes, ventricular hypertrophyVentricular hypertrophy is reflected in QRS axis deviation towards the hypertrophied ventricle, increased amplitude in the QRS complex, altered R wave progression, and possibly signs of ventricular strain - ST depression and T wave inversion. Note that ST changes can..., and cardiomyopathy. Cardiac medications such as digoxin and quinidine can also cause a tall U wave.
Figure 4.13 depicts the component parts of the QRS complexThe electrical representation of ventricular depolarization; the atrial repolarization is also a part of the QRS. ECG interpretation relies heavily on the QRS complex. The QRS complex represents the depolarization of the ventricles. The repolarization of the atria is also.... The QRS complexA collection of waveforms (i.e. QRS complex and the ECG complex). 1. Six Second ECG Guidebook (2012), T Barill, p. 194 consists of a series of waves, the ‘Q’, ‘R’, and ‘S’ waves. The ‘Q’ wave is the first negative deflection from baselineThe baseline or isoelectric line is a reference point for the waves, intervals and segments. While the PR segment is often used as the baseline, the TP segment - between the end of the T wave and the beginning of.... The ‘R’ wave is the first positive deflection above baseline. The ‘S’ wave follows the ‘R’ wave with a negative deflection. A QRS complex may or may not have all three waveforms. The ST segmentSegment (line) between the end of the QRS complex and the beginning of the T wave; the end of the QRS is marked by the J point. Between the QRS complex and the T wave, lies the ST segment. The... begins at the J pointA small notch in the QRS where the ST segment begins. The point where the S Wave ends and begins to flatten out. Figure 4.13 The QRS Complex, ST Segment and the T Wave Figure 4.13 depicts the component parts... and continues to the beginning of the T wave.
1. Six Second ECG GuidebookA Practice Guide to Basic and 12 Lead ECG Interpretation, written by Tracy Barill, 2012 Introduction The ability to correctly interpret an electrocardiogram (ECG), be it a simple six second strip or a 12 lead ECG, is a vital skill... (2012), T Barill, p. 80, 90, 208