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An R wave follows as an upward deflection, and the S wave is any downward deflection after the R wave. The T wave follows the S wave, and in some cases, an additional U wave follows the T wave. To measure the QRS interval start at the end of the PR interval (or beginning of the Q wave) to the end of the S wave.
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.
The next normal finding is a normal QRS. Since the impulse still travels down the bundle of His, the QRS will not be wide. Junctional rhythms can present with either bradycardia, a normal heart rate, or tachycardia. [9] The most obvious abnormal finding will be abnormal P waves. One of three options can occur: [12] 1. There are no P waves.
A wandering atrial pacemaker can be either normal or irregular in rate, much like a sinus arrhythmia the rate is normally between 60 - 100 bpm when it is normal and less than 60 when it is slow, the distinguishing feature of this rhythm is a p wave that varies in size, shape, and direction, the PR interval can either be normal or irregular ...
The term normal sinus rhythm (NSR) is sometimes used to denote a specific type of sinus rhythm where all other measurements on the ECG also fall within designated normal limits, giving rise to the characteristic appearance of the ECG when the electrical conduction system of the heart is functioning normally; however, other sinus rhythms can be ...
The shape of the T wave is usually asymmetrical with a rounded peak. T wave inversions from V2 to V4 leads are frequently found and normal in children. In normal adults, T wave inversions from V2 to V3 are less commonly found but can be normal. [4] The depth of the T wave also becomes progressively shallow from one to the next lead. [5]
On an ECG, the QRS complex will be abnormally shaped when looking at ventricular ectopic activity, often it occurs earlier with an absent P wave. It can be perceived as a skipped beat on both the ECG and through normal pulse-taking. [12] During atrial ectopic activity where the P wave is normally rounded can be inverted or peaked.
The hexaxial reference system can be used to visualise the directions in which the depolarisation wave may travel. On a hexaxial diagram (see figure 1): If the electrical axis falls between the values of -30° and +90° this is considered normal. If the electrical axis is between -30° and -90° this is considered left axis deviation.