Electrocardiography, Dr. D. Penney

Table 10. ECG TERMINOLOGY - INTERVALS (Continued...)


  • P-R Segment - conduction through AV node, junctional tissue, bundle & branches; not usually measured.

  • P-R Interval (actually P-Q) - includes P and Q waves; usually 120-200 msec.; rate related, the faster the heart rate, the shorter the P-R interval.
    [Segments are time between events (isoelectric); Intervals include the events]

  • T Wave - follows QRS; ventricular repolarization.

  • Q-T Interval - beginning of QRS to the end of the T wave (260-450 msec.); defines electrical systole; also rate related.

  • Isoelectric Lines - no net potential (P-R segment, R-T segment, T-P segment).

  • Repolarization of Atria - of low amplitude; buried in QRS complex.


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