ECG changes in healthy individuals
Last reviewed 01/2018
ECG changes in an ECG of an healthy individual:
- sinus arrythmia - this is a beat-to-beat variation in heart rate that depends
on respiration
- PR interval - the normal PR interval is 120 (3 little squares) to 200 ms
(5 little squares)
- cardiac axis - a normal cardiac axis means upright QRS complexes in leads
1, 2 and generally 3
- QRS complex - the width of the QRS complex is less than 120 ms
- the maximum height of R plus S is less than 35 mm, the maximum height of
an R wave is 25mm
- there is a gradual progression in height of the R wave from V1 to V6
- ST segments are isoelectic - this means that the ST segment is at the ECG
baseline
- T waves - there may be inversion in V1 and occasionally V2; the T waves in VR are generally inverted
Reference:
- Hampton J. Update (8/7/99), 79-82