ECG
Routine
At 25mm/s, 1 small
square = 0.04s.
1.Axis
- normal: +90 to -30
- I at 0, II at 60, III at 120; avL -30, avF 90, aVR -150
- more vertical in tall and thin, horizontal in short and stocky
- shift to left in the elderly.
2.
Rhythm
3.
Rate
- normal 60-100
4.
P-wave
- should be upright
- inversion can occur in AV nodal rhythms
- peaked in pulmonary hypertension
- biphasic in mitral valve disease
5. PR
interval
- range: 0.12-0.2s
6.
Q-waves
- normal in III and aVR
- and sometimes in V4, V5, V6
- width shd be no more than 0.04s
- depth shd be no more than one-quarter of height of R.
7. QRS
complex
- normal <0.12s
- wide 0.12s
8. ST
segment
- for ischaemia
- QT interval depends on rate
9. T
wave
- normally upright except in aVR
- inversion may also occur in III, V1, V2
10. U
wave
- seen in hypokalaemia
- normal when the t-wave is normal
- more prominent as t-wave flattens.