ECG waves and hyperkalaemia
aka BSCC Physiology 015
Basic Science in Clinical Context Examination: 2 minutes long in 2 parts.
Draw a normal ECG tracing showing the durations of the major intervals
Examinee response: Drawing and explanation in real-time video/audio
How does the ECG tracing change in hyperkalaemia
Examinee response: Drawing and explanation in real-time video/audio
Transcript
ECG waves and hyperkalaemia
There are a number of intervals on an ECG that are important:
- PR = 0.12-0.2 sec
- QRS = 0.08 – 0.1 sec
- QT = 0.4 – 0.43 sec
- ST = 0.32 sec
Changes with Hyperkalaemia and Hypokalaemia:
Hyperkalaemia:
- Initially peak T waves are present (T waves you would not want to sit on)
- As the hyperkalaemia progresses there is flattening of the P wave and PR prolongation with a peaked T wave.
- At higher levels no atrial activity is seen and QRS widening develops
- Severe hyperkalaemia causes idoventricular rhythms, sine wave and VF arrest.
Hypokalaemia:
- Initially the PR interval is prolonged but the QRS remains unchanged and a U wave develops
- As the hypokalaemia progresses there is still PR prolongation but ST depression, T wave inversions and a more prominent U wave can develop
Basic Science
in Clinical Context
Emergency Physician, FACEM. Visual & kinaesthetic learner. Multi-modal teacher. Occasional filmmaker. | @drdeannechiu |