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

BSCC Basic Science in Clinical Context 700 2

Basic Science

in Clinical Context

Emergency Physician, FACEM. Visual & kinaesthetic learner. Multi-modal teacher. Occasional filmmaker. | @drdeannechiu |

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