An Interesting ECG Case

Case:

•70 year old female presented to the emergency department after missing a dialysis session.

•No CP. Troponin elevated at 70. Repeat troponin in 2 hours was 74.

•We were contacted for abnormal ECG.

ECG 1:

- Junctional bradycardia (no p waves)
- Also, peaked T waves suggestive of hyperkalemia (potassium was 7.1)

Peaked T waves

•Definition: > 5 mm in limb leads, > 10 mm in precordial leads

•Differential diagnosis:

•Early signs of ST elevation

•Early repolarization

•Hyperkalemia

•Left ventricular hypertrophy

ECG 2:

- Ectopic atrial rhythm (p waves before every QRS however it is not upright in lead II)
- Peaked T waves have resolved (potassium 5.1 now)

ECG 3:

- Sinus bradycardia

Case summary

•Given the lack of chest pain and a flat troponin, this did not represent an acute plaque rupture

•However, this series of ECGs show the effect of hyperkalemia on heart rhythm, starting with junctional rhythm, ectopic rhythm and then returning to sinus bradycardia

•Also reviewed the definition and differential diagnosis of peaked T waves