Metabolic Mayhem

aka ECG Exigency 012

Two quick ECG cases for you!

Case 1

A 30-year old female with a history of Conn’s syndrome secondary to bilateral adrenal adenomas presents with generalised weakness and muscle pains after a change in her medications.

ECG 012 Metabolic Mayhem 001

Q1. Describe the ECG.

Answer and Interpretation

The ECG shows:

  • Sinus rhythm at around 70 bpm
  • Normal axis
  • PR interval 200ms (upper limit of normal)
  • Long QT (640ms, QTc 700ms)
  • Widespread downsloping ST depression / T wave inversion
  • Prominent U waves, especially in the precordial leads

NB. Note that the long QT in this case is an ‘apparent’ long QT due to fusion of the T wave and U wave (see comments below).


Q2. What is the diagnosis?

Answer and Interpretation

The combination of a markedly prolonged QT interval, widespread ST depression and T wave inversion with prominent U waves is pathognomonic of severe hypokalaemia.

  • This patient’s potassium was 1.7 mmol/L (she had recently stopped taking her spironalactone).
  • The muscle pain was rhabdomyolysis secondary to hypokalaemia.
  • She was treated in the high-dependency area for 3 days on a continuous potassium drip and made a good recovery.
U waves ECG hypokalemia
T wave inversion and prominent U waves in severe hypokalaemia

Full review of the ECG features of hypokalaemia


Case 2

A 24-year old male with type 1 diabetes presents to ED with 2 days of nausea and vomiting.

ECG 012 Metabolic Mayhem 002

Q1. Describe the ECG.

Answer and Interpretation

The ECG shows:

  • Sinus tachycardia at 120 bpm
  • Inferior axis (+90 degrees)
  • Normal intervals
  • Markedly peaked T waves, particularly in V3-4

Q3. What is the diagnosis?

Answer and Interpretation

Hyperkalaemia secondary to diabetic ketoacidosis (this patient’s potassium was 8.5 mmol/L)

This is his ECG after treatment, by which time the potassium was 5.5 mmol/L:

ECG 012 Metabolic Mayhem 003
Potassium now 5.5, T wave changes resolving

Full review of the ECG features of hyperkalaemia



ECG Exigency 700 4

CLINICAL CASES

ECG EXIGENCY

Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

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