aka ECG Exigency 012
Two quick ECG cases for you this week! (both real patients I managed in ICU recently)
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.
Q1. Describe the ECG.
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?
- 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.
For a review of the ECG features of hypokalaemia, check out this recent addition to the ECG library.
A 24-year old male with type 1 diabetes presents to ED with 2 days of nausea and vomiting.
Q3. Describe the ECG.
The ECG shows:
- Sinus tachycardia at 120 bpm
- Inferior axis (+90 degrees)
- Normal intervals
- Markedly peaked T waves, particularly in V3-4
Q4. What is the diagnosis?
- 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:
For a review of the ECG features of hyperkalaemia, check out this recent addition to the ECG library.