Question 15.2

Last updated 13/08/2023 - 03:34
 Topic: Cardiology
Pass rate
45.5%
Other SAQs in this topic:
Other SAQs in this paper:

A 45-year-old patient has been admitted to the hospital for investigation of syncope. A MET call is made for another syncopal episode. The 12 lead ECG is shown.

a.    Explain the ECG changes.    (10%marks)

b.    List the most likely diagnosis.    (10% marks)

c.    Explain the underlying pathophysiology.    (10% marks)

d.    List four clinical situations that can worsen this condition.    (20% marks)

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College answer

Aim: To allow the candidate to demonstrate expertise in the analysis of ECGs.

Key sources include: This is a repeat question from paper 2014.1 Q18. CanMEDS Medical Expert.

Discussion:

15.2    - Brugada syndrome was not identified and was misdiagnosed on the ECG in many cases.

Discussion

This SAQ was a repeat of Question 18.2 from the first paper of 2014, and so the image and interpretation were also a repeat. From that past SAQ, the following "college model answer" could be obtained:

a)

  • Coved ST segment elevation V1 – V2 > 2 mm.
  • Subsequent negative T wave in the same leads.

b)

  • Brugada syndrome (Type 1).

c)

  • A mutation in the cardiac sodium channel gene.

d)

  • Fever.
  • Myocardial ischaemia.
  • Medications E.g. Flecainide, Amitriptyline, Lithium, Bupivacaine, Propofol, Alcohol.
  • Hypokalaemia.
  • Hypothermia.
  • Cardioversion.

The criteria for the diagnosis of Brugada syndrome as well as  are explored to a fascinating depth by Edward Burns in his article for LITFL. The time-poor exam candidate will be interested in only the answers to this question:

Clinical criteria:

  • Characteristic ECG changes
    • "Coved" ST elevation:  the QRS complex finishes high, and the ST-segment slopes diagonally to form an inverted T-wave in V1 and V2
    • Inverted T waves
  • Also, one of the following:
    • documented polymorphic VT or VF
    • Family history of sudden cardiac death before the age of 45
    • Characteristic ECG changes in family members
    • Syncope
    • Induceable VT
    • Nocturnal agonal respiration

Clinical situations which can worsen this condition:

  • Ischameia
  • Hyperthermia or hypothermia
  • Hypokalemia
  • Cardioversion
  • Drugs:
    • Class 1 antiarrhythmics
    • Beta blockers and calcium channel blockers
    • Alpha-agonists
    • Nitrates
    • Cocaine and alcohol
    • Cholinergic agonists, eg. the "stigmine" drugs

References

Berne, Paola, and Josep Brugada. "Brugada syndrome 2012." Circulation Journal 76.7 (2012): 1563-1571.

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