Question 23.2
A 48-year-old male presented with chest pain. His ECG (ECG 23.2) is shown on page 10.
a) List the abnormal ECG findings. (15% marks)
b) List two likely differential diagnoses consistent with these ECG finidngs. (10% marks)
c) Explain how to differentiate these two differential diagnoses using ECG criteria. (20% marks)
College answer
Not available.
Discussion
The college answer and ECG image were both not available at the time of writing, so it is impossible to accurately reconstruct the original ECG, but judging from the question, it would have to have been either a question about Brugada criteria or Sgarbossa criteria. Seeing as the differentials generated by the application of Sgarbossa criteria are boring (they're infarcting, or they're not infarcting), the author settled on Brugada. The ECG is an example of VT from the LITFL page on broad complex tachycardias (example 2, to be precise).
So,
a) Major abnormalities:
- Tachycardia (rate almost 200)
- Broad QRS complexes (~150 msec)
- Extreme "northwest" axis
b) Two differentials:
- VT
- SVT with bundle branch block
c) how to differentiate these two differential diagnoses using ECG criteria:
- Brugada criteria:
- Absence of RS complex in all precordial leads
- R to S interval more than 100 msec in one precordial lead
- AV dissociation (P waves and QRS complexes at different rates)
- Morphology criteria for VT present in V1-2 and V6
- LBBB pattern:
- Initial R more than 40ms
- Slurred or notched downwards leg of S wave in leads V1 or V2
- Beginning of Q to nadir QS >60 ms in V1 or V2
- Q or QS in V6
- RBBB pattern:
- Monofasic R or qR in V1
- R taller than R' (rabbit-ear sign)
- rS in V6
- LBBB pattern:
- If any of these criteria are satisfied, VT is present
- In this case,
- AV dissociation is present, random P waves can be seen in V1