You are reviewing an 80-year-old female admitted to the Emergency Department after a fall and head injury. Her ECG is shown on page 15

RBBB%20%2B%20LPFB_0.jpg

What are the abnormalities? (25 % marks)

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College answer

Right axis deviation

Right bundle branch block

Bifasicular block.

Examiners Comments:

Many candidates appear to have examined the ECG, drawn a conclusion and then retrofitted findings to support that. Confabulation in answers was common. Acceptance in marking was made of relatively amorphous answers (e.g. "anterior" as opposed to specific leads) but even with this, lack of specificity was common. Many candidates ignored the highly pertinent history that was given, showing a lack of clinical context/Bayesian thinking.
 

Discussion

This image was shamelessly stolen from the website which is clearly identified on the watermark. The authors described it thus:

"Sinus tachycardia with a rate of 113. The QRS is wide at 158 ms. There is a monophasic R-wave in lead V1. There is a right axis deviation with qR complexes in the inferior leads and rS complexes in the high lateral leads"

LIFT lists ECG features of RBBB:

  • Broad QRS > 120 ms
  • RSR’ pattern in V1-3 (‘M-shaped’ QRS complex)
  • Wide, slurred S wave in the lateral leads (I, aVL, V5-6)

LIFT also lists features of LAFB:

  • Left axis deviation (usually between -45 and -90 degrees)
  • Small Q waves with tall R waves (= ‘qR complexes’) in leads I and aVL
  • Small R waves with deep S waves (= ‘rS complexes’) in leads II, III, aVF
  • QRS duration normal or slightly prolonged (80-110 ms)
  • Prolonged R wave peak time in aVL > 45 ms
  • Increased QRS voltage in the limb leads