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ECG library

RBBB with first-degree AV block

advanced

A 77-year-old with unexplained syncope. The ECG is 'only showing blocks'.

25 mm/s · 10 mm/mV · synthetic tracing
100%
IIIIIIaVRaVLaVFV1V2V3V4V5V6
II (rhythm)
Calipers:2000 ms50.0 small boxes30 bpm if R-RDrag the orange markers. One small box = 40 ms.

Key findings

  • Long PR and wide QRS together
  • RBBB morphology
  • Syncope makes this combination sinister

Learning points

  • Multiple conduction abnormalities in a fainter raise the stakes: the next failure may be complete block.
  • The pattern is a syncope workup finding, not an incidental one.

Connected