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Complete heart block – post-surgical — RACP Paediatrics MCQ

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ModerateCardiologyComplete heart block – post-surgicalRACP Paediatrics

A 7-year-old post cardiac surgery (VSD closure) develops a heart rate of 40 bpm. ECG shows P waves at a rate of 100/min with QRS complexes at 40/min, with no relationship between P waves and QRS complexes. What is the ECG diagnosis?

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Correct answer: B — Complete (third-degree) heart block

Complete AV dissociation with independent atrial and ventricular rates indicates complete (third-degree) heart block. Post-surgical CHB is a recognised complication of cardiac surgery near the conduction system (VSD repair, AVSD repair). If persistent (>7-10 days post-surgery), permanent pacemaker implantation is usually required.

Reference: RCH Melbourne – 2023 – Bradycardia CPG; RACP Paediatric Curriculum – Cardiology