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First-degree heart block — RACP Paediatrics MCQ

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EasyCardiologyFirst-degree heart blockRACP Paediatrics

An ECG in a well 8-year-old shows a PR interval of 240 ms (normal <200 ms for age) with every P wave followed by a QRS complex. What is the ECG diagnosis?

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Correct answer: D — First-degree heart block

A prolonged PR interval (>200 ms in older children) with 1:1 AV conduction (every P wave followed by a QRS) is first-degree AV block. In isolation, it is usually benign and may be a normal variant in athletes or during sleep. However, it can be an early sign of rheumatic carditis (in the context of ARF) or drug toxicity (digoxin, beta-blockers).

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