skip to main content

PR Interval Components — FRCA Primary MCQ

Instant feedback + full explanation. One question, done properly.

EasyPhysiology - CardiovascularPR Interval ComponentsFRCA Primary

In the cardiac conduction system the PR interval on the ECG represents the time from:

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Start of atrial depolarisation to the start of ventricular depolarisation (atrial depolarisation + AV nodal delay)

The PR interval (normal 0.12-0.20 seconds / 120-200 ms) represents the time from the onset of atrial depolarisation (P wave start) to the onset of ventricular depolarisation (Q wave start). It includes: intra-atrial conduction / AV nodal delay (the major component) / and His-Purkinje conduction. Prolonged PR (>200 ms) = first-degree heart block.

Reference: Power Kam 2018 Principles of Physiology for the Anaesthetist