Pacemaker Diathermy Interference — FRCA Final MCQ

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

ModerateAnaesthetic Equipment & SafetyPacemaker Diathermy InterferenceFRCA Final

A 55-year-old man (ASA III) with a pacemaker (DDD mode) is scheduled for hip replacement. During monopolar diathermy use, the pacemaker may interpret the electrical interference as:

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

Reveal the answer and explanation

Correct answer: D — A ventricular ectopic causing inappropriate inhibition of pacing output

Monopolar diathermy generates electromagnetic interference (EMI) that can be sensed by pacemaker leads. In a DDD pacemaker, the ventricular lead may interpret diathermy signals as intrinsic ventricular activity, causing inappropriate inhibition of pacing output – potentially resulting in asystole in a pacemaker-dependent patient. Additionally, EMI may cause mode switching, rate tracking, or rarely, reprogramming. Prevention: use bipolar diathermy where possible, keep diathermy current path away from the pacemaker, use short bursts, and have a magnet available (converts DDD to DOO asynchronous pacing). Programme to asynchronous mode pre-operatively if dependent.

Reference: Association of Anaesthetists – 2023 – Cardiac implantable electronic devices; RCOA – 2023 – Equipment safety