Phenylephrine reflex bradycardia — FRCA Primary MCQ

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

ModeratePharmacologyPhenylephrine reflex bradycardiaFRCA Primary

After induction, a patient develops vasodilatory hypotension and receives phenylephrine. Blood pressure improves but heart rate falls. What is the most likely explanation?

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

Reveal the answer and explanation

Correct answer: E — Baroreceptor-mediated reflex bradycardia

Phenylephrine is a predominantly α1 agonist; the rise in arterial pressure activates baroreceptors and increases vagal outflow, causing reflex bradycardia. It is not a β1 blocker and does not reduce vagal tone. Histamine release is not expected with phenylephrine. This reflex is important in patients with fixed stroke volume or bradyarrhythmia risk.

Reference: Peck, Hill & Williams Pharmacology for Anaesthesia and Intensive Care; Ganong Review of Medical Physiology