The Bezold-Jarisch reflex, triggered by inferior myocardial ischemia, is characterized by which triad?
- A Tachycardia, hypertension, and bronchospasm — mediated by sympathetic afferents
- B Bradycardia, hypertension, and increased cardiac contractility
- C Bradycardia, hypotension, and vasodilation — mediated by vagal afferents from cardiac chemoreceptors ✓
- D Tachycardia, hypotension, and peripheral vasoconstriction
Correct answer: C. Bradycardia, hypotension, and vasodilation — mediated by vagal afferents from cardiac chemoreceptors
Explanation
The Bezold-Jarisch reflex is a cardioinhibitory reflex triggered by stimulation of ventricular chemoreceptors (C-fiber endings) in the inferoposterior LV wall, activated by ischemia, serotonin, or veratrum alkaloids. Afferent signals travel via vagal unmyelinated C-fibers to the brainstem, eliciting paradoxical bradycardia, hypotension, and vasodilation. It explains the vagal response (nausea, bradycardia, hypotension) seen clinically in inferior STEMI, opposite to the expected sympathetic response.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
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