Vagal syncope during recurrent pulmonary embolism
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Updated: Aug 13, 2026

Lavage-induced Surfactant Depletion in Pigs As a Model of the Acute Respiratory Distress Syndrome (ARDS)
Published on: September 7, 2016
Abstract:
The mechanism for syncope during pulmonary embolism is not well understood. We describe two patients with transient sinus bradycardia and atrioventricular (AV) block during syncope from recurrent pulmonary embolism. Consciousness was regained each time the rhythm returned to normal. We believe that the syncope and bradyarrhythmia was caused by a parasympathetic reflex, since simultaneous slowing of the sinus rate with concomitant AV block is a common manifestation of increased vagal tone. Such a reflex is consistent with known cardiac reflexes, may occur frequently, and may be one of the mechanisms for syncope in patients with pulmonary embolism.
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