Vagal syncope during recurrent pulmonary embolism
R. J. Simpson Jr, R. Podolak, C. A. Mangano Jr, J. R. Foster and F. G. Dalldorf
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.
