Sinus bradycardia:A regular but unusually slow heart beat (50 beats/minute or less atrest).Sinus bradycardiacan be the result of many things including good physical fitness, medications, and some forms ofheart block. "Sinus" refers to thesinus node, the heart's natural pacemaker which creates the normal regular heartbeat. "Bradycardia" means that theheart rate比正常的慢。
Fainting can occur with sinus bradycardia if the heart slows down even more. This can occur, for example, when thevagus nervesends a signal to the heart that suddenly drops the heart rate.Chokingor gagging cantriggerthis response which is called the vasovagalreflex. US President George W. Bush has sinus bradycardia and had an episode of fainting due to a vasovagal response after choking on a pretzel.
