19 Vasovagal Syncope and Emotional Fainting

Question 1

What is vasovagal syncope?

Answer 1

frofound bradycardia and vasodilation leading to a big fall in ABP below the autoregulatory range

Question 2

What precedes vasovagal syncopy?

Answer 2

strong tachycardia and increase in contractility

more typically an alerting / defence response

Question 3

What causes vasovagal syncope?

Answer 3

sudden increase in vagal activity to the heart and a decrease in sympathetic activity to blood vessels

Question 4

What might cause a strong tachycardia and contractility?

Answer 4

strong baroreceptor reflex

exercise - induced

Question 5

What test might be used to see if someone needs treatment for fainting?

Answer 5

Head tilt and lower body negative pressure

Question 6

How might head tilt and LBNP cause vasovagal syncope?

Answer 6

venous pooling (decreases SV)
BRR increases HR
fall in CO
TPR increases to maintain ABP

Question 7

How does the vasovagal response work?

Answer 7

defence response - strong sympathetic effect

ventricles contract fast and strong, decreasing EDV

torsion of ventricle stimulates mechanoreceptors in wall

Vagus to NTS to lateral hypothalamus

reflex increase in vagal activity

Question 8

How might you treat it?

Answer 8

avoid fainting triggers
avoid hot crowded places
avoid alcohol
foot exercise, socks...
salt intake
fludocortisone acetate
pacemaker

Question 9

What does fludocortisone acetate do?

Answer 9

expands blood volume