Right Ventricular outflow obstruction in TOF

[codebluewinniethepooh]

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Hello,
Does anybody know the mechanism behind increasing Right ventricular outflow in fever, crying, exercise?
I failed to make sense out of it, here is how:
- with respect to fever --- it is a state of higher metabolic demand, so cardiac output will increase --- no explanation for my question

- with respect to crying: there is increase inspiration, increase preload, and increase compliance of the pulmonary --- contradictory explanation

- with respect to exercise: vasodilation and increase cardiac output and tachycardia --- Yeah! contradictory explanation
Thank you in advance,

 

[Brorthopedic]

By RV outflow obstruction, they're saying that more blood is shunted through the VSD (right -> left shunt) instead of through the Pulmonic valve. So, anything that causes an increase in pressure in the RV (i.e. greater preload) is going to worsen the right -> left shunt, causing greater cyanosis. Also, this is the same principle for when they squat, which increases the SVR (increasing LV pressure) and decreases the right -> left shunt, improving the cyanosis by allowing more blood to go through the pulmonic valve and get oxygenated.

 

[codebluewinniethepooh]

By RV outflow obstruction, they're saying that more blood is shunted through the VSD (right -> left shunt) instead of through the Pulmonic valve. So, anything that causes an increase in pressure in the RV (i.e. greater preload) is going to worsen the right -> left shunt, causing greater cyanosis. Also, this is the same principle for when they squat, which increases the SVR (increasing LV pressure) and decreases the right -> left shunt, improving the cyanosis by allowing more blood to go through the pulmonic valve and get oxygenated.

Thanks a lot Brorthopedic