UWSA 2 question (Spoilers)

[sharklasers]

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I didn't want to put this in the complicated concepts thread bc someone who hasn't taken this yet might see it.

But when does a kid with a VSD present with cyanosis? I know its not early on and they only present with signs of cyanosis later in life.

But in UWSA 2, there is a question about a 6 y/o russian who has a systolic murmur over the left sternal border and has O2 sat of 84% while supine and 91% while standing. What is the most likely diagnosis.

I chose VSD. First aid says that kids with VSD present with cyanosis late, so I thought 6 was a good age for that.

The answer was tetrology of fallot. I thought these kids would have severe symptoms much earlier than the age of 6?

Thanks!

 

[sharklasers]

Just to sum up a question since a lot of people have entered but not responded:

At what age does VSD shunt reversal become an acceptable answer for a cause of cyanosis?

 

[pvtbacon]

Just to sum up a question since a lot of people have entered but not responded:

At what age does VSD shunt reversal become an acceptable answer for a cause of cyanosis?

Couldn't find much but page 302 of Pediatric Cardiac Surgery says that in the case of VSD, irreversible changes in pulmonary vasculature will not occur before 1 to 2 years of age and I assume that apperance of right to left shunting will follow after this.

 

[sharklasers]

so this question with a 6 year old kid... wouldn't a VSD be more likely than ToF, since ToF would be way too bad by that age??

 

[pvtbacon]

so this question with a 6 year old kid... wouldn't a VSD be more likely than ToF, since ToF would be way too bad by that age??

I honestly didn't even consider the age of the patient when I did this question. I basically narrowed it down to this:

ToF: Early Right to left shunt
VSD: Early left to right shunt

and because going supine would increase preload -> more blood going into overriding aorta -> MIXING TIME

I also reasoned that valsalva/standing would do the opposite and help reduce the right to left shunt which explains his improvement.

And you're right uncorrected ToF would be very bad by his age. In fact I've found some questionable sources citing life expectancy figures as low as 24% for uncorrected ToF by age 10.