Split S2 Cardiac Auscultation: Inspiration, Wide, Paradoxical, Fixed | Pulmonic Aortic Stenosis, ASD


Uploaded by helphippo on 17.06.2012

Transcript:
In HelpHippo's introductory video, we simplified by saying:
S1 is the bottom valves closing, S2 is the top.
lub DUB, lub Dub
In reality, the bottom valves do close at the same time -
But the top two valves have unique challenges, and vary their closing times to adapt to changing
environments.
The aortic valve should close quickly - it has to control fast blood going far to the
head.
You normally don't hear the aortic valve close first - it's too fast
lub dub, lub dub
But when you inhale, your lungs expand, and with more room there is less pulmonic blood
pressure. With less pressure, the pulmonic valve procrastinates
closing, which can sound like an “Extra” third beat.
lub dub, lub dub, lub b'dub, lub b'dub, lub dub, lub dub
With pulmonic valve stenosis - you can get even wider splitting -
the stiff pulmonic valve takes even longer to close, definitely sounding like an “extra”
beat. lub b'dub, lub b'dub, *lub buh dub*, *lub
buh dub*, lub b'dub, lub b'dub
With aortic stenosis - you get “paradoxical splitting” -
the stiff aortic valve takes so long to close, that it closes AFTER the pulmonic valve.
And while normal folks are INSPIRED to split S2,
aortic stenosis causes the extra beat during exhalation.
*lub b'dub*, *lub b'dub*, lub dub, lub dub, *lub b'dub*, *lub b'dub*
--
Fixed splittting:
Normally, you have two separate chambers with two separate valves reacting to their unique
environments.
If you have a hole between the two chambers, like with an “Atrial Septal Defect” -
now you just have one BIG chamber, and there's less reason for the valves to react uniquely.
So the splitting is fixed: the split will always be the same, regardless of breathing.
lub b'dub, lub b'dub, lub b'dub, lub b'dub
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