Tag Archives: Shone’s syndrome

MR with Liezel + Dr. Meadows: Acute Aortic Insufficiency and Shone’s Syndrome

A young man w/ Shone’s syndrome (https://en.wikipedia.org/wiki/Shone%27s_syndrome), asthma, and alcohol use presents with subacute SOB, lower extremity edema, and back pain. He has good functional status and no history of heart failure in the past. On initial presentation, he was found to have a low grade fever, new afib, and a wide pulse pressure; these vitals alone pointed towards the ultimate diagnosis of aortic endocarditis cause acute aortic insufficiency. 
1. The physical exam can be KEY in helping you diagnose new AI
The findings are not subtle and no special maneuvers are required – you just need to know what to look for.
-Wide pulse pressure (this patient’s was 147/47)
-Bounding pulses and PMI
-Decrescendo diastolic murmur at LSB (for me, this is not always as easy as the first two findings – sometimes it’s very loud and other times hard to hear)
2. Why is acute AI so different from chronic AI?
 
a) Cardiac output drops rapidly in acute AI: In chronic AI, the heart dilates to maintain cardiac output (though ejection fraction drops as regurgitation develops, the dilation allows the stroke volume to remain the same). In acute AI, this doesn’t happen, so both ejection fraction AND stroke volume rapidly drop off. This can cause cardiogenic shock.
b) Pulmonary congestion is much worse in acute AI: The dilated hearts of chronic AI can better accommodate the regurgitation and pressure increases only slightly. In acute AI, new regurgitation against stiff hearts cause rapid pressure increases, backing up into the lungs and causing pulmonary edema.
 
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3. How do you manage acute AI?
Valve replacement! Medical management is limited but includes maintaining a good HR (if you drop it too low, regurgitant volume increases and CO decreases), diuresis if needed, and possibly dobutamine (reduces afterload and improves inotropy).