How aortic stenosis is systolic murmur and aortic regurgitation is diastolic murmur and whats mid diastolic click sound. Wat the fuck
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Got everything I need. Here's the full breakdown:
Heart Murmurs - The Logic Made Simple
Why Aortic Stenosis = Systolic Murmur
The aortic valve sits at the exit of the left ventricle into the aorta.
In aortic stenosis (AS), the valve leaflets are stiff/calcified and the opening is narrowed. The heart must squeeze (systole) to push blood out. When blood tries to exit through that tiny narrowed opening, it jets through at tremendous velocity and hits the aortic wall - that turbulence creates the murmur.
No squeezing = no murmur. Diastole is when the ventricle relaxes and fills - nothing is being pushed through the aortic valve at that point, so there's no sound.
"In persons with aortic stenosis, blood is ejected from the left ventricle through only a small fibrous opening of the aortic valve... a nozzle effect is created during systole, with blood jetting at tremendous velocity through the small opening... loud murmur occurs during systole." - Guyton & Hall Textbook of Medical Physiology
Character: Crescendo-decrescendo (diamond-shaped) harsh murmur, best heard at the right upper sternal border, radiates to the neck (carotids).
Why Aortic Regurgitation = Diastolic Murmur
The same valve, but now it's leaky - it doesn't close properly.
During diastole, the ventricle relaxes and the aortic valve should seal shut. In AR, it doesn't - so high-pressure blood from the aorta jets BACKWARDS into the relaxing ventricle. That backward jet through an incompetent valve during diastole creates the murmur.
During systole? The ventricle squeezes and blood goes forward normally - no regurgitation occurs, so no murmur from the leak.
"In aortic regurgitation, no abnormal sound is heard during systole, but during diastole, blood flows backward from the high-pressure aorta into the left ventricle, causing a 'blowing' murmur of relatively high pitch, with a swishing quality." - Guyton & Hall
Character: Early diastolic, decrescendo, high-pitched blowing murmur, best heard at the left sternal border with the patient sitting forward and holding their breath at end-expiration.
Bonus weirdness: In AR, you can ALSO hear a systolic murmur - because the huge regurgitant volume filling the LV during diastole gets ejected forward in systole, creating high-flow turbulence even across a normal aortic valve. So don't get confused if you hear both.
There's also the Austin Flint murmur - the backward blood jet in AR can hit the mitral valve leaflets during diastole, creating a functional mitral stenosis effect and a late diastolic rumble at the apex. Sounds just like mitral stenosis but without the opening snap.
The "Click" Sounds - You Were Thinking of Two Different Things
Mid-Systolic Click - Mitral Valve Prolapse (MVP)
This is SYSTOLIC, not diastolic. During mid-systole, the mitral valve leaflets bow backwards (prolapse) into the left atrium. The moment the chordae tendineae (the tiny cords holding the valve) get snapped taut - like a sail catching wind - you get a sharp clicking sound. It's followed by a late systolic murmur if the valve starts leaking.
"The click occurs when the chordae tendineae are stretched taut by the prolapsing mitral valve in mid-systole." - Goldman-Cecil Medicine
Key trick: the click moves earlier toward S1 when you stand up or do Valsalva (LV gets smaller, valve prolapses sooner). It moves later away from S1 when you squat (LV fills more, valve takes longer to prolapse).
Opening Snap - Mitral Stenosis (early DIASTOLIC)
This is the one that's diastolic - it's an early diastolic high-pitched snap, heard just after S2. In mitral stenosis (from rheumatic fever), the mitral valve leaflets are fused but still somewhat mobile. When the LV relaxes and pressure drops, the high-pressure left atrium forces the valve open - but because it's stiff, the leaflets snap open abruptly, making a crisp clicking sound, followed by the low-pitched mid-diastolic rumble of blood flowing through the narrowed mitral valve.
"The opening snap of rheumatic mitral stenosis is an early diastolic, high-pitched sound that originates from sudden tensing of abnormal leaflets and the subvalvular apparatus during valve opening." - Fuster & Hurst's The Heart, 15th Ed.
Clinical pearl: the shorter the gap between S2 and the opening snap (A2-OS interval), the more severe the stenosis - because a high left atrial pressure forces the valve open sooner.
Quick Summary Table
| Condition | Timing | Sound | Mechanism |
|---|---|---|---|
| Aortic Stenosis | Systolic | Harsh crescendo-decrescendo | Blood jets through narrow exit during LV squeeze |
| Aortic Regurgitation | Diastolic | Blowing decrescendo | Blood leaks backward into LV during relaxation |
| Mitral Regurgitation | Systolic (holosystolic) | Blowing, high-pitched | Blood leaks backward into LA during LV squeeze |
| Mitral Stenosis | Diastolic (mid) | Low rumble | Blood struggles through narrow mitral valve during LV filling |
| MVP | Systolic click + late murmur | Sharp click | Chordae snap taut as leaflet buckles into LA |
| Opening Snap | Early diastolic | Sharp snap | Fused mitral leaflets pop open under atrial pressure |
The core logic is always: which phase is the abnormal flow happening in? Stenosis of an outflow = sounds when blood pushes through it. Regurgitation of an inflow = sounds when blood leaks backward during relaxation.
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