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<b>Valvular heart disease, the causes of this can be congenital</b>
<b> in congenital heart disease.</b>
<b>Actually, most commonly is going to be bicuspid aortic </b>
<b>valve.</b>
<b>Roughly, one percent of the population will have a bicuspid </b>
<b>aortic valve</b>
<b>which leads to increased incidence and propensity</b>
<b>to develop calcific aortic degeneration with stenosis.</b>
<b>That's the most common congenital lesion.</b>
<b>But there are a variety of acquired lesions. Most impact the</b>
<b> mitral valve.</b>
<b>In fact, most valvular disease, if you had to take a guess </b>
<b>on the boards</b>
<b>which valve is going to be affected,</b>
<b>mitral valve is going to be the dominant player in most </b>
<b>valvular disease. Why is that?</b>
<b>Well, it's actually in part because it's the only native </b>
<b>valve that has just two leaflets.</b>
<b>All of the other valves have three.</b>
<b>And so, have a different flow configuration</b>
<b>and are much less prone to potential inflammatory </b>
<b>degenerative changes.</b>
<b>The other thing about the mitral valve is it sits between a </b>
<b>very low pressure left atrium</b>
<b>and a very high pressure left ventricle.</b>
<b>And so, the mitral valve has abnormal - not abnormal,</b>
<b>but very significant force differentials, and it's only got </b>
<b>two leaflets.</b>
<b>So, the majority of diseases affecting valves will affect </b>
<b>the mitral valve first.</b>
<b>Second behind them is going to be the aortic valve, third is</b>
<b> going to be the tricuspid valve,</b>
<b>and the pulmonic valve is very rarely affected.</b>
<b>So, when the mitral valve has acquired disease,</b>
<b>the most common acquired disease is regurgitation.</b>
<b>Stenosis, when it does occur, 85% of the time, mitral valve </b>
<b>stenosis is rheumatic,</b>
<b>and we'll talk about how rheumatic heart disease occurs.</b>
<b>The mitral valve diseases, whether it's regurgitation or </b>
<b>rheumatic can be acute or chronic.</b>
<b>And so, there is a tempo of effects on the mitral valve,</b>
<b>and clearly, there's a tempo of compensation by the </b>
<b>myocardium.</b>
<b>The aortic valve, which I said is second in the most common </b>
<b>valvular diseases</b>
<b>is most commonly stenosis especially in bicuspid valves.</b>
<b>So, the aortic valve can develop regurgitation, </b>
<b>insufficiency,</b>
<b>but more commonly, it's going to become fibrotic and </b>
<b>calcified, and therefore stenotic.</b>
<b>Insufficiency is usually due to dilation of the root.</b>
<b>So, it's not necessarily even the valve itself.</b>
<b>Remember that the annulus, I talked about the annulus of the</b>
<b> atrioventricular valves,</b>
<b>well, the annulus of the semilunar valves, the aortic and </b>
<b>pulmonic valve,</b>
<b>are also very important in maintaining valve integrity.</b>
<b>And if you have dilation on that root because of connective </b>
<b>tissue disorders</b>
<b>or dilation of the aorta for any particular reason,</b>
<b>then you will have the annulus pull apart and the leaflets </b>
<b>won't be able to close appropriately.</b>
<b>And again, aortic valve disease that's acquired can be acute</b>
<b> or chronic.</b>
<b>And again, depending on the tempo, you may be able to adapt </b>
<b>for long periods of time.</b>
<b>Acute fulminant endocarditis that causes valve destruction </b>
<b>of the aortic valve may be lethal.</b>
<b>Slow motion insufficiency of the aortic valve, say, due to a</b>
<b> progressive annular dilation</b>
<b>can be actually reasonably well-tolerated. So, tempo has an </b>
<b>effect.</b>
<b>Let's look at some of the ideologies of common valvular </b>
<b>diseases.</b>
<b>So, for mitral stenosis, as I've already said, 85% of mitral</b>
<b> stenosis</b>
<b>is due to a rheumatic heart disease causing valvular </b>
<b>fibrosis, valvular scarring.</b>
<b>So, that post-inflammatory scarring is demonstrated here in </b>
<b>the circle on the left.</b>
<b>You can see that the valve leaflets are quite thickened and </b>
<b>fibrotic, and they will become stiff.</b>
<b>So, you can have a degree of stenosis.</b>
<b>You can also have the valves, because they become so stiff, </b>
<b>become insufficient.</b>
<b>And it affects not just the valve, but also potentially the </b>
<b>chordae tendineae.</b>
<b>Aortic stenosis, being the most common lesion of the aortic </b>
<b>valve,</b>
<b>is now seen in the circle, is most commonly due to </b>
<b>age-related accumulation of calcification.</b>
<b>We'll talk a little bit more about that etiology,</b>
<b>but it's something that we're all going to be very prone to </b>
<b>over the course of our lifetimes.</b>
<b>And if you take care of patients in the geriatric </b>
<b>population, 70, 80, and 90,</b>
<b>they have a very high incidence of some degree of aortic </b>
<b>stenosis</b>
<b>due to the senile calcific degeneration.</b>
<b>The calcification will actually be accelerated</b>
<b>as we'll talk about in congenitally deformed valves</b>
<b>or bicuspid aortic valve is the most common thing.</b>
<b>So, we can see it, that same age-related change,</b>
<b>in patients who are 40, 50, and 60 years of age.</b>
<b>Aortic stenosis can also occur due to post-inflammatory </b>
<b>scarring.</b>
<b>So, I said the mitral valve is most prone to </b>
<b>post-inflammatory or rheumatic scarring,</b>
<b>aortic valves are second in line and will often be affected </b>
<b>in roughly 20 to 30% of cases.</b>
<b>Mitral regurgitation, on the other hand, is usually due to </b>
<b>abnormalities of the leaflets,</b>
<b>mitral valve prolapse, defective extracellular matrix </b>
<b>synthesis</b>
<b>such as in Marfan syndrome, or due to endocarditis.</b>
<b>So, those are the common causes of mitral regurgitation.</b>
<b>You can also have abnormalities of the chordae and the </b>
<b>papillary muscles.</b>
<b>So, rupture or scarring of the papillary muscle due to </b>
<b>ischemic heart disease</b>
<b>or rupture of the chordae tendineae due to collagen vascular</b>
<b> synthetic disorder</b>
<b>such as Marfan will also cause mitral regurgitation.</b>
<b>Left ventricular or annular changes as well, as we talked </b>
<b>about previously,</b>
<b>can be causes of mitral insufficiency.</b>
<b>So, a dilated left ventricle or calcification of the mitral </b>
<b>ring,</b>
<b>which will change the geometry of the mitral apparatus.</b>
<b>Aortic regurgitation is due to abnormalities primarily of </b>
<b>the cusps.</b>
<b>That can be post-inflammatory scarring or endocarditis,</b>
<b>but it can also be due to things that affect the aortic root</b>
<b> and the aortic annulus.</b>
<b>So, you can have degenerative aortic dilation which will </b>
<b>cause expansion</b>
<b>and widening dilation of the aortic annulus,</b>
<b>and that will cause the valve leaflets to not be able to </b>
<b>close appropriately.</b>
<b>You can have Syphilitic aortitis which will cause, </b>
<b>obviously, inflammatory destruction</b>
<b>of the ascending aortic because that's where most tertiary </b>
<b>syphilis involving the aorta occurs.</b>
<b>You can have various inflammatory aortitis.</b>
<b>Lesions, such as giant cell aortitis or IgG-4 associated </b>
<b>aortitis.</b>
<b>And then, connective tissue disorders where we have </b>
<b>diminished synthetic capacity</b>
<b>such as Marfan syndrome will also dilate the aortic root and</b>
<b> will cause valvular insufficiency.</b>