Valvular Diseases from a Clinical Perspective

Mitral Stenosis

• It is defined as the inability of the mitral valve to fully open and allow unimpeded flow from the left atria to the left ventricle during diastole.
• It can be caused by…
  • Rheumatic heart disease (a sequela of rheumatic fever), it is uncommon in the US
  • Mitral annular calcification-occurs in aging
  • It can also be obstructed by a tumor (atrial myxoma), a thrombus, or a membrane (cor triatriaum)
• Before mitral stenosis due to rheumatic heart disease was one of the most common disorders in the US, but due to better housing and better antibiotic use, its incidence has been greatly decreased.
• It still remains very common in developing world though. 
• For that reason, most US cases are seen in recent immigrants.

So what happens in the pathophysiology of this disease?

• It is caused by group A strep (strep pyogenes) and after you fight off the infection, there is collateral damage.  Your body has antigens similar to those of group A strep.  So your immune system attacks your body, including the mitral valve, causing stenosis.
• This causes left atrial dilatation and you can get mural thrombi in the atria, which can embolize and cause stroke, kidney infarction, etc.
• This disease untreated is fatal.
• So lets look at the history of rheumatic heart disease.
• It starts as strep throat and rheumatic fever and for decades you get slow narrowing of the valve. 
• The patient is asymptomatic and does not know this is occurring.
• Once you get to mild stenosis, less than 2.0 cm2, and you get symptoms and it progressively gets worse for 5-10 years until you die.

So how do you diagnose mitral stenosis

• The patient will have exercise intolerance, dyspnea (shortness of breath), orthopnea (shortness of breath while lying down or good breath while upright), and paroxysmal nocturnal dyspnea (waking up short of breath).
• On physical exam, there will be signs of congestive heart failure
• On auscultation, there will be a loud, S1 (closing of the mitral and tricuspid), an opening snap, and a diastolic rumble (the blood moving through the valve).
• It is best diagnosed through an echocardiography
• It can show you the MV orifice area, the transmitral pressure gradient and the left atrial size (remember, in mirtal stenosis the left atria is dilated)

The image above shows a stenotic opening, and the “hockey stick appearance of the anterior mitral leaflet which if the video works can be seen in action.

We can also measure pressure gradients with doppler and some fancy math we don’t need to know.  In this lady, it shows an 11 mmHg gradient, which is very high, considering normal is almost no gradient, since the valves should provide an unimpeded flow.  A serious stenosis is about 10 mmHg or above.  The same measurements can be done by catherization, which shows a pressure gradient of 14 mmHg.

Now we look at Mitral Regurgitation.

• It is defined as the inability of the mitral valve to fully close which results in backflow of blood from the left ventricle to the left atria during systole.
• It is caused by…
  • Mitral valve prolaspe (most common in general, esp. in young)
  • Endocarditis
  • Left ventricular disfunction, (common in the old)
  • Rheumatic heart disease, not as common
  • Congenital, also not as common

We were shown some videos of the prolapse. In this still shot you can see the hooded valve          

In infective endocarditis,we can see the vegetation

We also see this hot (yeah, I said HOT!) Doppler image of the mitral valve regurgitation, showing a pretzel like jet of blood going back into the atria
 

• The MV fails to create a seal between the atria and the ventricle
• The blood regurgitates into the left atria, which creates left atrial overload.
• This then causes a recirculation of the extra blood into the left ventricle, causing left ventricular overload and dilitation.  So both chambers become dilated.

What symptoms are seen?

• They are determined by the degree of LA pressure rise, which is determined by the regurgitant volume and LA stiffness.
• The stiffness is determined by whether the regurgitation is acute or chronic.  So which is worse?  ACUTE! As seen in this chart below

 In acute, the ventricle has not has time to dilate to accomadate the new blood.  So an acute regurg is fatal, though chronic can last for decade until you start to get problems.

So what are the signs and symptoms?

• The patient will have exercise intolerance, dyspnea (shortness of breath), orthopnea (shortness of breath while lying down or good breath while upright), and paroxysmal nocturnal dyspnea (waking up short of breath).
• On physical exam, there will be signs of congestive heart failure
• All of those are the same as mitral stenosis, since your body has only a certain amount of responses to what is going wrong with it.
• But on auscultation, you hear a soft S1 (the mitral valve does not snap shut as it normally would), an S3 gallop (caused by ventricular overload), and a holosystolic murmur, which is caused by the backflow of blood from the ventricle to the atria.

Now we move onto Aortic Stenosis.

• It is defined as the inability of the aortic valve to fully open and allow for unimpeded flow from the left ventricle to the aorta during systole.
• It can be caused by
  • Congenital abnormalities like biscuspid aortic valve, unicuspid aortic valve
  • Senile calcific (degenerative) aortic stenosis
  • Rheumatic heart disease
  •  

At this point in the notes I feel motivated to take a nap, be back with you in a bit…

Ok.

So onto the congenital abnormalities.

• The bicuspid aortic valve is the most common cardiac congential abnormality, it is found in 1-2% of people so probably 2-3 people in our class have it.
• It is autosomal dominant.
• In fact almost all cardiac problems are autosomal dominant.

So what about the senile calcific aortic stenosis?

• It is the most common reason for stenosis in the elderly.
• And we see a pretty picture of it to the right.
• It is also one of the most common causes for valvular surgery with mitral prolapse.
• The valve will barely open.

So what are the symptoms of aortic stenosis

• “The triad”:
  • Congestive heart failure
  • Angina
  • Syncope/sudden death
• On auscultation you will hear
  • Absent S2 due to improper closure of the aortic valve
  • S4 gallop due to ventricular overloading in diastole
  • A harsh late peaking crescendo-decrescendo murmur during systole due to bad blood flow through the aortic valve during contraction of the ventricle

You can diagnose aortic stenosis by an echo cardiogram showing the reduced flow and a reduced lumen in the aortic valve.

Or you can diagnose by catheterization, showing a difference in pressure between the left ventricle and the aorta.

Now we finish with aortic regurgitation

• It is defined as the inability of the aortic valve to fully close which results in backflow of blood from the ascending aorta to the left ventricle during diastole
• It is caused by…
  • Congenital aortic root dilation
    • If you stretch the aortic root, the leaflets cannot cover the enlarged opening and you get an insufficiency
    • Marfan’s syndrome (fibrillin gene mutation)
    • Ehler-Danlos symdrome (collagen gene mutation)
  • Endocarditis
  • Aortic dissection

  

Here we have an endo cardiogram of someone with a vegetation on their valve.  In fact, those leaflets that were cut out that we say before, those are these leaflets, now live and workin.

So what about aortic dissection?

There are 2 types like we learned before.

Type A (arch involved) we do a surgery.  Mortality is measure in minutes if not treated

Type B does not involve the arch.

Here we see the aortic dissection flap.

So what are the signs and symptoms? (Same as the others except for heart sounds)

• Exercise intolerance
• Dyspnea, orthopnea, paroxysmal nocturnal dyspnea
• Physical exam-signs of congestive heart failure
• On auscultation you will hear:
  • S2 soft or loud (apparently not normal)
  • Soft early diastolic murmur (blood going back into the left ventricle through the valve)
  • Mid-diastolic murmur of functional mitral stenosis (caused by vibration of the anterior mitral valve leaflet caused by the blood passing back through the aorta into the left ventricle)

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