What Is Mitral Valve Stenosis

Perhaps you’re a patient that’s recently been diagnosed with mitral stenosis. Or maybe you’re a cardiac sonographer whose job it is to monitor patients with mitral stenosis. Either way, you should have a clear understanding of what exactly mitral stenosis is.

Simply put, mitral stenosis is a narrowing of the mitral valve opening, or orifice. Because this opening in the valve has become smaller than normal, the blood that normally flows easily from the left atrium to the left ventricle is impeded.

Definition Of Mitral Valve Stenosis

Another way to describe mitral stenosis is this way.  Imagine you have an empty 2 liter soda bottle with the cap on that’s about ¼ full of sand.  Turn the bottle upside down, and the sand freely and easily flows to the other end of the bottle.  

With mitral stenosis, imagine the bottle now narrows in the middle like an hourglass.  Now turn the bottle upside down. What happens.  The sand is impeded, or significantly slowed down from traveling from one end of the bottle to the other.

Mitral stenosis is much the same way.  Blood normally flows smoothly and easily from one chamber of the heart to the other.  When the mitral valve narrows, as in mitral stenosis, the blood flow is significantly impeded from traveling from the left atrium to the left ventricle.  

What Is The Mitral Valve

The mitral valve is one of the largest cardiac valves which sits between the left atrium and left ventricle. The mitral valve has two leaflets, also known as cusps or flaps. The mitral valve allows blood to flow into the left ventricle when the left ventricle relaxes during diastole as well as when the left atrium contracts, or squeezes.

When the left ventricle contracts, the mitral valve closes, forcing blood flow out through the aortic valve and into the aorta.

The mitral valve leaflets do not turn inside out, or prolapse, because they are anchored by thin strands of tissue called chordae tendonae, or just chordae. The other end of the chordae are anchored to the inside wall of the left ventricle.

Common Causes Of Mitral Valve Stenosis

There is a list of reasons a patient could end up with mitral valve stenosis, but by far, the most common cause for mitral stenosis is rheumatic fever.  According to some studies, rheumatic fever accounts for up to 99% of cases of mitral valve stenosis.

Rheumatic Heart Disease

Rheumatic fever is basically a complication that is associated with strep throat. It is a serious illness that if left untreated can lead to heart damage, known as rheumatic heart disease. The most common type of heart damage involved is damage to the valves.

Rheumatic fever causes your body to attack itself, particularly the mitral valve, after it’s been infected with a certain strain of bacteria, the same one that causes strep throat. The inflammation that results can cause severe damage to the mitral valve leaflets leaving permanent damage and scarring.

It is this scarring of the mitral valve leaflets that leads to mitral valve stenosis.

Severe Mitral Annular Calcification 

With age, deposits of calcium can form on the heart valves, and the tissues around the valve. This is something that often times happens in older people.

Over time, the calcium deposits, or calcification, build up significantly enough that it begins to affect the function of the valve and leads to mitral valve stenosis. Another term for this kind of disease is functional mitral valve stenosis.

Congential Heart Disease 

Another common cause for mitral valve stenosis are abnormalities that a person is born with. These are called congenital heart abnormalities, or congenital heart disease.

Sometimes people are born with conditions that naturally cause the mitral valve to narrow.  An example of some of these congenital diseases that can result in congenital mitral valve stenosis are parachute mitral valve and double orifice mitral stenosis.

Signs And Symptoms Of People With Mitral Valve Stenosis

The most common symptom with mitral valve stenosis that people experience is dyspnea on exertion. Some sources state that up to 80% of people with mitral valve stenosis experience dyspnea on exertion.

The second most common symptom associated with mitral valve stenosis is hemoptysis. Up to 30% of mitral stenosis patients can experience this.  What is hemoptysis?  Hemoptysis is basically when people cough up blood.  

Other common symptoms mitral valve stenosis patients might experience are chest pain, palpitations, fatigue, syncope and right heart failure (especially in long standing mitral valve stenosis).

Physical signs you might encounter with mitral stenosis is low blood pressure levels and heart arrhythmias such as afib (atrial fibrillation).

What Complications Can Occur In Patients With Mitral Valve Stenosis?

Why is mitral valve stenosis worth worrying about?  There are numerous complications that can result from mitral stenosis that’s left untreated. But some of the more common complications you might run into are mitral regurgitation, pulmonary hypertension, left atrial thrombus, decreased cardiac output and right heart failure.

In mitral valve stenosis patients who also are in atrial fibrillation, nearly 80% of them will experience systemic embolization.  

What Is The Treatment For Mitral Valve Stenosis?

Some of the more common methods of treatment for mitral stenosis are prophylactic antibiotic therapy.  This is done to prevent recurrences of the rheumatic fever. This is typically done until the patient is 40 years old.

Anitibiotic prophylaxis is also given as a life long treatment to help prevent infective endocarditis.

In patients who are in afib, an electrical cardioversion may be ordered to bring their heart back into normal sinus rhythm. However, there is certain criteria the patient must meet for this to work.  For example, they must be in afib for less than 12 months and, the left atrial dimension in echocardiography must be less than 5 cm.

Other treatments that are common with patients who have mitral valve stenosis is anticoagulation therapy, antiarrhythmics, beta blockers and lastly, mitral valve replacement.

Echocardiography And Mitral Stenosis

For the echocardiographer, when approaching mitral stenosis, it’s important to always keep in mind that mitral valve stenosis is a pressure overload of the left atrium.  And since the cardiovascular system is a “closed” loop, mitral stenosis is therefore also a pressure overload to the pulmonary vascular tree and ultimately the right ventricle.

It’s also important for the echocardiographer to keep in mind that often times other valves may be diseased as well.  For example, in 30% of mitral valve stenosis cases the aortic valve will also show evidence of stenosis.  The tricuspid valve disease in combination with mitral valve stenosis is typically quite rare, only occurring in 2% to 3% of mitral valve stenosis cases.

It’s also important to mention that for some reason, mitral valve stenosis favors women over men 3 to 1!

What The Echocardiogram Will Tell You About Mitral Stenosis

Echocardiograms are an excellent way to find out exactly how narrow the mitral valve opening is.  With the use of spectral Doppler, the echocardiographer will be able to determine exactly how large the opening is and quantify it.   The doctor will be able to use this information to determine what kind of treatment plan to move forward with.

Once surgical repair of the mitral valve is considered an option, it’s not uncommon to be referred for an echocardiogram ever 6 months or so.  This is how the doctor will be able to closely monitor the progression of the mitral stenosis.  Once the mitral valve area reaches a certain threshold, surgical repair or even replacement can be done.

Conclusion

I hope this guide on mitral stenosis was able to help answer any questions you might have about this not so uncommon heart valve disease.

If you know someone who might have recently been diagnosed with this heart condition, share this article with them.  If you have any additional questions, please don’t hesitate to email me or leave a comment below.