What is Mitral Stenosis?
Mitral stenosis is a condition in which the mitral valve narrows and prevents the valve from completely opening. This abnormal valve blocks blood flow from the left atrium coming into the left ventricle, the main pumping chamber of the heart. The obstruction of blood flow results in an increased pressure in the left atrium and everything before the left atrium.
What are the causes?
The causes of mitral stenosis include:
Rheumatic fever– this is the most common cause of mitral stenosis which is a complication of strep throat. Rheumatic fever is the cause in about 70% of all patients with mitral stenosis. Valvular problems develop about 20 years after the onset of rheumatic fever.
Rare causes include:
Congenital heart defect- born with a narrowed mitral valve and prone to early valve stenosis.
Malignant carcinoid disease
Autoimmune disease- systemic lupus erythematosus (SLE), rheumatoid arthritis
Genetic disorders- Fabry disease, Hunter syndrome
Infectious causes- Whipple disease, infectious endocarditis
Mitral annular calcification
How does a normal heart work?
The heart consists of four chambers. The top two chambers (atria) receive blood while the bottom two chambers (ventricles) pump blood out.
Deoxygenated venous blood returns to the right atrium of the heart. Blood flows from the right atrium to the right ventricle by the opening of the tricuspid valve. Blood is prevented from going backwards into the atrium by the closure of the tricuspid valve. The right ventricle then contracts and pumps blood out through the pulmonary valve into the pulmonary artery. The pulmonary valve is closed and the blood is sent to the lungs where it picks up oxygen.
Oxygenated blood returns from the lungs by the pulmonary veins and enters the left atrium. From the left atrium, blood enters the left ventricle by the opening of the mitral valve. Blood is prevented from flowing back into the left atrium by the closure of the mitral valve. Blood is then pumped out the left ventricle to the aorta by the opening of the aortic valve. Blood is prevented from flowing back into the left ventricle by the closure of the aortic valve. From the aorta, oxygenated blood is pumped out to the entire body.
What happens in mitral stenosis?
The mitral valve is a funnel shaped valve with the apex in the left ventricle. The mitral valve consists of two leaflets (cusps) which connect to a ring called the mitral annulus. Heart valves only open in one direction. Once all of the blood has emptied out of the left atrium, the mitral valve tightly closes to ensure no backflow of blood.
In mitral stenosis, the leaflets become thickened or calcified preventing the valve to completely open. The thickening of the leaflets make the valve opening narrowed. The ejection of blood from the left atrium struggles to get through the narrowed opening. The complete emptying of oxygenated blood from the left atrium is limited, increasing pressure in the atrium, pulmonary vasculature, and the right side of the heart. Limiting of blood from entering the ventricle to fill the rest of the body with oxygenated blood can result in symptoms of fatigue and shortness of breath.
What are the risk factors?
Antibiotics: Mitral valve stenosis is less common than it was years ago because rheumatic fever is now rare in the United States. Rheumatic fever is more common in countries where antibiotics are not used.
History of rheumatic fever and recurrent strep infections
Medications- ergot preparations used for migraines
What are the symptoms?
Patients with mitral stenosis may have no symptoms at all. Mitral stenosis ranges from mild to severe. Symptoms typically develop in severe mitral stenosis. Symptoms include:
- Fatigue, especially with increased physical activity
- Shortness of breath, especially with increased physical activity or when lying flat
- Swollen feet and ankles (pedal edema)
- Heart palpitations (fluttering sensation in the chest)
- Frequent respiratory infections such as bronchitis
- Cough, possibly bloody (hemoptysis)
- Chest pain or discomfort (rare)- increases with activity, decreases with rest; radiates to the arm, neck, jaw, or other areas; tightness, pressure, squeezing constricting
How is it classified?
Mitral stenosis is classified as:
- Mild- valve area 1.6- 2.5cm2 and/or transvalvular gradient <5 mmHg
- Moderate- valve area 1.1- 1.5cm2 and/or transvalvular gradient 6- 10 mmHg
- Severe- valve area ≤1cm2 and/or transvalvular gradient ≥10 mmHg
- Normal- valve area 4.0- 6.0cm2 with no transvalvular gradient
What are the complications?
Complications of mitral stenosis include:
- Atrial fibrillation
- Blood clots (systemic thromboembolism)
- Pulmonary edema
- Heart failure
- Pulmonary hypertension
Call your doctor immediately if you have any of the following:
Call your doctor if you develop symptoms such as:
- Shortness of breath during physical activity
- Heart palpitations
- Chest pain
How is it diagnosed?
Mitral stenosis is usually diagnosed during a routine visit with your physician. Diagnosis is based around three parameters including patient history, physical examination, and tests.
- Patients may give history of rheumatic fever, although many may not recall a history of rheumatic fever usually because mitral stenosis manifests during the third or fourth decade of life
- Patients may complain of symptoms of shortness of breath in states with an increased heart rate
- History of hoarseness of voice may be told due to compression of a nerve by an enlarged heart
- History of severe cough that may be blood tinged (hemoptysis)
During a routine physical examination, your health care provider will notice the following:
- Distended neck veins may be noticed
- During auscultation a murmur may be heard that makes a distinct snapping sound
The following tests may be performed:
- Electrocardiogram (EKG) – a noninvasive test performed in our clinic which determines the electrical activity of your heart. This test may be used to detect left atrial enlargement, and commonly atrial fibrillation.
- Chest X-ray- a simple test performed in our office showing the size and shape of the heart to determine whether the left atrium is enlarged. Also reveals the presence of fluid in the lungs which may occur due to mitral stenosis.
- Echocardiogram (ECHO)- a noninvasive test using sound waves to determine the size and function of the heart’s chambers and the structure and function of the heart valves.
- Cardiac catheterization- a hospital procedure used to diagnose the type and severity of your heart condition. A thin tube (catheter) is inserted into an artery in your arm or groin to reach the heart. A contrast dye will be given to view the arteries and seen under x-ray guidance. This allows the physician to see any abnormalities in the arteries including blockage that may coexist with mitral stenosis.
How is it treated?
Treatments to prevent permanent damage to the heart from mitral stenosis include lifestyle modification, medications and invasive procedures.
- Salt restriction- a low-salt diet is required if pulmonary congestion is present
- Maintain a healthy weight- with a BMI <25
- Exercise- for at least 30 minutes a day 5 days a week
- Limit alcohol
- Do not smoke
Medications will not correct a defective mitral valve, although medications can reduce the symptoms by reducing the workload of the heart and regulating the heart rhythm.
The goal of medical treatment is to reduce the recurrence of rheumatic fever, provide prophylaxis for infective endocarditis, reduce symptoms of pulmonary congestion, control the heart rate and rhythm, and prevent complications.
- Diuretics- these are sometimes referred to as ‘water pills’ which helps excrete excess water
- Anticoagulants- these are sometimes referred to as “blood thinners” which prevent blood clots from forming and traveling to other parts of the body
- Beta blockers- this lowers the heart rate and decreases blood pressure
- Anti-arrhythmic medications- used to treat atrial fibrillation or other rhythm disturbances associated with mitral stenosis
- Cholesterol lowering medications– these act by decreasing the amount of cholesterol in blood, especially Lowering your low density lipoprotein (LDL- your Lousy cholesterol) and keep your high density lipoprotein (HDL- your Healthy cholesterol) High. Used to slow the progression of rheumatic mitral stenosis.
- Antibiotics- some patients who have had rheumatic fever may need long-term treatment with penicillin
To treat mitral stenosis, valve repair or valve replacement may be necessary. Both surgical and non-surgical options are available.
- Percutaneous mitral balloon valvuloplasty (PMBV) – this is a non-surgical procedure done in a hospital setting. The catheter is positioned into the narrowed mitral valve and the balloon-tipped catheter is inflated. The balloon pushes the mitral valve open and stretches the valve opening, improving blood flow. Balloon valvuloplasty may relieve mitral valve stenosis and symptoms, although re-stenosis of the valve is common.
Surgical approach involves:
- Mitral valve replacement- is the primary treatment for severe mitral stenosis. The entire mitral valve will be replaced by a surgeon. A mechanical (metal) or tissue valve (organic) may be used to replace the stenotic valve. A mechanical valve requires life- long anticoagulation therapy such as warfarin (Coumadin) to prevent blood clot formation. Tissue valves usually come from a pig or cow. Blood does not clot easily on tissue valves so patients may only need Coumadin or aspirin for only a short time. Tissue valves may wear out faster than mechanical valves and may need to be replaced sooner.
What is the prognosis?
Without treatment, an individual with mitral stenosis with symptoms or complications may do poorly.
The clinical outcomes are greatly improved in patients who undergo surgical or percutaneous interventions. However, longevity is still shortened due to the complications of the disease process.
There is also a risk that the new valve will stop working and may need to be replaced.
How can I prevent this?
Mitral stenosis itself often can not be prevented, although some of the complications may be prevented.
- Prevent rheumatic fever: See a physician when you have a sore throat. Treating strep infections promptly with antibiotics can prevent rheumatic fever that causes mitral stenosis.
- Reduce risk factors of coronary artery disease: Lower blood pressure, obesity, high cholesterol, and sugar. It is a good idea to maintain a healthy weight with a BMI below 25.
- Practice good oral hygiene: gum infections may also cause inflammation of the heart tissue called endocarditis.