What is mitral valve stenosis?
Mitral valve stenosis is a form of heart valve disease. In people with this condition, the opening of the heart’s mitral (bicuspid) valve is abnormally narrow. This restricts the flow of blood from the left atrium to the left ventricle and the body.
Stenosis of the mitral valve occurs when there is structural problem with one or more mitral apparatus components, narrowing the orifice of the bicuspid valve (to below cm² in size) and causing symptoms and complications.
What are the symptoms of mitral stenosis?
Some adults with stenotic mitral valves are asymptomatic, while others can live with mild symptoms for years. However, symptoms can appear suddenly and mild symptoms can worsen quickly. Symptoms are more common in older patients (aged 40+) and tend to appear or worsen with activities that raise the heart rate. Known triggers include physical stress, pregnancy, and infection.
Mitral stenosis symptoms may include dyspnea (breathlessness), paroxysmal nocturnal dyspnea (evening dyspnea attacks), orthopnea (dyspnea when lying down), bloody cough, palpitations, fatigue, and angina. Additionally, one may experience swelling of the feet and ankles (edema) and repeat respiratory infections such as bronchitis. Rarely, heart attacks and stroke may occur.
What causes mitral valve stenosis?
The number one cause of mitral stenosis is rheumatic fever. A strep throat infection complication, it is an inflammatory disease that damages the heart’s mitral valve by thickening or fusing together the mitral leaflets, causing stenosis over time. This is becoming less common, though, at least in developed countries, as healthcare and strep infection treatments continue to improve.
Less often, people are born with a stenotic bicuspid valve or congenital heart defects that cause narrowing or obstruction of the valve. Degenerative calcification (hardening due to calcium buildup that occurs naturally with age) can also narrow the mitral orifice and impede blood flow.
Other causes of mitral valve stenosis include infective endocarditis, rheumatoid arthritis, and carcinoid syndrome, systemic lupus erythematosus, whipple’s disease, and inborn errors of metabolism. Radiation treatments (of the chest) and certain medications can also cause mitral stenosis.
How is mitral stenosis diagnosed?
Mitral stenosis can be diagnosed upon studying a patient’s medical history and performing a thorough physical examination. The physician will look for signs like flushed cheeks, elevated jugular vein pressure, atrial fibrillation, enlargement of the liver, and fluid accumulation in the lower limbs. He will also listen for specific heart sounds with a stethoscope, which may reveal a heart murmur.
To confirm the diagnosis and determine the degree of stenosis, most doctors will order further testing. Tests may include holter monitor testing, an electrocardiogram (EKG), and an echocardiogram, as well as chest x-rays. An MRI (magnetic resonance imaging) scan or CT/CAT (computed tomography) scan may also be necessary. Cardiac chamber catheterization is another testing method.
How is mitral valve stenosis treated?
Mitral valve stenosis is treated surgically and/or with medication. The need for treatment depends on the cause and degree of the stenosis and the severity of the patient’s symptoms, as well as any underlying conditions. Many times, treatment involves both surgery and medications.
Medications that treat mitral stenosis include antiarrhythmic drugs like beta-blockers, anticoagulants like warfarin and aspirin, and vasodilators like ACE inhibitors and hydralazine. Diuretics, cardiac glycosides (digoxin), and antibiotic prophylaxis (amoxicillin) are other treatment options.
Surgery can involve repairing or replacing components of the mitral apparatus, which may be necessary in suitable candidates. However, a less invasive procedure known as balloon valvuloplasty (where a balloon device is inserted into the valve) is now preferred for less damaged valves.
What is the prognosis for patients with mitral stenosis?
The prognosis depends on the degree of stenosis, the patient’s risk factors and underlying disorders, and the natural progression of the disease. Stenosis may be mild and symptomless or it can be severe and disable the patient. Complications can be life threatening, especially if left untreated.
Possible complications include pulmonary hypertension, pulmonary edema, and congestive heart failure, as well as atrial enlargement/fibrillation/flutter, infective endocarditis, and stroke due to clotting. While serious complications normally only occur in those with severe mitral stenosis, the disease is progressive, so patients typically develop symptoms and complications over time.
Medications can help in relieving symptoms and preventing complications with stenosis of the mitral valve, but the majority of patients will at some point require surgical correction.