Mitral stenosis

Have you been lately experiencing an acute chest pain coupled with tiredness in weakness in the muscles? You might be suffering from Mitral stenosis (MS) – a relatively uncommon heart deformity that can cause complex cardiac problems in the future. Find out everything about this condition, including its types, symptoms, causes, treatment and complications.

Mitral stenosis Definition

It is a complicated cardiac disorder marked by narrowing of the opening or orifice of the mitral valve- a dual-flap valve that lies between the left atrium and left ventricle. In this heart defect, the valve is unable to close completely, restricting the blood to flow through it normally. In some cases, the condition is present as a congenital defect that may turn severe as patients reach adulthood.

Mitral stenosis Symptoms

Constriction of the orifice reduces the amount of blood pumped out into the body from the left ventricle. This generates a back pressure that builds up behind the narrowed valve, causing a host of serious problems in the heart. Generally, a mildly narrowed valve does not give rise to any significant symptoms. In severe cases, however, congestion of blood in the vessels may exert pressure on the left atrium. Acute chest pain is the first sign of the condition that normally increases with activity, but decreases upon lying down. The pain often radiates to the arm, neck and jaws. Affected patients often complain of a squeezing or tight chest pain. Symptoms like muscle wasting or weakening as well as tiredness may increase with exercise and pregnancy. Patients may develop Malar Flush- a condition manifested by a high color over the cheeks with a bluish tinge due to reduced oxygen concentration in the blood. Other signs of this valvular heart disorder may include:

Picture of Mitral stenosis

Picture 1 – Mitral stenosis

  • Shortness of breath
  • Fainting
  • Dizziness
  • Palpitations
  • Accumulation of fluid in the abdominal cavity, known as Ascites
  • Pulmonary infections
  • Hemoptysis or coughing of blood/blood-stained sputum
  • Swelling of the feet or ankles, called Edema

Mitral stenosis Causes

One of the most common causes of a defective mitral valve is Rheumatic fever – an inflammatory condition that occurs following a Streptococcus pyogenes infection. Many patients eventually develop rheumatic heart disorder after an episode of rheumatic fever. Affected individuals may even develop mitral regurgitation where there is a retrograde flow of blood into the left atrium. Streptococcal infection can affect the functioning of mitral valve in the following two ways:

  • Abnormal thickening or hypertrophy of the mitral valve leaflets, restricting its ability to open or close normally
  • Fusion of the mitral flaps that inhibits the valve from opening or closing properly

In addition to this inflammatory disorder, there are a few other causes of mitral valve narrowing like:

Congenital heart defect

A varied range of cardiac anomalies are known to cause complications in the valves and chambers of the heart. Constricted mitral valve is often seen as a severe consequence of atrial septal defect where a small aperture occurs in the wall between the left and right atria. In other cases, infants are born with a damaged mitral valve that places them at a risk of developing this condition.

Mitral annular calcification

It is a chronic, fibrous, non-inflammatory degenerative disorder of the mitral valve that commonly occurs in adults. In this heart ailment, excessive calcium deposits may form around the valve that slowly begins to constrict and harden the mitral orifice.

Infectious endocarditis

In this serious medical condition, the innermost lining of the heart called endocardium is infected by bacteria, inhabiting the skin, mouth and gastrointestinal tract. These infectious microorganisms directly migrate to the heart after entering the bloodstream and settle on the valves as well as chambers. This rapidly results in severe infection that ultimately destroys the valves, including mitral valve.

Mitral stenosis Pathophysiology

Under normal circumstances, the mitral valve opens during left ventricular diastole – the period during which the left ventricle relaxes, to let the blood flow from the left atrium to the left ventricle. The pressure in both the chambers is generally equal, owing to the smooth blood flow. In MS patients, however, the constricted valve opposes the blood to flow into the left ventricle. This gives rise to a pressure gradient across the two chambers. Pulmonary congestion occurs when the left atrium is filled with excessive blood, causing tremendous pressure inside the chamber. The continuous build up of high pressure leads to an abnormal enlargement of the left atrium, causing atrial fibrillation.

Mitral stenosis Types

The normal area of the mitral valve orifice varies from 4 to 6 cm2. Obstruction to the blood flow occurs when the size of the valve falls below 1-2 cm2, leading to an increase in the mean pressure gradient. Diastolic pressure is the lowest value to which the blood pressure falls between contractions of the ventricles. Pressure half-time is an important criterion that is essentially measured to assess the severity of the condition. It is defined as the time interval in milliseconds required for the diastolic pressure gradient across the mitral valve to fall to half of its initial value. A high pressure half time suggests a possibility of a heart failure in the affected patients. The following table gives the specific types of the disorder.

  • Mild MS – 1.5 Valve area (cm2) and 100 – 150 Pressure half- time (milliseconds)
  • Moderate MS – 5 – 10 Mean gradient (mmHg); 1.0 – 1.5 Valve area (cm2) and 150 – 220 Pressure half- time (milliseconds)
  • Severe MS – >10 Mean gradient (mmHg); 2) and >220 Pressure half- time (milliseconds)

Mitral stenosis in women

In the United States and Canada, women with rheumatic heart disorder are more likely to suffer from stenosis of mitral valve. The condition is also seen widely in around 25% of pregnant women.

Mitral stenosis Diagnosis

The diagnosis of the disorder begins with a thorough physical examination of the patients. Health care providers normally auscultate an affected patient using a stethoscope. The process is known as “Auscultation” that involves the act of listening to the internal sounds within the heart. During the initial check-up, physicians can hear a high-frequency opening snap followed by a rumbling murmur. These abnormal heart sounds can be directly related to a defective mitral valve. The distinct snapping sound is due to the tension in the mitral leaflets and delayed opening of the valve that occurs in early diastole. The timing of this sound is important as it indicates the severity of the condition with increase in the left atrial pressure. Physicians usually go for few laboratory tests and exams to accomplish complete evaluation of the condition. Some of these include:

Chest X-ray

Enlargement of the left atrium as a consequence of increased pressure in the chamber can be imaged using a chest radiograph.

Echocardiogram (ECHO)

The procedure enables health care providers to check for specific cardiac abnormalities. High-frequency waves are used to produce vivid images of the heart using a transducer. The partial obstruction to blood flow from the left atrium to the left ventricle is more evident in a transthoracic ECHO combined with color flow Doppler ultrasound.

Transesophageal echocardiogram involves an ultrasound transducer that is positioned on an endoscope to get a detailed view of the valves and chambers of the heart. The test can assess the overall function of the heart as well as evaluate abnormalities of the left atrium.

Wilkins score is a scoring system that is used to grade the morphological changes in the mitral valve during an ECHO. The following features are taken into consideration during this grading process:

  • Leaflet thickening
  • Leaflet mobility
  • Valve calcification
  • Subvalvular apparatus, comprising of the papillary muscles and the chordae tendineae

After a thorough assessment, the condition is assigned a grade from 0-4 that determines its severity. The total score is the sum of the four components that normally ranges between 4 and 16. Higher the score, greater is the severity of the disorder.

Electrocardiogram (ECG)

It is a very effective diagnostic tool that is routinely used to assess the electrical and muscular functions of the heart. The electrical activity of the heart in patients with prominent traits like left atrial enlargement, hypertrophy or fusion of the mitral flaps is quite poor.

Magnetic Resonance Imaging

The blood flow dynamics in the heart chambers, vessels and valves can be studied using this imaging technique. It even helps in detecting other congenital heart defects associated with this condition. Magnetic resonance angiography (MRA), which is a group of techniques based on MRI, is used to depict the blood vessels inside the heart. The technique generates images that typically show areas of constriction or narrowing of the heart valves.

Cardiac catheterization

This invasive imaging test involves insertion of a catheter into a blood vessel in the arm, groin, or neck, which is directly threaded to the heart with the help of a thin wire. A special contrast dye is then injected through the catheter. An X-ray machine is then used to view the internal structures of the heart for any type of anomaly.

Mitral stenosis Treatment

The severity of condition may vary substantially from one individual to another because of which, the treatment measures also tend to differ. Some of the approaches include:

Medication

Angiotensin-converting enzyme (ACE) inhibitors are very often used to treat symptoms of a heart failure. High blood pressure can be reduced with the help of diuretics or water tablets. Affected patients who have developed atrial fibrillation as a complication are generally administered with anti-arrhythmic drugs to control the abnormal heart rate. Beta blockers or calcium channel blockers are also prescribed to slow down the heart rate. Anticoagulants such as warfarin aim to prevent blood clots.

Cardioversion

This medical procedure is used to restore normal heart rhythm with the aid of electric shocks or drugs in patients who are also suffering from atrial fibrillation.

Surgery

In severe cases, a narrowed mitral valve should be corrected to prevent any leakage or irreversible damage. Some of the commonly-used surgical interventions include:

Balloon valvuloplasty

In this minimally invasive procedure, a catheter with a special balloon at the tip is guided through a blood vessel in the arm or groin to the heart. The tip of the catheter is then placed near the mitral valve opening. The balloon is inflated to push open the valve and stretch the orifice for proper blood flow.

Mitral valvotomy

In this procedure, the edges of the scarred mitral flaps that have undergone fusion are incised to widen the constricted valve and relieve the obstruction.

Valve replacement

In most cases, the impaired valve is replaced with a mechanical or bioprosthetic valve to prevent the leakage of blood into the left atrium.

Mitral stenosis Complications

Permanent damage of the valve may give rise to an array of serious complications like:

Image of Mitral stenosis

Picture 2 – Mitral stenosis Image

  • Pulmonary hypertension
  • Atrial fibrillation
  • Atrial flutter
  • Heart failure
  • Pulmonary edema
  • Blood clots

Mitral stenosis cannot be reversed by plain use of medication. However, it can ease the symptoms to a great extent. Surgical repair has a good success rate in critical cases where there is an extreme narrowing of the valve. Immediate medical intervention is required if a patient begins to show symptoms like chest pain and shortness of breath after a physical activity.