- It is a heart valve disorder.
- The heart's mitral valve does not close properly, causing blood to flow back into the atrium.
- Treatment depends on the severity of the condition, and signs and symptoms.
- Symptoms can be controlled with medication, but in severe cases valve repair or valve replacement may be needed.
Mitral insufficiency, mitral incompetence
What is mitral regurgitation?
Mitral regurgitation (MR) refers to an incompetent mitral valve. This results in some blood leaking back into the atrium with each contraction, instead of all of it being pumped out into the aorta.
What causes it?
Regurgitation is caused by one of three basic mechanisms:
- The leaflets of the valve do not close correctly. This is most commonly seen after rheumatic fever or endocarditis.
- The leaflets are normal, but the supporting ring becomes stretched, pulling them away from each other, so that they cannot close properly. Dilated cardiomyopathies, or neglected aortic valve stenosis may be the cause.
- The leaflets and ring are normal, but the papillary muscles and chordae (other supporting structures) are damaged. Chordae become thickened and shortened after rheumatic fever. Papillary muscles may be damaged as part of a heart attack.
Marfan's and Barlow's syndrome, both of which have a degree of degeneration of connective tissue, can also result in regurgitation, due to both leaflet problems, as well as stretching of the supporting valve ring.
What are the symptoms?
Most commonly symptoms develop gradually over the years following rheumatic fever. However, damage to the valve apparatus caused by a heart attack or by rampant infection, can cause symptoms to appear very suddenly.
With mild MR there may at first be no symptoms at all. As the leak increases, the heart may be able to compensate for a time. When the heart can no longer compensate for the huge leak, heart failure can set in.
Common symptoms include:
- Heart palpitations
- Shortness of breath
- Excessive urination
- Chest pain
- Heart murmur
How is it diagnosed?
The symptoms described by the patient will be very important, and the diagnosis will be supported by a murmur, which can be heard when the chest is examined. These heart murmurs vary in character, site and intensity, and provide much information on the state of the valve. •
A chest X-ray will show whether there is enlargement of the heart or congestion of the lungs.
An ECG will give an overall indication of the state of the heart muscle, and will also diagnose any rhythm disturbances, which are a common complication of valve disease.
The definitive investigative tool is the Echocardiogram. This is a "real-time" ultra-sound, which shows the heart contracting and the valves opening and closing as it happens. An external echocardiogram can be done in the cardiologist's rooms by a specially trained technician.
A far better and more accurate procedure, however, is a Trans Esophageal Echocardiogram, or TEE. This is also a real-time ultrasound, but is done while the patient anaesthetized, via a special probe which the patient swallows - very much like a gastroscopy. Very clear pictures and accurate measurements of blood flow, and valve anatomy and function provide valuable information used when deciding on the best treatment for the patient.
A cardiac catheterization may also be recommended. During this procedure a thin tube is inserted into a blood vessel in the arm or the groin and threaded up to the heart. The catheter is used to deliver dye into the heart chambers and the blood vessels of the heart. The dye appears on X-ray images as it moves through the heart and gives doctors detailed information about the heart and heart valves. Some catheters have sensors at the tips that can measure pressure within the heart chambers.
How is it treated?
Medical treatment is used to alleviate symptoms in patients whose valve problems are not yet serious enough to warrant surgery, or for patients on whom, for various reasons, surgery is not possible.
Several important aspects are:
- Reducing the workload of the heart - e.g. with Digitalis to improve effective contractions
- Reducing the amount of fluid the heart has to pump - e.g. with diuretics (water-pills) to shed excess fluid and salt
- Keeping the blood pressure normal/low - vasodilators reduce the systemic pressure to permit more blood to be pumped into the aorta, and less to be regurgitated back into the atrium.
- Anticoagulants - very important even in patients without rhythm disturbances, such as atrial fibrillation. In AF clots can form in the atrium, causing a stroke, heart attack or fatal pulmonary embolism. Anticoagulants such as Warfarin prevent these clots from forming. For those with Mitral valve prolapse, some physicians recommend the use of aspirin
- Antibiotic prophylaxis is vital to protect against infective endocarditis on the abnormal valve
- Assessing the patient for concomitant Coronary Artery Disease is important because this is often the underlying cause of the MR.
Mitral regurgitation (MR) can never be cured with medicine alone - this is a structural problem, needing structural repair. Criteria for surgery include
- Any patient with proven MR who has symptoms due to the MR
- Any patient with proven MR who has NO symptoms, but HAS
- Increase in size of the left ventricle
- New onset atrial fibrillation
- Pulmonary hypertension
Surgical options include
Valve repair, which may involve:
- inserting a supporting ring to reduce an overstretched valve ring to normal size, thereby eliminating the leak
- "tailoring" or trimming the cusps to allow better closure or less prolapse into the atrium
- specially placed sutures can help to "re-suspend" cusps
Valve replacement is much more effective , and can be done faster than a delicate repair.
Different types of valves can be used. Mechanical valves are made of a virtually indestructible substance called Pyrolytic carbon. Provided they are correctly inserted, these valves can last the patient's lifetime. Because they are a foreign substance and thus promote clot formation, the patient needs to use Warfarin anticoagulant permanently.
Bioprosthetic valves are harvested from cow or pig tissue and are treated to become inert (non-irritant). They therefore do not tend to cause clot formation which means that the patient may be spared using Warfarin. The disadvantage of these valves is that they have a limited lifespan and may calcify after 10-15 years, and therefore need to be replaced. If the patient has permanent AF, then s/he will need to use Warfarin anyway, but may still receive a bioprosthesis for other reasons.
What is the prognosis?
Valve surgery usually has an excellent outcome, especially if done by an experienced surgeon.
In time the body tries to re-line the valve with the same cells that line the inside of the heart.
Most valve replacements allow the patient to resume a near-normal life, with moderate exercise, etc. Attention to the need for anti-coagulation is vital, as is antibiotic prophylaxis. Other co-existing problems must also be managed.
Once a patient has had a valve replacement, s/he must be made aware of the need for antibiotic prophylaxis. This consists of a special type and dosage to be used before any surgical procedure, no matter how minor.
When to call your doctor
Call your doctor if you experience symptoms such like persistent tiredness, cough, rhythm disturbances and shortness of breath: these should immediately be investigated. Any chest discomfort - especially if it occurs with exercise - is significant.
How can it be prevented?
The most effective way to prevent mitral regurgitation is to prevent its common cause, i.e. rheumatic fever and to provide rapid, adequate treatment of diagnosed cases.
Eat less salt, maintain a healthy weight, do regular exercises, cut back on alcohol and manage hypertension.