Mitral valve prolapse (MVP) is the most common heart valve abnormality in the United States, affecting between 2 and 3 percent of the population. It occurs when the Mitral valve, which is located between the upper and lower chambers on the left side of the heart, has structural alterations. The mitral valve controls blood flow between these two chambers. It has two flaps that swing open and shut as blood travels from the upper chamber to the lower chamber on the left side of the heart.
In individuals with mitral valve prolapse, these flaps buckle back into the left atrium when the left ventricle contracts in a way that is similar to an open parachute. This action can prevent the valve from forming a tight seal between the chambers. This condition can be worsened in situations where the left ventricular cavity is smaller, such as when a patient is dehydrated or during standing. When a person is upright, the blood pools in the legs from gravity and less is present in the heart chamber. Many individuals with mitral valve prolapse have no significant valve leakage or hemodynamic abnormalities.
In the majority of cases, mitral valve prolapse causes no serious problems and does not require treatment. In a small percentage of cases, however, mitral valve prolapse can cause serious cardiac problems, including mitral valve regurgitation (when blood flows the wrong way), an infection of the heart valves and heart rhythm abnormalities. Although constant treatment is typically unnecessary for patients with mitral valve regurgitation, they may be given antibiotics before surgery or dental procedures to prevent infection of the heart valves. Physicians may choose to monitor a patient with mitral valve prolapse to make sure their condition is not worsening.
About mitral valve prolapse (MVP)
The mitral valve rests between the upper and lower chambers on the left side of the heart (the left atrium and left ventricle, respectively). The valve has two flaps that are connected to the heart muscle by cords called chordae tendineae.
In normal circulation, the mitral valve billows open to allow blood to flow from the left atrium to the left ventricle, where it is pumped out to the rest of the body through the aorta. In some cases, however, the flaps of the mitral valve or the chordae are abnormally formed, causing the valve to close incorrectly. This condition is known as mitral valve prolapse, or literally “the slipping of the mitral valve from its usual position in relation to other parts.”
MVP is the most common congenital heart valve abnormality in the United States. In the past, it was thought to affect from 5 to 15 percent of the population. However, researchers now believe that many of these individuals did not have MVP. Instead they had a bulging valve flap due to other conditions, such as a small heart or dehydration. With new criteria for diagnosing MVP, the National Heart, Blood, and Lung Institute estimates that less than 3 percent of the U.S. population actually have MVP.
In the vast majority of cases, mitral valve prolapse is benign, even if occasional symptoms are present. In fact, researchers have sometimes had difficulty assigning symptoms to mitral valve prolapse. Various studies have identified a wide range of symptoms that appear in people with mitral valve prolapse, such as chest pain or breathlessness. However, there is no consensus that these symptoms were actually caused by the prolapse or occurred by coincidence. Thus, mitral valve syndrome is a condition in which a variety of non-specific symptoms may be present, but may or may not be due to the prolapse.
Physicians may classify mitral valve prolapse in three categories:
Primary, or MVP that occurs on its own, for no apparent reason. In some individuals, it is accompanied by skeletal abnormalities (straight-back syndrome). It may also be inherited as familial mitral valve prolapse.
Secondary, or MVP that is associated with another disease, including Marfan syndrome, Ehlers-Danlos syndrome, polycystic kidney disease and others. The structural abnormalities in the mitral valve are the same with primary and secondary prolapse.
Functional, or MVP that is caused when an anatomically normal mitral valve is affected by abnormalities within the heart structure. This may occur in patients with hypertrophic cardiomyopathy.
Although most cases of mitral valve prolapse do not cause serious medical problems, the condition should be monitored. MVP is associated with more serious cardiac complications, including infective endocarditis, mitral valve regurgitation, arrhythmias and sudden cardiac death. Some research has also suggested that mitral valve prolapse is associated with transient ischemic attacks, or a temporary lack of blood flow to the brain that causes stroke symptoms. Although several studies have suggested a connection, other studies have not, and the link remains inconclusive.
Signs and symptoms of mitral valve prolapse
Approximately 60 percent of patients with mitral valve prolapse (MVP) do not have any symptoms. Among patients with symptoms, there is some question as to how directly the symptoms are linked to MVP. Nevertheless, certain symptoms are associated with mitral valve prolapse, including:
Chest pain or discomfort that is usually different from angina because of its character, duration and the events that trigger it.
A sense of a speeding pulse as a result of rapid heartbeat (tachycardia).
Strong, fast or “galloping” heartbeats (palpitations), usually on the left side of the body during periods of relaxation.
Fatigue, even with minimal levels of activity.
Anxiety and panic attacks that can range from mild to severe.
Shortness of breath (dyspnea).
Fainting (syncope).
Diagnosis methods for mitral valve prolapse
Thoroughly reviewing the patient’s medical history and giving the patient a physical examination are the first steps toward a diagnosis of MVP. During this exam, the physician will listen to the patient’s heartbeat through a stethoscope (a process called auscultation). MVP can be detected by a distinctive clicking sound (and, frequently, a heart murmur) at a given point in the cardiac cycle, just after the ventricles contract.
The next diagnostic step is usually an electrocardiogram (EKG), which is a recording of the heart’s electrical activity as a graph on a moving strip of paper or video monitor. The highly sensitive electrocardiograph machine helps to detect heart irregularities, disease, and damage by measuring the heart’s rhythms and electrical impulses. However, although an electrocardiogram will provide important information, a diagnosis of mitral valve prolapse cannot be made by this test alone.
When a history, physical examination and EKG suggest the possibility of MVP, an echocardiogram will usually follow. This test can provide detailed information about the extent of valve abnormality and verify the diagnosis. An echocardiogram is an ultrasound test that uses sound waves to track the structure and function of the heart. A moving image of the patient’s beating heart is played on a video screen, where a physician can study the heart’s thickness, size and function. The image also shows the motion pattern and structure of all four heart valves, revealing any potential billowing, leakage (regurgitation) or narrowing (stenosis). During this test, a Doppler ultrasound and color Doppler are required to fully assess each valve. If MVP is diagnosed, patients are encouraged to have repeat echocardiograms performed every 2 to 5 years, depending upon the severity of the regurgitation.
The physician may need additional tests to determine how the heart responds under physical stress. Therefore, an exercise stress test may be ordered. In an effort to detect abnormal heart rhythms (arrhythmias), the exercise stress test may reveal an excessively rapid heart rhythm called a supraventricular tachycardia. It may also reveal other electrical disturbances that account for the palpitations often felt by patients with MVP.
In order to help correlate the rhythm abnormalities with the symptoms (e.g., palpitations), the physician may order a Holter monitor test. A Holter monitor is a continuous EKG that is temporarily attached to an ambulatory (freely moving) patient for a 24-hour period. This test can detect or diagnose abnormal arrhythmias. It can also help to evaluate the effectiveness of any medications, especially antiarrhythmics, that the patient may be taking.
The physician may also order a chest x-ray to see whether the heart is enlarged, or whether there is excessive fluid in the lungs.
Occasionally, a more invasive procedure called a cardiac catheterization needs to be done. As part of the cardiac catheterization, two tests may be performed: a coronary angiogram to ensure that the coronary anatomy is normal and not the cause of the chest pain, and a left ventriculogram to visualize the left ventricle and mitral valve.
To perform the coronary angiogram, the physician inserts a thin tube (catheter) through a blood vessel, usually in the upper thigh, and up into the coronary arteries. Once the catheter is in place, the physician can inject a special dye (contrast medium) through the catheter and into the coronary arteries. Once the dye has highlighted the area, an x-ray is taken.
To perform a left ventriculogram, the catheter is then placed in the left ventricle and dye is injected. Following the injection of the dye, the physician is able to assess for the presence of MVP and the strength and motion of the left ventricle.
Although the physician typically numbs the area where he or she inserts the catheter, the patient is awake for the entire cardiac catheterization. The patient receives a mild sedative before the procedure and does not ordinarily feel the movement of the catheter within the blood vessels, although he or she may feel the contrast dye when it is injected.
Treatment options for mitral valve prolapse
Patients with no symptoms and no abnormal heart rhythms (arrhythmias) due to mitral valve prolapse (MVP) are usually placed on a “wait and watch” basis, with tests repeated about five years from the initial diagnosis. However, all patients, even those without symptoms, may be advised to do the following:
Take antibiotics shortly before any dental or medical/surgical procedure that involves the risk of bacteria entering the bloodstream. This is due to a higher risk of developing a potentially life-threatening infection of the heart valve called valvular endocarditis. In revised guidelines by the American Heart Association, this pre-medication “antibiotic prophylaxis” pertains to MVP individuals withregurgitation. Those who have MVP without regurgitation generally do not need prophylaxis.
Eat a good diet, including avoiding caffeine, limiting sugar and eating a high-protein snack in the afternoon (e.g., nuts). This may help patients to sustain an adequate energy level and guard against fatigue.
Drink plenty of caffeine-free beverages (e.g., water). This can improve low energy and feelings of dizziness or weakness.
Engage in regular exercise. With guidance from a physician, exercise can help to relieve symptoms and improve overall health and energy levels.
Depending on the patient’s symptoms, medications may also be prescribed. These include:
Beta blockers. These drugs minimize the effects of stress hormones on cardiovascular functions, slowing the heart rhythm and minimizing the stress on the floppy mitral valve. Beta blockers also often help to relieve the associated chest pain.
Vasodilators. These medications help expand the blood vessels and reduce the workload on the heart. They may be used for patients who have significant regurgitation and to prevent serious symptoms.
Antiarrhythmics. To regulate heart rhythms. Although beta blockers remain the initial therapy for arrhythmias, side effects sometimes lead to the use of alternative antiarrhythmic medications.
If the MVP progresses to significant leakage (regurgitation) and heart failure, then treatment will shift to address those conditions accordingly.
It is only in the more major cases of MVP with significant regurgitation that a patient will require surgery. Only 2 to 5 percent of MVP patients under the age of 70 develop sufficient regurgitation to require surgery. A surgical treatment would entail heart valve repair or replacement. The chordae may also be treated by the surgeon, as needed. The primary goal of surgery is improve the patient's symptoms and reduce the risk of heart failure.
Researchers are examining the repair of mitral valve regurgitation with a less-invasive procedure. During this procedure, the physician threads a catheter to the mitral valve and fastens a tiny clip to the abnormal valve, thus reducing blood leakage. This treatment is being performed in only a few medical centers and has not yet been shown in large studies to be more effective than traditional surgery.
Questions for your doctor
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to mitral valve prolapse (MVP):
Why do you suspect I have mitral valve prolapse?
What tests will be used to verify the diagnosis?
How serious is my condition and how will it affect my health?
Will I need treatment for MVP? If so, what type?
If I need surgery, what will be involved?
What types of symptoms can I experience with MVP?
Which symptoms indicate a medical emergency?
Do I have any restrictions with my condition?
Should I be taking any medications?
Are there any lifestyle changes I can make that might improve my condition?
