1. Most Murmurs are Benign
A heart murmur is a common medical condition. It is often found incidentally during a routine physical exam. A murmur is the sound of blood flowing across heart valves. It can be due to valves that are narrowed or leaky or can be due to increased flow across normal valves. The majority of murmurs identified by your family doctor are harmless. Cases that require attention are related to the presence of symptoms.
2. Aortic Valve Disease
The aortic valve opens during the heart's contraction. Blood flows out of the heart, to the brain and onward. Blood flows to the coronary circulation during relaxation of the heart in a passive state. A restriction of the aortic valve's opening is known as aortic stenosis. A typical opening is a approximately 4cm2. When the area drops below 1cm2, a patient will often experience breathing problems or chest pains with exertion. Severe cases often experience blackouts or develop heart failure with swelling of the legs and breathing difficulty at rest. Aortic stenosis is often seen in older patients and commonly affects the elderly. The most common adult congenital heart defect is bicuspid aortic valve, which can predispose patients under 60 years of age to develop aortic stenosis.
Aortic regurgitation is a condition in which the valve fails to close completely. This results in an overload of the heart which can cause it to enlarge. Aortic regurgitation is typically a slowly progressing disease. Patients with severe regurgitation often tolerate it for an extended period, but they eventually will develop heart failure if the heart continues to dilate.
3. Mitral Valve Disease
The mitral valve opens during the heart's relaxation phase (diastole), and allows freshly oxygenated blood from the lungs to enter the pumping chamber (left ventricle). The most common abnormality of this valve is regurgitation (or leaking). When the leaflets fail to close fully, blood flows back into the upper chamber from where it just came (left atrium). This constant regurgitation dilates the upper chamber and can result in atrial fibrillation (which is associated with stroke). Over time, the lower chamber can dilate. This combines with the back flow into the upper chamber to produce a dangerous drop in the heart's pumping efficiency. The end result: symptoms of heart failure, swollen legs and severe breathing difficulty.
Mitral stenosis, when the mitral valve fails to open fully, is rare in the United States, although it is seen often in developing countries. It is associated with rheumatic fever. Patients often have a dilated left atrium, atrial fibrillation, and difficulty breathing. It can be seen in younger patients and often is identified in women who are pregnant for the first time, as previously symptom-free patients develop trouble breathing when the heart rate and blood volume increases with the pregnancy.
4. High Flow States
Innocent murmurs are often seen in states with increased cardiac function. These include low blood counts (anemia) and elevated thyroid hormone levels, (hyperthyroid). In the setting of a systemic infection, a murmur can be due to the high output state or an infection of the valve. Infective endocarditis is a serious consequence of a systemic infection in the bloodstream. If the valve is seeded with extensive bacteria, material can embolize from the valve to cause stroke or peripheral emboli.
5. Treatment of Valve Disease
The treatment of valve disease is often surgical. When patients develop symptoms, such as breathing difficulty or chest pains, and severe valve disease is identified, treatment is usually indicated. Cases in which severe heart failure develops indicate the possibility of a long-standing disease. After the heart function drops significantly, the probability of successful treatment decreases. In the case of leaking valves, treatment with medications to lower blood pressure can improve forward flow and decrease regurgitation.
Mitral stensosis often can be treated without surgery by inflating a balloon across the valve to improve the flow (valvuloplasty). Treatment of aortic valve disease involves replacing the valve with a mechanical valve or tissue valve (usually made from cow or pig tissue). The choice of valve is often based on the patent's age and ability to be compliant with medications. A tissue valve may only last ten years, which may require another surgery to replace it in a young patient.
A mechanical valve lasts indefinitely but requires long-term treatment with coumadin. This can be a problem for younger patients. Coumadin also is contraindicated in pregnancy, as it can cause severe birth defects. The mitral valve often can be repaired surgically so that it closes fully, and there is no need for an implant. However, replacement is performed when repair is not feasible. There has been a wave of new technology in the treatment of valve disease through percutaneous routes. Several studies are underway with techniques to replace the aortic valve via the artery in the leg and repair the mitral valve by placing a specialized clip via the leg veins.
