Regurgitation is the inability of a valve to close completely, which results in significant backward flow of blood through the valve. The major causes of regurgitation are rheumatic fever, bacterial endocarditis, coronary artery disease, and venereal disease.
There are two common conditions that can occur when a natural heart valve becomes defective. They are:
- stenosis (valve narrowing)
- regurgitation (leaky valve)
- This can occur in just one valve, or in more than one valve.
Stenosis is the narrowing of a valve opening that results in lower blood flow through the valve. The primary cause of stenosis is calcification resulting from diseases such as rheumatic fever, infection and congenital abnormalities. Other causes include bacterial endocarditis and venereal disease. With the exception of stenosis caused by congenital abnormalities, the development of a stenotic valve begins with scarring of the valve cusps caused by disease, infection, etc. Over time, two processes might occur. Scar tissue may accumulate to the point where the leaflets become thickened and begin to lose their flexibility. Or, the rougher scar tissue may serve as the site for calcification. That is, calcium present in the blood may collect at these sites, forming calcified masses which, in turn, reduce the flexibility of the leaflets. As the leaflets lose their flexibility, the valve becomes more stenotic. The area through which blood flows is gradually reduced. So, less and less blood can pass through the valve with each contraction. As the heart meets greater resistance to blood flow through the valve, the heart chamber before that valve feels greater and greater pressures.
Over time this increasing pressure gradually stretches the muscles of the chamber wall which respond by becoming thicker. The result is an enlarged heart. This condition should not be confused with the larger, stronger heart of, for example, an athlete. Rather, an enlarged heart simply means one with a stretched chamber and increased muscle mass. The possible complication with an enlarged heart is an increased likelihood of blood clots forming. The incidence of this complication increases because the blood that is backed up in the enlarged chamber is more stagnant. The more blood pools in one spot, the greater possibility for it to form a clot. This complication arises more frequently when the heart is not in sinus rhythm. (Recall that sinus rhythm refers to normal, coordinated contraction of heart muscles.)
- First, infections can cause lesions (scars or rough spots) on the flaps. This scar tissue can build up to the point where the cusps are so rigid (and stenotic) that they cannot close properly. This results in backflow through the valve. Thus, it is possible for a valve to be regurgitant in addition to being stenotic.
- Second, infections may cause tissue to break down, tear or form holes in the valves or around the perimeter of the valve (perivalvular leaks).
- Third, blockage of a coronary artery due to coronary artery disease can cause papillary muscle dysfunction (inadequate or impaired function) due to a disruption in the supply of nutrients and oxygen to the muscle tissue. Papillary muscles are structures that contract to make the mitral and tricuspid valves open.
- Infection and myocardial infarction can also cause other problems with the supporting valve structures that cause problems with valve closure. As in stenosis, regurgitation can progress through stages of severity over time, resulting in worsening of the condition and onset of the symptoms.
- Generally, even though the initial damage to a valve may happen early in life, the early effects are mild and the defect progresses slowly. Although some regurgitation occurs with all valves, when the regurgitation rate attains a significant level, clinical problems may become noticeable and symptoms are felt by the patient.
Diagnosis of Valve Disease
Before a patient sees a primary care physician or a cardiologist (a doctor who specializes in understanding the heart) concerning a heart valve problem, he or she has probably experienced some type of physical sign or discomfort. Some physical signs of heart valve disease include: angina (chest pain), tiredness, shortness of breath, light-headedness or loss of consciousness.
Cardiologists and surgeons have many ways of diagnosing heart valve disease. They usually begin with simple tests such as listening to heart beats and taking blood samples. By listening to the heart, cardiologists can hear the valves opening and closing and sounds of blood flow through the valves.
Electrocardiography (ECG or EKG) is an important tool used in diagnosing heart disease. An electrocardiogram is a recording of the electrical activity of the heart. Electrical activity is detected by electrodes which are attached to the patient’s skin. The electrical impulses are recorded in the form of waves. The ECG gives information about heart rate (the rhythm of the heart), the presence of heart muscle damage or inadequate blood and oxygen supply to the heart muscle and abnormalities of heart structure. The ECG can be done at rest or during exercise.
A chest X-Ray can be important in the detection of calcium deposits in the heart such as on heart valves. It will also show the size and shape of the heart and lungs.
A nuclear scan shows features of the heart’s function and blood flow. It can show the size of the heart’s chambers, how well the heart pumps (ventricular function) and how well the coronary arteries supply the heart with blood. Nuclear scanning works by injecting radioactive materials into the bloodstream which give off radiation as they travel through the body. This radiation is detected with a special camera as it passes through the heart. An image of the heart is produced and the size of the ventricles during systole (when the heart squeezes) and diastole (when the heart relaxes) can be calculated as well as the volume of blood in the ventricles.
Echocardiography is a special application of ultrasound. Ultrasound waves that are sent into the body detect the echoes bouncing back from the heart’s structures. A computer translates the sound waves into an image.
Another type of echo is transesophageal echo in which a tube with an ultrasound probe is inserted down the throat near the heart.
Cardiac catheterization (angiography) helps to determine the function of the coronary arteries and the heart valves. Cardiac catheterization is the process by which a tube is inserted into the blood vessels and/or heart. The tube injects a contrast medium (dye) which is then visualized with X-rays. Coronary angiography is particularly useful for analyzing the coronary vessels of the heart.