Ventricular septal defects are heart defects that are present at birth (congenital). The normal heart has four chambers. The two upper chambers, known as atria, are separated from each other by a fibrous partition known as the atrial septum. The two lower chambers are known as ventricles and are separated from each other by the ventricular septum. Valves connect the atria (left and right) to their respective ventricles. The aorta, the main vessel of arterial circulation, carries blood from the left ventricle and away from the heart.
Ventricular septal defects can occur in any portion of the ventricular septum. The size and location of the defect determine the severity of the symptoms. Small ventricular septal defects can close on their own; (spontaneously) or become less significant as the child matures and grows. Moderately-sized defects can cause congestive heart failure, which is characterized by an abnormally rapid rate of breathing (tachypnea), wheezing, unusually fast heartbeat (tachycardia), enlarged liver (hepatomegaly), and/or failure to thrive. Large ventricular septal defects can cause life-threatening complications during infancy. Persistent elevation of the pressure within the artery that carries blood away from the heart and to the lungs (pulmonary artery) can cause permanent damage to the lungs. The exact cause of ventricular septal defects is not fully understood.
Infants with small ventricular septal defects may have no symptoms unless they experience infection that spreads to the lining of the heart and the valves (infective endocarditis). This form of the disease is known as Roger’s disease.
Infants with moderate ventricular septal defects may experience the symptoms of congestive heart failure. These may include excessive fatigue and difficulty breathing during feeding or periods of activity. Some infants may experience poor feeding; cold, grayish arms and legs; and/or rapid, shallow breathing. Ventricular septal defects of moderate size are also characterized by abnormal enlargement of the heart (cardiomegaly) and heart murmurs.
A large ventricular septal defects can cause severe symptoms in infants. If the septum is entirely absent, the 2 ventricles come together to form a single chamber. This condition is known as common ventricle or cor triloculare biatriatum. In infants and children, large defects generally cause growth retardation and progressive heart failure. Other symptoms may include poor feeding; a slight bluish discoloration on the skin, lips, and mouth (cyanosis); rapid difficult breathing; excessive accumulation of fluid in the lungs and around the heart (pulmonary edema), and/or the elevation of pressure within the major artery that sends blood to the heart (pulmonary artery hypertension).
Older children and adults with ventricular septal defects may develop Eisenmenger syndrome, which is characterized by the progressive impairment of the pulmonary blood vessels (vascular obstructive disease). Symptoms may include chest pain, difficulty breathing (dyspnea) after physical exertion, and episodes of fainting. Other symptoms may include the coughing up of blood from the lungs (hemoptysis) and abnormally low levels of oxygen in the circulating blood (hypoxia). Over time, hypoxia can result in clubbing of the fingers and the proliferation of red blood cells (polycythemia).
Some infants with small or moderate sized ventricular septal defects may be at increased risk for acute inflammation of the valves and lining of the heart (infective endocarditis).
The exact cause of VSDs is not known. These defects probably occur as the result of errors in the development of an embryo. During the early part of fetal development there is no wall (septum) to separate the left and right ventricles. As the fetus grows, so does a muscular wall that splits the lower chamber into two ventricles. If the muscle does not form a solid wall, a hole remains and is what is called the ventricular septal defect. The why and how of these developmental errors is not fully understood. However, research suggests that they may occur as the result of the complex interaction of many factors, both genetic and environmental (multifactorial).
Ventricular septal defects are rare congenital malformations of the heart that occur more frequently in males than females. Approximately 1 percent of newborns have a congenital heart defect. About 25 to 30 percent of these infants are diagnosed with ventricular septal defects. Of the babies born with VSDs, 80 to 90 percent present with a small hole and mild symptoms.
Most infants with ventricular septal defects have a single malformation that is not associated with any other disorder. Occasionally, infants may have ventricular septal defects in association with other malformation syndromes. These may include fetal alcohol syndrome, trisomy syndromes, fetal hydantoin syndrome (associated with a drug used to treat epilepsy), postrubella infection (German measles), maternal phenylketonuria (PKU), and other disorders.
The diagnosis of ventricular septal defects is confirmed by a thorough clinical evaluation and specialized tests that allow physicians to evaluate the structure and function of the heart as well as the exact nature of the defect. X-ray studies and electrocardiogram (EKG) results may help to confirm the diagnosis. In one procedure, ultrasonic waves are directed toward the heart (Doppler echocardiogram), enabling physicians to study the motion and function of the heart and the surrounding vessels. During cardiac catheterization, a small hollow tube (catheter) is inserted into a large vein and threaded through the blood vessels that lead to the heart. This procedure allows physicians to determine the rate of blood flow through the heart, measure pressure within the heart, and thoroughly identify anatomical abnormalities.
Although surgery is the definitive treatment for ventricular septal defects, it may not be recommended for all infants with these defects. Surgery is not indicated for infants with small ventricular septal defects that may close on their own or become less significant as the child matures and grows. Conservative treatment may include careful monitoring of symptoms and heart function.
Medical management of infants with ventricular septal defects before surgery includes treatment of the symptoms related to congestive heart failure. Drugs such as digoxin may help to prevent irregular heartbeats and excessively rapid heartbeats (tachycardia). Restriction of salt in the diet, drugs that help to eliminate excessive fluid from the body (diuretics), and bed rest may also be effective therapies for congestive heart failure. Nutritional considerations are also important in infants with ventricular septal defects. Respiratory infections should be treated vigorously and early. Because of the risk of bacterial infection of the lining of the heart and the valves (endocarditis), individuals with ventricular septal defects should be given antibiotic drugs before any surgical procedure, including dental procedures such as tooth extractions.
If symptoms persist after conservative treatment, open heart surgery is usually recommended to repair ventricular septal defects. Surgery during infancy or childhood has a high rate of success and it can prevent pulmonary vascular disease. One of several surgical procedures may be considered for the repair of the defect. The exact procedure is selected based upon the severity and location of the defect. Surgery may consist of closure of the hole in the septum with stitches (sutures) or with a patch (dacron or allograft).
Other indications for surgical repair in infants with ventricular septal defects include congestive heart failure that is not responsive to medical management, poor weight gain, and/or significant pulmonary artery hypertension. Surgery is also suggested when the heart is abnormally enlarged (cardiomegaly) or there is significant exchange of blood from the left to right side of the heart (shunting), with resistance to the entry of blood into the lungs.
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Studies are underway to devise nonsurgical techniques that may improve the treatment of ventricular septal defects.
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