The miracle of life: A baby develops from the joining of two cells following a predictable path. The heart, essential for pumping blood, begins to form during the first weeks of life. It begins as a tube that grows so fast it must bend and twist, forming the familiar shape. By the sixth week of pregnancy the heart begins pumping blood, according to MayoClinic.com. The complex interactions between dividing and differentiating cells can lead to errors resulting in abnormalities within the heart.
Heart Valve Function
The heart consists of four chambers; the two upper chambers known as the atria receive blood, and the two lower chambers known as ventricles pump blood. A wall called the septum separates the right and left side of the heart. Heart valves separate the atria and the ventricles as well as the ventricles and the arteries. The heart valves function like trap doors, opening and closing in conjunction with the contractions of the heart to ensure that blood flows in only one direction.
Types of Heart Valve Defects
The most common valve defect, according to the National Heart Lung and Blood Institute, involves the narrowing of the pulmonary valve that separates the right ventricle and the pulmonary artery leading to the lungs--a condition known as pulmonary valve stenosis. The flaps of the valve that open and close, known as leaflets, develop too thick and stiff or may even be fused together, preventing the valve from opening fully.
Other heart valve abnormalities prevent the valve from closing completely, causing regurgitation--the backflow of blood. Atresia, a more serious type of heart valve defect, occurs when an opening for the blood to flow through fails to form.
Causes
In most cases doctors cannot determine the actual cause of the heart valve abnormality. Genetics may play a role in some types of defects. Therefore, a parent with a congenital heart valve defect may be more likely to have a child with the same type of defect. The occurrence of other genetic defects, such as Down syndrome, increases the likelihood of a heart defect. Smoking during pregnancy also increases the risk for defects in utero, including heart defects.
Signs and Symptoms
Mild heart valve defects produce no other signs or symptoms except for a heart murmur---a swishing sound that doctors can hear through a stethoscope. More serious defects can affect the flow of blood, resulting in signs such as rapid or labored breathing, fatigue and poor feeding. Heart valve abnormalities can cause the heart to work harder to pump blood, which over time can lead to an enlarged heart, known as cardiomyopathy, and heart failure---the inability of the heart to pump enough blood to meet the body's needs.
Outlook
Congenital heart defects affect 8 of every 1000 babies born, making it the most common type of birth defect, according to the National Heart Lung and Blood Institute. Mild defects to heart valves require no specific treatments, while more complex defects need to be fixed through either a catheter procedure or open heart surgery. In either case, advancement in treatment allows most children to survive to adulthood leading active, normal lives.
