Congenital heart diseases occur due to abnormal heart development before a child is born. According to Medline Plus, a website of the National Institutes of Health, congenital heart disease is the most common type of birth defect and is responsible for more deaths in the first year of life than any other birth defect. "Essentials of Pathophysiology: Concepts of Altered Health States" by Carol Porth says that congenital heart disease can be classified as cyanotic or acyanotic.
Normal Blood Flow
To grasp the concepts of cyanotic and acyanotic heart disease, it is important to first understand how blood normally flows through the heart. Deoxygenated blood is transported to the right atrium of the heart and then to the right ventricle. The lungs then receive blood from the right ventricle through the pulmonary artery. The de-oxygenated blood becomes oxygenated in the lungs; from there, it flows to the left atrium and then the left ventricle. The oxygenated blood is then circulated to the rest of the body through the aorta.
Cyanotic and Acyanotic
Cyanotic and acyanotic heart diseases are defined based on how blood moves through the heart and occur due to abnormal openings or defects in the heart.
In cyanotic heart disease, de-oxygenated blood moves from the right side of the heart to the left side through abnormal openings or defects. It mixes there with oxygenated blood and is then distributed to the body through the aorta.
In acyanotic heart disease, oxygenated blood moves from the left side of the heart to the right side and then to the lungs. This occurs as a result of a hole between the left and right atria.
In cyanotic heart disease, blood that is not rich in oxygen and nutrients is delivered to all the organs in the body. This causes a child with cyanotic heart disease to develop bluish skin and mucus membranes due to low oxygen levels.
In acyanotic heart disease, the body receives oxygenated and non-de-oxygenated blood from the heart. Bluish skin coloration does not occur with acyanotic heart disease except when the body needs more oxygen than the heart can supply.
Types of Acyanotic Heart Disease
Acyanotic heart disease can be caused by an opening between the wall of the ventricles resulting in ventricular septal defect, or VSD. It can also be caused by a hole in the wall separating the atria of the heart which leads to atrial septal defect, or ASD. Other acyanotic heart diseases include patent ductus arteriosus, a defect in which there is an opening between the pulmonary artery and the aorta; pulmonary valve stenosis, a narrowing of the valve between the right ventricle and the pulmonary artery; aortic valve stenosis, a narrowing of the valve between the left ventricle and the aorta; and coarctation of the aorta, which is a narrowing in the part of the aorta that supplies blood to the entire body.
Types of Cyanotic Heart Disease
Tetralogy of Fallot is a cyanotic heart disease that is caused by four heart defects—a narrowing of the valve between the right ventricle and the pulmonary artery; an enlarged right ventricle; a hole between the left and right ventricles; and an aorta that is connected to both the right and left ventricles rather than the left. Transposition of the great vessels—another cyanotic heart disease—occurs when the pulmonary artery originates from the left ventricle and the aorta arises from the right ventricle. Other cyanotic heart diseases are pulmonary atresia, truncus arteriosus and hypoplastic left heart syndrome.
According to the National Heart Lung and Blood Institute, some congenital heart defects that lead to cyanotic or acyanotic heart diseases can be corrected through surgery while others may require no treatment at all. Holes in the heart can be stitched shut via surgery while narrowed valves can be opened using surgical procedures as well. Narrow blood vessels can also be widened during surgery. Medications are used to treat mild congenital heart defects, while a heart transplant may be necessary if a complex heart defect can't be repaired.