Birth Defects of the Heart
This study aims to find the genes that influence susceptibility to congenital heart defects. It is part of a larger study called the National Birth Defects Prevention Study (NBDPS) conducted by the Centers for Disease Control and Prevention (CDC). This study is looking at many factors that may contribute to birth defects, including genetic, environmental and lifestyle factors. The specific conditions studied include left-sided heart defects and conotruncal defects.
Conotruncal Heart Malformations
Conotruncal heart defects are structural abnormalities of the cardiac outflow tract. This means that the pathway for the blood to leave the heart and circulate to the body or to the lungs is disrupted.
Tetralogy of Fallot (TOF)
Generally, there are four defects of the heart in individuals with Tetralogy of Fallot (TOF). These are:
- A ventricular septal defect (VSD): a hole between the two bottom chambers (ventricles) of the heart.
- Pulmonic stenosis: Right ventricular outflow tract obstruction, which is caused by a narrowing at or just below the pulmonary valve. The degree of stenosis, or narrowing of the vessel, varies among individuals with TOF.
- Overriding aorta: The aorta is positioned over the ventricular septal defect VSD instead of in the left ventricle.
- Right ventricular hypertrophy (RVH): The right ventricle has more muscle than normal and may also be dilated.
Truncus Arteriosus (TA)
TA is a defect in which a large, single great vessel arises from the ventricular septal defect (VSD).
A VSD is a hole between the two bottom chambers (ventricles) of the heart.
The truncus arteriosus carries blood to both the body and the lungs. Surgical repair is necessary to separate the blood outflow to the body from the blood outflow to the lungs.
Interrupted Aortic Arch (IAA)
IAA a defect in which the great vessel that carries blood from the heart to the body, called the aorta, is divided into two parts.
Coarctation of the Aorta
Aortic coarctation is a defect in which the great vessel that carries blood from the heart to the body, called the aorta, is narrowed.
Transposition of the Great Arteries (TGA)
TGA is a defect in which the position of the aorta and the pulmonary artery are reversed. Normally, the aorta carries blood rich in oxygen from the heart to the body, and the pulmonary artery carries blood low in oxygen from the heart to the lungs.
In individuals with TGA, the aorta carries blood low in oxygen and circulates it to the body while the pulmonary artery carries oxygen rich blood back to the lungs.
Double Outlet Right Ventricle (DORV)
DORV is a defect in which both the aorta and the pulmonary artery arise from the right ventricle. Normally the pulmonary artery arises form the left ventricle.
In DORV, the only outlet from the left ventricle is a ventricular septal defect (VSD) or a hole between the right and left ventricles.
Hypoplastic Left Heart Syndrome (HLHS)
HLHS is characterized by underdevelopment or hypoplasia of the left side of the heart such that the heart cannot effectively pump blood to the body.
Bicuspid Aortic Valve (BAV)
Normally, the aortic valve, which separates blood in the left ventricle from blood in the aorta has three flaps or leaflets.
BAV is a defect in which the valve has only two leaflets instead of three. This can cause valve leakage or obstruction of blood flow across the valve.
Atrial Septal Defect (ASD)
The heart has four chambers, a right and left upper chamber or atruim and a right and left lower chamber or ventricle.
The right and left sides of the atria and ventricles are separated by a wall or septum. An ASD is an abnormal hole in the septum separating the atria.
Ventricular Septal Defect (VSD)
A VSD is a hole in the wall, or septum, between the two bottom chambers or ventricles of the heart.