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Congenital Heart Defects

When the heart or blood vessels near the heart do not develop normally before birth, a condition called congenital heart defect occurs (congenital means "existing at birth").

Most heart defects either cause an abnormal blood flow through the heart or obstruct blood flow in the heart or vessels (obstructions are called stenoses and can occur in heart valves, arteries or veins). A hole between two chambers of the heart is an example of a very common type of congenital heart defect.

More rare defects include those in which:

  • The right or left side of the heart is incompletely formed (hypoplastic)
  • Only one ventricle is present
  • Both the pulmonary artery and aorta arise from the same ventricle
  • The pulmonary artery and aorta arise from the "wrong" ventricles

Obstructive Defects

  • Aortic stenosis (AS): The aortic valve between the left ventricle and the aorta did not form properly and is narrowed, making it difficult for the heart to pump blood to the body. A normal valve has three leaflets or cusps, but a stenotic valve may have only one cusp (unicuspid) or two cusps (bicuspid). In some children, chest pain, unusual tiring, dizziness or fainting may occur. Otherwise, most children with aortic stenosis have no symptoms. But, even mild stenosis may worsen over time, and a catheter-based procedure or surgery may be needed to correct the blockage or the valve may need to be replaced with an artificial one.
  • Pulmonary stenosis (PS): The pulmonary, or pulmonic, valve, located between the right ventricle and the pulmonary artery opens to allow blood to flow from the right ventricle to the lungs. When a defective pulmonary valve does not open properly, it causes the heart to pump harder than normal to overcome the obstruction. Usually, the obstruction can be corrected by a catheter-based procedure known as balloon valvuloplasty, although in some patients, open heart surgery may be needed.
  • Bicuspid aortic valve: In this condition, an infant is born with a bicuspid valve which has only two flaps. (A normal aortic valve has three flaps that open and close). If the valve becomes narrowed, it is more difficult for the blood to flow through, and often the blood leaks backward. Symptoms usually do not develop during childhood, but are often detected during the adult years.
  • Subaortic stenosis: This condition refers to a narrowing of the left ventricle just below the aortic valve. Normally, blood passes through it to go into the aorta. However, subaortic stenosis limits the blood flow out of the left ventricle, often resulting in an increased workload for the left ventricle. Subaortic stenosis may be congenital or caused by a form of cardiomyopathy.
  • Coarctation of the aorta (coarct): In this condition, the aorta is narrowed or constricted, obstructing blood flow to the lower part of the body and increasing blood pressure above the constriction. Usually there are no symptoms at birth, but they can develop as early as the first week after birth. If severe symptoms of high blood pressure and congestive heart failure develop, surgery is necessary. Less severe cases may not be detected until a child is older but can result in long-term health problems if not corrected.

Septal Defects

Some congenital heart defects allow blood to flow between the right and left chambers of the heart because an infant is born with an opening in the wall (or septum) that separates the right and left sides of the heart. Septal defects include:

  • Atrial septal defect (ASD): In this condition, there is an opening between the two upper chambers of the heart — the right and left atria — causing an abnormal blood flow through the heart. The ASD may be closed by catheter-based techniques or open-heart surgery. Closing the atrial defect by open heart surgery in childhood can often prevent serious problems later in life.
  • Ventricular septal defect (VSD): In this condition, a hole is present between the two lower chambers of the heart. Because of this hole, blood from the left ventricle flows back into the right ventricle, due to higher pressure in the left ventricle. This causes extra blood to be pumped into the lungs by the right ventricle, which can create congestion in the lungs. While some VSDs close on their own, others require surgery to repair the hole.

Cyanotic Defects

Cyanotic defects are defects in which blood pumped to the body contains less-than-normal amounts of oxygen. Cyanotic defects include:

  • Tetralogy of Fallot
  • Tricuspid atresia
  • Transposition of the great arteries

Other Defects

  • Hypoplastic left heart syndrome (HLHS): In this condition, the left side of the heart, including the aorta, aortic valve, left ventricle and mitral valve, is underdeveloped. Within a few days of birth, babies with this syndrome become ashen (gray), have diminished or absent pulses in the legs, have difficulty breathing and are unable to feed. Treatment is surgical and typically requires three operations.
  • Patent ductus arteriosus (PDA): This condition results from failure of the PDA to close normally after birth, allowing blood to mix between the pulmonary artery and the aorta. When it does not close, extra blood may flood the lungs and cause pulmonary congestion. Patent ductus arteriosus is often seen in premature infants.
  • Ebstein's anomaly: In this defect, there is a downward displacement of the tricuspid valve (located between the upper and lower chambers on the right side of the heart) into the right bottom chamber of the heart (or right ventricle). This means the atrium is larger than normal and the ventricle is smaller than normal, which can lead to rhythm abnormalities and heart failure. It is usually associated with an atrial septal defect.

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