Congenital Heart Defects

Congenital heart defects are among the most common form of birth defects. More than 32,000 infants are born each year with some form of heart defect (1 out of every 125 to 150). The defect can be so slight that its effect does not appear for many years or until adulthood, while at other times the defect may require immediate attention.
Although heart defects are the leading cause of death in birth defect-related deaths, advances in medical care over the past few decades have drastically increased the chances of survival.

Congenital Heart Defects: Causes, Symptoms, Treatment, and Prevention

Congenital heart defects are sometimes also called congenital heart diseases, heart defects, and congenital cardiovascular malformations.

What is a congenital heart defect?

A congenital heart defect is a structural problem in the heart that is present at birth, whether it is inherited or caused by the environment. A baby’s heart begins to develop early and begins beating just 22 days after conception.
Between days 22 and 24, the heart begins to bend to the right and fold itself into a loop. By day 28, the tube has a general heart-shaped form with the structures of the chambers and blood vessels in place. It is during this time of development that structural defects can occur. These defects can affect the different parts of the heart as well as how it functions.
Congenital heart defects can disrupt the normal flow of blood through the heart. The defect may cause the blood flow to slow down, go in the wrong direction, go to the wrong place, or it may block the flow completely.

How does the heart work?

The heart is a muscle that pumps blood through the body. It is composed of four hollow sections (called chambers). Two are located on the right and two are on the left side, with the larger chambers toward the front and the smaller to the back.
Each chamber has a one-way opening that allows blood to flow in one direction only. The right side of the heart pumps blood to the lungs through vessels called pulmonary arteries where the blood picks up oxygen. This oxygen-filled blood then returns to the heart’s left side by way of the pulmonary veins, through the aorta and out to the various parts of the body.
As the oxygen is used by the body, the blood becomes darker and returns to the heart by the veins where the process begins all over again.

What causes congenital heart defects?

Heart defects can be caused by prenatal environmental hazards as well as genetic factors. Most of the time, the actual cause of heart abnormality is unknown.

Environmental factors

  • Viral Infections – Women who contract rubella (German Measles) during the first three months of pregnancy have an increased risk of having a baby with a heart defect. According to the Centers for Disease Control and Prevention (CDC), women should avoid becoming pregnant for one month after receiving the MMR vaccine. If a woman is not vaccinated, she should talk to her healthcare provider about any possible risks.
  • Medication – Some medications can increase the risk. These medications include lithium (used to manage bipolar disorder), Accutane (acne medication) and, possibly, some anti-seizure medications.
  • Alcohol – Consuming alcohol during pregnancy may cause heart defects. Babies born with fetal alcohol syndrome (FAS) often have problems with their heart.
  • Smoking – According to the U.S. National Library of Medicine and the National Institute of Health, HealthDay News reported on November 14, 2006, that a new study indicates that women who smoke during early pregnancy are more likely to have a child with congenital heart defects. The study seems to indicate that women who smoked at some point in the month before conception through the end of the first trimester were 60% more likely to have babies with congenital heart defects. Exposure to second-hand smoke also increases the risk of congenital heart defects.
  • Cocaine – Studies suggest that the use of cocaine during pregnancy increases the risk of heart defects in infants.
  • Maternal chronic illnesses – These may include diabetes, phenylketonuria (PKU) and a deficiency in the B vitamin folic acid.

Genetic factors

  • Heredity – Malformations are more likely to occur in siblings or offspring of individuals with heart defects than those without.
  • Mutations – Several mutations can affect the formation of the heart and lead to congenital heart malformations such as atrial septal defect (a hole between the upper chambers of the heart).
  • Linked with other birth defects – More than one-third of children born with Down syndrome have heart defects. About 25% of girls with another chromosomal abnormality called Turner syndrome have heart defects.

Is it possible to detect congenital heart defects before birth?

Many heart defects can be detected before birth through the use of a special type of sonography called fetal echocardiography. Sound waves are used to create a picture of the baby’s heart. Health care providers can use the information from this ultrasound to diagnose the condition and develop a treatment plan.
Sometimes medications can be used to alter the beating of the heart and prevent further damage. If the heart defect can’t be treated before birth, the health care providers will be prepared to give treatment as soon as needed after birth.

What are the signs and symptoms?

Serious heart defects usually become evident within a few days, weeks or months of life.
The most common signs and symptoms in newborns include:

  • A heart murmur
  • A bluish tint to skin, lips, and fingernails (“blue baby”)
  • Fast breathing/shortness of breath
  • Poor feeding in infants because they tire easily while nursing
  • Poor weight gain in infants

The signs and symptoms vary depending on the severity of the defect. Some infants have no signs or symptoms while others have severe or life-threatening symptoms.

What are various types of congenital heart defects?

The number of congenital heart defects is vast. According to the National Heart Lung and Blood Institute, the most common types of congenital heart defects are:

  • Anomalous pulmonary venous return
  • Atrial septal defect (ASD)
  • Atrioventricular septal defect (AVSD)
  • Aortic valve stenosis
  • Coarctation of the aorta
  • Ebstein’s anomaly
  • Patent ductus arteriosus (PDA)
  • Pulmonary valve atresia
  • Pulmonary valve stenosis
  • Tetralogy of Fallot
  • Transposition of the great arteries or vessels
  • Tricuspid valve atresia
  • Truncus arteriosus
  • Ventricular septal defect (VSD)

How can congenital heart defects be treated?

Today, there is good news for babies diagnosed with congenital heart defects. Most heart defects can be either corrected or at least helped through surgery, medicine or special devices such as artificial valves, catheters, and pacemakers.
Heart transplants are also a possibility. These advances have helped nearly 1 million children in the United States with heart defects to survive to adulthood. Many of these surgeries are performed before the age of two.

Can congenital heart defects be prevented?

Most congenital heart defects cannot be prevented. A woman can do some things to reduce the risk of congenital heart defects though. She can have a preconception appointment with her health care provider especially if she has any chronic health conditions, such as PKU, diabetes or a seizure disorder.
During this appointment, she can discuss things such as what type of dietary supplements should be taken and the necessity and safety of a Rubella vaccine. The woman should also avoid substances such as alcohol, tobacco and any unnecessary prescription or non-prescription medications.

What about a future with congenital heart defects?

Much research is being conducted both into the cause and the treatment of congenital heart defects. Many types of congenital heart defects are repairable. In many cases, the defect will have no long-term effect on the child’s health or activities and may not even be identified until adulthood.

Want to Know More?

The following organizations can provide additional information:
March of Dimes:
U.S. National Library of Medicine:
National Heart Lung and Blood Institute:
Mayo Clinic:
Congenital Heart Defects:

Compiled using sources from:
American Heart Association,
March of Dimes,
Mayo Clinic,
National Heart Lung and Blood Institute,
U.S. National Library of Medicine and the National Institutes of Health,