Cardiovascular diseases

Congenital heart defects

Cardiovascular diseases
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Congenital heart defects
Last update: 03-07-2025

How else can it be called?

  • Congenital heart diseases

  • ICD-10: Q24

  • ICD-11: LA8A

Introduction

Congenital heart defects, or congenital heart diseases, are abnormalities in the structure and function of the heart present from birth.

The defect can be so mild that the baby appears healthy for many years, or so severe that it is life-threatening at birth.

Heart defects are among the most common congenital anomalies and the leading cause of death related to them. However, advances in diagnosis and surgical treatment over the past 50 years have significantly improved survival rates.

Heart defects begin in early pregnancy, during heart formation, and often become apparent in early infancy

They can affect any part of the heart or its function.

What is the incidence of congenital heart defects?

Congenital heart defects are the most common congenital anomaly in newborns, affecting 8 out of every 1,000 births worldwide.

Only 2 or 3 out of every 1,000 newborns present with severe symptoms.

In about 50% of cases, the diagnosis is made within the first week of life.

Currently, around 80% of patients survive, resulting in a significant adult population with congenital heart disease, representing 0.3% of all adults.

What are the main functions of the heart?

The heart is a muscle that pumps blood throughout the body. It is divided into four hollow chambers: two atria and two ventricles. One atrium and one ventricle are located on the right side of the heart, and the other two on the left side. Inside the heart, there are four valves (one-way openings) that allow blood to flow forward but prevent it from flowing backward.

Blood travels from the heart to the lungs, where it picks up oxygen. The oxygen-rich (bright red) blood returns to the heart. The heart then pumps this oxygenated blood throughout the body via the arteries. As the body's tissues and organs use the oxygen, the blood turns dark red and returns to the heart through the veins, where the process begins again.

What are the main congenital heart defects?

The most common congenital heart defects, according to their frequency, are:

  • Septal defects: Holes in the wall (septum) dividing the upper or lower chambers prevent proper circulation, forcing the heart to work harder. Surgery involves closing the hole with stitches or a patch. Small holes may close on their own or may not require treatment.
    • Ventricular septal defect: 30 to 35% of all congenital heart disease cases.
    • Atrial septal defect (foramen secundum): 6 to 8%.
  • Patent ductus arteriosus: 6 to 8% of cases. Before birth, blood bypasses the lungs through the ductus arteriosus. This vessel should close shortly after birth. If it remains open, blood flow is abnormal. It is more common in premature babies. Treatment is usually with medication; surgery is needed if it does not close.
  • Coarctation of the aorta: 5 to 7%. The aorta is narrowed at birth, obstructing normal blood flow. Surgery may involve removing the narrowed segment or widening it with a balloon catheter.
  • Tetralogy of Fallot: 5 to 7%. A combination of four defects prevents blood from reaching the lungs, causing cyanosis (bluish skin). Early surgery allows most children to live normal or near-normal lives.
  • Heart valve abnormalities: Some babies are born with closed or narrowed valves, blocking blood flow. Surgery or balloon catheters can repair or replace the valves.
    • Pulmonary valve stenosis: 5 to 7%
    • Aortic valve stenosis: 4 to 7%.
  • Transposition of the great arteries (TGA): 3 to 5%. The main arteries (aorta and pulmonary artery) are reversed, causing improper circulation. Advances in surgery have improved survival in these cases.
  • Other congenital heart defects include:
    • Truncus arteriosus
    • Tricuspid atresia
    • Single ventricle
    • Double outlet right ventricle

What causes congenital heart defects?

In most cases, the cause of abnormal heart development in babies is unknown.

Genetic factors seem to play a primary role, although environmental factors are involved in 2 to 4% of cases.

Genetic factors: Although most families have only one child with congenital heart disease, the risk is higher in siblings or offspring of individuals with heart defects. Heart defects can also be part of genetic syndromes. For example:

  • Nearly 50% of children with Down syndrome have congenital heart disease.
  • About 90% of children with trisomy 18 (Edwards syndrome).
  • Around 40% with Turner syndrome.

Environmental factors:

  • Maternal illnesses during pregnancy, mainly diabetes mellitus, phenylketonuria, systemic lupus erythematosus, and viral infections like rubella during the first trimester (congenital rubella syndrome).
  • Certain medications, such as isotretinoin, lithium (for mental disorders), some anti-seizure drugs, warfarin, and vitamin A derivatives.
  • Alcohol and cocaine during pregnancy may also increase the risk.

What are the symptoms of a congenital heart defect?

Some babies and children with heart defects have no symptoms. Many may present an abnormal sound during auscultation, called a murmur.

The main sign that can indicate a congenital heart condition is a bluish or purplish coloration of the skin, called cyanosis, which is caused by a lack of oxygen in the blood.

Certain heart defects prevent the heart from pumping enough blood to the lungs or other parts of the body, which can lead to heart failure.

The affected child may experience palpitations and difficulty breathing, especially during physical activity. In infants, this difficulty occurs during feeding, causing them to be unable to eat properly and preventing normal weight gain.

Swelling (edema) may also appear in the legs, abdomen, or around the eyes.

How is a congenital heart defect diagnosed?

In general, all newborns undergo skin color monitoring and pulse oximetry, a test that measures blood oxygen levels through the skin, to detect congenital heart defects that may cause cyanosis at an early stage.

If oxygen levels are low, the skin appears cyanotic, or there are other symptoms suggestive of a heart condition, two initial tests are performed:

  • Chest X-ray
  • Electrocardiogram

If these tests show abnormal results, oxygen saturation remains below 95% on pulse oximetry, or murmurs or other problems are detected during physical examination, an echocardiogram is performed by an experienced cardiologist to make the definitive diagnosis.

What is the treatment for a congenital heart defect?

The outlook has never been better for infants and children with congenital heart defects. Today, most defects can be corrected, at least partially, through surgery, medication, or devices such as artificial valves and pacemakers.

Until very recently, temporary repairs were often necessary to delay corrective surgery until later in childhood. Today, half of the children who require surgical repair undergo surgery before the age of 2.

How can a congenital heart defect or its complications be prevented?

The fetus inside the womb can be observed using sound waves, known as ultrasound. A special type of ultrasound, echocardiography, can accurately detect many heart defects. If a heart defect cannot be treated before birth, knowing about it allows doctors to be prepared to provide the necessary treatment as soon as the baby is born.

Most congenital heart defects cannot yet be prevented. However, there are some steps that can reduce the risk of having a baby with a heart defect.

Every woman of childbearing age should ensure, before any pregnancy, that she is immune to rubella, and get vaccinated if she is not.

Every pregnant woman should avoid alcohol and drugs.

Women with chronic illnesses such as diabetes, epilepsy, or phenylketonuria should consult their doctors before trying to conceive so that their medications and/or diets can be adjusted to improve the baby's prospects.

Parents who have had an affected child are more likely than others to have a second child with the same heart defect, although the chances are generally very small.

Parents who themselves carry a congenital heart defect are also at greater risk of having a child with a heart defect. In these cases, detailed ultrasounds during pregnancy can be very helpful in enabling early treatment.

Medically reviewed by Yolanda Patricia Gómez González Ph.D. on 03-07-2025

Bibliography

  • First Aid for the Basic Sciences: Organ Systems (3rd Ed) 2017, Tao Le, William L. Hwang, Vinayak Muralidhar, Jared A. White and M. Scott Moore, ISBN: 978-1-25-958704-7, Pag. 7.
  • Robbins Basic Pathology (10th Ed) 2018, Vinay Kumar, Abul K. Abbas, Jon C. Aster, ISBN: 978-0-323-35317-5, Pag. 403.

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