• Ventricular septal defect is the most common congenital heart defect

• Many common congenital heart defects are treatable with timely intervention

• Some CHDs may close on their own, while others require surgery

• Early diagnosis improves survival and long-term outcomes

• Most children with CHD now survive into adulthood with proper care

Congenital heart defects (CHDs) are the most common congenital malformations seen at birth and represent the most common congenital heart defects diagnosed worldwide. They are structural abnormalities of the heart present at birth and develop during early fetal life when the heart does not form as expected. CHDs are the most frequently occurring birth defects worldwide and contribute significantly to infant morbidity and mortality. ¹

Congenital heart defects affect approximately 1 percent of live births worldwide and arise from disruptions in heart development during the first six weeks of fetal life.

While some congenital heart defects are mild and compatible with normal growth and daily life, others require early medical or surgical intervention to prevent complications.

Among the wide spectrum of heart defects, a small group accounts for the majority of diagnosed cases.

Congenital heart defects arise during early cardiac development in the embryo. Genetic factors, environmental exposures, and disruptions in normal heart formation pathways contribute to their occurrence. Despite advances in genetic research, the exact cause remains unidentified in many cases.²

Ventricular septal defect is the most common congenital heart defect diagnosed worldwide. It involves an opening in the wall that separates the heart’s two lower chambers, known as the ventricles. This opening allows blood to pass from the left ventricle to the right ventricle, increasing blood flow to the lungs.

Small VSDs may close on their own during infancy, while larger defects can cause breathing difficulty, poor weight gain, and recurrent respiratory infections. Diagnosis usually occurs through echocardiography, and treatment depends on the size and clinical impact of the defect.¹

Quick facts

• Most common CHD worldwide

• Small defects may close spontaneously

• Large defects may cause heart failure symptoms

An atrial septal defect is a hole in the wall separating the two upper chambers of the heart, called the atria. This defect allows oxygen-rich blood from the left atrium to mix with oxygen-poor blood in the right atrium.

ASDs often produce few symptoms during early childhood and may remain undetected until adulthood. Over time, untreated ASDs can lead to enlargement of the right side of the heart and pulmonary hypertension. Closure using catheter-based techniques or surgery is recommended for significant defects.¹

Quick facts

• Often asymptomatic in childhood

• May present in adulthood

• Can cause pulmonary hypertension if untreated

Patent ductus arteriosus occurs when a normal fetal blood vessel, the ductus arteriosus, fails to close after birth. This vessel normally diverts blood away from the lungs before birth but should close shortly after delivery.

When it remains open, extra blood flows into the lungs, increasing the workload on the heart. PDAs are more common in premature infants. Treatment may include medications, catheter-based closure, or surgery, depending on the size and symptoms.¹

Quick facts

• More common in premature babies

• Causes excess blood flow to lungs

• Treatable with medication or closure procedures

Pulmonary stenosis refers to narrowing of the pulmonary valve or the artery leading from the heart to the lungs. This narrowing restricts blood flow from the right ventricle to the lungs.

Mild cases may cause no symptoms, while severe narrowing can lead to fatigue, shortness of breath, and cyanosis. Balloon valvuloplasty or surgical repair is commonly used to relieve obstruction.²

Quick facts

• Severity varies from mild to severe

• Balloon valvuloplasty is commonly used

• Symptoms depend on degree of narrowing

Tetralogy of Fallot is the most common cyanotic congenital heart defect. It consists of four structural abnormalities: ventricular septal defect, pulmonary stenosis, right ventricular hypertrophy, and displacement of the aorta.

These combined defects reduce oxygen delivery to the body, causing bluish discoloration of the skin and lips. Surgical repair during infancy is the standard treatment and has significantly improved survival into adulthood.³

Quick facts

• Causes reduced oxygen delivery

• Leads to cyanosis

• Surgical repair is standard treatment

Genetic and Developmental Factors

Advances in prenatal diagnosis, surgical techniques, and long-term care have improved outcomes for children born with the most common congenital heart defects.

Both isolated gene changes and broader genetic syndromes contribute to these conditions. However, the exact cause remains unidentified in many cases. ^2,3

Outlook

Advances in prenatal diagnosis, surgical techniques, and long-term care have improved outcomes for individuals with congenital heart defects.

Many affected children now survive into adulthood and lead active lives, although ongoing medical follow-up is often required. ³

References

1. Lucile Houyel and Sigolène M. Meilhac, “Heart Development and Congenital Structural Heart Defects,” Annual Review of Genomics and Human Genetics 22 (August 31, 2021): 257–284, https://doi.org/10.1146/annurev-genom-083118-015012.

2. Brian Kloesel, Joseph A. DiNardo, and Simon C. Body, “Cardiac Embryology and Molecular Mechanisms of Congenital Heart Disease: A Primer for Anesthesiologists,” Anesthesia & Analgesia 123, no. 3 (September 2016): 551–569, https://doi.org/10.1213/ANE.0000000000001451.

3. Connor M. Stark, Benjamin N. Hughes, Jacob P. Schacht, and Tania M. Urbina, “Decoding Hearts: Genetic Insights and Clinical Strategies in Congenital Heart Disease,” NeoReviews 26, no. 2 (February 1, 2025): e73–e88, https://doi.org/10.1542/neo.26-2-010.