- Congenital heart defects (CHDs) are structural abnormalities of the heart or great vessels that are present at birth and represent the most common type of congenital malformation worldwide. They arise from disruptions in the complex process of embryonic heart development, which involves coordinated cell migration, proliferation, and morphogenesis.
- CHDs can range from relatively minor anomalies that may resolve spontaneously or cause few symptoms, to severe malformations that are life-threatening without medical or surgical intervention. Advances in prenatal screening, surgical techniques, and long-term care have greatly improved outcomes for individuals with CHDs, but they remain a leading cause of infant morbidity and mortality related to congenital conditions.
- The causes of CHDs are multifactorial, involving a combination of genetic, epigenetic, and environmental influences. Genetic contributions may include chromosomal abnormalities such as Down syndrome (trisomy 21), Turner syndrome, or DiGeorge syndrome (22q11.2 deletion), as well as mutations in single genes regulating cardiac morphogenesis. Environmental risk factors include maternal diabetes, viral infections (such as rubella), exposure to teratogenic drugs or alcohol, obesity, and poor nutritional status (e.g., folate deficiency). In many cases, however, the exact cause remains unknown.
- Clinically, CHDs are categorized into cyanotic and acyanotic defects, depending on whether they cause mixing of oxygenated and deoxygenated blood, leading to reduced oxygen levels in systemic circulation. Acyanotic defects include conditions such as ventricular septal defect (VSD), atrial septal defect (ASD), patent ductus arteriosus (PDA), and coarctation of the aorta. These defects typically increase blood flow to the lungs (left-to-right shunt) and may present with symptoms like shortness of breath, poor growth, or recurrent respiratory infections. Cyanotic defects, such as tetralogy of Fallot, transposition of the great arteries, and truncus arteriosus, result in systemic circulation of poorly oxygenated blood (right-to-left shunt), leading to cyanosis, digital clubbing, and in severe cases, hypoxemic spells.
- Diagnosis of CHDs often occurs through prenatal imaging using fetal echocardiography, or postnatally through detection of murmurs, cyanosis, or heart failure symptoms. Echocardiography is the primary diagnostic tool, while chest X-rays, electrocardiography (ECG), cardiac MRI, and CT angiography may provide additional details. Newborn screening with pulse oximetry has become an important tool for early detection of critical CHDs.
- Treatment strategies depend on the type and severity of the defect. Some small ASDs or VSDs may close spontaneously and require only monitoring, while larger defects or complex malformations often need surgical or catheter-based interventions. For example, surgical correction of tetralogy of Fallot, arterial switch procedure for transposition of the great arteries, and device closure of septal defects are common interventions. Medical management may include drugs such as diuretics, prostaglandins (to maintain ductus arteriosus patency in critical CHDs), or ACE inhibitors for heart failure symptoms. Lifelong follow-up is often necessary, as repaired CHDs can still predispose individuals to complications such as arrhythmias, pulmonary hypertension, valve dysfunction, and heart failure.
- Beyond childhood, improvements in surgery and medical care mean that many individuals with CHDs now survive into adulthood, giving rise to a growing population of adults with congenital heart disease (ACHD). This group often requires specialized long-term care, including monitoring for complications, pregnancy counseling, and psychosocial support. Research into stem cell therapy, tissue engineering, and advanced surgical techniques continues to offer hope for improving outcomes and quality of life in CHD patients.
