Congenital Heart Defect

A congenital heart defect (CHD), also known as congenital heart anomaly or congenital heart disease, is a structural defect of the heart or major vessels present at birth. These defects are classified as cardiovascular diseases and can range from minor, asymptomatic issues to severe, life-threatening conditions.

The symptoms and severity depend on the specific type of CHD, which can include rapid breathing, bluish skin (cyanosis), poor weight gain, and fatigue. CHD is the most common type of birth defect, affecting millions globally and leading to a significant number of birth defect-related deaths annually.

Normal and defective heart structures

Signs and Symptoms

CHD symptoms vary widely, with some individuals exhibiting no symptoms while others may present with severe signs such as shortness of breath, cyanosis, fainting, heart murmurs, underdeveloped limbs and muscles, poor feeding or growth, and respiratory infections. Heart murmurs, which can sometimes be detected by auscultation, are often indicative of CHD but are not exclusive to it.

Digital clubbing with cyanotic nail beds

Associated Conditions

CHD is frequently associated with other medical conditions, collectively known as the VACTERL association, which includes vertebral anomalies, anal atresia, cardiovascular anomalies, tracheoesophageal fistula, esophageal atresia, renal anomalies, and limb defects.

Causes

The causes of CHD can be genetic, environmental, or a combination of both.

Genetic Factors

Genetic mutations are a major cause of CHD, often involving specific genes that regulate heart development. Some genetic syndromes associated with CHD include Down syndrome, Turner syndrome, and Marfan syndrome. Genetic testing methods such as karyotyping and chromosomal microarray analysis can identify these mutations.

Environmental Factors

Environmental factors that increase the risk of CHD include infections during pregnancy (e.g., rubella), maternal illnesses, and exposure to certain drugs or toxins. Maternal obesity and poor nutritional status also contribute to the risk.

Mechanisms and Development

The development of the heart is a complex process involving precise timing of cell growth, migration, and apoptosis. Disruptions at any stage can result in congenital defects. The heart starts as a simple tube in the embryo and undergoes folding and septation to form a four-chambered structure. Failures in these processes can lead to various CHDs, such as septal defects, obstructions, and anomalies in the great vessels.

Diagnosis

CHD can often be diagnosed prenatally using foetal echocardiography, typically performed during the second trimester of pregnancy. Postnatal diagnosis may occur immediately if the newborn exhibits cyanosis or later if symptoms develop over time.

Classification

CHDs are classified into several types:

• Hypoplasia: Underdevelopment of heart chambers, leading to conditions like hypoplastic left heart syndrome.
• Obstructive Defects: Narrowing or blockage of heart valves or vessels, such as pulmonic stenosis and aortic stenosis.
• Septal Defects: Openings in the septum between heart chambers, including atrial and ventricular septal defects.
• Cyanotic Defects: Conditions causing cyanosis, such as tetralogy of Fallot and transposition of the great vessels.

Treatment

Treatment options for CHD include medications like diuretics and digoxin, catheter-based procedures, and surgeries to correct structural abnormalities. In severe cases, multiple surgeries or heart transplantation may be necessary. Lifelong cardiac care from specialists is often required.

Mental health support is also very important, as individuals with CHD may experience emotional and psychological challenges, including depression and anxiety.

Epidemiology

CHD is the most common birth defect, occurring in about 1% of live births. Advances in medical care have improved survival rates, but CHD remains a leading cause of birth defect-related mortality.

Congenital heart anomalies deaths per million persons in 2012

Terminology

CHD is referred to by various terms, including congenital heart anomaly, congenital heart disease, and congenital cardiovascular malformations.