Congenital Heart Disease

Congenital heart disease is a structural abnormality of the heart or great vessels that is present from birth, arising from abnormal development of the heart during embryonic life. It ranges from simple lesions, such as small septal defects, to complex malformations affecting the connections and chambers of the heart, and it is the most common group of birth defects.

Definition

Congenital heart disease is a structural malformation of the heart or great vessels present at birth, resulting from abnormal cardiac development and producing abnormal flow through shunts, obstruction to flow, or abnormal chamber and vessel connections.

Scope

This topic covers the concept of a developmentally-acquired structural cardiac lesion, the broad categories of defect (shunt lesions, obstructive lesions, and complex malformations), the distinction between cyanotic and acyanotic physiology, and the growing population of adults living with congenital heart disease. It is a reference entry on the concepts and classification, not clinical guidance for any individual.

Core questions

• Which structures are malformed — septa, valves, great vessels, or chamber connections?
• Does the lesion produce an abnormal shunt, obstruction to flow, or a complex combination?
• Is the physiology cyanotic or acyanotic, and how does the lesion change across the lifespan?

Key concepts

• Shunt lesions (e.g. septal defects, patent ductus)
• Obstructive lesions (e.g. coarctation, valvar obstruction)
• Cyanotic versus acyanotic physiology
• Left-to-right and right-to-left shunting
• Eisenmenger physiology
• Adult congenital heart disease (ACHD)
• Embryonic cardiac development

Mechanisms

Congenital defects arise when the embryonic heart's septation, valve formation, or great-vessel connections develop abnormally. The resulting lesions are often grouped by their effect on flow: shunt lesions create an abnormal communication between chambers or vessels (such as atrial or ventricular septal defects and patent ductus arteriosus), typically driving left-to-right flow and a volume load; obstructive lesions impede flow (such as coarctation of the aorta or valvar stenosis) and impose a pressure load; and complex malformations combine several abnormalities. Defects that allow deoxygenated blood to reach the systemic circulation produce cyanotic physiology. Long-standing high-flow shunts can raise pulmonary vascular resistance until shunt flow reverses (Eisenmenger physiology). Because lesions and their repairs evolve over decades, many patients require lifelong follow-up as adults (Baumgartner, 2021).

Clinical relevance

Congenital heart disease is the most common category of birth defect and, thanks to advances in surgery and catheter-based treatment, most affected children now survive to adulthood, creating a large adult congenital population with distinctive long-term needs. The physiology also has specific relevance in pregnancy (Regitz-Zagrosek, 2018). This entry describes concepts and classification and is not a basis for individual diagnosis or treatment.

Epidemiology

Congenital heart disease affects roughly a few to several per thousand live births and is the most common group of structural birth defects; with modern treatment the majority of patients reach adulthood, so the number of adults living with congenital heart disease now exceeds the number of affected children in many high-income settings (Baumgartner, 2021).

History

Systematic understanding of congenital heart disease advanced with the development of paediatric cardiology, cardiac catheterisation, and cardiac surgery in the twentieth century, which transformed once-fatal malformations into survivable, often correctable conditions. The resulting survival of patients into adulthood gave rise to adult congenital heart disease as a distinct field, codified in dedicated guidelines (Baumgartner, 2021).

Seminal works

• baumgartner-2021
• regitz-zagrosek-2018

Frequently asked questions

What does it mean for a heart defect to be congenital?

It means the structural abnormality of the heart or great vessels is present from birth, having arisen during the heart's development before birth, as opposed to acquired heart disease that develops later in life.

Why is adult congenital heart disease now a distinct field?

Advances in surgery and catheter-based treatment mean that most children with congenital heart disease now survive into adulthood. This has created a large and growing population of adults with repaired or unrepaired lesions whose long-term physiology and follow-up needs differ from those of children.