Congenital Heart Defects: Comprehensive Overview
Classification and Epidemiology
Congenital heart disease (CHD) occurs in approximately 0.4% to 1% of live births, with over 85% of affected infants now surviving to adulthood due to improved surgical and medical management. 1
CHD is fundamentally divided into three complexity categories based on anatomic and physiological severity 1:
Simple CHD (Class I)
- Isolated small atrial septal defect (ASD) 1
- Isolated small ventricular septal defect (VSD) 1
- Mild isolated pulmonic stenosis 1
- Previously repaired secundum ASD or VSD without residual shunt 1
Moderate Complexity CHD (Class II)
- Atrioventricular septal defects (AVSD) 1
- Coarctation of the aorta 1
- Patent ductus arteriosus (moderate to large) 1
- Ebstein anomaly 1
- Repaired tetralogy of Fallot 1
- Congenital aortic or mitral valve disease 1
- Pulmonary valve stenosis or regurgitation (moderate or greater) 1
- Anomalous coronary arteries 1
Great Complexity CHD (Class III)
- All cyanotic congenital heart defects (unrepaired or palliated) 1
- Single ventricle physiology (including hypoplastic left heart) 1
- Fontan procedure 1
- Transposition of the great arteries (d-TGA or l-TGA) 1
- Truncus arteriosus 1
- Pulmonary atresia 1
- Double-outlet ventricle 1
Signs and Symptoms by Defect Type
Acyanotic Lesions
The primary clinical concern in acyanotic lesions is congestive heart failure rather than hypoxia. 2
Key presenting features include: 2
- Feeding difficulties with concurrent tachypnea 2
- Sweating during feeds 2
- Subcostal retractions 2
- Severe growth impairment/failure to thrive 2
Cyanotic Lesions
In cyanotic lesions, hypoxia is the predominant problem rather than congestive heart failure. 2
Clinical manifestations include: 3, 2
- Central cyanosis (visible in mucous membranes) 3
- Hypoxemic episodes ("tet spells" in tetralogy of Fallot) 3
- Clubbing of digits (in chronic cases) 3
- Exercise intolerance 3
Physiological Staging
The 2018 AHA/ACC guidelines classify physiological severity into four stages (A-D) regardless of anatomic complexity: 1
- Stage A: NYHA Class I, no hemodynamic sequelae, normal exercise capacity 1
- Stage B: NYHA Class II, mild hemodynamic sequelae, abnormal exercise testing 1
- Stage C: NYHA Class III, significant valvular disease or ventricular dysfunction, hemodynamically significant shunt, controlled arrhythmias 1
- Stage D: NYHA Class IV, severe complications including Eisenmenger syndrome, refractory arrhythmias, severe pulmonary hypertension, refractory end-organ dysfunction 1
Diagnostic Approach
Initial Evaluation
Chest radiography (posterior-anterior and lateral) is the first-line imaging test for suspected CHD, providing rapid assessment of cardiac contours, mediastinal anatomy, and pulmonary vascularity. 1
Advanced Imaging Modalities
All adults with suspected CHD require definitive imaging for diagnosis, and nearly all adults with known CHD require periodic imaging for monitoring. 1
Recommended imaging includes: 1
- Echocardiography (transthoracic and transesophageal) - provides intracardiac anatomy and hemodynamics 1
- Cardiac MRI (CMR) - superior for vascular anatomy and ventricular function 1
- Cardiac CT angiography - excellent for great vessel anatomy 1
- Cardiac catheterization with angiography - gold standard for hemodynamic assessment and intervention 1
Common pitfall: Approximately 10% of patients with common CHD survive undetected until adulthood, particularly those with small VSDs or ASDs. 1
Management and Treatment
General Principles
Patients with complex CHD have significantly better outcomes when managed in specialized, multidisciplinary ACHD (Adult Congenital Heart Disease) programs with board-certified ACHD cardiologists, congenital cardiac surgeons, and dedicated imaging services. 1
Acyanotic Defects
Ventricular Septal Defect (VSD)
Small, isolated VSDs without hemodynamic significance require observation only. 1
VSDs with associated abnormalities (such as aortic regurgitation from valve prolapse) or moderate-to-large shunts require surgical closure. 4
Critical surgical consideration: Complete heart block is a significant risk after perimembranous VSD repair because the His bundle passes along the defect rim. 4
Atrial Septal Defect (ASD)
Small ASDs without chamber enlargement require monitoring only. 1
Moderate to large ASDs with hemodynamically significant shunts require closure, either surgically or via transcatheter device. 1
Patent Ductus Arteriosus (PDA)
Small PDAs may be observed, but moderate to large PDAs require closure to prevent pulmonary vascular disease. 1
Transcatheter closure is preferred when anatomically feasible. 1
Coarctation of the Aorta
All significant coarctations require intervention to prevent hypertension, heart failure, and premature coronary disease. 1
Treatment options include surgical repair or balloon angioplasty with stenting. 1
Cyanotic Defects
Tetralogy of Fallot
Total surgical correction is the treatment of choice for tetralogy of Fallot. 3, 5
Some patients require initial palliation with a modified Blalock-Taussig shunt before complete repair, particularly those with severe pulmonary stenosis or hypoplastic pulmonary arteries. 3, 5
After repair, patients require lifelong monitoring for pulmonary regurgitation, right ventricular dysfunction, and arrhythmias. 1
Transposition of the Great Arteries (TGA)
For d-TGA with intact ventricular septum or simple VSD: arterial switch (Jatene) procedure is the definitive treatment. 3, 5
For d-TGA with VSD and pulmonary stenosis: Rastelli procedure (VSD closure with right ventricle to pulmonary artery conduit) is required. 3, 5
Neonates often require prostaglandin E1 infusion to maintain ductal patency and/or balloon atrial septostomy prior to definitive surgery. 3, 5
Tricuspid Atresia
Initial palliation is required at presentation: 3, 5
- Modified Blalock-Taussig shunt for inadequate pulmonary blood flow 3, 5
- Pulmonary artery banding for excessive pulmonary blood flow 3, 5
Staged Fontan procedure follows: 3, 5
- Bidirectional Glenn anastomosis (typically 4-6 months) 3, 5
- Fenestrated Fontan with extracardiac conduit (typically 2-4 years) 3, 5
Truncus Arteriosus
Surgical repair involves VSD closure combined with right ventricle to pulmonary artery conduit placement. 3, 5
Palliative pulmonary artery banding is no longer recommended. 5
Total Anomalous Pulmonary Venous Connection (TAPVC)
Non-obstructed TAPVC: elective surgical anastomosis of the common pulmonary vein to the left atrium. 3
Obstructed TAPVC: emergency surgical repair is required immediately at presentation to prevent death. 3
Hypoplastic Left Heart Syndrome and Other Single Ventricle Lesions
These require multistage surgical palliation (Norwood, Glenn, Fontan sequence) or cardiac transplantation. 3
Long-Term Complications and Monitoring
Adults with CHD develop acquired comorbidities including hypertension, atherosclerosis, coronary artery disease, pulmonary disease, and renal disease, which complicate management. 1
Common late complications requiring surveillance: 1
- Arrhythmias (atrial and ventricular) 1
- Ventricular dysfunction (systemic or pulmonary) 1
- Valvular disease progression 1
- Pulmonary hypertension and Eisenmenger syndrome 1
- Heart failure 1
- Thromboembolic events 1
Critical pitfall: Over half of adult CHD patients have undergone prior surgery, and 37% of all CHD hospital admissions are now adults, requiring specialized ACHD expertise. 1
Preventive Care
Follow-up should include routine well-child/adult care with modifications: 2