Residency · Residency · Cardiology

Adult Congenital Heart Disease

Epidemiology and General Principles

Scope of Adult CHD

Approximately 1.5 million adults are currently living with congenital heart disease in the United States, a population that continues to grow as a result of dramatically improved surgical outcomes in childhood. Adults now outnumber children with congenital heart disease, with the majority having simple or moderate complexity lesions. These patients require lifelong cardiology follow-up at specialized adult congenital heart disease centers, with follow-up intervals determined by the complexity of their underlying condition.

Complexity Classification

Congenital heart disease in adults is classified into three complexity categories that guide management intensity and referral patterns. Simple lesions include isolated small atrial septal defects, isolated small ventricular septal defects that are closed or hemodynamically insignificant, mild pulmonic stenosis, bicuspid aortic valve without significant stenosis, regurgitation, or aortopathy, and successfully repaired patent ductus arteriosus or septal defects without residua. Moderate complexity encompasses repaired tetralogy of Fallot, coarctation repair, moderate aortic stenosis or regurgitation, partial anomalous pulmonary venous return, atrioventricular canal defects, Ebstein anomaly, and moderate right ventricular outflow tract dysfunction. Complex or severe lesions include Fontan circulation, transposition of the great arteries with atrial switch operations (Mustard or Senning), cyanotic congenital heart disease whether unrepaired or palliated, Eisenmenger syndrome, double-outlet right ventricle, truncus arteriosus, pulmonary atresia, and single ventricle physiology.

Atrial Septal Defect

ASD Types and Management

Types

Atrial septal defects are classified by their anatomic location within the interatrial septum. Secundum defects, comprising 75% of all atrial septal defects, result from deficiency in the fossa ovalis region and are amenable to percutaneous device closure. Primum defects account for 15 to 20% of cases and are part of the atrioventricular canal spectrum, positioned adjacent to the atrioventricular valves and often associated with a cleft mitral valve. These require surgical repair. Sinus venosus defects comprise 5 to 10% and occur as either a superior type near the superior vena cava-right atrial junction, frequently associated with anomalous drainage of the right upper pulmonary vein, or an inferior type near the inferior vena cava. Both types require surgical repair and are not suitable for device closure. Coronary sinus defects, also termed unroofed coronary sinus, are rare and result from a deficiency in the roof of the coronary sinus creating a left atrial-to-right atrial communication, often associated with a persistent left superior vena cava.

Hemodynamics and Clinical Features

The magnitude of the left-to-right shunt through an atrial septal defect is proportional to defect size and the relative compliance of the two ventricles. Chronic volume overload of the right atrium and right ventricle produces right ventricular dilation and paradoxical septal motion. Pulmonary hypertension develops in 10 to 15% of patients, more commonly with large unrepaired defects, and may progress to Eisenmenger syndrome when pulmonary vascular resistance exceeds systemic vascular resistance, resulting in shunt reversal with cyanosis. Atrial arrhythmias, including atrial fibrillation and atrial flutter, increase in prevalence with age, affecting more than 50% of patients by age 60 with unrepaired atrial septal defects.

Indications for Closure

Closure of an atrial septal defect is a Class I recommendation when there is a significant shunt with a pulmonary-to-systemic flow ratio of 1.5 or greater accompanied by right atrial and right ventricular volume overload, or when paradoxical embolism has occurred with stroke or transient ischemic attack through the defect. Platypnea-orthodeoxia syndrome, characterized by positional cyanosis and dyspnea from right-to-left shunting exacerbated by the upright position, is another indication. Closure is contraindicated in Eisenmenger syndrome because irreversible pulmonary vascular resistance elevation means that closing the defect would eliminate the right-to-left "pop-off" and worsen right ventricular failure. Percutaneous device closure with devices such as the Amplatzer or Gore Cardioform is suitable for secundum defects with adequate tissue rims of 5 mm or greater, particularly from the aorta and atrioventricular valves, performed under transesophageal or intracardiac echocardiographic guidance. Surgical closure is required for primum defects necessitating concurrent mitral valve repair, sinus venosus defects requiring baffle or patch redirection of anomalous veins, and large secundum defects with inadequate rims for device anchoring.

Ventricular Septal Defect

Types

Ventricular septal defects are classified by their position within the interventricular septum. Perimembranous defects account for approximately 80% of cases, are located near the tricuspid valve and the conduction system, and carry a risk of progressive aortic regurgitation due to aortic cusp prolapse. Muscular defects may occur anywhere in the muscular septum, may be multiple creating a "Swiss cheese" pattern, and small muscular defects often close spontaneously during childhood. Outlet defects, also known as supracristal or doubly committed subarterial defects, account for 5 to 8% of cases and are more prevalent in Asian populations. These are positioned below both the pulmonic and aortic valves and carry a high risk of progressive aortic regurgitation from aortic cusp prolapse. Inlet or atrioventricular canal type defects are located in the posterior septum near the atrioventricular valves.

Adult Management

Small restrictive ventricular septal defects are characterized by a high-velocity jet on echocardiography and normal pulmonary artery pressures. These patients require lifelong endocarditis prophylaxis and surveillance for the development of aortic regurgitation. Moderate-to-large defects with volume overload of the left atrium and left ventricle and a pulmonary-to-systemic flow ratio exceeding 1.5 warrant closure, provided pulmonary artery pressures are not severely elevated. Eisenmenger ventricular septal defect presents with cyanosis, digital clubbing, and erythrocytosis, and closure is absolutely contraindicated. Management focuses on pulmonary arterial hypertension-targeted therapy for symptom relief, with bilateral lung transplantation plus defect repair or heart-lung transplantation considered for end-stage disease. Residual ventricular septal defects following prior repair are common, with small residual shunts typically requiring no intervention and hemodynamically significant large residual defects potentially requiring redo surgery or catheter-based device closure for selected muscular defects.

Patent Ductus Arteriosus

The patent ductus arteriosus produces the classic continuous machinery murmur best heard at the left infraclavicular area and causes volume overload of the left atrium and left ventricle. Small patent ductus arteriosus are usually incidental findings, but closure is recommended when an audible murmur is present due to the risk of endocarditis. Moderate-to-large patent ductus arteriosus causing left ventricular dilation, heart failure symptoms, or pulmonary hypertension warrant closure. Percutaneous device closure using the Amplatzer Duct Occluder is preferred for most adults, with surgical ligation reserved for large or complex anatomy. In Eisenmenger patent ductus arteriosus, the characteristic finding is differential cyanosis, with the lower extremities appearing cyanotic and the upper extremities pink, because the right-to-left ductal shunt delivers desaturated blood to the descending aorta distal to the left subclavian artery origin.

Tetralogy of Fallot (Repaired)

Common Residual Issues in Adults

The majority of adults with repaired tetralogy of Fallot face a set of predictable long-term complications. Pulmonary regurgitation is the most common long-term problem following transannular patch repair, with chronic severe pulmonary regurgitation causing progressive right ventricular dilation and dysfunction, exercise intolerance, and an increased risk of arrhythmias. Right ventricular dilation and dysfunction may result from chronic pulmonary regurgitation, residual right ventricular outflow tract obstruction, or the surgical patch itself. Residual ventricular septal defects from patch leaks or missed additional defects occur in a subset of patients. Right ventricular outflow tract aneurysms serve as a substrate for ventricular tachycardia. Progressive aortic root dilation develops in approximately 15% of adults with repaired tetralogy of Fallot, representing an aortopathy similar to that seen with bicuspid aortic valve. Arrhythmias are a significant concern, with atrial flutter or fibrillation affecting 30% of patients by age 55 and monomorphic ventricular tachycardia arising from right ventricular outflow tract scar. The risk of sudden cardiac death is estimated at approximately 2% per decade.

Pulmonary Valve Replacement (PVR) Indications

Pulmonary valve replacement is indicated for severe pulmonary regurgitation with symptoms of exercise intolerance or heart failure, or with objective decline in exercise capacity. In asymptomatic patients, indications include severe pulmonary regurgitation with progressive right ventricular dilation, defined as a right ventricular end-diastolic volume index exceeding 150 to 160 mL/m squared, or declining right ventricular function with a right ventricular ejection fraction below 45% on serial cardiac magnetic resonance imaging. Significant residual right ventricular outflow tract obstruction with a peak gradient exceeding 50 mmHg and sustained atrial or ventricular arrhythmias attributed to right ventricular volume overload are additional indications. Options include surgical bioprosthetic valve replacement as the standard approach and transcatheter pulmonary valve implantation using the Melody, Harmony, or Alterra platforms for appropriate anatomy, including existing conduits, bioprosthetic valves, or native right ventricular outflow tracts with adequate landing zones.

<image> A diagram showing the anatomy of repaired Tetralogy of Fallot in an adult patient. Show a four-chamber cross-section of the heart with the following post-surgical features: (1) VSD patch (green patch on membranous septum, labeled), (2) RVOT reconstruction with transannular patch (blue patch extending from RVOT across the pulmonary annulus, labeled), (3) markedly dilated RV from chronic severe pulmonary regurgitation (RV chamber noticeably larger than LV), (4) severe PR shown as a broad color flow jet from the PA back into the RV (red jet, labeled), (5) dilated PA and branch PAs, (6) overriding aorta (original anatomy preserved by patch closure of VSD). Include a small CMR inset showing RV volume quantification with RVEDVi 180 mL/m^2 and RVEF 38%, highlighting the indication for pulmonary valve replacement. Label the RVOT scar/aneurysm region as a potential VT substrate. Use anatomic coloring with surgical patches in distinct colors. </image>

Coarctation of the Aorta

Anatomy and Residual Issues

Coarctation of the aorta is a discrete narrowing of the aorta typically located just distal to the left subclavian artery origin at the juxtaductal position. Childhood repair may have been accomplished through surgical end-to-end anastomosis, patch aortoplasty, subclavian flap repair, or balloon angioplasty with or without stenting. Re-coarctation occurs in 5 to 15% of patients after repair, manifesting as hypertension with an arm-to-leg blood pressure gradient exceeding 20 mmHg. Persistent hypertension occurs in 30 to 50% of adults even after successful repair, attributed to vascular remodeling, enhanced renin-angiotensin-aldosterone system activity, and reduced aortic compliance. Aneurysm formation at the repair site, particularly after Dacron patch repair, carries a risk of rupture and requires MRI surveillance. An associated bicuspid aortic valve is present in approximately 50 to 85% of patients, necessitating ongoing surveillance of both the aortic valve and the ascending aorta for aortopathy. The increased risk of intracranial berry aneurysms, estimated at 5 to 10%, raises the question of screening magnetic resonance angiography, though this remains controversial.

Management

Surveillance consists of MRI or magnetic resonance angiography or computed tomography of the entire aorta every 3 to 5 years, annual arm-to-leg blood pressure gradient assessment, and echocardiography for bicuspid aortic valve and left ventricular function monitoring. Re-intervention for re-coarctation in adults favors stenting as the percutaneous approach, with surgical repair reserved for complex anatomy, associated aneurysm, or long-segment coarctation. Blood pressure management targets less than 130/80 mmHg, with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers as preferred agents.

Transposition of the Great Arteries (Post-Atrial Switch)

Mustard/Senning Physiology

In patients who underwent Mustard or Senning atrial switch operations for transposition of the great arteries, intra-atrial baffles redirect systemic venous blood to the left ventricle, which serves as the subpulmonic ventricle, and pulmonary venous blood to the right ventricle, which remains the systemic ventricle. The systemic right ventricle faces lifelong systemic pressures, leading to progressive dilation and dysfunction resembling dilated cardiomyopathy, with approximately 30% of patients developing significant systemic ventricular dysfunction by age 30 to 40. Baffle complications include baffle leaks causing either left-to-right or right-to-left shunting and baffle obstruction of the superior or inferior vena cava pathways, evaluated with MRI or angiography. Loss of sinus node function occurs in 50 to 60% of patients by adulthood, and intra-atrial reentrant tachycardia (atrial flutter) is extremely common, with an associated risk of sudden death. Tricuspid regurgitation, affecting the systemic atrioventricular valve, is progressive and contributes to systemic right ventricular failure, with limited surgical options given the complexity of reoperations in this population.

Arterial Switch (Jatene) -- Modern Repair

The arterial switch operation represents the modern anatomic repair for transposition of the great arteries. The great arteries are switched to their correct alignment and the coronary arteries are reimplanted, resulting in the left ventricle serving as the systemic ventricle. Long-term issues include supravalvar pulmonary stenosis from neo-pulmonary root narrowing, coronary artery anomalies from kinking or stenosis at reimplantation sites, and progressive neo-aortic root dilation with aortic regurgitation.

Fontan Circulation (Single Ventricle Physiology)

Physiology

The Fontan circulation provides passive pulmonary blood flow without a subpulmonic ventricle, with systemic venous return flowing directly to the pulmonary arteries through the Fontan connection. Cardiac output in this circulation is dependent on low pulmonary vascular resistance, adequate systemic ventricular function, absence of atrioventricular valve regurgitation, and maintenance of sinus rhythm. The inherent consequence is chronically elevated central venous pressure, typically 12 to 18 mmHg, with reduced cardiac output both at rest and during exercise.

Fontan Circulation: Key Complications

Common Complications

Atrial arrhythmias, including intra-atrial reentrant tachycardia and atrial fibrillation, are poorly tolerated in single ventricle physiology because loss of atrioventricular synchrony significantly impairs cardiac output. Management includes rate control with anticoagulation, catheter ablation, and in selected patients, conversion to an extracardiac conduit with concurrent Maze procedure.

Fontan-associated liver disease is universal to some degree, resulting from hepatic congestion caused by chronically elevated central venous pressure. This condition progresses from fibrosis to cirrhosis and carries a risk of hepatocellular carcinoma. Liver surveillance with ultrasound and alpha-fetoprotein every 1 to 3 years, along with liver stiffness assessment by elastography for disease staging, is essential. Protein-losing enteropathy results from intestinal protein loss driven by elevated mesenteric venous pressure, manifesting as albumin below 3.0 g/dL, edema, ascites, and diarrhea. Treatment options include diuretics, sildenafil, Fontan revision, and heart transplantation for refractory cases.

Plastic bronchitis arises from lymphatic dysfunction with cast formation in the airways and is increasingly treated with thoracic duct embolization and other lymphatic interventions. Thromboembolic events are common because the Fontan circuit is a low-flow system, with approximately 25% of patients developing intracardiac thrombus at some point. Anticoagulation with warfarin or direct oral anticoagulants is recommended, though evidence remains limited. Cyanosis may result from right-to-left flow through a fenestration, pulmonary arteriovenous malformations from hepatic factor deficiency, or systemic venous collaterals.

Management

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers have unproven benefit in the Fontan population but are commonly used on the theoretical basis of afterload reduction on the single ventricle. Anticoagulation at minimum includes aspirin, with warfarin recommended for patients with atrial arrhythmias, prior thromboembolic events, or other clinical indications. Direct oral anticoagulants are increasingly used. Regular moderate-intensity exercise is recommended, though exercise capacity is limited by chronotropic incompetence and reduced cardiac output augmentation. Heart transplantation is the definitive treatment for failing Fontan circulation, though it is technically challenging due to prior surgeries, elevated pulmonary vascular resistance, and liver disease. Combined heart-liver transplantation is considered for patients with advanced Fontan-associated liver disease.

Eisenmenger Syndrome

Pathophysiology

Eisenmenger syndrome develops from irreversible pulmonary vascular disease resulting from longstanding unrestricted left-to-right shunting through defects such as ventricular septal defects, atrial septal defects, patent ductus arteriosus, or atrioventricular canal defects. When pulmonary vascular resistance exceeds systemic vascular resistance, the shunt reverses direction from right-to-left, producing systemic cyanosis. Once established, surgical closure of the underlying defect is absolutely contraindicated because it removes the "pop-off" pathway for the right ventricle.

Management

Pulmonary arterial hypertension-targeted therapy constitutes the primary medical intervention. Endothelin receptor antagonists, particularly bosentan as demonstrated in the BREATHE-5 trial, improve 6-minute walk distance and reduce pulmonary vascular resistance in Eisenmenger patients. Phosphodiesterase-5 inhibitors and prostacyclin analogs provide additional therapeutic options that improve functional capacity, though none reverse fixed pulmonary vascular resistance. Phlebotomy should be performed only for symptomatic hyperviscosity with a hematocrit exceeding 65%, presenting as headache, visual changes, or paresthesias, and must always be accompanied by isovolemic volume replacement. Routine phlebotomy is harmful because it induces iron deficiency, which paradoxically worsens both cyanosis and hyperviscosity symptoms. Supplemental oxygen is provided if it offers symptomatic benefit, though no proven survival benefit exists. Pregnancy is absolutely contraindicated in Eisenmenger syndrome, carrying a 30 to 50% maternal mortality risk, making effective contraception an essential component of care. Transplantation options for end-stage disease include bilateral lung transplantation with defect repair or heart-lung transplantation.

<image> An anatomical illustration comparing normal cardiac anatomy with Eisenmenger syndrome secondary to a large VSD. Two side-by-side heart cross-sections. Left panel "Normal": normal-sized chambers, intact IVS, normal PA diameter, normal oxygen saturations labeled (RA 75%, RV 75%, PA 75%, LA 98%, LV 98%, Aorta 98%). Right panel "Eisenmenger VSD": massively dilated RV and PA (PA diameter >> aorta), markedly thickened RV free wall (pressure overload hypertrophy), large VSD with bidirectional/predominantly right-to-left shunt (blue arrow from RV to LV through VSD), cyanotic desaturated blood mixing with oxygenated blood in LV, oxygen saturations labeled showing desaturation (RA 70%, RV 70%, PA 70%, LA 98%, LV 85%, Aorta 85%). The pulmonary arterioles are shown in the lung field with thickened walls (plexiform lesions) in the Eisenmenger panel. Include a small fingertip inset showing clubbing and cyanosis. Label the key features: RV hypertrophy, PA dilation, R-to-L shunt, and pulmonary vascular disease. Use blue for deoxygenated blood paths and red for oxygenated. </image>

Key Clinical Pearls

• All adults with moderate or complex CHD should be followed at a specialized ACHD center -- these patients have unique physiology that general cardiologists are not trained to manage
• The systemic RV (post-Mustard/Senning or congenitally corrected TGA) will eventually fail in most patients -- standard HFrEF medications (ACEi, beta-blockers) have limited evidence in systemic RV failure; early transplant referral is critical
• Erythrocytosis in cyanotic CHD is a compensatory response -- routine phlebotomy causes iron deficiency, which paradoxically WORSENS hyperviscosity symptoms; only perform isovolemic phlebotomy for symptomatic hyperviscosity with Hct > 65%
• Fontan-associated liver disease is universal and progressive -- all Fontan patients require regular liver surveillance (imaging + serologies) starting in adolescence; hepatocellular carcinoma can develop even in young adults
• Device closure of secundum ASD is contraindicated in Eisenmenger syndrome -- always confirm PA pressures and PVR before ASD closure; if PVR > 2/3 SVR or PVR > 5 WU, closure is generally contraindicated without vasoreactivity testing
• Pregnancy carries prohibitive risk (30-50% mortality) in Eisenmenger syndrome, severe pulmonary hypertension, Fontan circulation, and systemic RV dysfunction -- reproductive counseling and contraception are essential components of ACHD care

References

• Stout KK, et al. 2018 AHA/ACC Guideline for the Management of Adults with Congenital Heart Disease. Circulation. 2019;139:e698-e800.
• Baumgartner H, et al. 2020 ESC Guidelines for the Management of Adult Congenital Heart Disease. Eur Heart J. 2021;42:563-645.
• Gatzoulis MA, et al. Adult Congenital Heart Disease: A Cardiovascular Discipline Come of Age. Lancet. 2016;387:1233-1240.
• Drenthen W, et al. Outcome of Pregnancy in Women with Congenital Heart Disease: A Literature Review. JACC. 2007;49:2303-2311.
• Galie N, et al. Bosentan Therapy in Patients with Eisenmenger Syndrome (BREATHE-5). Circulation. 2006;114:48-54.

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