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Congenital Heart Defects in Adults (Adult Congenital Heart Disease - ACHD)

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1. Etiology

Genetic/Chromosomal Causes

Non-Genetic / Teratogenic Causes

• Maternal infections: Rubella (PDA, pulmonary artery stenosis), CMV, Coxsackievirus
• Maternal medications: Thalidomide, lithium (Ebstein anomaly), valproic acid, retinoic acid, phenytoin
• Maternal conditions: Diabetes mellitus (VSD, TGA, HCM), systemic lupus erythematosus (heart block), phenylketonuria, alcohol use (FAS - VSD, ASD)
• Environmental: Radiation exposure, organic solvents

"About 20% of congenital heart defects are associated with a syndrome or chromosomal anomaly." - Goldman-Cecil Medicine

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2. Epidemiology

• CHDs are diagnosed in approximately 1% of live births in the United States
• Prevalence in adults: 3-4 per 1,000 adults
• An estimated 2.4 million people in the United States currently live with CHD - two-thirds are adults, a dramatic shift from prior decades when most patients died in childhood
• Approximately 300,000 Americans have severe CHD (defined as two or more abnormalities, typically with cyanosis at birth)
• Advances in surgical and medical therapy have pushed the median age of patients with severe lesions from childhood into late adolescence and adulthood

Relative Prevalence of Specific Lesions in Adults

Goldman-Cecil Medicine, p. 604

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3. Pathophysiology

A. Left-to-Right Shunts (Acyanotic)

• Abnormal communication allows oxygenated left-sided blood to enter the pulmonary circulation
• Examples: ASD, VSD, PDA, atrioventricular septal defect (AVSD)
• Increased pulmonary blood flow and pressure → right ventricular hypertrophy → right-sided heart failure
• With time, elevated pulmonary vascular resistance can cause shunt reversal (right-to-left), producing late-onset cyanosis (Eisenmenger syndrome)
• Cyanosis is NOT an early feature; it signals irreversible pulmonary vascular disease

B. Right-to-Left Shunts (Cyanotic)

• Deoxygenated blood bypasses the pulmonary circulation and enters the systemic arterial system
• Examples: Tetralogy of Fallot, transposition of great arteries (TGA), truncus arteriosus, tricuspid atresia
• Results in: cyanosis, clubbing, polycythemia, hyperviscosity

C. Obstructive Lesions

• Narrowing of chambers, valves, or great vessels obstructs flow
• Examples: Pulmonary stenosis, aortic stenosis (including bicuspid AV), coarctation of the aorta
• Leads to pressure overload, ventricular hypertrophy, and eventually failure

Eisenmenger Syndrome

Robbins & Kumar Basic Pathology, p. 347-348

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4. Clinical Signs and Symptoms

General Presentation

1. Previously undiagnosed CHD presenting for the first time in adulthood (often milder lesions like secundum ASD, bicuspid aortic valve, small VSD, PDA)
2. Repaired or palliated CHD surviving into adulthood with residual defects, sequelae, or complications

Common Symptoms

• Dyspnea on exertion - most common; reflects reduced cardiac output or elevated pulmonary pressures
• Palpitations / arrhythmias - atrial fibrillation, flutter, supraventricular or ventricular tachycardia
• Fatigue - from reduced cardiac reserve
• Cyanosis - central (mucous membranes, tongue), right-to-left shunts
• Syncope / presyncope - outflow obstruction or arrhythmia
• Chest pain - coarctation, aortic stenosis, coronary anomalies
• Stroke / TIA - paradoxical embolism through PFO or ASD, atrial arrhythmias
• Leg fatigue / claudication - coarctation of the aorta
• Hemoptysis - Eisenmenger syndrome, pulmonary AVMs (Hereditary Hemorrhagic Telangiectasia)

Key Physical Signs by Lesion

• Wide, fixed splitting of S2 (hallmark) - pathognomonic
• Systolic ejection murmur at pulmonary area (increased flow)
• With large shunt: right ventricular heave
• With pulmonary hypertension: loud P2, tricuspid regurgitation murmur

• Holosystolic murmur at left lower sternal border
• With large shunt: displaced apex, S3, signs of left ventricular failure

• Continuous "machinery" murmur at left upper sternal border/infraclavicular area
• Wide pulse pressure, bounding pulses
• With Eisenmenger: differential cyanosis (lower extremities more cyanosed than upper)

• Pulmonary regurgitation murmur (most common residual)
• Right ventricular heave
• Tet spells (hypercyanotic) less common in adults

• Upper extremity hypertension with weak/absent femoral pulses
• Blood pressure differential: arms > legs (>20 mmHg)
• Systolic murmur over the posterior mid-thoracic region
• "3 sign" on chest X-ray (notched aorta)
• Bilateral rib notching (posterior 3rd-8th ribs from collateral flow)
• Tortuous ("corkscrew") retinal arteries
• Left ventricular hypertrophy on ECG

• Apically displaced tricuspid valve
• Right-sided cardiomegaly ("box-shaped heart" on CXR)
• Right bundle branch block, Wolff-Parkinson-White pattern on ECG

• Central cyanosis, clubbing
• Polycythemia with hyperviscosity symptoms (headache, blurred vision, fatigue)
• Signs of pulmonary hypertension: loud P2, right heart failure

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5. Diagnosis

History & Physical Examination

• Detailed birth and surgical history
• Prior catheterization and imaging reports
• Current symptom burden and functional class (NYHA classification)

Electrocardiography (ECG)

• Right axis deviation / right bundle branch block: ASD, right heart lesions
• Left ventricular hypertrophy: aortic stenosis, coarctation
• PR prolongation: Ebstein anomaly, AVSDs
• Delta waves (Wolff-Parkinson-White): Ebstein anomaly (up to 20-25%)
• QTc prolongation: post-repair Tetralogy of Fallot (marker for sudden death risk)

Chest X-Ray

• Cardiomegaly, pulmonary vascular markings
• "3 sign" and rib notching: coarctation
• "Boot-shaped heart": Tetralogy of Fallot
• "Box-shaped heart": Ebstein anomaly
• Enlarged pulmonary artery: pulmonary stenosis, Eisenmenger

Echocardiography (Primary Imaging Modality)

• Transthoracic echo (TTE): First-line; evaluates anatomy, shunts (Doppler, bubble contrast), ventricular function, valve lesions, gradients
• Transesophageal echo (TEE): Better for sinus venosus ASD, PFO, complex anatomy
• Bubble contrast echo: Detects right-to-left shunting (PFO, ASD)
• Estimation of pulmonary artery pressures, shunt size (Qp:Qs ratio)

Cardiac MRI (Gold Standard for Many Lesions)

• Best modality for:
  • Visualizing aortic anatomy (coarctation, aneurysms)
  • Right ventricular volumes and function (e.g., post-Tetralogy repair)
  • Quantifying pulmonary regurgitation
  • Complex anatomy not well-seen by echo
• Provides accurate flow quantification and tissue characterization

CT Angiography

• Useful for coronary anatomy, vascular anomalies, and pre-procedural planning
• Alternative when MRI is contraindicated

Cardiac Catheterization

• Hemodynamic assessment: Pulmonary artery pressures, pulmonary vascular resistance (PVR), Qp:Qs ratio
• Vasoreactivity testing: In pulmonary hypertension to assess operability
• Required before surgical correction when pulmonary hypertension is suspected
• Diagnostic and therapeutic (transcatheter closure, stenting)

Exercise Testing

• Assess functional capacity and identify exercise-induced arrhythmias
• Important for risk stratification and sports participation guidance

Holter / Event Monitoring

• For arrhythmia detection in symptomatic patients and those with high arrhythmia risk

Lab Work

• CBC: Polycythemia in cyanotic CHD (compensatory)
• BNP/NT-proBNP: Heart failure monitoring
• Iron studies: Iron-deficiency anemia in cyanotic CHD (blunts adaptive polycythemia)
• Coagulation studies: Bleeding risk in Eisenmenger

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6. Differential Diagnosis

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7. Treatment

A. Medical Management

• Standard HF therapy (ACE inhibitors/ARBs, beta-blockers, diuretics) for systemic LV dysfunction
• Caution in right-dominant or single-ventricle physiology - standard HF drugs may not apply uniformly

• Eisenmenger syndrome: Endothelin receptor antagonists (bosentan - approved specifically for Eisenmenger), phosphodiesterase-5 inhibitors (sildenafil), prostacyclin analogues
• These improve functional class and exercise capacity but do not cure the underlying anatomy

• Anti-arrhythmic drugs (sotalol, amiodarone for atrial arrhythmias)
• Anticoagulation (warfarin or DOACs) for atrial fibrillation and flutter
• Rate control vs. rhythm control individualized to anatomy

• Recommended for high-risk lesions:
  • Unrepaired cyanotic CHD (including palliative shunts)
  • Completely repaired CHD with prosthetic material during the first 6 months post-procedure
  • Repaired CHD with residual defects at or adjacent to prosthetic patches/devices
  • Cardiac transplant recipients who develop cardiac valvulopathy
• Prophylaxis before dental procedures involving gingival manipulation

• Mechanical prosthetic valves: warfarin (mandatory)
• Fontan circulation: anticoagulation or antiplatelet therapy
• Atrial arrhythmias: individualized

B. Catheter-Based (Interventional) Procedures

Intervention for coarctation is recommended when peak catheterization gradient ≥20 mmHg with systemic hypertension or significant collateral flow on imaging. - Goldman-Cecil Medicine, p. 609

C. Surgical Treatment

• Repair of complex anatomy: Sinus venosus ASD (requires patch + anomalous vein rerouting), primum ASD with mitral cleft repair
• Re-operation for residual or recurrent lesions after initial childhood repair
• Tetralogy of Fallot: Pulmonary valve replacement for severe pulmonary regurgitation causing RV dilation/failure
• Fontan revision/conversion for failing Fontan circulation
• Ross procedure / aortic valve replacement: For bicuspid aortic valve disease
• Maze procedure: For refractory atrial arrhythmias at time of cardiac surgery
• Heart/Heart-Lung transplantation: End-stage Eisenmenger syndrome or failing single-ventricle/Fontan (last resort)

D. ICD / Pacemaker Implantation

• ICD for primary prevention of sudden cardiac death in high-risk ACHD (especially repaired Tetralogy of Fallot with QRS >180 ms, severe RV dysfunction, significant arrhythmia burden)
• Pacemaker for complete heart block (post-operative or congenital)

E. Pregnancy Considerations

• ACHD patients planning pregnancy require pre-conception counseling at specialized centers
• High-risk conditions include Eisenmenger syndrome, severe pulmonary hypertension, severe systemic ventricular dysfunction (EF <30%), severe obstructive lesions
• Modified WHO classification guides risk stratification for pregnancy in CHD

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8. Complications

Arrhythmias

• Most common long-term complication of ACHD
• Atrial fibrillation and intra-atrial re-entrant tachycardia (IART) are the most frequent, especially after atrial surgery (Mustard, Senning, Fontan procedures)
• Ventricular tachycardia (VT) - risk in repaired Tetralogy of Fallot, especially with wide QRS (>180 ms), significant RV dilation, or LV dysfunction
• Accessory pathways: WPW in Ebstein anomaly (risk of sudden death)
• Complete heart block: post-operative or progressive

Heart Failure

• Occurs due to pressure/volume overload, ventricular dysfunction, valvular regurgitation, or poor surgical outcomes
• Systemic right ventricle (e.g., TGA after Mustard/Senning repair) is particularly prone to failure - RV not designed as systemic ventricle
• Fontan failure: protein-losing enteropathy, plastic bronchitis, hepatic complications

Pulmonary Hypertension / Eisenmenger Syndrome

• Irreversible pulmonary vascular obstructive disease from chronic left-to-right shunts
• Disqualifies patient from most corrective interventions
• Significantly reduced life expectancy

Infective Endocarditis

• Increased risk in patients with prosthetic valves, residual defects, complex CHD, and after procedures
• Predisposing structural lesion + bacteremia = vegetation formation
• CHD is one of the leading underlying conditions for endocarditis in younger patients

Stroke and Systemic Embolism

• Paradoxical embolism through PFO/ASD (especially cryptogenic stroke in patients <55 years)
• Atrial arrhythmias with thrombus formation
• Polycythemia and hyperviscosity in Eisenmenger syndrome → thrombotic events

Aortopathy

• Aortic root/ascending aortic dilation common in bicuspid aortic valve, coarctation, Marfan syndrome, Tetralogy of Fallot, TGA
• Risk of aortic dissection and rupture

Residual and Recurrent Defects

• Residual shunts, valve regurgitation, outflow obstruction after repair
• Re-operations are common in complex CHD

Polycythemia and Hyperviscosity (Cyanotic CHD)

• Secondary erythrocytosis compensates for chronic hypoxia
• Symptoms: headache, blurred vision, fatigue, myalgias
• Risk of both thrombosis AND paradoxical bleeding (thrombocytopenia, platelet dysfunction)
• Phlebotomy reserved for symptomatic hyperviscosity only; indiscriminate phlebotomy is harmful

Sudden Cardiac Death (SCD)

• Leading cause of death in ACHD
• Risk factors: QRS >180 ms (Tetralogy), severe ventricular dysfunction, inducible VT, prior sustained VT/VF, severe outflow obstruction

Hepatic Complications (Fontan)

• Fontan-associated liver disease (FALD): congestive hepatopathy → fibrosis → cirrhosis → hepatocellular carcinoma

Psychosocial Issues

• Anxiety, depression, reduced quality of life
• Transition from pediatric to adult care is a high-risk period for loss to follow-up

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9. Prevention

Primary Prevention (Reducing Risk of CHD)

• Folic acid supplementation (400-800 mcg daily before conception and in first trimester) reduces neural tube defects and may reduce some CHDs
• Optimize pre-existing maternal conditions: diabetes (tight glycemic control periconceptionally), PKU (low-phenylalanine diet), hypothyroidism
• Rubella vaccination of women of childbearing age (prevents congenital rubella syndrome including PDA, pulmonary stenosis)
• Avoid teratogenic medications (especially lithium, thalidomide, valproate, isotretinoin, ACE inhibitors) during pregnancy

• Avoidance of alcohol, smoking, and illicit drugs
• Avoidance of organic solvents and ionizing radiation exposure
• Infectious precautions (avoid exposure to rubella, CMV)

• Families with known genetic syndromes or prior affected children
• Recurrence risk is ~3-5% if one parent or sibling has CHD; higher with specific single-gene disorders
• Prenatal diagnosis via fetal echocardiography (ideally at 18-22 weeks) for high-risk pregnancies

Secondary Prevention (Preventing Complications in Known CHD)

• Regular follow-up at ACHD centers - lifelong surveillance is mandatory; even repaired CHD is not cured
• Endocarditis prophylaxis in eligible patients (dental hygiene is paramount)
• Anticoagulation in appropriate patients (mechanical valves, AF, Fontan)
• Exercise restrictions individualized to lesion complexity and hemodynamics (2025 ACC/AHA guideline provides specific recommendations by lesion)
• Contraception counseling for women with high-risk CHD
• Avoid phlebotomy unless symptomatic hyperviscosity with Hct >65% in cyanotic patients
• Avoid dehydration in polycythemic/cyanotic patients (increases viscosity and thrombosis risk)
• Occupational guidance: Certain careers (aviation, diving) restricted based on lesion
• Transition planning: Structured transition from pediatric to adult congenital care to prevent gaps in follow-up

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Key References

• Goldman-Cecil Medicine, International Edition - Chapter 55: Congenital Heart Disease in Adults (Judith Therrien & Ariane J. Marelli)
• Robbins & Kumar Basic Pathology - Chapter 9: Congenital Heart Disease, p. 347-350
• 2025 ACC/AHA/HRS/ISACHD/SCAI Guideline for the Management of Adults With Congenital Heart Disease - Gurvitz et al., J Am Coll Cardiol / Circulation, Feb 2026 [PMID: 41411480] - this is the most current guideline, replacing the 2018 AHA/ACC guideline

Note: The 2025 ACC/AHA guideline published in February 2026 is the current authoritative standard for ACHD management, incorporating evidence from 2017-2024. This supersedes the 2018 guideline. Key updates include revised recommendations on transcatheter interventions, arrhythmia management, and heart failure therapy for complex lesions.

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CONGENITAL HEART DEFECTS IN ADULTS

Organized by Category, Each Defect Covered Separately Under All 9 Headings

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CATEGORY 1: LEFT-TO-RIGHT SHUNTS (ACYANOTIC)

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1. ATRIAL SEPTAL DEFECT (ASD)

Etiology

• Genetic/Chromosomal: Turner syndrome (45,X) - most common chromosomal association; Down syndrome (trisomy 21); chromosomal 22q11 deletion
• Sporadic multifactorial in most cases
• Specific gene mutations: NKX2.5, GATA4, TBX5 mutations associated with familial ASD
• Types by embryologic origin:
  • Ostium secundum - enlarged foramen ovale or excessive resorption of septum primum (most common, ~70%)
  • Ostium primum - abnormal endocardial cushion development; associated with cleft mitral valve
  • Sinus venosus - defect at the junction of SVC and right atrium; associated with anomalous pulmonary venous drainage
  • Coronary sinus type - rare; associated with anomalous left superior vena cava
• Lutembacher syndrome: Combination of secundum ASD + acquired mitral stenosis

Epidemiology

• Constitutes 30-40% of all CHD in adults
• Ostium secundum accounts for 7% of all congenital lesions
• Prevalence: ~1 per 1,500 live births; more common in females (2:1)
• Most commonly undiagnosed until adulthood due to subtle symptoms in early life
• >70% of patients become symptomatic by the 5th decade
• Patent foramen ovale (PFO) - a related but distinct entity - is present in up to 30% of the general adult population; prevalence is 3x higher in cryptogenic stroke patients under age 55

Pathophysiology

• Left atrial pressure slightly exceeds right atrial pressure → left-to-right shunt
• Right atrial and right ventricular dilation occurs when pulmonary-to-systemic flow ratio (Qp:Qs) > 1.5:1
• Superimposed LV stiffening (from systemic hypertension, coronary artery disease, age) increases left atrial pressure and worsens the shunt
• Chronic right-sided volume overload → right atrial/ventricular dilation → atrial arrhythmias, right heart failure
• Pulmonary hypertension develops: unusual before age 20, present in 50% of patients >40 years
• Pulmonary vascular obstructive disease (PVOD) develops in 15-20% overall
• Eisenmenger complex (shunt reversal) - a late, rare complication of isolated secundum ASD, occurring in only 5-10% (unlike VSD/PDA where it is more common)
• Stroke via paradoxical embolism (venous thrombus crosses ASD to systemic circulation) or atrial arrhythmias
• Mitral valve disease in up to 15% of patients >50 years

Clinical Signs and Symptoms

• Minimally symptomatic in the first 3 decades; >70% impaired by 5th decade
• Exercise intolerance, dyspnea on exertion, fatigue (right heart failure, pulmonary hypertension)
• Palpitations (atrial fibrillation/flutter)
• Syncope and stroke (paradoxical embolism or arrhythmia)

• Wide, fixed splitting of S2 - pathognomonic hallmark (RV preload constant regardless of respiration)
• Soft systolic ejection murmur at pulmonary area (increased flow across pulmonary valve, not the ASD itself)
• Right ventricular heave (left parasternal or subxiphoid)
• Dilated pulmonary artery palpable at 2nd left intercostal space in large shunts
• Loud P2 and signs of pulmonary hypertension in advanced disease
• Tricuspid regurgitation murmur from RV dilation

Diagnosis

• ECG: Right axis deviation, incomplete/complete RBBB, right atrial enlargement; primum ASD shows superior axis (left axis deviation)
• Chest X-ray: Cardiomegaly (right heart), prominent pulmonary vasculature, dilated main pulmonary artery
• Echocardiography (TTE/TEE): Identifies defect location, size; right ventricular dilation; Doppler estimates shunt direction and Qp:Qs; bubble contrast study confirms right-to-left shunting; TEE best for sinus venosus ASD
• Cardiac MRI: Gold standard for quantifying shunt volume (Qp:Qs), right ventricular volume/function
• Cardiac catheterization: Measures pulmonary artery pressure and PVR; oxygen step-up at right atrium confirms shunt; required before closure if pulmonary hypertension present

Differential Diagnosis

Treatment

• Closure is indicated if Qp:Qs ≥ 1.5:1 with right heart dilation, OR symptoms, in absence of severe irreversible pulmonary hypertension (PVR >8 Wood units)
• Transcatheter closure (Amplatzer device, Helex): First-line for ostium secundum ASD; performed percutaneously; requires adequate rims around the defect
• Surgical closure: For sinus venosus ASD (requires SVC/pulmonary vein rerouting), primum ASD (requires mitral cleft repair), large secundum ASDs not amenable to transcatheter approach
• PFO closure: Recommended for patients with cryptogenic stroke age 18-60 years after ruling out other causes (Class IIa, 2019 European Position Paper)
• Medical therapy: Diuretics for right heart failure; anticoagulation for atrial arrhythmias; pulmonary vasodilators (bosentan) if PAH complicates closure

Complications

• Atrial fibrillation/flutter (most common long-term complication; risk persists even after closure, especially if closed after age 40)
• Right heart failure
• Pulmonary arterial hypertension / Eisenmenger syndrome (5-10%)
• Paradoxical embolism and stroke
• Mitral valve disease (in elderly patients)
• Post-closure: small residual shunt in some patients; atrial arrhythmias still possible even after successful closure

Prevention

• No specific primary prevention; rubella vaccination reduces overall CHD risk
• Endocarditis prophylaxis: NOT routinely recommended for unclosed ASD (low risk); recommended for 6 months after device/surgical closure until endothelialization complete
• Regular surveillance echocardiography and clinical follow-up recommended lifelong (even post-closure)
• Genetic counseling: ~5% recurrence risk in offspring of affected parents

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2. VENTRICULAR SEPTAL DEFECT (VSD)

Etiology

• Most common congenital heart defect overall (most close spontaneously in childhood)
• Chromosomal: Trisomy 21 (Down syndrome), trisomy 13, trisomy 18 (~90% of patients)
• 22q11 deletion (DiGeorge/CATCH-22): associated with conotruncal defects including outlet VSDs
• Maternal teratogens: Alcohol, retinoic acid, valproate
• Maternal diabetes mellitus: increased risk of VSD
• Types by anatomic location:
  • Perimembranous (infracristal): ~80% of VSDs; adjacent to tricuspid valve; may close spontaneously or develop aortic valve prolapse
  • Muscular: in the trabecular septum; highest rate of spontaneous closure
  • Outlet (supracristal/infundibular): below the pulmonary valve; associated with aortic regurgitation
  • Inlet (posterior): associated with Down syndrome; adjacent to AV valves

Epidemiology

• Represents 15-20% of all congenital lesions; most common CHD in children
• Prevalence in adults is lower due to high spontaneous closure rate (30-40% close by age 2)
• Solitary VSD in adults represents a small hemodynamically insignificant defect in the majority of cases
• Large unrepaired VSDs in adults are uncommon in developed countries (patients have usually developed Eisenmenger syndrome or been repaired)

Pathophysiology

• Small (restrictive) VSD: High-velocity jet from LV to RV; minimal hemodynamic consequences; Qp:Qs ~ 1.0-1.5:1; primarily risk of endocarditis and aortic regurgitation
• Moderate VSD: Left-to-right shunt; increased pulmonary blood flow and pressure; left atrial/ventricular dilation; right ventricular hypertrophy
• Large (non-restrictive) VSD: LV and RV pressures equalize; massive left-to-right shunt initially; progressive pulmonary vascular remodeling → Eisenmenger syndrome
• Aortic regurgitation can develop in outlet VSDs when the aortic cusp prollapses into the defect
• Septal aneurysm formation may cause tricuspid insufficiency

Clinical Signs and Symptoms

• Often asymptomatic; discovered incidentally on auscultation
• Grade ≥4/6 loud, harsh, high-frequency pansystolic murmur at 3rd-4th left intercostal space (the louder the murmur, the smaller and more restrictive the VSD)
• Otherwise normal exam ("a lot of noise from a small hole")

• Dyspnea on exertion
• Diffuse, displaced LV apical impulse
• Right ventricular heave if pulmonary hypertension develops
• Pansystolic murmur (softer if PA pressure rises)
• Accentuated P2

• Central cyanosis and clubbing
• Murmur may disappear as pulmonary and systemic pressures equalize
• Signs of right heart failure, loud P2, pulmonary regurgitation

Diagnosis

• ECG: Small VSD - normal; moderate/large - left atrial enlargement, LVH; with pulmonary hypertension - right axis deviation, RVH
• Chest X-ray: Small VSD - normal; larger - left ventricular and atrial enlargement, shunt vascularity; with Eisenmenger - dilated central pulmonary arteries, pruned peripheral vessels
• Echocardiography: Identifies defect location, size, shunt direction by Doppler; estimates RV pressure; assesses left heart enlargement; LA:Ao ratio reflects shunt magnitude
• Cardiac catheterization: Oxygen step-up at right ventricle; measures PVR and vasoreactivity (crucial before surgical decision if pulmonary hypertension present)

Differential Diagnosis

• Tricuspid regurgitation (pansystolic murmur)
• Mitral regurgitation (apex radiates to axilla)
• HOCM (dynamic obstruction murmur)
• Aortic stenosis (ejection murmur)
• Pulmonary stenosis (ejection murmur)

Treatment

• Small VSD: No closure needed; annual surveillance; endocarditis prophylaxis NOT routinely recommended (unless prior endocarditis)
• Moderate VSD (hemodynamically significant): Closure indicated if Qp:Qs ≥ 2:1 or evidence of LV volume overload; transcatheter closure (muscular, perimembranous VSDs) equally effective as surgical with fewer minor events
• Large VSD with Eisenmenger: Closure contraindicated; manage medically with pulmonary vasodilators
• Outlet VSD with aortic regurgitation: Surgery required to prevent progressive AR
• Surgical closure: Standard patch repair; preferred for inlet and outlet types
• Post-repair monitoring: For residual shunt, arrhythmias (RBBB ~30-65%, complete heart block <10%)

Complications

• Eisenmenger syndrome (with large unrepaired VSDs)
• Aortic regurgitation (outlet VSDs)
• Endocarditis (higher rate than ASD)
• Right bundle branch block after surgical repair (30-65%)
• Complete heart block after repair (<10%)
• Sudden cardiac death after repair (~2%)
• Residual shunt post-repair (up to 20%; ~5% require reoperation)
• Tricuspid regurgitation from septal aneurysm

Prevention

• Maternal folic acid and rubella vaccination (general CHD prevention)
• Neonatal/pediatric screening to allow timely repair before Eisenmenger develops
• Endocarditis prophylaxis for 6 months after repair with prosthetic material
• Regular surveillance even after repair

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3. PATENT DUCTUS ARTERIOSUS (PDA)

Etiology

• Failure of normal closure of the ductus arteriosus (connects descending aorta to main pulmonary artery, near left subclavian artery origin)
• Normal postnatal closure is triggered by rising oxygen tension and falling prostaglandins
• Premature birth (most common cause; lower oxygen tension, higher prostaglandins)
• Congenital rubella infection (classic cause of PDA + peripheral pulmonary artery stenosis)
• High-altitude birth (lower ambient oxygen)
• Maternal NSAID use during pregnancy can paradoxically promote earlier closure; conversely prostaglandin analogues keep it open
• Association with chromosomal syndromes less strong than other lesions

Epidemiology

• Accounts for 5-10% of all congenital cardiac lesions in infants with normal birthweight
• PDA in adults is rare (most are closed in childhood, either spontaneously or surgically)
• More common in females (2:1)
• Congenital rubella syndrome - historically important cause; now rare with vaccination

Pathophysiology

• Aortic pressure exceeds pulmonary artery pressure throughout the cardiac cycle → continuous left-to-right shunt (aorta → pulmonary artery)
• Left atrium and left ventricle dilate (volume overload)
• Right heart progressively affected as pulmonary hypertension develops
• Small PDA: Continuous flow with no chamber dilation; hemodynamically insignificant but carries ~0.45% per year risk of infectious endarteritis after the second decade
• Moderate/large PDA: Volume-pressure overload; symptoms emerge in 2nd-3rd decade; mortality rises to 3-4% per year by 4th decade; two thirds die by age 60 without intervention
• Eisenmenger physiology develops in ~5% of isolated PDAs: pulmonary pressure exceeds systemic → right-to-left shunt → deoxygenated blood enters descending aorta → differential cyanosis (lower extremities cyanosed more than upper extremities)

Clinical Signs and Symptoms

• Small PDA: Asymptomatic; incidentally detected
• Moderate/large PDA: Dyspnea, palpitations, exercise intolerance
• Physical signs:
  • Continuous "machinery" murmur best heard at 1st-2nd left intercostal space below left clavicle (pathognomonic)
  • As PA pressure rises, the diastolic component shortens; with Eisenmenger physiology, the murmur may completely disappear
  • Wide pulse pressure (diastolic runoff into pulmonary artery lowers diastolic BP)
  • Bounding arterial pulse (increased stroke volume)
  • Variable LV and RV impulses depending on degree of volume overload vs. pulmonary hypertension
  • Differential cyanosis and clubbing in toes > fingers (classic for Eisenmenger PDA)

Diagnosis

• ECG: Normal in small PDA; LVH ± LAH in moderate/large; RVH with pulmonary hypertension
• Chest X-ray: Dilated ascending aorta and main pulmonary artery; left heart enlargement; increased pulmonary vascularity; calcification at PDA site in older adults
• Echocardiography: May not directly visualize PDA; Doppler identifies continuous retrograde flow in main pulmonary artery; left heart enlargement quantified
• Cardiac catheterization: Oxygen step-up at pulmonary artery; measures PVR; required before closure if pulmonary hypertension present

Differential Diagnosis

• Venous hum (disappears with jugular vein compression; position-dependent)
• Aorto-pulmonary window
• Ruptured sinus of Valsalva aneurysm
• Coronary artery fistula
• Mammary souffle (pregnancy)
• Combined aortic stenosis + aortic regurgitation ("to and fro" murmur - not truly continuous)

Treatment

• Percutaneous coil or device closure (Amplatzer duct occluder): First-line in adults; indicated when left-sided heart enlargement is present or prior endarteritis has occurred
• Surgical ligation/division: For large PDAs, calcified PDAs (higher procedural risk), or failed transcatheter closure
• Closure is contraindicated in Eisenmenger complex (severe, irreversible pulmonary hypertension with right-to-left shunt)
• Ibuprofen/indomethacin: Promotes closure in preterm infants (NOT effective in adults)
• After ligation in infancy/early childhood: cardiac function typically normalizes with no special follow-up required
• Operative mortality: <1% in uncomplicated cases; up to 8% if calcified/complicated

Complications

• Infectious endarteritis (~0.45%/year for even small PDAs)
• Pulmonary arterial hypertension / Eisenmenger syndrome (~5%)
• Left heart failure (volume overload from large shunt)
• Differential cyanosis (Eisenmenger PDA)
• Aneurysmal dilation of the duct (rare; risk of rupture)
• Laryngeal nerve palsy (recurrent laryngeal nerve wraps around ligamentum arteriosum - surgical risk)

Prevention

• Rubella vaccination of women of childbearing age
• Antenatal care to minimize premature delivery risk
• In preterm neonates: conservative fluid management, indomethacin/ibuprofen prophylaxis in selected cases
• Endocarditis prophylaxis NOT routinely recommended for unclosed small PDA; recommended 6 months after closure

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CATEGORY 2: RIGHT-TO-LEFT SHUNTS (CYANOTIC)

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4. TETRALOGY OF FALLOT (TOF)

Etiology

• Results from anterior malalignment of the infundibular septum during embryogenesis
• The four anatomical components (Fallot's tetrad):
  1. Large subaortic VSD (non-restrictive, perimembranous)
  2. Right ventricular outflow tract (RVOT) obstruction (infundibular stenosis ± valvular pulmonary stenosis)
  3. Overriding aorta (straddles the VSD, receiving blood from both ventricles)
  4. Right ventricular hypertrophy (secondary to RVOT obstruction and pressure overload)
• Chromosomal: ~15% have 22q11 deletion (DiGeorge/CATCH-22) - higher prevalence with right aortic arch; also associated with Down syndrome, CHARGE syndrome, VACTERL association
• Maternal: Diabetes, phenylketonuria, retinoic acid exposure
• Often sporadic; ~3-4% recurrence risk in offspring

Epidemiology

• Most common cyanotic congenital heart defect in adults
• Accounts for 5-12% of all CHD in infants (together with TGA)
• Represents ~10% of all CHD
• With surgical correction (most done in infancy/early childhood since 1950s), the majority now survive to adulthood
• ~35,000 adults with repaired TOF in the United States

Pathophysiology

• Severity determined by degree of RVOT obstruction
• Severe obstruction: RV pressure equals/exceeds LV → right-to-left shunt through VSD → deoxygenated blood enters aorta → cyanosis and polycythemia
• Mild obstruction ("pink Fallot"): left-to-right shunt through VSD (acyanotic form)
• Hypercyanotic ("tet") spells: Acute RVOT spasm → sudden increase in right-to-left shunting → severe cyanosis, hyperpnea, possible loss of consciousness (more common in children)

• Most common residual lesion: pulmonary regurgitation (PR) - consequence of RVOT patch repair/transannular patch
• Chronic PR → progressive right ventricular dilation and dysfunction
• RV dilation → ventricular arrhythmias, sudden cardiac death
• Residual RVOT obstruction, VSD patch leak, branch pulmonary artery stenosis, aortic root dilation are other sequelae

Clinical Signs and Symptoms

• Central cyanosis, digital clubbing
• Polycythemia
• Squatting posture (raises SVR, decreases right-to-left shunt)
• Tet spells (episodic severe cyanosis)
• Growth retardation

• Often asymptomatic for years post-repair, then:
• Progressive exercise intolerance and dyspnea (from RV failure secondary to PR)
• Palpitations / syncope (ventricular arrhythmias - VT/VF)
• Right ventricular heave (RV dilation)
• Pulmonary regurgitation murmur - low-pitched, decrescendo diastolic murmur at left sternal border (most common physical finding in repaired TOF)
• Residual systolic ejection murmur (RVOT obstruction)
• Signs of right heart failure in advanced disease

Diagnosis

• ECG: RBBB (almost universal post-repair); prolonged QRS ≥ 180 ms - key marker of sudden death risk; right axis deviation; right ventricular hypertrophy
• Chest X-ray: "Boot-shaped heart" (upturned cardiac apex from RVH, concave pulmonary artery segment) in unrepaired; post-repair - sternal wires, normalized cardiac silhouette
• Echocardiography: Confirms anatomy, residual VSD, PR severity, TV regurgitation, RVOT gradient; RV size and function (technically challenging)
• Cardiac MRI (gold standard for repaired TOF): Precisely quantifies pulmonary regurgitant fraction, RV end-diastolic volume index (RVEDVI >160 mL/m² suggests need for pulmonary valve replacement), LV function, aortic root size
• Holter monitoring: For VT burden assessment
• Exercise testing: Functional capacity, arrhythmia provocation, response to exercise

Differential Diagnosis

• Other cyanotic CHD (TGA, pulmonary atresia + VSD, truncus arteriosus)
• Acquired pulmonary regurgitation (post-procedural)
• Arrhythmogenic right ventricular cardiomyopathy (ARVC) - in patients with large RV
• Dilated cardiomyopathy

Treatment

• Pulmonary valve replacement (PVR): Indicated for severe PR with RV dilation (RVEDVI >160 mL/m²), RV dysfunction, symptoms, or significant arrhythmia
  • Surgical PVR (traditional) or Transcatheter pulmonary valve replacement (TPVR) - Melody or Sapien valves (for conduit stenosis/regurgitation)
• Re-intervention for RVOT obstruction (catheter balloon dilation/stenting or surgery)
• ICD implantation: For primary prevention of SCD in high-risk patients (QRS ≥ 180 ms, inducible VT, severe RV dysfunction, syncope)
• Catheter ablation: For intra-atrial re-entrant tachycardia, sustained VT
• Aortic root surveillance and surgery if aortic dilation progresses
• Medical management of heart failure, arrhythmias as indicated

Complications

• Pulmonary regurgitation - most common long-term residual (nearly universal after transannular patch repair)
• Right ventricular failure from chronic volume overload
• Ventricular tachycardia / Sudden cardiac death - QRS >180 ms is most powerful predictor; incidence ~0.5-2% per year in adults
• Atrial arrhythmias (AF, AFL, IART)
• Aortic root dilation and aortic regurgitation (aorta receives biventricular output before repair)
• Residual RVOT obstruction or VSD
• Re-operation rate high over lifetime (prosthetic valves wear out)
• Infective endocarditis (prosthetic valves, residual defects)

Prevention

• Genetic screening and counseling for 22q11 deletion in patients and families
• Early definitive surgical repair in infancy (before irreversible RV damage)
• Lifelong follow-up at ACHD specialist center
• Timely pulmonary valve replacement before irreversible RV dysfunction
• Risk stratification with cardiac MRI and Holter monitoring
• Endocarditis prophylaxis per guidelines

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5. EISENMENGER SYNDROME

Etiology

• Not a primary defect but a final common pathway of large unrepaired left-to-right shunts
• Underlying defects:
  • Most common: Large VSD (non-restrictive)
  • Also: Large PDA, large ASD (less commonly than VSD/PDA), AVSD, aortopulmonary window, truncus arteriosus
• Progressive pulmonary vascular remodeling due to chronic exposure of pulmonary vasculature to high flow and pressure
• Unknown why only a subset of patients develop Eisenmenger; more common in women; genetic/environmental factors contribute
• Due to improved CHD diagnosis and treatment, Eisenmenger syndrome is becoming less prevalent in developed countries

Epidemiology

• Prevalence: ~1-9 cases per million population; decreasing with improved early surgical repair
• Predominantly affects young adults (teens to 30s when unrepaired defects are eventually diagnosed)
• 2:1 female predominance
• Life expectancy significantly reduced: mean survival 20-50 years for those with Down syndrome; somewhat better for those without genetic syndromes

Pathophysiology

• Chronic high-flow, high-pressure exposure from large left-to-right shunt causes:
  • Pulmonary vascular smooth muscle hypertrophy and intimal proliferation → progressive increase in pulmonary vascular resistance (PVR)
  • When PVR approaches or exceeds systemic vascular resistance (SVR): shunt reverses to right-to-left
  • Deoxygenated right-sided blood enters systemic circulation → central cyanosis
  • Secondary erythrocytosis (compensatory polycythemia) → hyperviscosity
  • Progressive right ventricular pressure overload → RV hypertrophy → eventually failure
  • Coagulopathy: Paradoxically both thrombotic (hyperviscosity) and bleeding (thrombocytopenia, platelet dysfunction, acquired von Willebrand deficiency)
  • Hyperuricemia from increased red cell turnover → gout
  • Brain abscesses from right-to-left shunt bypassing pulmonary filtration

Clinical Signs and Symptoms

• Central cyanosis (bluish discoloration of mucous membranes and tongue - not just peripheries)
• Digital clubbing (bilateral, symmetrical for most lesions; differential cyanosis - toes more than fingers - specific for Eisenmenger PDA)
• Dyspnea on exertion (reduced exercise capacity)
• Chest pain (right ventricular ischemia, pulmonary artery dilation)
• Hemoptysis (in situ pulmonary artery thrombosis, hypertensive pulmonary vascular rupture)
• Palpitations and syncope (arrhythmias, RV failure)
• Symptoms of hyperviscosity: Headache, blurred vision, dizziness, fatigue, myalgias, paresthesias
• Signs of right heart failure: Elevated JVP, hepatomegaly, peripheral edema, ascites
• Loud P2 and signs of pulmonary hypertension
• Original shunt murmur disappears (as pressure gradient equalizes)
• Pulmonary regurgitation murmur (Graham Steell murmur) and TR murmur from pulmonary hypertension

Diagnosis

• Clinical: Cyanosis + clubbing + known or suspected prior CHD
• ECG: Right axis deviation, right ventricular hypertrophy, right atrial enlargement
• Chest X-ray: Dilated central pulmonary arteries; pruned peripheral vessels ("peripheral pruning"); right heart enlargement
• Echocardiography with bubble study: Right-to-left shunting confirmed; elevated RV pressure (often near-systemic or supra-systemic); anatomy of underlying defect
• Cardiac catheterization (definitive): Elevated PVR (≥8 Wood units); confirms anatomy; vasoreactivity testing (failure to respond to vasodilators indicates fixed/irreversible disease; closure then contraindicated)
• Labs: Polycythemia (elevated Hgb, Hct); thrombocytopenia; elevated uric acid; iron deficiency anemia may coexist (blunts polycythemia - important to detect and treat)
• 6-minute walk test: Prognostic tool

Differential Diagnosis

• Idiopathic/heritable pulmonary arterial hypertension (no structural CHD)
• Chronic thromboembolic pulmonary hypertension (CTEPH)
• Severe COPD/emphysema with hypoxemia
• Cyanotic CHD without pulmonary hypertension (e.g., unrepaired TOF)
• Methemoglobinemia (cyanosis with normal O2 sat by pulse oximetry vs. co-oximetry)

Treatment

• Targeted PAH therapies:
  • Endothelin receptor antagonists: Bosentan (FDA-approved specifically for Eisenmenger syndrome) - improves exercise capacity and functional class; ambrisentan
  • Phosphodiesterase-5 inhibitors: Sildenafil, tadalafil
  • Prostacyclin analogues: Epoprostenol (IV), treprostinil, iloprost (inhaled) - for advanced disease
  • Combination therapy increasingly used
• Iron supplementation: If iron deficiency is identified (crucial to not allow iron-deficiency to blunt compensatory erythrocytosis)
• Avoid: Dehydration, excessive exercise, iron depletion phlebotomy, systemic vasodilators (calcium channel blockers unless vasoreactive), pregnancy (extremely high risk), NSAIDs, aminoglycosides, contrast dye
• Anticoagulation: Controversial; thrombosis risk balanced against bleeding risk; individualized
• Phlebotomy: Only for symptomatic hyperviscosity with Hct >65% - not routine (causes iron deficiency and paradoxically worsens symptoms)

• Defect closure is contraindicated once Eisenmenger physiology established
• Heart-Lung transplantation (or bilateral lung transplant with defect repair): Last resort; reserved for end-stage disease; limited by organ availability

Complications

• Sudden cardiac death
• Right heart failure (progressive, ultimately fatal)
• Stroke/TIA from paradoxical embolism or in situ pulmonary artery thrombosis
• Brain abscess (right-to-left shunt bypasses pulmonary filter)
• Hemoptysis (potentially fatal)
• Gout (hyperuricemia from polycythemia)
• Iron-deficiency anemia (worsens hypoxemia)
• Renal dysfunction
• Pregnancy (extremely high risk; maternal mortality 30-50% - absolute contraindication)
• Infective endocarditis

Prevention

• Primary prevention of Eisenmenger = timely surgical correction of underlying left-to-right shunts in infancy/childhood before pulmonary vascular disease becomes established
• Mandatory follow-up of all known large CHD lesions
• For established Eisenmenger: avoid precipitating factors; regular specialist follow-up

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6. EBSTEIN ANOMALY

Etiology

• Failure of normal delamination of the tricuspid valve leaflets from the right ventricular myocardium during embryogenesis
• The septal and posterior leaflets of the tricuspid valve are apically displaced into the right ventricle; the anterior leaflet is large, sail-like, and abnormally attached
• Maternal lithium exposure during first trimester (historically cited; association is weaker than previously thought but still recognized)
• Association with maternal benzodiazepine use (debated)
• Often sporadic; some familial cases reported
• Commonly associated with:
  • ASD or PFO (present in ~80-90%)
  • Wolff-Parkinson-White (WPW) syndrome - accessory pathways (present in 20-25%)
  • Other CHD (pulmonary stenosis, VSD, corrected TGA)

Epidemiology

• Rare: ~1 per 20,000 live births; accounts for <1% of all CHD
• Clinical severity varies enormously (from neonatal hydrops to asymptomatic adult discovery)
• Many mildly affected patients survive to adulthood undiagnosed
• Adults with mild Ebstein may be referred for palpitations or an incidental murmur

Pathophysiology

• Apical displacement of tricuspid valve creates an "atrialized" portion of the right ventricle (wall functions as atrium, not ventricle)
• Functional right ventricle is small; "atrialized RV" is thin, akinetic
• Tricuspid regurgitation (severe, from abnormal coaptation of displaced leaflets)
• Right atrial dilation (massive; from TR + atrialized RV)
• Paradoxical right-to-left shunt through ASD/PFO (especially with elevated RA pressure) → cyanosis in more severe cases
• Arrhythmias from the massive dilated right atrium; multiple accessory pathways in WPW
• Right ventricular failure with progressive disease

Clinical Signs and Symptoms

• Mild cases: Palpitations, fatigue; discovered on ECG (RBBB, delta waves) or echo
• Moderate-severe: Dyspnea, exercise intolerance, cyanosis (if right-to-left shunting through ASD)
• Palpitations, SVT, syncope (accessory pathway-mediated tachycardia, atrial arrhythmias)
• Paradoxical embolism (right-to-left through PFO/ASD)
• On exam: Holosystolic TR murmur; right-sided S3 and S4 ("quadruple" or "sail sound" from large anterior leaflet snapping)
• Massive cardiomegaly with rightward shift of cardiac silhouette ("box-shaped heart" on CXR)
• Cyanosis and clubbing in more severe cases
• Right bundle branch block on ECG is near universal
• Delta waves on ECG (WPW) in ~20-25%

Diagnosis

• ECG: RBBB (broad RSR'); giant P waves (RA enlargement); tall, broad P waves in V1; delta waves if WPW; prolonged PR interval
• Chest X-ray: Massive cardiomegaly, "box-shaped heart" with right heart predominance
• Echocardiography: Diagnostic - demonstrates apical displacement of septal tricuspid leaflet >8mm/m² (or >2 cm apically displaced); severity of TR; ASD/PFO; RV/RA size and function
• Cardiac MRI: Volume quantification of functional RV; arrhythmia substrate assessment
• EP study: Required if accessory pathways suspected; mapping before ablation

Differential Diagnosis

• Other causes of right heart enlargement (idiopathic TR, ASD, ARVC)
• WPW without Ebstein (delta waves alone)
• Dilated cardiomyopathy
• Pericardial effusion (large heart silhouette on CXR)

Treatment

• Medical: Antiarrhythmic drugs; anticoagulation for atrial arrhythmias and PFO/ASD with right-to-left shunting
• Catheter ablation: For symptomatic accessory pathways (WPW) - important to map multiple pathways; right-sided pathways can be challenging
• Tricuspid valve repair or replacement: For symptomatic severe TR, progressive RV failure; repair preferred over replacement (cone reconstruction - novel technique with excellent results)
• ASD/PFO closure: At time of valve surgery, or if significant right-to-left shunting causing cyanosis
• Bidirectional Glenn (SVC to RPA): Unloads the failing RV in severely compromised cases
• Heart transplantation: End-stage RV failure with complex anatomy

Complications

• Sudden cardiac death from WPW (antidromic AF → VF via accessory pathway)
• Atrial fibrillation and flutter (massive RA)
• Paradoxical embolism and stroke
• Right heart failure (progressive)
• Cyanosis (right-to-left through ASD)
• Pregnancy risk: moderate to high depending on severity

Prevention

• Caution with lithium in first trimester (use alternative mood stabilizers where possible, or monitor fetal echo)
• Regular specialist follow-up for all known Ebstein cases
• Accessory pathway ablation before pregnancy in WPW to prevent malignant arrhythmias

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CATEGORY 3: OBSTRUCTIVE LESIONS

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7. BICUSPID AORTIC VALVE (BAV) AND AORTIC STENOSIS

Etiology

• Most common congenital cardiac anomaly in adults (~2% of general population)
• Failure of normal tricuspidization of the aortic valve during embryogenesis; two leaflets fuse (most commonly right + left coronary cusps)
• Highly heritable: Autosomal dominant with incomplete penetrance; mutations in NOTCH1 gene; familial clustering strong (~10% of first-degree relatives affected)
• Associated with: Coarctation of the aorta (up to 50%), Turner syndrome, Williams syndrome (supravalvular AS variant)
• Types by cusp fusion pattern: Right-left (most common, ~75%), right-noncoronary (~20%), left-noncoronary (~5%)
• The abnormal valve undergoes accelerated degenerative calcification → stenosis typically 20-30 years earlier than tricuspid aortic stenosis

Epidemiology

• Prevalence: ~2% of general population; male:female ~3:1 for stenosis
• Most common cause of aortic stenosis requiring surgery in patients under age 70
• Accounts for up to 50% of surgical cases of aortic stenosis in adults
• Significant aortic stenosis or regurgitation develops in ~30-40% of BAV patients by age 60-70

Pathophysiology

• Turbulent flow across abnormal leaflets → endothelial injury → inflammation → calcification → progressive aortic stenosis
• LV pressure overload → concentric LVH → diastolic dysfunction → eventually LV failure
• Alternatively, leaflets may not coapt normally → aortic regurgitation → LV volume overload → eccentric LVH

• Intrinsic aortic medial abnormality (regardless of valve function): cystic medial necrosis, elastin fragmentation
• Progressive aortic root and ascending aortic dilation independent of valve hemodynamics
• Risk of aortic dissection at smaller diameters than Marfan syndrome (~4-5 cm vs. >5 cm)

Clinical Signs and Symptoms

• Asymptomatic; incidental finding
• Systolic ejection click (hallmark in young adults) - best heard at the apex or aortic area; does NOT vary with respiration (unlike pulmonary ejection click)
• Soft systolic ejection murmur (flow murmur across abnormal valve)

1. Angina - myocardial oxygen demand > supply from LVH; coronary arterial disease often coexists
2. Syncope / presyncope - inadequate cardiac output with exertion; vasovagal syncope from baroreceptor activation
3. Dyspnea (exertional then at rest) - LV failure, pulmonary venous congestion

• Harsh, late-peaking systolic ejection murmur at aortic area (2nd right ICS), radiates to carotids
• Pulsus parvus et tardus (weak, delayed carotid upstroke)
• Sustained, forceful LV apex beat (pressure overload)
• Absent or soft A2 (calcified, immobile leaflets); paradoxical splitting of S2 in severe stenosis
• S4 gallop (stiff LV)

Diagnosis

• ECG: Left ventricular hypertrophy with strain (deep S in V1, tall R in V5-6; ST depression/T-wave inversion in lateral leads)
• Chest X-ray: Post-stenotic aortic dilation (dilated ascending aorta); aortic valve calcification; LV prominence; pulmonary edema in decompensated AS
• Echocardiography (key diagnostic tool):
  • Identifies bicuspid morphology; calcification/restriction
  • Doppler: peak/mean gradient across valve; valve area (normal ≥2.0 cm²; severe <1.0 cm²)
  • LV size, wall thickness, function
  • Aortic root and ascending aortic dimensions (critical for aortopathy monitoring)
• Cardiac CT: Best for valve calcium scoring (Agatston score >2000 AU = severe AS in males, >1200 in females); aortic anatomy pre-procedurally
• Cardiac catheterization: When non-invasive findings discordant or coronary anatomy needed pre-surgery

Differential Diagnosis

• Calcific tricuspid aortic stenosis (elderly)
• Hypertrophic obstructive cardiomyopathy (HOCM) - dynamic murmur; Valsalva differentiates
• Supravalvular aortic stenosis (Williams syndrome)
• Subvalvular aortic stenosis (discrete fibromuscular ring)
• Aortic sclerosis (no hemodynamic gradient)
• Mitral regurgitation (pansystolic, apex → axilla)

Treatment

• No medication slows BAV stenosis progression; statins do NOT prevent calcification
• Treat systemic hypertension (important for aortopathy)
• Aortic surveillance imaging: TTE annually if aorta ≥4.5 cm, every 3-5 years if smaller
• Endocarditis prophylaxis if history of prior endocarditis

• Aortic valve replacement (AVR) - indicated for severe symptomatic AS (Class I); also in severe AS if undergoing other cardiac surgery; or very severe AS (AVA <0.6 cm², mean gradient >60 mmHg) even if asymptomatic
  • Surgical AVR (SAVR): Traditional; can also replace aorta simultaneously; preferred if concomitant aortic surgery needed
  • Transcatheter AVR (TAVR): Effective in BAV - increasing evidence; anatomy requires careful CT assessment (elliptical annulus, bulky calcium); endorsed in 2025 ACC/AHA guidelines for appropriate anatomy
  • Ross procedure: Pulmonary autograft to aortic position + pulmonary homograft; preferred in young patients; avoids anticoagulation
• Aortic surgery: Aortic root replacement if root >5.0 cm (BAV) or 4.5 cm with high risk features (rapid growth >0.5 cm/year, family history of dissection, coarctation)

Complications

• Progressive aortic stenosis (natural history: rapid valve calcification)
• Aortic regurgitation
• Aortic dissection/aneurysm (due to intrinsic aortopathy)
• Infective endocarditis (higher risk than tricuspid valve)
• Sudden cardiac death (in severe unrepaired AS)
• LV failure
• Post-procedure: stroke, paravalvular leak, permanent pacemaker requirement (especially TAVR)

Prevention

• Echocardiographic screening of first-degree relatives of BAV patients
• Annual/biennial surveillance echo once BAV diagnosed
• Strict blood pressure control to slow aortopathy progression
• Endocarditis prophylaxis as indicated
• High-risk physical activities and competitive sports restricted in patients with significant AS or aortic dilation

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8. PULMONARY STENOSIS (PS)

Etiology

• Most common form: Valvular pulmonary stenosis (90% of cases)
• Abnormal development of the pulmonary valve cusps; often doming or dysplastic
• Associated syndromes: Noonan syndrome (commonest genetic cause - dysplastic pulmonary valve, often with thick leaflets that do not respond to balloon dilation); Williams syndrome (peripheral PA stenosis); Alagille syndrome; Rubella syndrome (peripheral PS + PDA)
• Other types: Subvalvular (infundibular - as part of TOF), supravalvular, branch pulmonary artery stenosis
• Carcinoid heart disease: Acquired PS (and TR) in adults from fibrous deposits on right heart valves (serotonin-mediated)

Epidemiology

• Accounts for 3-10% of all congenital lesions
• One of the better tolerated lesions; many patients survive to adulthood without symptoms
• Prevalence in adults: mild PS is very common; severe isolated PS is less common (often treated in childhood)

Pathophysiology

• Obstruction to RV outflow → RV pressure overload → concentric RV hypertrophy
• RV compensation is generally effective for decades
• Severe long-standing PS → right heart failure (RV dilation, TR, elevated RA pressure)
• Post-stenotic pulmonary artery dilation (from turbulent jet)
• Right-to-left shunting through PFO/ASD may develop if RA pressure exceeds LA → cyanosis
• Infundibular hypertrophy can develop secondary to severe valvular obstruction (worsens obstruction further)

Clinical Signs and Symptoms

• Asymptomatic; incidental finding
• Soft systolic ejection murmur at upper left sternal border

• Fatigue, exertional dyspnea
• Chest pain (RV ischemia)
• Syncope (inadequate cardiac output on exertion)
• Right heart failure symptoms (oedema, ascites)
• Peripheral cyanosis if right-to-left through PFO/ASD

• Systolic ejection click at pulmonary area that diminishes with inspiration (unlike aortic click; this is because the valve opens early with increased venous return on inspiration)
• Systolic ejection murmur - harsh, crescendo-decrescendo at 2nd left ICS; radiates to back and left shoulder; peaks later and becomes longer with increasing severity
• Wide splitting of S2 with soft P2 (delayed RV ejection, P2 comes late and is soft from reduced PA diastolic pressure)
• Right ventricular heave
• Elevated JVP with prominent A wave (forceful RA contraction against non-compliant RV)

Diagnosis

• ECG: Right axis deviation; right ventricular hypertrophy; P pulmonale (RA enlargement) in severe cases
• Chest X-ray: Post-stenotic dilation of main pulmonary artery (and left PA); diminished pulmonary vascularity in severe cases; normal to enlarged heart
• Echocardiography (diagnostic): Domed or dysplastic pulmonary valve; peak gradient across PV (mild <40 mmHg, moderate 40-70 mmHg, severe >70 mmHg); RV hypertrophy, TR severity, RA size; detect ASD/PFO
• Cardiac catheterization: Required in some cases for hemodynamic assessment; simultaneous balloon valvuloplasty

Differential Diagnosis

• Atrial septal defect (wide splitting of S2 - but fixed; flow murmur at PA)
• Tetralogy of Fallot (associated VSD, overriding aorta, RVH)
• Carcinoid heart disease (TR + PS in older adults with carcinoid syndrome)
• Pulmonary artery hypertension (PA systolic murmur absent; loud P2)

Treatment

• Mild PS (peak gradient <40 mmHg): No intervention; observation; endocarditis prophylaxis not routinely recommended; good prognosis (normal life expectancy)
• Moderate-Severe PS (peak gradient >40-50 mmHg, or symptomatic): Intervention recommended
  • Balloon pulmonary valvuloplasty (BPV): First-line treatment; excellent results for typical domed valvular PS; not effective for dysplastic valves (Noonan syndrome) - those require surgery
  • Surgical valvotomy or pulmonary valve replacement: For dysplastic valves, failed BPV, or subvalvular/supravalvular obstruction
• After successful BPV: Pulmonary regurgitation is the main residual lesion (usually mild and well tolerated)
• Pulmonary valve replacement may eventually be required if PR becomes severe

Complications

• Right ventricular failure (long-term severe PS)
• Paradoxical right-to-left shunt through PFO/ASD → cyanosis
• Atrial arrhythmias (from RA dilation)
• Infective endocarditis
• Post-BPV pulmonary regurgitation (usually well tolerated)
• Carcinoid heart disease (if in context of carcinoid syndrome)

Prevention

• Neonatal/pediatric echocardiographic screening and early intervention before severe RV dysfunction
• Rubella vaccination (reduces congenital rubella syndrome including peripheral PS)
• Lifelong surveillance even after successful valvuloplasty
• Genetic testing and counseling for Noonan syndrome families

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9. COARCTATION OF THE AORTA

Etiology

• Discrete narrowing of the thoracic aorta, typically at or just distal to the ductus arteriosus (juxtaductal)
• Pathogenesis: abnormal migration of ductal tissue into the aortic wall with subsequent contraction, or abnormal flow patterns during fetal development reducing aortic isthmian diameter
• Two classic forms:
  • Preductal ("infantile"): Aortic arch hypoplasia proximal to PDA; associated with other major defects; presents in infancy
  • Postductal ("adult"): Discrete ridge-like infolding adjacent to ligamentum arteriosum; typically isolated; classic form seen in adults
• Chromosomal: Turner syndrome (45,X) - coarctation in ~10-20% of patients (most important genetic association)
• Frequently associated with: Bicuspid aortic valve (in ~50-80% of cases), berry aneurysms of the circle of Willis (risk of intracranial hemorrhage), VSD, mitral valve abnormalities
• Male predominance (~2:1)

Epidemiology

• Accounts for 3-10% of all congenital cardiac lesions
• 5-8% of all CHD in hospital-based series
• Can present at any age; mild coarctation is frequently undiagnosed until adulthood
• Most common cause of hypertension in a young adult if the diagnosis is missed

Pathophysiology

• Obstruction creates a pressure gradient across the narrowing:
  • Upper body (proximal to coarctation): Hypertension → LV pressure overload → LVH → premature coronary artery disease, aortic complications
  • Lower body (distal to coarctation): Relative hypoperfusion → collateral arterial development (internal mammary → intercostal arteries → below coarctation)
• Persistent upper body hypertension after repair in patients repaired as adults (50% if repaired after age 40)
• Bicuspid aortic valve coexists → aortopathy, stenosis/regurgitation (independent of coarctation)
• Berry aneurysms of circle of Willis → risk of subarachnoid hemorrhage (hypertension-related)

Clinical Signs and Symptoms

• Asymptomatic young adults discovered due to upper extremity hypertension (most common presentation in adults)
• Coarctation should always be considered in young men with unexplained upper extremity hypertension
• Pressure-related symptoms: Headache, epistaxis
• Limb symptoms: Leg fatigue, claudication (lower body underperfusion)
• Older patients: angina, heart failure, vascular complications

• Blood pressure differential: arm > leg (>20 mmHg)
  • Blood pressure should be measured in all four limbs; popliteal systolic BP should exceed brachial BP by ≥10 mmHg; if not, suspect coarctation
  • Pressure differential >30 mmHg between right and left arms → left subclavian artery involvement
• Weak/absent femoral, popliteal, pedal pulses (radio-femoral delay)
• Bounding right brachial pulse (hyperdynamic) vs. weak lower extremity pulses
• Systolic murmur heard posteriorly in the mid-thoracic region (the coarctation itself); length correlates with severity
• Anterior systolic murmurs in infraclavicular areas and sternal edge (collateral flow)
• Systolic ejection click (if associated bicuspid aortic valve)
• Tortuous "corkscrew" retinal arteries (from chronic hypertension)
• LV pressure overload impulse on precordial palpation

Diagnosis

• ECG: Left ventricular hypertrophy (in adults); right ventricular hypertrophy in infants/severe neonatal cases
• Chest X-ray:
  • "3 sign" - indentation of the aorta between the dilated left subclavian artery above and the post-stenotic aortic dilation below creates a figure-of-3 on the left mediastinal border
  • Bilateral rib notching (posterior 3rd-8th ribs) - from dilated posterior intercostal arteries used as collaterals; absent if repair was done in childhood or if coarctation is proximal to left subclavian
• Echocardiography: Documents gradient in descending aorta; assesses LVH; associated BAV; may not visualize coarctation directly in adults (limited acoustic windows)
• Cardiac MRI (best modality in adults): Gold standard for visualizing anatomy of descending aorta, length and severity of narrowing, collateral vessels, associated aortic abnormalities; quantifies gradient
• CT angiography: Alternative to MRI; excellent anatomical detail; useful for pre-procedural planning
• Cardiac catheterization: Measures hemodynamic gradient; used when intervention planned

Differential Diagnosis

• Essential hypertension (but no blood pressure differential between arms and legs)
• Renovascular hypertension (renal artery stenosis)
• Takayasu arteritis (inflammatory aortopathy - adults, more diffuse narrowing)
• Peripheral arterial disease (lower extremity claudication, older patients, atherosclerotic risk factors)
• Neurofibromatosis (associated with aortic stenoses)
• Turner syndrome (always screen for coarctation)

Treatment

• Transcatheter balloon dilation + stenting (preferred in adults for discrete native coarctation and re-coarctation): Safe, effective; stent deployment prevents elastic recoil; endovascular approach preferred in adults
• Surgical repair: For long-segment coarctation, complex anatomy, very small aorta, or concurrent aortic or cardiac defects requiring surgery; techniques include resection with end-to-end anastomosis, subclavian flap, patch aortoplasty, interposition graft
• Post-repair monitoring: Lifelong follow-up mandatory
  • Residual hypertension: 50% of patients repaired after age 40 have persistent hypertension; <10% if repaired age 1-5 years
  • Annual MRI/CT of aorta to monitor for re-coarctation, aneurysm at repair site, aortic dilation

Complications

• Persistent/residual hypertension (most common long-term issue, even after repair)
• Re-coarctation (especially after patch repair or surgical repair in childhood)
• Aortic aneurysm at the repair site (common with Dacron patch repair)
• Aortic dissection (from aortopathy ± associated BAV)
• Premature coronary artery disease (from chronic hypertension)
• Cerebrovascular events: Intracerebral hemorrhage or rupture of intracranial berry aneurysms (associated in ~10% of coarctation patients)
• Stroke (paradoxical emboli, hypertensive hemorrhage)
• LV failure
• Infective endocarditis / endarteritis

Prevention

• Screen all Turner syndrome patients with echocardiography
• Screen first-degree relatives of coarctation patients
• Screen for coarctation in all patients with BAV (echocardiography)
• Screen for intracranial berry aneurysms with MRA (especially if family history of SAH or severe/uncontrolled hypertension)
• Lifelong blood pressure control post-repair (even if "normal" gradient at rest, exercise hypertension is common)
• Regular MRI/CT surveillance of the entire thoracic aorta post-repair

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SUMMARY TABLE: All 9 Headings Across All Defects

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What Was Covered

Category 1 - Left-to-Right Shunts (Acyanotic)

1. Atrial Septal Defect (ASD) - including PFO
2. Ventricular Septal Defect (VSD)
3. Patent Ductus Arteriosus (PDA)

Category 2 - Right-to-Left Shunts (Cyanotic)

1. Tetralogy of Fallot (TOF) - both repaired and unrepaired adults
2. Eisenmenger Syndrome - as a shared final pathway
3. Ebstein Anomaly

Category 3 - Obstructive Lesions

1. Bicuspid Aortic Valve / Aortic Stenosis - most common adult CHD
2. Pulmonary Stenosis
3. Coarctation of the Aorta

Key clinical pearls across all defects:

• Fixed split S2 = ASD (pathognomonic)
• Machinery murmur = PDA
• Differential cyanosis (toes > fingers) = Eisenmenger PDA
• QRS >180 ms = high sudden death risk in repaired TOF
• BP differential arms > legs = Coarctation
• Ejection click not varying with respiration = Bicuspid aortic valve
• Box-shaped heart + RBBB + delta waves = Ebstein anomaly
• The 2025 ACC/AHA Guideline [PMID: 41411480] is the current authoritative standard, published February 2026

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CONGENITAL HEART DEFECTS IN ADULTS — CONCISE REFERENCE

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CATEGORY 1: LEFT-TO-RIGHT SHUNTS (ACYANOTIC)

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1. ATRIAL SEPTAL DEFECT (ASD)

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2. VENTRICULAR SEPTAL DEFECT (VSD)

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3. PATENT DUCTUS ARTERIOSUS (PDA)

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CATEGORY 2: RIGHT-TO-LEFT SHUNTS (CYANOTIC)

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4. TETRALOGY OF FALLOT (TOF)

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5. EISENMENGER SYNDROME

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6. EBSTEIN ANOMALY

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CATEGORY 3: OBSTRUCTIVE LESIONS

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7. BICUSPID AORTIC VALVE (BAV) / AORTIC STENOSIS

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8. PULMONARY STENOSIS (PS)

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9. COARCTATION OF THE AORTA

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MASTER QUICK-REFERENCE TABLE

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