How would an 18-year-old male typically present with undiagnosed Tetralogy of Fallot (ToF)?

Presentation of Undiagnosed Tetralogy of Fallot in an 18-Year-Old Male

An 18-year-old male with undiagnosed Tetralogy of Fallot (ToF) typically presents with mild cyanosis, exercise intolerance, and a loud precordial murmur that may have been mistaken for a small ventricular septal defect (VSD) earlier in life. 1 This presentation represents the "pink tetralogy" variant, where the patient has survived to adulthood due to relatively mild pulmonary obstruction.

Clinical Presentation

Cardinal Features:

• Cyanosis: May be mild or only present during exertion 1
• Exercise intolerance: Reduced capacity for physical activity
• Dyspnea on exertion: Shortness of breath with activity 2
• Loud precordial murmur: Often mistaken for a small VSD 1
• Clubbing of fingers and toes: May be present in varying degrees depending on chronicity and severity of cyanosis 3

Physical Examination Findings:

• Heart murmur: Typically a loud systolic ejection murmur at the left sternal border
• Widely split second heart sound: With diminished pulmonary component 1
• Right ventricular heave: Due to right ventricular hypertrophy
• Possible squatting posture: May be adopted during episodes of dyspnea to increase systemic vascular resistance

Diagnostic Features

ECG Findings:

• Right ventricular hypertrophy: Dominant R waves in right precordial leads
• Right axis deviation: Due to right ventricular dominance
• Possible right bundle branch block: Especially if there is significant right ventricular outflow tract obstruction 1

Chest X-ray Findings:

• Boot-shaped heart ("coeur en sabot"): Due to right ventricular hypertrophy with uplifted cardiac apex
• Decreased pulmonary vascular markings: Due to reduced pulmonary blood flow
• Right-sided aortic arch: Present in approximately 25% of cases 1
• Normal or slightly increased heart size: Unless significant right ventricular dilation has occurred 1

Hemodynamic Presentation

The severity of presentation depends on the degree of right ventricular outflow tract obstruction:

1. Mild obstruction: Minimal cyanosis ("pink tetralogy"), can reach adulthood without surgical correction 1
2. Moderate obstruction: Intermittent cyanosis, especially with exertion
3. Severe obstruction: More pronounced cyanosis, but survival to adulthood is possible if abundant aortopulmonary collaterals have developed 1

Associated Complications in Unrepaired Adult ToF

• Right ventricular dysfunction: Due to chronic pressure overload 3
• Paradoxical hypertension: Can occur despite right ventricular dysfunction 3
• Arrhythmias: Atrial and ventricular arrhythmias may develop
• Polycythemia: Secondary to chronic hypoxemia
• Aortic root dilation: May be present due to volume overload of the aorta 4
• Brain abscess or paradoxical emboli: Due to right-to-left shunting
• Congestive heart failure symptoms: Especially in later stages 2

Unusual Survival Characteristics

It is remarkable for a patient with unrepaired ToF to reach adulthood without intervention. Such survival typically occurs due to:

1. Balanced pulmonary stenosis: Sufficient to prevent pulmonary overcirculation but not severe enough to cause profound hypoxemia
2. Development of adequate collateral circulation to the lungs
3. Preserved right ventricular function despite chronic pressure overload

Management Considerations

For an 18-year-old with newly diagnosed ToF:

• Immediate referral to an Adult Congenital Heart Disease (ACHD) center for comprehensive evaluation 1
• Complete surgical repair remains the gold standard treatment, even in adulthood 2
• Percutaneous approaches may be considered in selected cases deemed high-risk for surgery 5

Important Caveats

• Survival to adulthood without surgical repair is rare, with less than 5% of patients reaching middle age without intervention 3
• The diagnosis may have been missed in childhood if cyanosis was minimal and the murmur was attributed to a small VSD
• Adults with unrepaired ToF should undergo genetic testing for 22q11 deletion, which is present in approximately 15% of ToF patients 1
• Pregnancy is not advised in women with unrepaired ToF due to high maternal and fetal risks 1