Tetralogy of Fallot: Clinical Case and Viva QnA

Clinical Case: Tetralogy of Fallot

A 6-month-old male infant is brought to the emergency department by his parents due to episodes of cyanosis and difficulty breathing. The parents report that these episodes occur especially during feeding or when the baby cries. They've noticed a bluish tint to his lips and fingertips during these spells.

History:

• Full-term birth with no complications
• Poor weight gain since birth
• Easily fatigued during feeding
• No history of respiratory infections

Physical Examination:

• Weight: 5.8 kg (below 3rd percentile)
• Heart rate: 145 bpm
• Respiratory rate: 50 breaths/min
• Oxygen saturation: 85% on room air
• Visible cyanosis of lips and nail beds
• Clubbing of fingers
• Grade 3/6 systolic ejection murmur at the left sternal border
• Quiet second heart sound

Investigations:

• Chest X-ray: Boot-shaped heart, decreased pulmonary vascular markings
• ECG: Right axis deviation, right ventricular hypertrophy
• Echocardiogram: Large ventricular septal defect, overriding aorta, right ventricular outflow tract obstruction, right ventricular hypertrophy

Diagnosis:

Tetralogy of Fallot

Management:

1. Oxygen therapy
2. IV fluids for hydration
3. Propranolol to prevent hypercyanotic spells
4. Surgical repair scheduled for 3 months later

Outcome:

The patient underwent successful total surgical repair at 9 months of age. Post-operative course was uneventful, and he was discharged after 10 days. Follow-up at 1 year showed significant improvement in growth and development, with no residual cyanosis.

5 Varieties of Tetralogy of Fallot Presentation

1. Classic Tetralogy of Fallot:

   • Presents in infancy with cyanosis
   • Hypercyanotic spells (tet spells)
   • Poor feeding and failure to thrive
   • Systolic murmur at left sternal border

2. Pink Tetralogy of Fallot:

   • Minimal or no cyanosis at rest
   • Adequate pulmonary blood flow
   • May present later in childhood
   • Exercise intolerance and easy fatigability

3. Tetralogy of Fallot with Pulmonary Atresia:

   • Severe cyanosis from birth
   • Absence of murmur due to complete obstruction of right ventricular outflow
   • Dependent on patent ductus arteriosus for pulmonary blood flow
   • May have major aortopulmonary collateral arteries (MAPCAs)

4. Tetralogy of Fallot with Absent Pulmonary Valve:

   • Aneurysmal dilatation of pulmonary arteries
   • To-and-fro murmur due to pulmonary stenosis and regurgitation
   • Respiratory symptoms due to bronchial compression by dilated pulmonary arteries
   • May present with heart failure

5. Tetralogy of Fallot with Complete Atrioventricular Septal Defect:

   • Features of both TOF and AVSD
   • Severe cyanosis
   • Single AV valve with common atrium
   • More complex surgical repair required
   • Often associated with Down syndrome

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