Many babies with Fallot are pink at birth but gradually become cyanosed over the first few months of life as RVOT obstruction worsens.
- Commonest cause of Congenital cyanotic heart disease
- 1. Overriding Aorta with respect to the ventricular septum
- 2. Right ventricular hypertrophy secondary to the RV outflow obstruction
- 3. Sub-Pulmonary stenosis (Right ventricular outflow obstruction) - at and below the valve)
- 4. VSD - usually large
- The main problem is that the right-sided outflow obstruction leads to poor pulmonary blood flow and impaired blood oxygenation.
- Everything depends upon RV outflow. The large VSD just shunts even more blood into the right ventricle until eventually as RV pressures rise the RV pressure exceeds LV and deoxygenated blood passes into the systemic system and the patient now has Eisenmenger syndrome and is centrally cyanosed. This takes time to happen and the baby may not be cyanosed at birth.
- In some patients the RV outflow gradually gets worse up to 6-9 months of age.
- Cyanosis - may not be apparent at birth
- Murmur - harsh ejection systolic murmur left sternal edge. Absent P2
- Babies have "tet spells" possibly due to increases in the RVOT gradient and increased R to L shunting where they become hypercyanosed which can lead to MI or stroke
- Finger and toe clubbing
- CXR shows a "boot-shaped" heart due to RVH
- Pulmonary Oligaemia - Decreased pulmonary markings due to reduced blood flow
- ECG - RVH, Echocardiography
- Medical management up to 6 months
- Definitive surgery to close VSD and reduce RVOT obstruction with a patch at 6 months
- Cyanosed neonate may need Blalock -Taussig shunt from subclavian artery to pulmonary artery until definitive surgery. Alternatively, balloon dilatation of RVOT is possible
- Prolonged Tet spells - Morphine reduces pain, IV Propranolol, Sedation, Hydration, Bicarbonate for acidosis, ventilation and muscle paralysis to reduce oxygen demand