Tetralogy of Fallot

Tetralogy of Fallot is one of the most common, if not the most common, form of cyanotic congenital heart disease it is a constellation of cardiac findings that share the following common anatomic abnormalities: a large malaligned ventricular septal defect, overriding of the aorta over the septal defect, right ventricular outflow obstruction, and right ventricular hypertrophy.

Vena Cava Superiore
Arteria Polmonare
Vene Polmonari Vene Polmonari
Atrio Sinistro
Atrio Destro
Ventricolo Sinistro
Ventricolo Destro
Vena Cava Inferiore

-Fig 6.1
Tetralogy of Fallot. Because of the obstruction on the right ventricle outflow, this empties partially in aorta through the ventricle septal defect. This causes cyanosis-.

The clinical manifestations of patients are wide and reflect the variable severity of right ventricular outflow obstruction. Some patients exhibit severe cyanosis because of profound right-to-left ventricular level shunting, whereas other patients may be fully saturated and have a net left-to-right shunt. Consistent hemodynamic features include right ventricular hypertension because of the large ventricular defect, with normal or low pulmonary artery pressures. However with the time there is always the tendency to a progressive worsening of the cyanosis. The child with tetralogy of Fallot is cyanotic at rest and cyanosis increases with exercise. Growth may be slowed down and with the time clubbing of the fingers will appear. Some children with tetralogy of Fallot may have acute cyanosis crisis that start with weeping; these acute cyanotic crisis are life threatening but can be cured in hospital. If it is not possible to control those crisis it is urgent to proceed with surgery.

Before surgery the child must have complete laboratory investigations, cardiac catheterization and angiography to have a precise morphology and size of the pulmonary artery.

-Fig. 6.2
Blalock - Taussig intervention in Tetralogy of Fallot. The large arrow indicates right subclavian artery connected to the pulmonary artery-.

The VSD is closed with a synthetic patch suture on the margins of the defect. The pulmonary valve is opened and usually it is necessary to enlarge the right ventricle outflow by opening the valve annulus and placing a transannular patch across the valve ring. Actually this surgery is performed by one year of age. If the child needs surgery in the first months of live, a palliative intervention is performed which consist in creating a communication between subclavian and pulmonary arteries (Blalock - Taussig intervention). This allows an improve in blood oxygenation to wait the time for the radical surgery.