Tetralogy of Fallot (TOF) is the most common cyanotic heart disease.
It consists of 4 defects in the heart of the child (tetralogy):
- Pulmonary Stenosis and Infundibular Stenosis (obstruction to right ventricular outflow due to narrowing of one or more points from right ventricle to Pulmonary artery).
- Ventricular Septal Defect (VSD)- Abnormal opening or hole in the septum between the two ventricles.
- Overriding of Aorta over the VSD- The Aorta is placed over the VSD, instead of being over left ventricle.
- Right Ventricular Hypertrophy: abnormal enlargement of heart muscle of right ventricle.
Blood is shunted from right side of heart to left side of heart with varying degrees of cyanosis.
If mild, patient may not have visible cyanosis- known as Pink TOF.
With severe disease, cyanosis is visible in neonatal period- known as Ductal Dependent TOF.
Clinical Features:
- Cyanosis: Bluish discoloration of skin due to inadequate oxygenation of blood.
- Rapid breathing or dyspnea while feeding or exercise (playing).
- Clubbing of fingers and toes.
- Tet Spells.
Tet Spells:
Acute onset of hyperpnea and restlessness, increased cyanosis, gasping, syncope. Child will squat to feel better. Squatting increases systemic vascular resistance and decreases the right to left shunt.
Management of Tet spells: Child is placed in lateral knee-chest position, oxygen, beta blocker and s/c morphine are given.
On Examination:
Systolic thrill along third to fourth intercostal space, harsh ejection systolic murmur (ESM) at upper sternal end, preceded by a click. Single S2 (or soft P).
CXR: Boot Shaped Heart, with dark lung fields (decreased pulmonary blood flow).
ECG: Right axis deviation.
Treatment:
- Depends on degree of obstruction.
- PGE1 infusion- prevents ductal closure- given if child is cyanotic at birth.
- Modified Systemic to Pulmonary Shunt (Ex- Modified Blalock Taussig shunt-To augment pulmonary blood flow.
- Corrective surgery (electively at 4 to 12 months): Removal of obstructive muscle, valvulotomy and closing the VSD.
Prognosis and Life Expectancy:
Most of the patients have a normal life going upto 40 years of age. But there are reports of patients living longer life than average TOF patients- A TOF lady lives 87 years without any surgery. and story of Asha. Science can give averages but its different in real life. Each person is different and so is their life.
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