Fallot’s Tetralogy Clinical features of Fallot’s Tetralogy Symptoms Complications WITH Treatment
- it is the commonest congenital cyanotic heart disease.
- This congenital heart disease consists of ventricular septal defect, pulmonary stenosis, overriding of aorta and right ventricular hypertrophy.
- When there is moderate PS and small VSD, there is acyanotic Tetralogy of Fallot. As these children survive to adulthood it is also called adult Tetralogy of Fallot.
- When there is severe pulmonary stenosis and very small VSD it presents like isolated pulmonary stenosis.
- The pulmonary stenosis is valvular as well as supravalvular. There may be severe pulmonary stenosis or even pulmonary atresia.
- With pulmonary atresia there is intense cyanosis since birth. All the blood flows into the aorta.
- When there is severe pulmonary stenosis and large VSD cyanosis is moderate. This is the classic Tetralogy of Fallot.
- Right sided aortic arch and descending aorta is seen in 25% of patients.
Clinical features of Fallot’s Tetralogy
- Cyanosis occurs within first 6th months to one year.
- TOF are largely dependent upon the degree of right ventricular outflow obstruction.
- As the ductus closes reducing the blood flow to lungs, child gets hypoxic spells.
- Some patients have features of pown’s syndrome
- Children with minimal obstruction may present with pulmonary overcirculation and heart failure.
- moderate obstruction and balanced pulmonary and systemic flow may be noticed during elective evaluation for a murmur.
- severe obstruction and inadequate pulmonary flow typically present in the immediate newborn period with profound cyanosis.
Symptoms are progressive due to :
- Growth of child
- Closure of PDA
- Increased activity
- Increased obstruction to right ventricular outflow.
- Patients of Tetralogy usually do not have congestive heart failure unless there is severe anaemia, infective endocarditis, systemic hypertension, congenital mitral regurgitation, absent pulmonary valve, absent pulmonary artery, partial atrioventricular canal.
- Unoperated cases of Fallot’s Tetralogy do not survive after 10 years age in 25% cases.
Physical examination —
- On inspection, individuals with TOF are usually comfortable and in no distress.
- If cyanosis is present, it is most easily seen in the nail beds and lips.
- Peripheral pulses are usually normal, although the presence of prominent pulses may suggest the existence of a significant patent ductus arteriosus
- Hepatomegaly is uncommon
Hypoxic spells :
- Child becomes blue, weak and limp.
- There is dyspnoea, syncope and tachypnea.
- Hypoxic spells are seen commonly at the age of 2-3 years.
- Child is restless, irritable and cyanosed. Eyes roll back.
- Sometimes there is generalized stiffness or convulsions.
- Spell lasts 5 – 10 minutes. Oxygen saturation becomes low Systolic murmur disappears
- Episodes are most common in the morning . Precipitating factors are:
- · crying, sucking, defecating, hot weather, infection, exercise, standing, tachycardia.
- · hypoxic spells may occur several times a day or once a month.
Cause of Hypoxic Spells:
- Infundibular spasm causes a sudden additional reduction in pulmonary blood flow causing hypoxic spells .
- Any factor that raises pC02 causes hyperpnea, increases systemic venous return causing hypoxic spells .
- Any stimulus that decreases blood and tissue oxygen saturation and pH can cause the spells .
- More common in children
- Squatting occurs because patient can relieve his dyspnoea and prevent syncope.
- Squatting reduces right-to-Ieft shunt and increases saturation of mixed venous blood by :
- · Squatting increases arterial oxygen saturation when patient squats or rests after exercise.
- Children with Fallot’s tetralogy avoid hanging their limbs and always sit with legs tucked under their body or lie in a knee-chest or lateral position with the legs drawn up
- · Increasing peripheral resistance
- · Trapping venous blood of low oxygen saturation in the lower limbs
- · Decreasing hydrostatic pooling.
- On examination heart is not enlarged. There is no precordial prominence.
- No parasternal heave. There is no LVH.
- A systolic murmur is maximal in the second and third intercostals spaces at the left sternal border and varies in duration and configuration depending on the severity of the pulmonary stenosis. The ventricular septal defect is apparently silent.
- In mild Tetralogy a grade 3-4 systolic murmur extends into the aortic component of the S2.
- If P2 is audible then pulmonary stenosis is not severe.
- In valvular pulmonary stenosis, a pulmonary ejection sound is found. A2 is loud.
- In severe Tetralogy, murmur is short, soft and early systolic.
- A2 is loud and P2 inaudible.
- Aortic ejection sound is heard at the left sternal border and apex.
- A continuous murmur of pulmonary collateral circulation is heard in pulmonary atresia with ventricular septal defect.
- Shows right ventricular enlargement and right atrial hypertrophy.
- Shows boot-shaped heart (Coeur en sabot) due to right ventricular hypertrophy, and concave pulmonary conus.
- Pulmonary vascular markings are faint and aortic arch and aortic knob may be seen on the right side.
- Shows overriding of aorta, pulmonary stenosis and right ventricular hypertrophy.
Complications of Fallot’s Tetralogy
- Infective endocarditis, paradoxic embolism, coagulation defects, cerebral infarction or abscess.
Treatment of Fallot’s Tetralogy
- Corrective surgery is done after evaluation of the pulmonary vascular system.
- If there is pulmonary atresia, then full correction is deferred and a palliative operation is done i.e. creation of a systemic pulmonary arterial shunt.
- The later the corrective surgery is done the lower the risk. But an early corrective surgery prevents progressive obstruction of the pulmonary outflow tract, prevents growth impairment, and complications due to hypoxemia, erythrocytosis.