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 .

Squatting:

• 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.

ECG

• Shows right ventricular enlargement and right atrial hypertrophy.

X-ray

• 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.

2D echocardiography

• 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.