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.
Fallot's Tetralogy Clinical features

Fallot’s Tetralogy Symptoms Complications WITH Treatment

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.

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.


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