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Tetralogy of Fallot


Arshika Singh is an Child Health Nurse, has completed her masters from CMC, Ludhiana.

Tetralogy of Fallot

Definition of Tetralogy of Fallot

Tetralogy of Fallot (pronounced te-tral-uh-jee of Fal-oh) is a congenital cyanotic birth defect that affects normal blood flow through the heart in the circulatory system. Tetralogy of Fallot consists of the combination of four congenital heart defects:

a) ventricular septal defect (Ventricular Septal Defect);

b) obstructed outflow of blood from the right ventricle to the lungs (pulmonary stenosis);

c) displaced aorta, which causes blood to flow into the aorta from both the right and left ventricles (deposition or overriding aorta);

d) abnormal enlargement of the right ventricle (right ventricular hypertrophy).

The severity of the TOF symptoms largely related to the degree of blood circulation through VSD from the right ventricle.

Causes and Risk Factors of Tetralogy of Fallot

The exact causes of Congenital heart defects are unknown, but some risk factors are associated with the condition :

  1. Elderly Primigravida ( Maternal age above 40 yrs)
  2. Diabetes
  3. Maternal Alcoholism.
  4. Nutritional Deficiencies during prenatal period.

Pathophysiology of Tetralogy of Fallot

Symptoms of Tetralogy of Fallot

The symptoms of Tetrology of Fallot may be present at birth or shortly afterward.

They include:

  • Delicate Looking child
  • failure to gain weight
  • a bluish skin color, mucous membranes and finger nails.
  • clubbed fingers, or growths of skin and bone around the fingernails
  • chocked spells while taking feed and turns blue.
  • Tet Spells - occurs in 2 to 3 years of life
  1. 20 - 70 % of infant suffers with Tet Spells.
  2. The spells often occurs at time of feeding, crying, straining, or on awakening in the mornings. ( due to increased use of oxygen demand of the body)
  • Delayed growth and development.

Diagnostic Procedures :

  • Lab Test - RBC count or Hemoglobin level will be elevated, due to the body physiology to compensate for oxygen deficiency.
  • Electrocardiogram: It reflects the electronic waves due to structural defects mainly, Ventricular septal defects.
  • Chest X- ray: It reveals the characteristic "Boot Shaped " Heart.
  • Echo cardiogram: This imaging test is key to TOF . It basically demonstrate the ventricular septal defect, the degree of pulmonary stenosis, and it will reveal all the anticipated defects.
  • Cardiac catheterization: is the procedure which helps to evaluate the size and origin distribution of pulmonary arteries and all the branching pattern of coronary arteries. It also demonstrate the pattern of flow flow across the heart (normal or abnormal).

Tetralogy of Fallot Repair:

Surgical Repair of Tetralogy of Fallot

The Surgical Repair of Child can be done through Open - Heart surgery soon after the birth or later in infancy period, depending on Rule of Ten .

Rule of Ten - Says 10 months of Age, 10 Hemoglobin and 10 kg of weight.

The Two Surgical Repair options available according to the practice are -

  1. Complete Repair : The Physician removes the narrowing of the pulmonary artery to facilitate the normal blood flow to the lungs. Meantime, the sepal defect between the ventricles are also repaired either placing the patch or by ligation, depending on the size of septal defect to prevent the mixing of blood.with this approach other two defects i.e overriding of aorta and right ventricular hyper trophy also fixes.
  2. Temporary or Palliative Repair: If the condition of the child is not good enough for the surgery, then this approach can be opted. The surgeon widens the passageway between the right ventricle and the pulmonary artery to improve blood flow to the lungs. The ventricular septal defect is patched to stop the mixing of high-oxygen blood with low-oxygen blood between the ventricles.

Picture of Infant with Surgical Repair of Tetralogy of Fallot

Possible Complications of Tetralogy of Fallot

If this congenital birth defect if left untreated, it will cause many complications:

  1. Blood Clots
  2. Congestive Heart Failure.
  3. Abnormal Heart rhythms.
  4. Frequent chest infections.
  5. Death.

Prognosis of Tetralogy of Fallot after Surgical Repair

From the retrospective cohort study, researchers assessed registry data from year 1982–2014 from the Pediatric Cardiac Care Consortium, the Organ Procurement and Transplantation Network, and the National Death Index that patients shows a good long term survival rates i.e around 94% with staged heart repair operations.

This content is for informational purposes only and does not substitute for formal and individualized diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed medical professional. Do not stop or alter your current course of treatment. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2021 Anu

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