Symptoms and causes of TOF

by Miguel Carlos

• The most common cause of Blue Baby Syndrome; and 
• The most common cyanotic heart defect.

The condition was named after Etienne-Louis Arthur Fallot, a French physician. TOF is more common in men than in women.

Tetralogy of Fallot Signs & Symptoms

Infants with TOF usually develop cyanosis during their first year of life. This includes:

• The lips, mucous membranes and the skin inside the mouth as well as the nose feature a noticeable dusky blue color.
• Infants with severe obstruction of the "right ventricle outflow" turning blue at night.
• If pulmonary stenosis is mild or if the ventricular septal defect is so small or even both, children with TOF never turn blue.
• Children whose cyanosis is subtle, the disease may go undetected for years. 

Symptoms of TOF are:

• A slower growth and development, especially if there is severe pulmonary stenosis. Even puberty can get delayed if left untreated.
• Child gets tired easily and starts panting at the slightest exertion. After playing for a very short time, the child will sit or lie down.
• When the child starts walking, he or she may assume a squatting position just to catch his or her breath before he resumes physical activity. This is since squatting can increase the pressure in the aorta as well as left ventricle transiently. If this is done, less blood flow will move to the left ventricle and more from the pulmonary artery towards the lungs. 
• During the first two to three years of life, the child may show episodes of extreme blue coloring. This is also referred to as "tet spells" or "hypercyanosis". During this stage:
• The child may feel a difficulty in breathing; he or she may turn blue; and he or she may become faint or extremely irritable. 
• These spells are usually experienced by 20% to 70% of children with TOF.
• These spells usually happen during crying, feeding, straining or during waking in the morning.
• These spells can last for a few minutes an even a few hours.

Tetralogy of Fallot Causes

TOF is perceived to be a result of genetic or environmental factors. There are times when it is a combination of these two factors. The condition is also associated with the DiGeorge syndrome and with chromosome 22 deletions. This also includes: NKX2-5, JAG1, ZFPM2 and VEGF.

(Tetralogy of Fallot is a combination of four congenital abnormalities. The four defects are a ventricular septal defect (VSD), pulmonary stenosis, a misplaced aorta and a thickened right ventricular wall (right ventricular hypertrophy). They usually result in an insufficient amount of oxygenated blood reaching the body.--Mayo Clinic Medical)