Tetralogy of Fallot (T O F) Custom Search Tetralogy of Fallot is a congenital heart disease with four abnormalities in the heart (Tetra meaning four). The condition leads to mixing of oxygenated and deoxygenated blood in the heart resulting in supply of incompletely oxygenated blood to all the organs. The supply of such blood leads to bluish discoloration of the skin and inner lining of organs (visible as bluish color of tongue) medically known as cyanosis. Those congenital abnormalities of heart which lead to cyanosis are called as cyanotic congenital heart diseases while those congenital abnormalities of heart which do not cause cyanosis are called as acyanotic congenital heart diseases. TOF is the most common among cyanotic congenital heart diseases while ventricular septal defect is the most common of all the congenital heart diseases (including both cyanotic and acyanotic). The four abnormalities of tetralogy of fallot are as follows. Pulmonary stenosis: Stenosis means narrowing. Pulmonary stenosis means narrowing of the pulmonary artery which causes obstruction to the flow of blood from the right ventricle into the pulmonary artery. Ventricular septal defect (V S D): This is a defect in the inter-ventricular septum. Due to pulmonary stenosis the pressure in the right ventricle goes up. The increased right ventricular pressure pushes blood into the left ventricle through the defect resulting in right to left shunt. Abnormalities of TOF Please click on the graphic to enlarge
As the right ventricle contains deoxygenated blood, the shunted blood results in admixture of oxygenated blood in the left ventricle (which comes from the lungs via the pulmonary veins) and deoxygenated blood from the right ventricle. . It is this blood which is pumped by the left ventricle into all the tissues of body. Hence a child with TOF does not get fully oxygenated blood leading to many problems. Hypertrophy of right ventricle: The obstruction to blood flow from the right ventricle causes additional stress to the muscles of right ventricle. Hence they increase in size to become stronger. This is called hypertrophy. Overriding of the aorta: The opening of the aorta is located just above the ventricular septal defect. It is connected to both left and right ventricles. Normally the aorta is connected only to the left ventricle. Symptoms and signs: The severity of clinical features depends on the degree of obstruction at the pulmonary artery. If the obstruction is very severe lot of blood from the right ventricle is shunted to left ventricle and the body gets highly deoxygenated blood. In very severe obstruction cyanosis can be observed in the new born baby. But usually the cyanosis occurs after the newborn period. Cyanotic spells are common. During a cyanotic spell the cyanosis worsens and there may alteration in consciousness due to decreased oxygen to the brain. These children get fatigued easily. Because of decreased oxygen supply to tissues there is a compensatory increase in number of red blood cells. A murmur is usually heart when examined with a stethoscope. Echocardiography is needed to confirm the diagnosis. Treatment: All patients with tetralogy of fallot require surgery. The age of surgery depends on the severity and the experience of the concerned doctors. Those who are symptomatic very early may need a 2 stage operation. In the first stage a shunt is established between the sabclavian artery (a big artery in the neck which supplies blood to the upper limb) and the pulmonary artery of the same side. This procedure is called Blacock Taussig shunt. This improves pulmonary blood flow. Some centers use a balloon to dilate the pulmonary artery.
During total correction the V S D is closed and the obstruction at the pulmonary opening removed. Custom Search
Page last reviewed on 2nd January 2011
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