children s health issues
Tetralogy of Fallot
Introduction
In tetralogy of Fallot, four specific heart defects occur together. This condition includes four heart defects that can lead to oxygen-poor blood going directly to the body. Symptoms include mild to severe cyanosis (a bluish discoloration of the skin due to lack of oxygen in the blood), life-threatening attacks of intense cyanosis due to a rapid drop in oxygen in the blood, and a heart murmur (a sound created by turbulent blood flow through narrowed or leaking heart valves or through abnormal heart structures). The diagnosis is suspected based on a characteristic murmur and on the presence of cyanosis and is confirmed based on the results of echocardiography. Surgery is required to correct the defect. (See also Overview of Heart Defects .) The four heart defects are A narrowing of the outflow passage from the right side of the heart A large Atrial and Ventricular Septal Defects (a hole in the wall that separates the left from the right ventricle) Displacement of the aorta that allows oxygen-poor blood to flow directly from the right ventricle to the aorta (causing a Shunting of blood flow ), which is also called overriding aorta A thickening of the wall of the right ventricle In infants with tetralogy of Fallot, the narrowed passage from the right ventricle restricts blood flow to the lungs. The restricted blood flow causes the oxygen-poor blood in the right ventricle to pass through the septal defect to the left ventricle and into the aorta ( Shunting of blood flow ). The more oxygen-poor blood (which is blue) that flows to the body, the bluer the body appears. Infants with severe or complete blockage of blood flow from the right side of the heart may depend on having an open ductus arteriosus for survival. The ductus arteriosus is a blood vessel in the fetus that connects the two great arteries leaving the heart, the pulmonary artery and the aorta (see Normal Fetal Circulation ). After birth, the ductus arteriosus is no longer needed and usually closes within the first days of life. However, if the ductus stays open after birth in infants with severe tetralogy, some blood from the aorta can flow back into the lungs through the open ductus and thus pick up oxygen. 