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Tetralogy of Fallot (TOF) is a congenital heart defect which is classically understood to involve four anatomical abnormalities of the heart (although only three of them are always present). It is the most common cyanotic heart defect and the most common cause of blue baby syndrome.〔Breitbart R, Fyler, D. Tetralogy of Fallot. In Nadas' Pediatric Cardiology, 2ed, Ed. Keane, Locke, & Fyler, Philadelphia: Saunders-Elsevier, 2006, p. 559.〕 TOF is usually a right-to-left shunt, in which higher resistance to right ventricular outflow results in more severe cyanosis symptoms. TOF is treated with corrective surgery, usually within the first year of life, but presents with long-term problems including arrhythmia, pulmonary regurgitation, and re-operation. In the United States, the prevalence of TOF is 3.9 per 10,000 live births and accounts for 7-10% of congenital heart diseases. It was described in 1672 by Niels Stensen, in 1773 by Edward Sandifort, and in 1888 by the French physician Étienne-Louis Arthur Fallot, after whom it is named. ==Signs and symptoms== Tetralogy of Fallot results in low oxygenation of blood due to the mixing of oxygenated and deoxygenated blood in the left ventricle via the ventricular septal defect (VSD) and preferential flow of the mixed blood from both ventricles through the aorta because of the obstruction to flow through the pulmonary valve. This is known as a right-to-left shunt. The primary symptom is low blood oxygen saturation with or without cyanosis from birth or developing in the first year of life. If the baby is not cyanotic then it is sometimes referred to as a "pink tet." Other symptoms include a heart murmur which may range from almost imperceptible to very loud, difficulty in feeding, failure to gain weight, retarded growth and physical development, dyspnea on exertion, clubbing of the fingers and toes, and polycythemia. Children with tetralogy of Fallot may develop "tet spells." The precise mechanism of these episodes is in doubt, but presumably results from a transient increase in resistance to blood flow to the lungs with increased preferential flow of desaturated blood to the body. Tet spells are characterized by a sudden, marked increase in cyanosis followed by syncope, and may result in hypoxic brain injury and death. Older children will often squat during a tet spell, which increases systemic vascular resistance and allows for a temporary reversal of the shunt. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「tetralogy of fallot」の詳細全文を読む スポンサード リンク
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