FALLOT, TETRALOGY OF

also called Fallot's tetralogy, or blue baby syndrome congenital heart disease characterized by cyanosis (bluish discoloration of the skin) usually after the neonatal period, hypoxic spells (which include difficult or laboured respiration, sudden onset of cyanosis, alterations in consciousness), digital clubbing, and heart murmur. Tetralogy of Fallot (named for tienne-Louis-Arthur Fallot, who first described it) is the result of a combination of cardiac defects including a defect in the intraventricular septum (the partition that separates the lower chambers of the heart), pulmonary stenosis (narrowing of the opening to the pulmonary artery), dilation and displacement of the aorta to override the ventricular septum, and right ventricular hypertrophy (thickening of the muscle of the right ventricle). This condition causes the deoxygenated venous blood to be shunted from the right to the left side of the heart into arterial circulation. Total correction of the condition is possible with surgical repair of the septal defect, removal of the obstruction to the right ventricular outflow, and opening of the right ventricle. This procedurewhich has a high rate of successproduces marked improvement, but dysrhythmia may still occur unexpectedly.