pediatrics
Tetralogy of Fallot
Key Points
Tetralogy of Fallot involves a large ventricular septal defect (VSD), right ventricular outflow tract and pulmonary valve obstruction, and over-riding of the aorta. Pulmonary blood flow is decreased, the right ventricle hypertrophies, and unoxygenated blood enters the aorta via the VSD. Manifestations depend on the degree of right ventricle outflow obstruction; severely affected neonates have marked cyanosis, dyspnea with feeding, poor weight gain, and a harsh grade 3 to 5/6 systolic ejection murmur. The murmur comes from the pulmonary stenosis; the VSD shunt is silent. Hypercyanotic spells are sudden episodes of profound cyanosis and hypoxia that may be triggered by a fall in oxygen saturation (eg, during crying, defecating), decreased systemic vascular resistance (eg, during playing, kicking legs), or sudden tachycardia or hypovolemia. The murmur diminishes or disappears during a spell. Give neonates with severe cyanosis an infusion of prostaglandin E1 to open the ductus arteriosus. Place infants with hypercyanotic spells in the knee-chest position and give oxygen; sometimes, opioids (morphineorfentanyl), volume expansion,sodium bicarbonate, beta-blockers (propranololoresmolol), orphenylephrinemay help. Repair surgically at 2 to 6 months or earlier if symptoms are severe. 