pediatrics
Tetralogy of Fallot
Symptoms and Signs of Tetralogy of Fallot
Neonates with severe right ventricular outflow obstruction (or atresia) have severe cyanosis and dyspnea during feeding, leading to poor weight gain. Neonates with mild obstruction may not have cyanosis at rest. Hypercyanotic spellsmay be precipitated by activity and are characterized by paroxysms of hyperpnea (rapid and deep respirations), irritability and prolonged crying, increasing cyanosis, and decreasing intensity or disappearance of the heart murmur. The spells occur most often in young infants; peak incidence is age 2 to 4 months. A severe spell may lead to limpness, seizures, and occasionally death. During play, some toddlers may intermittently squat, a position that increases systemic vascular resistance and aortic pressure, which decreases right-to-left ventricular shunting and thus raises arterial oxygen saturation. ). The murmur in tetralogy is due to the Pulmonic Stenosis ; the ventricular septal defect is usually silent because it is large and has no pressure gradient. Therefore, as the pulmonary outflow obstruction becomes more severe, the murmur becomes softer. The second heart sound (S2) is usually single because the pulmonary component is markedly reduced. A prominent right ventricular impulse and a systolic thrill may be present. 