Left to right shunt is present when systemic resistance is higher than pulmonary resistance. Right to left shunt is present when pulmonary vascular resistance is higher than systemic resistance. Pulmonic stenosis would decrease blood flow to the lungs and, consequently, decrease the amount of oxygen returned to the left heart. One of the most common congenital cardiac defects that causes cyanosis. Some infants may be cyanotic at birth, other may have mild cyanosis that progresses over the first year.
Anoxic spells occur when the infant's oxygen requirements exceed the supply.
Clubbing, squatting, and poor growth may be present. All patients are at risk for emboli, cerebrovascular disease, loss of consciousness, or sudden death. Murmur is present. Surgical Interventions Elective repair is usually performed in the first year of life. Indications for repair include increasing cyanosis and hypercyanotic spells.