Cyanotic Vs Acyanotic Heart Defects

Congenital heart defects are the most common category of congenital anomaly. Canadian surveillance has reported birth prevalence in the order of 8 to 12 per 1,000 births, although the number changes with the case definition and with how long infants are followed. Approximately one in four affected infants has a critical defect requiring surgery or catheter intervention during the first year of life. “Cyanotic” and “acyanotic” describe physiology, not simply a named defect. - Acyanotic lesions either send oxygenated blood from the left side back to the lungs through a left-to-right shunt or obstruct blood flow without creating a shunt. Systemic arterial blood still receives adequate oxygen, at least initially. - Cyanotic lesions allow desaturated blood to enter systemic circulation through a right-to-left shunt, mix pulmonary and systemic venous blood, or place the pulmonary and systemic circulations in parallel. The direction of blood flow can change as pulmonary vascular resistance falls or the ductus arteriosus closes. A defect that appears quiet immediately after birth may become symptomatic weeks later, while a ductal-dependent lesion may deteriorate abruptly when ductal flow decreases....