pediatrics
Overview of Congenital Cardiovascular Anomalies
Pathophysiology of Congenital Heart Anomalies
Congenital heart anomalies are classified (see table) as Cyanotic Acyanotic (left-to-right shunts or obstructive lesions) The physiologic consequences of congenital heart anomalies vary greatly, ranging from a heart murmur or discrepancy in pulses in an asymptomatic child to severe cyanosis, heart failure, or circulatory collapse. Classification Classification Examples Examples Cyanotic Cyanotic — Tetralogy of Fallot None Transposition of the Great Arteries (TGA) None Tricuspid Atresia None Pulmonary atresia with intact ventricular septum None Persistent Truncus Arteriosus None Total Anomalous Pulmonary Venous Return (TAPVR) None Acyanotic Acyanotic Left-to-right shunt Ventricular Septal Defect (VSD) None Atrial Septal Defect (ASD) None Patent Ductus Arteriosus (PDA) None Atrioventricular Septal Defect None Obstructive Pulmonic Stenosis None Aortic Stenosis None Coarctation of the Aorta None Hypoplastic Left Heart Syndrome (often also manifests with cyanosis, which may be mild) * In approximate decreasing order of frequency. Varying amounts of deoxygenated venous blood are shunted to the left heart (right-to-left shunt), reducing systemic arterial oxygen saturation. 50 g/L) of deoxygenated hemoglobin, cyanosis results. Complications of persistent cyanosis include Perinatal Polycythemia and Hyperviscosity Syndrome , clubbing, thromboembolism (including stroke), bleeding disorders, brain abscess, and hyperuricemia. Hypercyanotic spells can occur in infants with unrepaired Depending on the anomaly, pulmonary blood flow may be reduced, normal, or increased (often resulting in heart failure in addition to cyanosis), resulting in cyanosis of variable severity. Heart murmurs are variably audible and are not specific. Oxygenated blood from the left heart (left atrium or left ventricle) or the aorta shunts to the right heart (right atrium or right ventricle) or the pulmonary artery through an opening or communication between the 2 sides. Immediately after birth, pulmonary vascular resistance is high and flow through this communication may be minimal or bidirectional. Within the first 24 to 48 hours of life, however, the pulmonary vascular resistance progressively falls, at which point blood will increasingly flow from left to right. The additional blood flow to the right side increases pulmonary blood flow and pulmonary artery pressure to a varying degree. The greater the increase, the more severe the symptoms; a small left-to-right shunt typically does not cause symptoms or signs. High-pressure shunts (those at the ventricular or great artery level) become apparent several days to a few weeks after birth; low-pressure shunts ( Atrial Septal Defect (ASD) ) become apparent considerably later. If untreated, elevated pulmonary blood flow and pulmonary artery pressure may lead to pulmonary vascular disease and eventually Blood flow is obstructed, causing a pressure gradient across the obstruction. The resulting pressure overload proximal to the obstruction may cause ventricular hypertrophy and heart failure. The most obvious manifestation is a heart murmur, which results from turbulent flow through the obstructed (stenotic) point. Examples are congenital Aortic Stenosis , which accounts for 3 to 6% of congenital heart anomalies, and congenital Some congenital heart anomalies (eg, Bicuspid Aortic Valve , mild aortic stenosis) do not significantly alter hemodynamics. Other anomalies cause pressure or volume overload, sometimes causing The ductus arteriosus is a normal connection between the pulmonary artery and aorta; it is necessary for proper fetal circulation. At birth, the rise in PaO2 and decline in prostaglandin concentration cause closure of the ductus arteriosus, typically beginning within the first 10 to 15 hours of life. Some congenital cardiac disorders are dependent on the ductus arteriosus remaining open to maintain systemic blood flow (eg, Hypoplastic Left Heart Syndrome , critical 1.Daubeney PEF, Rigby ML, Niwa K, Gatzoulis MA (eds):Pediatric Heart Disease: A Practical Guide. Wiley-Blackwell 2012 . 2.Hoffman JI, Kaplan S: The incidence of congenital heart disease.J Am Coll Cardiol39(12):1890-1900, 2002. doi:10.1016/s0735-1097(02)01886-7 