Pathophysiology of Congenital Heart Defects
Congenital heart defects are:
Acyanotic group (no communication between circulations)
1) right-sided aorta
2) Ebstein’s anomaly (downward displaced tricuspid valve)
3) coarctation of aorta
4) tricuspid atresia
Cyanotic group (permanent right-to-left shunt)
5) tetralogy of Fallot
6) truncus arteriosus
7) transposition of great vessels
Cyanose tardive group (initially left-to-right shunt, then late development of right-to-left shunt of Eisenmenger’s)
8) VSD
9) ASD
10) PDA
11) persistent truncus arteriosus
12) anomalous pulmonary venous drainage
Signs and Symptoms
1) Eisenmenger’s syndrome – cyanosis, clubbing, pulmonary hypertension, heart failure
2) VSD – infective endocarditis, failure to thrive, paradoxical emboli
3) ASD – early fatigability, dyspnea of exertion, paradoxical emboli
4) truncus arteriosus – heart failure, recurrent pulmonary infections
Histology/Gross Pathology
Eisenmenger’s syndrome has thickening of pulmonary artery walls
Associated Conditions
1) increased incidence of congenital heart defects in – rubella (PDA), Down’s syndrome, Turner’s syndrome (coarctation of aorta), steroids, lithium, alcohol use during pregnancy, phenytoin, prematurity (PDA)
2) increased incidence in congenital heart defects of – infective endocarditis and paradoxical pulmonary emboli (VSD and ASD)
Inheritance/Epidemiology
1) 1% of all live births
2) 6% of occurring in second child if firstborn child is affected
Tips for USMLE
1) in transposition of great vessels, the pulmonary artery drains left ventricle and aorta drains right ventricle
2) truncus arteriosus is always associated with a VSD
3) cyanotic shunts at birth are the five Ts – tetralogy of Fallot, truncus arteriosus, transposition of great vessels, tricuspid atresia, and total anomalous pulmonary venous congestion
4) most common congenital heart defect is VSD
5) most common type of VSD is a defect in the membranous septum (usually in superior part)
6) most common type of ASD is ostium secundum
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