Congenital heart defects Flashcards
Basic principles
Arise during embryogenesis (usually weeks 3-8)
- seen in 1% of live births
- most are sporadic
- often results in shunting between left (systemic) and right (pulmonary) circulations
- defects with left to right shunting may be relatively asymptomatic at birth, but the shunt can eventually reverse
- increased flow through the pulm circulation results in hypertrophy or pulmonary vessels and pulmonary htn
- increased pulm resistance eventually results in reversal of shunt, leading to late cyanosis (eisenmenger syndrome) with RV hypertrophy, polycythemia and clubbing
- defects with right to left shunting usually present as cyanosis shortly after birth
VSD
Defect in the septum that divides the right and left ventricles
- most common congenital heart defect
- associated with fetal alcohol syndrome
- results in l to r shunt –> size of defect determines extent of shunting and age at presentation –> small defects are often asymptomatic; large defects can lead to eisenmenger syndrome
- treatment –> surgical closure; small defects may close spontaneously
ASD
defect in the septum that divides right and left atria; most common type is ostium secundum (90%) of cases
- ostium primum type is associated with down syndrome
- results in l to r shunt and split S2 on auscultation (increased blood in the right heart delays closure of pulmonary valve)
- paradoxical emboli are an important complication
PDA
Failure of ductur areriosus to close – associated with congenital rubella
- results in L to R shunt between the aorta and the pulmonary artery –> during development, the ductur arteriosus normally shunts blood from the pulmonary artery to the aorta, bypassing the lungs
- asymptomatic at birth with continuous machine like murmur; may lead to eisenmenger synerome, resulting in lower extremity cyanosis
- treatment involves indomethacin –> decreased PGE, resulting in PDA closure (PGE maintains patency of the DA)
Tetralogy of fallot
Characterized by
- stenosis of the right ventricular outflow tract
- right ventricular hypertrophy
- VSD
- an aorta that overrides the VSD
Right to left shunt leads to early cyanosis – degree of stenosis determines the extent of shunting and cyanosis
- patients learn to squat in response to a cyanotic spell –> increased arterial resistance decreases shunting and allow more blood to reach the lungs
Boot shaped heart on x ray
Transposition of the great vessels
Characterized by pulm artery arising from the left ventricle and aorta arising from the right ventricle
- associated with maternal diabetes
Presents with early cyanosis - pulm and systemic circuits do not mix
- creation of shunt allowing blood to mix after birth is required for survival
- PGE can be administered to maintain a PDA until definitive surgical repair is performed
- results in hypertrophy of the RV and atrophy of the LV
Truncus arteriosus
Characterized by a single large vessel arising from both ventricles
- truncus fails to divide
- Presents with early cyanosis; deoxygenated blood from the RV mixes with oxygenated blood from the LV before pulmonary and aortic circulations separate
Tricuspid atresia
tricuspid valve orific fails to develop - right ventricle is hypoplastic
- often associated with ASD, resulting in a right to left shunt, presents with ealry cyanosis
Coarctation of the aorta
Narrowing of the aortic - classically divided into infantile and adult forms
Infantile form - associated with a PDA - coarctation lies after the aortic arch, but before the PDA
- presents as lower extremity cyanosis in infants, often at birth
- associated with turner syndrome
Adult form - not associated with a PDA; coarc lies after the aortic arch
- presents as htn in the upper extremities and hypotension with weak pulses in the lower extremities - classically discovered in adulthood
- collateral circulation develops across the intercostal arteries - engorged arteries cause notching of ribs on x ray
- associated with BAV
