Master the board step 3

Master the Boards: USMLE Step 3
Basic Science Correlate
Ventricular septal defect results from incomplete formation of the
interventricular septum, leaving an incomplete closure of the interventricular
foramen.
The ductus arteriosus connects the pulmonary artery and descending aorta
during development. It allows the blood to bypass the lungs, since the fetus
is not receiving any oxygen from them in utero.
Aortic stenosis occurs when the leaflets of the valves fuse together. It can
be congenital or acquired over time.
Cyanotic lesions
Heart Defect
Tetralogy of Fallot
Transposition
of the great
arteries
Comments
Most common CHD beyond infancy
Defects include ventricular septal defect, right ventricular hypertrophy, right outflow
obstruction, and overriding aorta
Substernal right ventricular impulse, systolic thrill along the left sternal border
Intermittent hyperpnea, irritability, cyanosis with decreased intensity of murmur
Treatment: Give oxygen, beta blocker, PGE1 infusion for cyanosis present at birth
Surgical repair at 4–12 months
Most common cyanotic lesion presenting in the immediate newborn period. More common in
infant of diabetic mother.
S2 usually single and loud, murmurs usually absent
Ductus-dependent: Give PGE1 to keep ductus open.
Definitive surgical switch of aorta and pulmonary artery needed as soon as possible.
Antibiotic Prophylaxis and Prevention of Endocarditis
Antibiotics prior to genitourinary or gastrointestinal procedures are no longer
recommended, even in high-risk patients. Giving antibiotics prior to dental
procedures is no longer recommended except with the following:
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Prosthetic valves
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Previous endocarditis
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Congenital heart disease (unrepaired or repaired with persistent defect)
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Cardiac transplantation patients with cardiac valve abnormalities
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