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CONGENITAL DEFECTS

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I. BASIC PRINCIPLES
A. Arise during embryogenesis (usually weeks 3 through 8}; seen in 1% of live births
1. Most defects are sporadic.
B. Often result in shunting between left (systemic} and right (pulmonary) circulations.
C. Defects with left-to-right shunting may be relatively asymptomatic at birth, but the
shunt can eventually reverse.
1. Increased flow through the pulmonary circulation results in hypertrophy of
pulmonary vessels and pulmonary hypertension.
2. Increased pulmonary resistance eventually results in reversal of shunt, leading
to late cyanosis (Eisenmenger syndrome) with right ventricular hypertrophy,
polycythemia, and clubbing.
D. Defects with right-to-left shunting usually present as cyanosis shortly after birth.

II. VENTRICULAR SEPTAL DEFECT (VSD)
A. Defect in the septum that divides the right and left ventricles
I. Most common congenital heart defect
2. Associated with fetal alcohol syndrome
B. Results in left-to-right shunt; size of defect determines extent of shunting and age
at presentation. Small defects are often asymptomatic; large defects can lead to
Eisenmenger syndrome.
C. Treatment involves surgical closure; small defects may close spontaneously.

III. ATRIAL SEPTAL DEFECT (ASD)
A. Defect in the septum that divides right and left atria; most common type is ostium
secundum (90% of cases).
B. Ostium primum type is associated with Down syndrome.
C. Results in left-to-right shunt and split S2 on auscultation (increased blood in right
heart delays closure of pulmonary valve)
D. Paradoxical emboli are an important complication.

IV. PATENT DUCTUS ARTERIOSUS (PDA)
A. Failure of ductus arteriosus to close; associated with congenital rubella
B. Results in left-to-right shunt between the aorta and the pulmonary artery
1. During development, the ductus arteriosus nonnally shunts blood from the
pulmonary artery to the aorta, bypassing the lungs.
C. Asymptomatic at birth with holosystolic ‘machine-like’ murmur; may lead to
Eisenmenger syndrome, resulting in lower extremity cyanosis
D. Treatment involves indomethacin, which decreases PGE, resulting in PDA closure
(PG£ maintains patency of the ductus arteriosus).
V. TETRALOGY OF FALLOT
A. Characterized by (1) stenosis of the right ventricular outflow tract, (2) right
ventricular hypertrophy, (3) VSD, and (4) an aorta that overrides the VSD
B. Right-to-left shunt leads to early cyanosis; degree of stenosis determines the extent of
shunting and cyanosis.
C. Patients learn to squat in response to a cyanotic spell; increased arterial resistance
decreases shunting and allows more blood to reach the lungs.
D. ‘Boot-shaped’ heart on x-ray (Fig. 8.10)

Vl. TRANSPOSITION OF THE GREAT VESSELS
A. Characterized by pulmonary artery arising from the left ventricle and aorta arising
from the right ventricle

B. Associated with maternal diabetes
C. Presents with early cyanosis; pulmonary and systemic circuits do not mix.
1. Creation of shunt (allowing blood to mix) after birth is required for survival.
2. PGE can be administered to maintain a PDA until definitive surgical repair is
performed.
D. Results in hypertrophy of the right ventricle and atrophy of the left ventricle

VII. TRUNCUS ARTERIOSUS
A. Characterized by a single large vessel arising from both ventricles
l. Truncus fails to divide.
B. Presents with early cyanosis; deoxygenated blood from right ventricle mixes ·with
oxygenated blood from left ventricle before pulmonary and aortic circulations
separate.
VIII. TRICUSPID ATRESIA
A. Tricuspid valve orifice fails to develop; right ventricle is hypoplastic.
B. Often associated with ASD, resulting in a right-to-left shunt; presents with early
cyanosis.

IX. COARCTATION OF THE AORTA
A. Narrowing of the aorta (Fig. 8.11A); classically divided into infantile and adult forms
B. Infantile form is associated with a PDA; coarctation lies after (distal to) the aortic
arch, but before (proximal to) the PDA.
l. Presents as lower e>..’tremity cyanosis in infants, often at birth
2. Associated with Turner syndrome
C. Adult form is not associated with a PDA; coactation lies after (distal to) the aortic
arch.
l. Presents as hypertension in the upper extremities and hypotension with weak
pulses in the lower extremities; classically discovered in adulthood
2. Collateral circulation develops across the intercostal arteries; engorged arteries
cause ‘notching’ of ribs on x-ray (Fig. 8.11 B).
3. Associated with bicuspid aortic valve

VALVULAR DISORDERS
I. BASIC PRINCIPLES
A. The heart has four valves (tricuspid, pulmonary, mitral, and aortic) that prevent
backflow.

II. ACUTE RHEUMATIC FEVER
A. Systemic complication of pharyngitis due to group A P-hemolytic streptococci;
affects children 2- 3 weeks after an episode of streptococcal pharyngitis (“strep
throat”)
B. Caused by molecular mimicry; bacterial M protein resembles proteins in human
tissue.

C. Diagnosis is based on Jones criteria.
1. Evidence of prior group A ~-hemolytic streptococcal infection (e.g., elevated
A$0 or anti-DNase B titers) with the presence of major and minor criteria
2. Minor criteria are nonspecific and include fever and elevated ESR.

3. Major criteria
i. Migratory polyarthritis- swelling and pain in a large joint (e.g., wrist, knees,
ankles) that resolves within days and “migrates” to involve another large
joint
ii. Pancarditis
a. Endocarditis-Mitral valve is involved more commonly than the aortic
valve. Characterized by small vegetations along lines of closure that lead
to regurgitation (Fig. 8.12A)
b. Myocarditis with Aschoff bodies that are characterized by foci of chronic
inflammation, reactive histiocytes with slender, wavy nuclei (Anitschkow
cells), giant cells, and fibrinoid material (Fig. 8.12B,C); myocarditis is the
most common cause of death during the acute phase.
c. Pericarditis-leads to friction rub and chest pain

iii. Subcutaneous nodules
iv. Erythema marginatum- annular, nonpruritic rash with erythematous
borders, commonly involving trunk and limbs
v. Sydenham chorea (rapid, involuntary muscle movements)
D. Acute attack usually resolves, but may progress to chronic rheumatic heart disease;
repeat exposure to group A p-hemolytic streptococci results in relapse of the acute
phase and increases risk for chronic disease.

Ill. CHRONIC RHEUMATIC HEART DISEASE
A. Valve scarring that arises as a consequence of rheumatic fever
B. Resul ts in stenosis with a classic ‘fish-mouth’ appearance
l. Almost always involves the mitral valve; leads to thickening of chordae tendineae
and cusps
2. Occasionally involves the aortic valve; leads to fusion of the commissures (Fig.
8.13)
3. Other valves are less commonly involved.
C. Complications include infectious endocarditis.

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