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An acyanotic
congenital heart
disease characterized by constriction of the aorta.
Incidence is 5-7%
of all congenital cardiac lesions. Age of first detection is in the
newborn period, with childhood risk factors of Trisomy 18 and 13, Turner
Syndrome, Fetal Hydantoin Syndrome, fetal valproate effect, Maternal PKU,
and Crouzon Syndrome
Collaterals
provide flow around the obstructed segment of the aorta, with branches
provided from the subclavian, superior intercostal, internal mammary,
and axillary arteries (for a BP differential between upper and lower
limbs must have at least a 50% reduction in the size of the aorta).
Clinical
presentation
includes an asymptomatic picture (presents in later childhood, or in an
adult, as part of a work up for hypertension and/or murmur). Symptomatic
presentation includes congestive heart failure at 2 weeks, 4-6 months,
or as adults; dyspnea, lethargy, difficulty feeding, and organomegaly at
2 weeks (usually associated with a L>R shunt (VSD, PDA)), and at 4-6
months of age (good response to medical therapy).
There are
weak/absent femoral pulses, with a BP differential between upper & lower
limbs (SBP >30), a quiet precordium, but with an S1 (due to
hypertension), and an S2 - narrow split. A systolic bruit at the back
between the scapulae, axillae, and latissimus dorsi muscles may be
auscultated.
Investigations
include a chest X-Ray (cardiomegaly with increased pulmonary vascular
markings, hypoplastic aortic knob with a dilated poststenotic segment of
the aorta ("reverse 3" sign), and possibly rib notching. An ECG will
reveal LVH. An echocardiogram will confirm the diagnosis.
Management
includes the following:
a.
Supportive - although mild coarctations may be well
tolerated during childhood, patients should avoid
vigorous or competitive sports. Congestive heart failure
may be treated with digoxin and lasix.
b.
Surgical:
i. Age greater than 1 year of age, to avoid
recoartation due to poor growth of suture and/or
remaining ductal tissue
ii. Late repair of coarct does not correct the
hypertension which can lead to later coronary
artery disease
iii. Gradient across coarctation >30mmHg
iv. Increased surgical risk of poor peripheral
perfusion post-op if gradient <30mmHg
v. Difference in systolic BP >60mmHg between
upper and lower limbs during a stress (exercise)
test
Prognosis is
good, but with a 30% incidence of recoarctation.
This edited version is
being used with the permission of its original author, Dr.
Alan Gandy.
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