Aneurysm
and Coarctation of the Aorta
The arch of the aorta lies behind the manubrium sterni. A
gross dilatation of the aorta (aneurysm) may show itself as a pulsatile swelling
in the suprasternal notch.
Coarctation of the aorta is a congenital narrowing of the aorta
just proximal, opposite, or distal to the site of attachment of the ligamentum
arteriosum. This condition is believed to result from an unusual quantity of
ductus arteriosus muscle tissue in the wall of the aorta. When the ductus
arteriosus contracts, the ductal muscle in the aortic wall also contracts, and
the aortic lumen becomes narrowed. Later, when fibrosis takes place, the aortic
wall also is involved, and permanent narrowing occurs.
Clinically, the cardinal sign of aortic coarctation is
absent or diminished pulses in the femoral arteries of both lower limbs. To
compensate for the diminished volume of blood reaching the lower part of the
body, an enormous collateral circulation develops, with dilatation of the
internal thoracic, subclavian, and posterior intercostal arteries. The dilated
intercostal arteries erode the lower borders of the ribs, producing
characteristic notching, which is seen on radiographic examination. The
condition should be treated surgically
Patent
Ductus Arteriosus
The ductus arteriosus represents the distal portion of the
sixth left aortic arch and connects the left pulmonary artery to the beginning
of the descending aorta. During fetal life, blood passes through it from the
pulmonary artery to the aorta, thus bypassing the lungs. After birth, it
normally constricts, later closes, and becomes the ligamentum arteriosum. Failure
of the ductus arteriosus to close may occur as an isolated congenital
abnormality or may be associated with congenital heart disease. A persistent
patent ductus arteriosus results in high-pressure aortic blood passing into the
pulmonary artery, which raises the pressure in the pulmonary circulation. A
patent ductus arteriosus is life threatening and should be ligated and divided
surgically.
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