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COARCTATION OF AORTA

“Narrowing or the constriction of the lumen of the aorta” may occur anywhere along its length but is most common distal to the origin of the left subclavian artery near the insertion of the ligamentum arteriosum. Coarctation may be diffused or localized. Diffused coarctation may be known as hypoplasia of aorta and provides the higher resistance for blood flow through the main vessels. It represents about 5-10% of all the congenital heart disease most frequently with Patent Ductus Arteriosus (PDA), bicuspid aortic valve, or septal defects. Males predominate twice but some authors suggest there is no sex difference.

Clinical Features:
High resistance against the blood flow through the aorta provides clinical symptoms and depends on the site and the extent of obstruction and the presence of associated anomalies. Most children and young adults with isolate, discrete coarctation are asymptomatic. Headache, epistaxis, cold extremities, clamps in lower limbs and claudication on exercise may occur. On examination, there is difference in timing of pulses of upper limb (radial) and lower limb (femoral). Femoral pulse is delayed; blood pressure is higher in the upper limb. Pulsations are visible in neck. Enlarged and tortuous arteries in the intercostal space anteriorly, in axilla and posteriorly around the scapular region are palpable due to collateral circulation. Inspection and palpation of the precordium shows signs of left ventricular hypertrophy. On auscultation, there is an ejection systolic murmur on the aortic area. Infants usually are irritated, feed uninterestingly, tachycardia and tachypnoae are main signs. Scott and Bahnson discovered that antilateral renal transplantation previously to obstructed area diminishes the degree of hypertension. They explained this event as an influence of renal factors on circulatory mechanism.

In premature infants, so – called prostaglandin therapy may be useful, because prostaglandin E1, re-opens ductus arteriosus and as a result of this, circulatory disorders diminish. In many cases coarctation occurs previously to PDA. X – Ray films show cardiomegaly. Aortic counter is changed. The undersurface of the ribs show notching due to erosion or hypertrophied intercostal arteries.

Treatment:
There are 3 types of surgeries:
  • Classical method used by Crawford and Gross. It is the resection of the obliterated area and creation of end –to – end anastomosis
  • Prosthetic patch autoplasty: After the obstructed area is incised, longitudinally incision of aorta, prosthetic patch is inserted into lumen, and then dilatation of the obstructed area is done.
    Disadvantage: After dilation, aneurysm and rupture may occur.
  • Subclavian Flap Aortoplasty, by Nahrworld, 1996. (It is confines to the ligation of subclavian artery, incised longitudinally and in this way; flap should be sutured into obliterated portion of aorta).
Complication:
Hemorrhage in hilothorax occurs if main lymphatic duct is damaged and the accumulation of lymph occurs in thoracic cavity, which follows the recurrent nerve paralysis, infection and thrombosis. Paraplegia is the most dreadful complication (1-2%).

If PDA occurs, then it should be ligated simultaneously with aortic repair.

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This article has been written by Dr. M. Javed Abbas.
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21:06 21/12/2002