In post ductal coarctation of aorta, collaterals to the lower limb are formed by all except
A. Vertebral artery
B. Suprascapular artery
C. Posterior Intercostal artery
D. Internal Thoracic artery
A. Vertebral artery
B. Suprascapular artery
C. Posterior Intercostal artery
D. Internal Thoracic artery
Ans. A. Vertebral artery
Explanation:
1. Coarctation of the aorta, or aortic
coarctation, is
a congenital condition whereby the aorta narrows in the area where the ductus
arteriosus ligamentum arteriosum after regression. inserts
2. There are three types:
a. Preductalcoarctation: The
narrowing is proximal to the ductus arteriosus. If severe, blood
flow to the aorta distal to the narrowing supplying lower body. is dependent on a patent ductus arteriosus,
and hence its closure can be life-threatening. Preductal coarctation results
when an intracardiac anomaly during fetal life decreases blood flow through the
left side of the heart, leading to hypoplastic development of the aorta. This
is the type seen in approximately 5% of infants with Turner Syndrome.
b. Ductal coarctation: The
narrowing occurs at the insertion of the ductus arteriosus. This kind usually
appears when the ductus arteriosus closes.
3. Postductal coarctation: The narrowing is distal to the insertion of
the ductus arteriosus. an extensive collateral circulation develops
involving the branches of subclavian &axillarvarteries with
the distal arteries given by aorta e.g., posterior intercostal arteries, .
But the vertebral artery is not playing significant role in this
collateral circulation. Even with an open ductus arteriosus blood flow to the
lower body can be impaired. This type is most common in adults. It is
associated with notching of the ribs, hypertension in the upper extremities,
and weak pulses in the lower extremities. This type is most likely the result
of muscular ductal ductus arteriosis.
extends into the aorta during fetal life.
4. The purpose of this extensive collateral circulation is to send blood
into the distal branches of the aorta namely — posterior intercostalsand
iliac arteries.
5. The enlarged branches of subclavian artery are suprascapular, costocervical
trunk first &second posterior intercostals. and the internal thoracic arteries.
6. The branches of axillary artery involved are thoraco-acromial, lateral
thoracic and the subscapular,
7. The internal thoracic arteries give anterior intercostal
arteries and the superior epigastric arteries. Anterior intercostals
carry blood to the posterior intercostalsand thence into the descending
aorta.
8.
The superior epigastric artery anastomoses with the inferior
epigastric in the rectus sheath. and
sends blood into the external iliac artery and thence mainly towards the
lower limb.
9. High vascularity is observed in the anterior thoracic wall as
well as over the posterior thoracic wall, especially in the interscapular
area.
10. Radiographic evidence of ‘Rib notching’ is seen in the inferior
margins of the ribs due to greatly enlarged posterior intercostal arteries.