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B. Suprascapular artery
C. Posterior Intercostal artery
D. Internal Thoracic artery
In post ductal coarctation of aorta, collaterals to the lower limb are formed by all except
A. Vertebral arteryB. 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
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) Preductal coarctation: 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 &axillary
arteries 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 intercostals and 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 intercostals and thence into the descending aora.
8. The superior epiastj_c artery
anastomoses with the inferior epigastric (in the rectus sheath) and
sends blood into
theexternal 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. Also the radiographic shadow of
enlarged left
subclavian artery is quite evident clinically.