| From your Guide Dr.MANI |  | |
Coarctation of Aorta | ||
| From your Guide Dr.MANI | | |
Coarctation of Aorta | ||
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And what about the parts of the body BEYOND the coarctation area ?
They receive LESS blood than normal, and at a LOWER PRESSURE than normal. And this also
is not good.
When the lower half of the body gets less blood than it requires, it cannot grow and develop
normally. In the extreme case, the lower limbs may be thin and weak. The ability to walk, run or
play is limited. This is because, during exercise, the muscles of the legs demand more oxygen and
blood flow. This cannot be provided when there is a CoA. So, the muscles get tired sooner, and
limit exercise tolerance. The child complains of weakness or pain in both legs - called
CLAUDICATION.
A more serious consequence of the reduced blood flow is its effect on the KIDNEYS. The kidneys
are organs that make urine, and through it remove many waste materials from the body. It also
plays an important role in keeping the blood pressure in the body within normal limits. When the
kidneys receive low blood flow, they send signals to the rest of the body which makes the blood
pressure HIGHER STILL. This is another mechanism for the hypertension of CoA. If left alone for
long, there is permanent damage to the kidneys. This may cause the blood pressure to remain high
even AFTER successful repair of CoA !
So how does the body compensate for this state of affairs ?
Nature is wonderful. For most defects, Nature has provided a method of compensation, which
reduces or even sometimes totally abolishes the ill-effects produced by that disease. It is true of
CoA also.
In coarctation of the aorta, we have an interesting situation. The upper half of the body has too
HIGH a blood pressure, and the lower part has a very LOW pressure. How can this be
equalized ? Simply, by opening up channels that connect the portions of the aorta above the CoA
with the portion below it.
Normally, many small blood vessels connect branches from the upper body with the branches to
the lower body. Since in a normal person the blood pressure is equal in both parts, these small
channels are insignificant. But in CoA, when there is such a great difference in pressure between the
two halves of the body, these small channels become larger and dilated. They act as Nature's
"bypass channels" to divert blood from the upper half to the low pressure lower half.
These channels are called COLLATERAL ARTERIES. They may be absent or small at birth. But
as the child grows, these collaterals become larger and more important. In an older child, these
collaterals may even be VISIBLE ! They produce pulsations over the back.
So the more the collateral supply, the better - Right ?
Not always. Or atleast, not to the surgeon. When operation is performed for CoA, the chest is
opened at the left side. If collateral arteries are very large, they may be injured causing profuse
bleeding. It makes the operation more difficult. That is why surgery is advised early in life, before
collaterals become very prominent.
What other defects may be seen along with CoA ? Check them out .....
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