Heart Center: Coarctation of the Aorta
A Coarctation of the Aorta is a narrowing (the Coarctation) of the major blood vessel that leaves the heart and carries blood to the body (the Aorta). It typically occurs just after the takeoff of vessels that feed the head and arms. It can occur spontaneously or after previous surgery on the aorta (as in the Norwood procedure for hypoplastic left heart syndrome). It may show at birth as a major problem requiring immediate surgery or it may not be diagnosed until the teenage years, often during a school or athletics physical. It results in an elevated blood pressure in the arms and a relatively decreased blood pressure in the legs.
Some coarctations must be repaired surgically. This requires the surgeons to make an incision in the left side of the chest between the ribs. The majority of the time the narrowing is cut out and the vessel is sewn back together (called an "end-to-end anastomosis").
Many coarctations can be treated in the catheterization lab. There are two major types of procedures. The balloon dilatation procedure involves threading a small balloon into the narrowing and inflating it to increase the diameter of the vessel. The second involves placement of a stent, a small mesh tube that becomes part of the vessel and holds the vessel open.
Both procedures are done under general anesthesia and in both the patient is typed and crossmatched for at least one unit of blood (see the page on general information for more about this). Prior to either procedure a catheter (or catheters) is placed into the area above and below the coarctation to measure the pressures and determine the difference (called the gradient). An angiogram is done to determine the location, size and other characteristics of the vessel.
In this procedure a catheter with a small balloon on the end of it is introduced into the narrowing. Prior to doing this the balloon is filled with contrast (the dye used to make the pictures) and all air is removed. After the position is correct the balloon is inflated with a special syringe that monitors the pressure (to prevent the balloon from being overinflated). The balloon is held inflated for approximately five seconds. It may require multiple balloon inflations or the use of other balloons to achieve the desired result. After the balloon is removed the pressures are redone to determine the new gradient and another angiogram is done to look at the changes made to the vessel.
To the left are AP views (front-to-back) of a 13 month old with recurrent coarctation of the aorta after a Norwood procedure and Glenn shunt for Hypoplastic Left Heart Syndrome. The coarctation was balloon dilated, which reduced the gradient.
In this procedure a small mesh tube called a stent is placed into the narrowing. The stent is placed over a balloon and crimped into place prior to being placed in the vessel. The balloon is inflated, which expands the stent and causes it to grip the walls of the vessel. Stents are typically made out of platinum, nickel, titanium or some combination of those metals. They are eventually surrounded by tissue and become part of the vessel. They can often be expanded again in another procedure if needed.
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