• Coarctation of the Aorta/Interrupted Aortic Arch

     
     
     
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    2/13/2012

    Coarctation of the aorta is a congenital condition where there is narrowing of the aorta, the main blood vessel that carries oxygen-rich blood from the heart to the body. The narrowed segment (coarctation) is typically short, with the aorta opening up to normal size past the coarctation. However, the coarctation can cause problems with increased work on the heart and high blood pressure.

    Typically, the narrowed segment occurs where the ductus arteriosus connects to the aorta. The ductus arteriosus is a blood vessel that is present in all newborns. It should shrink and eventually close within the first few days of life. In some cases, the narrowing of the ductus causes the main aorta to narrow as well where some of this ductal tissue has extended to the aorta, creating a coarctation. If this occurs, newborn infants can become sick with feeding problems, fussiness, sweating, paleness, and difficulty breathing. Also, it becomes difficult to feel pulses on the baby. 

    Symptoms

    The classic findings on physical exam for coarctation of the aorta are high blood pressure in the arms compared to the legs and weak pulses felt in the lower extremities. Coarctation of the aorta can be confirmed by echocardiography or by a cardiac MRI scan. If severe, coarctation of the aorta can cause heart failure in infancy as the heart must work too hard to try to get blood to pass through the area of narrowing. The baby may become rapidly sick, breathing heavily and feeding poorly. However, if heart failure does not occur, some people may not have coarctation diagnosed until later in life, perhaps as an adult. The body tries to get blood around the coarctation by rerouting blood through other vessels such as the intercostal (under the ribs) arteries or other collateral vessels. This allows more blood to reach the lower body than would otherwise pass through the narrowed aorta.

    Progression and Possible Complications

    Without treatment to correct coarcation of the aorta, average life expectancy is 34 years. Even when the narrowed artery is corrected, adults who were born with coarctation of the aorta may face ongoing health problems, including high blood pressure, weakening of the aorta wall, and aneurysm. With aneurysm, the vessel wall weakens and it “balloons,” or forms a “sack,” making it vulnerable to rupture. Some people with coarctation of the aorta may also have cerebral (in the head) aneurysm.

    Treatments

    If a coarctation is detected in a newborn, a medicine that is used to keep the ductus open, called prostaglandin E1, is given through an IV. As the ductus remains open, it keeps the surrounding aorta from narrowing. Once the baby is stabilized, the coarctation is treated with surgery. This usually involves cutting out the narrowed segment of the aorta and reconnecting the normal aortic tissue. Opening of the coarctation area in a hospital’s catheterization lab using angioplasty is generally not performed due to a high incidence of recurrent narrowing. Placement of a stent - a small, wire cage - to hold the aorta open is also generally not performed in infants since these stents generally cannot be expanded to full adult size over time. However, there are some instances where these procedures may be considered. 

    When cases of coarctation are not diagnosed in the newborn period, but when the child is older, surgery or angioplasty  and stenting may be options. Angioplasty and stenting for coarctation of the aorta are similar to the procedures performed on coronary arteries in adults, except on a larger scale. The narrowed area can be dilated in a hospital’s catheterization lab with a special angioplasty catheter (a flexible tube) with a balloon on the end. The balloon is inflated within the narrowed segment to dilate and disrupt the surrounding tissue. When the balloon is deflated, the aorta should stay enlarged. It is hoped that remodeling of the tissue will occur that will allow future continuing growth of the vessel in this area. When a stent is used, it is placed over the balloon and inflated within the narrowed area. When the balloon is deflated, the stent remains open inside the vessel and keeps it from narrowing down.

    Interrupted Aortic Arch (IAA)

    Interrupted aortic arch is a severe form of aortic narrowing where one part of the aorta is disconnected from the rest of the aorta. Therefore, the aortic arch does not look like its usual candy cane appearance. Interrupted aortic arch may be classified by where this disconnection exists: 

    •  Type A occurs after the takeoff of the left subclavian (arm) artery. 
    •  Type B occurs between the left carotid (head) artery and left subclavian artery. 
    •  Type C occurs between the two carotid arteries. 

    Interrupted aortic arch, particularly type B, may be associated with other cardiac abnormalities, such as a small bicuspid aortic valve, narrowing of the outflow tract below the aortic valve (subaortic stenosis), and ventricular septal defect. Sometimes, interrupted aortic arch is associated with genetic abnormalities such as DiGeorge Syndrome (deletion in the 22nd chromosome).  

    Symptoms

    An open (patent) ductus arteriosus is necessary to allow blood flow to the lower part of the body. The ascending aorta supplies blood to the head and arms (depending on the type of interrupted aortic arch), while the lower body receives blood that would otherwise pass through to the lungs. This blood passing through the ductus arteriosus contains less oxygen than in the ascending aorta. This results in the classic finding of lower oxygen levels in the blood in the legs than in the right arm (differential cyanosis). If the ductus arteriosus begins to close, the lower body receives too little blood flow, which may result in liver and kidney failure. Congestive heart failure may result. Symptoms in infants are similar to severe coarctation - poor feeding, sweating with feeding, and rapid/hard breathing. Rarely, a child may grow to be an adult with interrupted aortic arch if the ductus arteriosus never closes on its own.

    Since interrupted aortic arch is a problem of the midline of the chest and neck (conotruncal defect), other structures may be affected, such as the palate of the mouth, parathyroid glands and thymus gland. The roof of the mouth (palate) may not be completely formed, resulting in a cleft. This may result in feeding difficulties due to uncoordinated swallowing and reflux of milk into the nasal cavities. Due to incomplete development of the parathyroid glands, some patients with interrupted aortic arch may have associated problems with calcium metabolism resulting in abnormally low levels in the blood. This may result in seizures. If the thymus gland is absent or abnormal, these patients may have problems with their immune systems, resulting in a reduced ability to fight infections.

    Progression and Complications

    For some patients with calcium and immune system problems, these issues may become better with time. Others will need special medications to control calcium levels and additional immunizations to fight infections. Rapid onset heart failure and shock may develop in infants when the ductus arteriosus closes. 

    Treatments 

    If interrupted aortic arch is diagnosed in an infant, an intravenous prostaglandin E1 (PGE1) infusion is started to keep the ductus arteriosus open. Interrupted aortic arch requires surgical repair, though there have been some instances where a short segment interruption has been opened in the catheterization lab with angioplasty and stents. If interrupted aortic arch is associated with additional cardiac abnormalities, staged separated surgeries may be necessary. If there is renarrowing of the aorta after surgical repair, balloon angioplasty or stenting may be options.