Coartation of the Aorta
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Coarctation of the Aorta 1
COARCTATION OF THE AORTA
Coarctation of the Aorta
Coarctation of the Aorta 2
Coarctation of the aorta is defined by Medicine.net as (1996-2007) “a congenital constriction of the aorta, impeding the flow of blood below the level of the constriction and increasing blood pressure above the constriction.” It is a defect in the vessel media, which allows a prominent posterior in folding (Shah, 2005, p. 1). This can extend around the entire circumference of the aorta or just effect a portion. “The gross pathology of coarctation varies considerably,” (Shah, 2005, p. 1). The lesion can be long, segmental or tortuous. It is commonly found distal to the origin of the left subclavian artery (Shah, 2005, p. 1). The abnormality occurs in embryological development. Coarctation is do to an abnormality in the left fourth and sixth aortic arches that occurs at this stage. This anomaly “can be explained by 2 theories, the ductus tissue theory and the hemodynamic theory,” (Shah, 2005, p. 2).
In the ductus tissue theory it is thought, “coarctation develops as the result of migration of ductus smooth muscle cells into the periductal aorta, with subsequent constriction and narrowing of the aortic lumen” (Shah, 2005, p. 2). This theory does not explain all coarctation cases including transverse arch and abdominal aorta coarctations (Shah, 2005, p. 2).
The hemodynamic theory seeks to explain these coarctation cases along with others. In the hemodynamic theory it is hypothesized that “coarctation results from reduced volume of blood flow through the fetal aortic arch and isthmus” (Shah, 2005, p. 2). “Based on this theory, lesions that diminish the volume of left ventricular outflow in the fetus also decrease flow across the aortic isthmus and promote development of coarctation” (Shah, 2005, p. 2). This theory explains the lesions associated with coarctation such as VSD, bicuspid aortic valve, left ventricular outflow obstruction and tubular hypoplasia of the transverse aortic arch.
It does not explain isolated coarctation without associated intracardiac lesions (Shah, 2005, p. 2).
Coarctation of the Aorta 3
Which brings us to how coarctation is classified. Coarctation is classified as either simple/isolated or complex with association. In simple coarctation the abnormality is isolated and has no other associated defect. In complex coarctation it is associated with other congenital defects of the heart (Rocchini, 1999, p. 1). Most notably with VSD (Ventricular Septal Defect) and or bicuspid aortic valve. These two defects are the most commonly seen defects with complex coarctation.
Coarctation is two times more common in boys than girls. Coarctation rarely runs in families and therefore is not hereditary. Turners syndrome has a strong correlation with coarctation. In this syndrome a female child has only one instead of two x chromosomes and is usually without functioning ovaries. This correlation is of unknown origin. Coarctation of the aorta is the 7th or 8th most common form of congenital heart disease. (Rocchini, 1999, p. 1)
The disease process of coarctation allows for “a narrowing of the aorta resulting in a selective elevation in blood pressure in the upper extremity blood vessels and ultimately in an increased workload for the heart” (Rocchini, 1999, p. 1). Low blood pressure ensues below the coarctation. In general pulses below the femoral site are either absent or unable to be palpated.
If untreated surgically individuals with coarctation