Coarctation of the aorta
|Classification and external resources|
There are three types:
- 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.
- Ductal coarctation: The narrowing occurs at the insertion of the ductus arteriosus. This kind usually appears when the ductus arteriosus closes.
- Postductal coarctation: The narrowing is distal to the insertion of the ductus arteriosus. 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 (because of collateral circulation), hypertension in the upper extremities, and weak pulses in the lower extremities. Postductal coarctation is most likely the result of the extension of a muscular artery (ductus arteriosus) into an elastic artery (aorta) during fetal life, where the contraction and fibrosis of the ductus arteriosus upon birth subsequently narrows the aortic lumen.
Signs and symptoms
Arterial hypertension in the right arm with normal to low blood pressure in the lower extremities is classic. Poor peripheral pulses and a weak femoral artery pulse may be found in severe cases.
If the coarctation is situated before the left subclavian artery, asynchronous radial pulses will be detected in the right and left arms. A radial-femoral delay between the right arm and the femoral artery would be apparent, whilst no such delay would occur under left arm radial-femoral palpation.
A coarctation occurring after the left subclavian artery will produce synchronous radial pulses, but radial-femoral delay will be present under palpation in either arm.
Imaging and diagnosis
With imaging, resorption of the lower part of the ribs may be seen, due to increased blood flow over the neurovascular bundle that runs there. Post-stenotic dilation of the aorta results in a classic 'figure 3 sign' on x-ray. The characteristic bulging of the sign is caused by dilatation of the aorta due to an indrawing of the aortic wall at the site of cervical rib obstruction, with consequent post-stenotic dilation. This physiology results in the '3' image for which the sign is named. When the esophagus is filled with barium, a reverse 3 or E sign is often seen and represents a mirror image of the areas of prestenotic and poststenotic dilatation.
Coarctation of the aorta can be accurately diagnosed with magnetic resonance angiography. In teenagers and adults echocardiograms may not be conclusive. In adults with untreated coarctation blood often reaches the lower body through collaterals, e.g. internal thoracic arteries via. the subclavian arteries. Those can be seen on MR, CT or angiography. An untreated coarctation may also result in hypertrophy of the left ventricle.
Therapy is conservative if asymptomatic, but may require surgical resection of the narrow segment if there is arterial hypertension. The first operations to treat coarctation were carried out by Clarence Crafoord in Sweden in 1944. In some cases angioplasty can be performed to dilate the narrowed artery. If the coarctation is left untreated, arterial hypertension may become permanent due to irreversible changes in some organs (such as the kidney).
For fetuses at high risk for developing coarctation, a novel experimental treatment approach is being investigated, wherein the mother inhales 45% oxygen three times a day (3 x 3–4 hours) beyond 34 weeks of gestation. The oxygen is transferred via the placenta to the fetus and results in dilatation of the fetal lung vessels. As a consequence, the flow of blood through the fetal circulatory system increases, including that through the underdeveloped arch. In suitable fetuses, marked increases in aortic arch dimensions have been observed over treatment periods of about two to three weeks
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- Aortic Coarctation information from Seattle Children's Hospital Heart Center
- Diagram at kumc.edu
- Overview and diagram at umich.edu
- Down's Heart Group Specific information relating to heart conditions and Down's Syndrome.
- http://www.uniklinik-bonn.de/dzft Specific information about hyperoxygenation approach (Note: in German)
- "English version" of some (other?) information from the [same web site as the] above source
- 3D CT Angiogram Radiology of Coarctation
ar:تضيق الأبهر de:Aortenisthmusstenose es:Coartación aórtica fa:کوآرکتاسیون آئورت fr:Coarctation de l'aorte it:Coartazione dell'aorta ja:大動脈縮窄 no:Koarktasjon av aorta nn:Koarktasjon pl:Koarktacja aorty pt:Coarctação da aorta ru:Коарктация аорты sr:Коарктација аортеuk:Коарктація аорти
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