What is the technique for balloon angioplasty in the surgical repair of coarctation of the aorta (CoA)?

Updated: Nov 20, 2018
  • Author: Syamasundar Rao Patnana, MD; Chief Editor: Stuart Berger, MD  more...
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Answer

Cardiac catheterization and selective cineangiography are performed to confirm the clinical diagnosis, to exclude other cardiac defects, and to assess suitability for balloon angioplasty. Once balloon angioplasty is chosen, a 4F-6F multi-A2 (Cordis) catheter is introduced into the femoral artery percutaneously and is positioned across the aortic coarctation. Then, a 0.021-0.035 in J-tipped guide wire is passed through the catheter into the ascending aorta and the tip of the wire positioned in the ascending aorta. A 4F-7F balloon angioplasty catheter is then positioned across the aortic coarctation. The balloon is inflated with diluted contrast material to approximately 3-5 atm of pressure or higher, depending on the manufacture's recommendations.

Monitoring pressure of inflation via any of the commercially available pressure gauges is recommended. The balloon is inflated for 5 seconds. A total of 2-4 balloon inflations are performed 5 minutes apart. Aortography and measurement of pressure gradients across the coarctation of the aorta are performed. The heart rate, systemic pressure, and cardiac index are recorded prior to and 15 minutes after balloon dilatation to ensure that the change in pressure gradient is related to balloon dilation rather than changes in patient status.

The author generally performs this procedure with the patient under conscious sedation, whereas others advocate general anesthesia. Most cardiologists use percutaneous femoral artery approach for cardiac catheterization and balloon angioplasty. Occasionally, femoral artery cutdown or left axillary artery cutdown is necessary if the percutaneous approach is unsuccessful. The authors and others have used a transumbilical approach in neonates in an attempt to avoid the use of the femoral arteries. [15, 60] In patients in whom the aorta can be entered from the right ventricle (either directly in patients with transposition of the great arteries or double outlet right ventricle or indirectly through a ventricular septal defect), balloon angioplasty may be performed transvenously.

The size of the balloon chosen for angioplasty is 2 or more times the size of the coarcted segment, but no larger than the size of the descending aorta at the level of the diaphragm, as measured from a frozen video recording. The authors usually choose a balloon that is midway between the size of the aortic isthmus (or transverse aortic arch) and the size of the descending aorta at the level of diaphragm. If the relief of obstruction is not adequate (pressure gradient reduction to < 20 mm Hg and angiographic improvement), a balloon as large as the diameter of the descending aortic at the level of diaphragm is chosen for additional dilatation. [48, 61]

The authors usually give 100 U of heparin per kilogram prior to introducing the balloon-angioplasty catheter. Activated clotting times should be measured every 30 minutes and maintained between 200 and 250 seconds. The heparin effect is neither reversed nor continued after the procedure. Administering adequate doses of heparin to prevent thromboembolism is important. [48, 62]

The balloon inflation pressure should be monitored and attempts should be made not to exceed that stated by the manufacturer; this is to prevent balloon rupture and its adverse effects. [37, 48]

A catheter or a guide wire must not be manipulated over the site of a freshly dilated coarctation of the aorta. A guide wire should always be left in place across the coarctation segment, and all angiographic and balloon-dilatation catheters should be exchanged over the guide wire.

Balloon size should be carefully chosen to prevent aneurysm.

Use of large-caliber angioplasty catheters may result in significant femoral artery compromise. Availability of balloon catheters that can be introduced through 4F sheaths appears to reduce the femoral artery injury. Even these may injure the femoral artery in the young infant; in such situations, the authors use 3F sheaths through which the more recently available balloon dilatation catheters (eg, Mini-Tyshak [Braun] catheters) can be introduced, which may further reduce such complications.


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