Ascending Sliding Arch Aortoplasty for Coarctation of the Aorta and Hypoplastic Aortic Arch to Avoid Compression of a Retroaortic Innominate Vein

In its usual course in situs solitus, the left brachiocephalic (innominate) vein runs obliquely from left to right, anterior to the aortic arch and supra-aortic vessels, and joins the right brachiocephalic (innominate) vein to form the superior vena cava. On rare occasions, the vein follows an abnormal path inferior to the aortic arch, crossing either anteriorly or posteriorly to the ascending aorta. When crossing anteriorly, the vein follows its course posterior to the descending aorta and, therefore, for both variants, the term “retro-aortic innominate vein” has been commonly used regardless of whether it is a “retro-ascending aortic” or “retro-descending aortic” innominate vein. These anatomic variants, when present in an isolated way, do not alter normal physiology and have no clinical relevance. Their real prevalence, therefore, is not known but, based on tomographic studies, are estimated to be present in approximately 1.7% of patients with congenital heart disease. ¹ However, when they exist along with coarctation of the aorta (CoA) and aortic arch hypoplasia, some technical considerations need to be made at the time of the surgical correction of the aorta to avoid compression of the vein.

At the present time, aortic arch advancement is our treatment of choice for most neonates with CoA and aortic arch hypoplasia. This technique, performed through a median sternotomy, with cardiopulmonary bypass, allows the surgeon to bring the normally sized descending aorta to the distal part of the similarly normally sized ascending aorta or proximal part of the arch, with a very low incidence of recoarctation. ² In older children, in whom the aortic tissue becomes less distensible, this technique carries a higher risk of recoarctation. For this group of patients McKenzie and colleagues described the technique of “ascending sliding arch aortoplasty,” that allows the surgeon to perform the repair using the ascending aorta to enlarge the aortic arch without significant tension. This technique employs native aortic tissue exclusively, potentially enhancing circumferential growth, and preserving the normal contour and elasticity of the arch, with good short- and mid-term outcomes. The procedure includes, after resecting the area of coarctation, opening the inferior wall of the arch longitudinally, and transecting the ascending aorta to bring its distal end to the proximal reconstructed descending aorta. ³

At our Institution, since 2001 we have adopted the technique of aortic arch advancement, through a median sternotomy, for the treatment of neonates and infants with CoA and aortic arch hypoplasia. For older children, beyond two years of age, we currently perform the technique of “ascending sliding arch aortoplasty.”

From our series of 198 consecutive arch advancements done since 2001, a retroaortic course of the innominate vein was diagnosed in two infants, at seven and eight months of age. In both patients the vein coursed posterior to the ascending aorta and inferior to the aortic arch (Figure 1). In one patient the diagnosis was made preoperatively and, in the other, the malformation was found incidentally during surgery. Although in both cases, due to their age, an aortic arch advancement could have technically been done, two anatomical situations were foreseen. If the vein had been left posterior during the repair, it would have been compressed between the neoarch and the posterior mediastinal structures. If left in its natural position, the shortened arch would have inevitably compressed the vein downward. In both patients, we decided to perform an “ascending sliding arch aortoplasty” to be able to bring the innominate vein anterior to the aortic arch, in a normal anatomic postion. Through a median sternotomy, the ascending aorta, aortic arch, coarctation area, and proximal descending aorta were extensively dissected. Systemic blood perfusion through a Polytetrafluoroethylene graft anastomosed to the brachiocephalic trunk, bicaval cannulation, and hypothermia to 18 °C was used. During cooling, with the heart beating, the coarctation was resected and a ¾ anastomosis was performed between the descending aorta and the isthmus. After cross-clamping the aorta, and using antegrade cold cardioplegia, antegrade cerebral perfusion was initialed, applying tourniquets around the supra-aortic vessels. The ascending aorta was transected distally in an oblique way, and the innominate vein brought anteriorly to the ascending aorta (Figure 2). The undersurface of the arch was opened longitudinally, and the long ascending aorta was then advanced and anastomosed to the descending aorta and undersurface of the aortic arch as described by McKenzie et al (Figure 3). Postoperative echocardiogram and computed tomography at follow-up showed no evidence of compression at the innominate vein (Figures 4-6).

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Figure 1.

Innominate vein with retroaortic course.

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Figure 2.

Transection lines of aorta.

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Figure 3.

Aortic arch reconstructed with innominate vein in anterior position.

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Figure 4.

Preoperative computed tomography (CT) scan shows retroaortic innominate vein.

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Figure 5.

Postoperative computed tomography (CT) scan shows innominate vein anterior to the repaired aortic arch.

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Figure 6.

Postoperative axial CT image showing no compression of the innominate vein (*).

Discussion

The technical challenge of repairing CoA with hypoplastic aortic arch and retroaortic innominate vein has been previously considered by Konstantinov et al. ⁴ In their publication, the authors describe transecting the ascending aorta and performing an arch advancement, anastomosing the descending aorta at the site of the end-to-end ascending aorta anastomosis, with good anatomical results.

The technique of “ascending sliding arch aortoplasty” used for our two cases is a good alternative to this technique for infants to avoid compression of the innominate vein, but could also be used in older children with hypoplastic arch and retroaortic innominate vein, to bring the innominate vein to a normal anatomical position.