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Role of Cross-Sectional Imaging in Repair of Neonatal Hypoplastic Aortic Arch

Rabin Gerrah, MD; Dianna Bardo, MD; Rachel Sunstrom, PAC; Rich Reed, PAC; Stephen Langley, MD


Introduction

Hypoplastic Aortic Arch (HAA) is a common diagnosis in Congenital Heart Diseases. Altogether, aortic malformations account for 15-20% of all congenital cardiovascular diseases.[1] HAA may occur as an isolated lesion or in conjunction with other congenital cardiac anomalies. Hypoplasia might entail single or multiple segments of the aorta and, hence, the wide range of surgical options. The surgical treatment for HAA has evolved with advances in surgical techniques and improved imaging modalities. As a general rule, the anomalies of the distal arch and descending aorta are approached via left thoracotomy and the ascending and proximal portion of the arch are approached through midsternotomy. Different guidelines regarding when to use each approach based on anatomic landmarks or morphologic characteristics have been described.[2] A management dilemma rises when the common hypoplasia of the distal arch is extended towards the transverse arch. In some instances, the presence of aortic arch hypoplasia has been ignored in the setting of severe isthmus stenosis or a coarctation with the hypothesis that reestablishing flow in the aorta after relief of obstruction will stimulate the aorta to grow and the hypoplasia will resolve.[3,4] Instead, in many institutions any extension of hypoplasia proximal to the distal arch is considered Complex Arch Disease and repaired through a midsternotomy approach. The major differences between the two approaches are the need for cardiopulmonary bypass (CPB) to reconstruct the aorta and cerebral perfusion techniques or deep hypothermic circulatory arrest in the midline approach versus no CPB in the thoracotomy approach. Achieving the same outcome with no CPB would exclude the complications associated with the use of it, and would be a preferred approach, if feasible.


FIGURE 1 Segmentation of the aortic arch. Asc Ao= Ascending aorta, BC= Brachiocephalic, Desc Ao= Descending aorta, LCC= Left common carotid, LSC= Left subclavian, RCC= Right common carotid, RSC= Right subclavian.



Echocardiography, has become the gold standard for imaging and diagnosis in Congenital Heart Disease (CHD). It is used primarily for surgical decision-making regarding the approach for repair of HAA. This diagnostic modality has limitations, such as lack of appropriate acoustic windows in specific body habitus or posterior structures, and limited spatial resolution. Recently, cross sectional imaging (CSI) including: computerized tomography (CT) and Magnetic resonance imaging (MRI), have become a strong modality in diagnosis of CHD. The different variations of HAA are repaired based on surgeons’ experience and preference and to-date, no standard morphological or anatomical definitions or numeric parameters exist to define the exact type of pathology and the appropriate repair-type based on these definitions.


To read the full article, please go to the April 2016 Issue of CCT.