Imaging of Aortic Arch Anomalies and Associated Findings

Abstract and Introduction

Abstract

Imaging is important in the diagnosis of aortic arch disease. Echocardiography is the test of choice. It possess minimal risk, can be performed at the bedside without sedation and provides a complete evaluation of the heart and the great vessels. Cardiac magnetic resonance imaging (cMRI) is an alternative when echocardiography is limited by acoustic windows. It does not use ionizing radiation or nephrotoxic contrast. 3D reconstruction and soft tissue characterization are possible. cMRI evaluates physiology and may be an alternative to diagnostic catheterization. Longer scan times, need for sedation and the presence of implantable metal devices that may be a contraindication for cMRI are the main limiting factors. Computed tomography with angiography has very short scanning times, limiting the need for sedation. It has high spatial resolution and can evaluate physiology. Its use is limited because it uses radiation, has poor temporal resolution compared with cMRI and uses iodinated contrast. Catheterization is the test of choice, and can serve for diagnostic and therapeutic purposes.

Introduction

Imaging of the heart and great arteries is a stepping stone in the diagnosis and management of congenital heart disease (CHD). Aortic arch anomalies include a heterogeneous group of diagnosis, including native disease of the aortic arch alone or in association with intracardiac disease and anomalies secondary to surgical repairs or palliation. Echocardiography, cardiac magnetic resonance imaging (cMRI), computed tomography with angiography (CTA) and cardiac catheterization angiography are important modalities used in pediatric cardiology to diagnose and treat aortic arch disease and associated anomalies.

This review article introduces the reader to the basic principles of echocardiography, cMRI, CTA and angiography. We discuss the advantages and disadvantages of each modality and focus on the evaluation of the aortic arch. We review specific examples of native disease and postoperative disease, focusing on important anatomic findings and their physiologic consequences and/or associations. Images concentrate on native disease as opposed to surgical repairs.

Examples of native disease included are vascular rings, coarctation of the aorta and truncus arteriosus (TA). Postoperative aortic arch anomalies discussed are aortopulmonary connections (Damus–Kaye–Stansel), evaluation post-repair of coarctation and truncus.

Table 1. Safety and image artifact profiles of implantable metallic objects.
	Comments	Artifact
Absolute contraindication
Intracranial, intraocular or intraocular metallic object¹¹ PPM lead without generator
*Relative contraindication*
PPM lead, AICD^7,11,30	MRI-compatible systems are designed to minimize thermal damage and risk for unintended stimulation The system should have been in place for at least 6 weeks; before this time the safety profile is unknown The PPM should be programmed into MRI safety mode (no sensing, only basic pacing)^7,11,30	PPM and AICD produce small artifacts^7,11,30
*No contraindication*
Temporary pacemaker leads without generator, sternal wires, hemostatic clips, stainless steel, nonferromagnetic or minimally ferromagnetic stents, stainless steel or platinum vascular coils, Rashkind, Clamshell, CardioSEAL®, STARFlex® and Amplatzer™ occluder devices and prosthetic valves^7,11		Small artifact: sternal wires, clips, stainless steel stents, CardioSEAL, STARFlex and Amplatzer occluder devices, and prosthetic valves Large artifact: stainless steel coils, Rashkind and Clamshell occluder devices. The remaining objects produce none or trivial artifact^7,11

Box 1. Types of vascular rings.
Double aortic arch Most common kind of vascular ring. Usually both arches are patent. Sometimes an arch is atretic, most commonly the left arch RAA with vascular ring Completed by a ligamentum arteriosus or patent duct: RAA with aberrant left subclavian and left PDA/ligamentum RAA with aberrant innominate artery Right circumflex aortic arch RAA mirror image branching with PDA from the descending aorta LAA with vascular ring Completed by a ligamentum arteriosus or patent ductus Left circumflex aortic arch LAA with aberrant right subclavian and right PDA/ligamentum