Double aortic arch with atretic proximal left arch

Abstract

Aortic arch anomalies are rare and represent about 1% of all congenital cardiac lesions. Double aortic arch with atretic proximal left arch is one of the rare causes of respiratory symptoms in neonates, often missed by preoperative imaging studies. Preoperative identification and differentiating this entity from other arch anomalies is imperative to plan appropriate surgical management.

Introduction

Aortic arch anomalies are rare and represent about 1% of all congenital cardiac malformations. These are the result of either incomplete involution or abnormal persistence of embryonic vascular structures. The double aortic arch results from the persistence of embryonic right and left arches. It frequently presents with respiratory difficulties owing to the compression of the trachea or the bronchus. A double aortic arch with an atretic proximal left arch is one of the rare causes of respiratory symptoms, which is often difficult to diagnose on preoperative imaging because of its incomplete nature.

Case history

A 6-month-old male, full term, birth weight of 3.4 kg, requiring ventilatory support (bilevel positive airway pressure (BIPAP) dependent) soon after birth was referred to our center for further management. There were multiple failed attempts to wean off BIPAP. Auscultation of the lungs revealed crepitations and conducted sounds. Results of cardiac and abdominal examinations were normal. On clinical examination, the child was tachypneic and had chest retractions on BIPAP support (spontaneous/timed (S/T) mode, 40 breaths per minute, inspiratory positive airway pressure (IPAP) 12, expiratory positive airway pressure (EPAP) 8, FiO₂: 40%) with oxygen saturation of 100%. Hemodynamics were stable.

A chest X-ray and an electrocardiogram (ECG) did not show any significant abnormalities. A two-dimensional (2D) echocardiogram showed normal cardiac anatomy and a suspicious aortic arch. A thoracic computerized tomogram (CT) with 3D reconstruction showed a double aortic arch with a mirror-image branching pattern viz, right common carotid (RCCA), right subclavian (RSCA), left subclavian artery (LSCA), and left common carotid (LCCA) with discontinuity of the left arch proximal to the LCCA, a nipple-like projection from the main pulmonary artery (? representative of a ligamentum), moderate left bronchial compression (Figs. 1 and 2).

Fig. 1.

Computerized tomogram (CT) thorax with 3-D reconstruction. RCCA—right common carotid artery, RSCA—right subclavian artery, LCCA—left common carotid artery, LSCA—left subclavian artery, LPA—left pulmonary artery, MPA—main pulmonary artery, T—trachea, RT—Ryle’s tube (esophagus), arrow—tiny stump of ligamentum arteriosus, L Arch—Left arch, R Arch—Right arch

Fig. 2.

Computerized tomogram (CT) thorax—coronal view. The arrow indicates proximal left main bronchus compression

The possible diagnosis of a vascular ring was made and planned for division of the vascular ring. A left posterolateral thoracotomy was performed. Intraoperative arch dissection revealed a double aortic arch with an atretic left arch in the form of a fibrous chord proximal to the origin of the LCCA compressing the left main bronchus. There was a ligamentum completing the vascular ring. The fibrous chord and the ligament were divided, relieving the compression on the left bronchus.

The perioperative period was uneventful, and the child was extubated on the first postoperative day. At 6 months follow-up, the child is asymptomatic and doing well.

Discussion

A vascular ring occurs when the trachea and esophagus are completely surrounded by the aortic arch and its associated branches. Incomplete double aortic arch represents a rare variety of the vascular ring, in which the segment of the minor arch, usually the left, is atretic. In most of the cases, the atretic segment is distal to the left subclavian artery [1]. Usually, this atretic segment persists as a fibrous chord, tethering the anterior aortic arch to the descending aortic diverticulum. Despite many classification systems of the double aortic arch, most surgeons currently use the nomenclature scheme proposed by the Society for Thoracic Surgeons [2, 3]. However, diagnosis by imaging is not straightforward and needs a high index of suspicion especially with echocardiography. Despite newer echocardiographic diagnostic techniques for the double aortic arch, the diagnosis is always challenging [4]. Thankavel et al. highlighted the importance of CT and/or magnetic resonance imaging (MRI) in the preoperative planning of patients with arch anomalies [5]. However, the differentiation between atresia and involution is still a big challenge. The definitive diagnosis can be established at the time of surgery.

An incomplete double aortic arch with an atretic proximal left arch is a rare cause of neonatal respiratory distress. This is often missed by preoperative imaging and needs a high index of suspicion.

Funding

None.

Declarations

Ethics approval

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Informed consent

There is no patient identifiable data in the manuscript. Patient’s consent to participate in the study was obtained from the parents.

Human and animal rights

Not applicable.

Conflict of interest

The authors declare no competing interests.