Surgical repair of interrupted right-sided cervical aortic arch with hypoplasia of the descending thoracic aorta in a child with PHACE syndrome

Abstract

Obstruction of a right cervical aortic arch in association with hypoplasia of the descending aorta is a rare congenital cardiac malformation. We report the case of a 6-month-old boy with posterior fossa anomalies, hemangioma, arterial anomalies, cardiac anomalies and eye anomalies (PHACE) syndrome and interruption of a right-sided cervical aortic arch. The descending thoracic aorta in the child had a long hypoplastic segment and the patient also had small ventricular septal defect and pulmonary valve stenosis. The surgical technique of reconstruction of the aortic arch and the descending thoracic aorta through a median sternotomy is described.

INTRODUCTION

Posterior fossa anomalies, hemangioma, arterial anomalies, cardiac anomalies and eye anomalies (PHACE) syndrome is a rare congenital anomaly with a highly significant association with ipsilateral hemangiomas and aortic arch anomalies [1]. Simultaneously, obstruction of a right cervical aortic arch is also a rare congenital cardiac malformation [2]. We report the successful surgical management of a 6-month-old boy with PHACE syndrome and complex right-sided tortuous cervical aortic arch who also had a long segment hypoplasia of descending aorta. An informed consent was taken from the parents and the ethical committee approved this report (SRC#CR 21/2022).

CASE REPORT

A 6-month-old boy presented with a right facial capillary and lip hemangioma and was diagnosed to have PHACE syndrome. Transthoracic echocardiogram (TTE) revealed a 5 mm restrictive perimembranous ventricular septal defect (VSD) shunting left to right with peak gradient of 48 mmHg and pulmonary valve stenosis with peak gradient of 60 mmHg. He was also found to have complex aortic arch anatomy that was difficult to delineate by TTE. A cardiac computerized tomography (CT) displayed a good size ascending aorta and left innominate artery and then the arch appeared to be interrupted. After that, there was a tortuous, hypoplastic right cervical arch (2.5 mm diameter), giving the origin to the right carotid, vertebral and the subclavian arteries. Then, the cervical aortic arch descended and was connected to the proximal segment of descending thoracic aorta. The upper segment of the descending thoracic aorta was also hypoplastic (3 mm diameter) for a length of 30 mm. Lower down, the diameter of aorta was 6 mm. (Fig. 1A). There was a large left internal mammary supplying the lower body. At the age of 6 months (weight: 6.8 kg; height 66.5 cm), the child was asymptomatic. A head CT angiography demonstrated a complete circle of Willis (Fig. 1C). The TTE examination revealed a patent foramen ovale with a left to right shunt. The size of the VSD was found to have become smaller (2.2 mm), was covered by an aneurysmal tissue and with a pressure gradient of 50 mmHg between both ventricles. The arterial duct was not patent. TTE also demonstrated an increase in the peak pressure gradient across the pulmonary valve to 85 mmHg. Therefore, the child underwent pulmonary balloon valvuloplasty. During cardiac catheterization, the peak pressure gradient between the ascending aorta and the femoral artery was more than 40 mmHg. Therefore, the child was scheduled for a surgical reconstruction of the arch and descending aorta. If the surgical reconstruction was not feasible, there was a contingency ‘Plan B’ of either placing an extra-anatomical conduit between the ascending aorta and the descending thoracic aorta or stenting the cervical arch and descending thoracic aorta.

The surgical repair was done through a median sternotomy. Following aortic canulation of the distal ascending aorta that was done just below left innominate artery and bi-caval venous cannulation, cardiopulmonary bypass was instituted and the child was cooled to 25°C (nasopharyngeal) temperature. The left ventricle was vented through right upper pulmonary vein. The VSD size was 2.2 mm and the decision was not to arrest the heart and close it considering its small size with no haemodynamic consequence. The heart continued to beat albeit at a low rate without the need for hypothermic circulatory arrest. Throughout the surgical procedure, bilateral near-infrared spectroscopy was monitored and there was no discrepancy between the right and left sides values (range: 65 bilaterally). Extensive mobilization of the aortic arch up to the normal size descending thoracic aorta (8 mm diameter) that was at the level of the dome of the left atrium was done. When the hypoplastic cervical arch was incised, there was no backflow from the right common carotid and right subclavian arteries. Therefore, it was assumed that they were atretic and it was completely divided and oversewed. The hypoplastic segment of the descending was completely incised longitudinally. The segment was brought anterior to the right bronchus and augmented with a bovine pericardial patch. After that, it was brought back to its anatomical position posterior to the right bronchus and connected to the distal segment of the ascending aorta by an end to side anastomosis (Fig. 2, Video 1). The patient had an uneventful postoperative course. Follow-up CT demonstrated wide open anastomosis with no obstruction across the reconstructed segments of the aorta. The sizes of both right common carotid and right subclavian arteries vessels increased probably due to collateral flow from descending aorta (Fig. 1B). At 1-year follow-up, the child was asymptomatic. The non-invasive blood pressure recordings (systolic/diastolic) at the time of follow-up showed satisfying outcome of the procedure (right upper arm: 80/40 mmHg; left upper arm; 109/58 mmHg; right lower limb: 109/56 mmHg; left lower limb: 113/55 mmHg).

DISCUSSION

Cervical right aortic arch is a rare congenital anomaly that was first described in 1914 [3]. Patients with cervical right arch have variable branching pattern, laterality of the arch and abnormal structural abnormalities. Two potential theories described the development of the cervical arch. The first theory is the persistence of the embryonic third arch and the regression of the ipsilateral fourth arch. The second theory is the failure of the descent of the fourth arch with anomalous development of the pharyngeal arches [2]. Our patient was diagnosed to have PHACE syndrome based on his facial hemoangioma, aortic arch and cardiac anomalies. The aetiology of this syndrome is thought to be attributed to an insult in neural crest cells migration that result in diffuse aortocranial vasculopathy and few reports highlight the association of PHACE syndrome with complex aortic arch anomalies including Corkscrew aortic arch [4].

The surgical management of these anomalies is challenging. There are very few reported cases with similar long segment of atresia and hypoplasia of cervical arch and descending thoracic aorta and some of those patients underwent extra-anatomical bypass to relive the arch obstruction [5]. Comprehensive diagnostic imaging and the use of intraoperative flexible bronchoscopy aid in the surgical planning and understanding the anatomical course of the hypoplastic aorta. Complete dissection and mobilization of the hypoplastic thoracic aorta from the nearby structures such as the oesophagus, trachea, right main bronchus, left atrium are important to facilitate the complex reconstruction. The completeness of the circle of Willis contributed to the decision to sacrifice the atretic right carotid and the subclavian arteries and without the need to not reimplant the carotid artery onto the reconstructed aortic arch.

In conclusion, establishing the continuity of the aortic arch in patients with complex cervical arch with tortuosity and with long segment of hypoplasia is feasible with excellent outcome. This offers a theoretical advantage of a potential for aortic growth over the extra-anatomical bypass; however, long-term follow-up is necessary to evaluate outcome of this approach.

Conflict of interest: none declared.

DATA AVAILABILITY

The data underlying this article are available in the article and in its online supplementary material.

Reviewer information

Reviewer information European Journal of Cardio-Thoracic Surgery thanks Katarzyna Januszewska and the other, anonymous reviewer(s) for their contribution to the peer review process of this article.

REFERENCES