Graphical abstract
Keywords: Congenital cardiac surgery, Cardiac anomaly, Embryology, Imaging
Highlights
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PFAA is extremely rare and has multiple variants.
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Multimodality imaging with three-dimensional rendering is key to surgical planning.
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Surgical repair included amalgamation of fourth and fifth arches.
Introduction
Persistent fifth aortic arch (PFAA) is a very rare anomaly, with an estimated incidence of 0.01%.1 From the initial description in 1969 until 2023, only 104 cases have been reported in the literature,2,3 and few of those have been right-sided PFAA.4, 5, 6
The anomaly is hypothesized to arise from failure of regression of the fifth embryonic aortic arch on one side, which results in a wide range of arch and great vessel configurations including double-lumen aortic arch and true bovine aortic arch.7 Several classifications for PFAA exist based on the presence and type of an interruption and the fifth arch insertion.3 There is, however, little embryological evidence for a fifth pharyngeal arch in normal embryologic development, and some suggested naming rather than a numbering convention for the pharyngeal arches.8, 9, 10
Case Presentation
The patient is a 6-week-old female infant with a prenatal diagnosis of a right aortic arch and aberrant left subclavian artery. The patient was delivered vaginally at 37+1/40, weighing 2.44 kg (16th centile) to a G1P1 mother and was admitted to the neonatal intensive care unit for respiratory support. Initial transthoracic echocardiography (TTE) was suspicious for a persistent narrowed fifth aortic arch with a peak gradient of 29 mm Hg (Figure 1A, 1B). A cardiac computed tomography (CCT) scan confirmed the diagnosis (Figure 2). Chromosomal microarray showed long contiguous regions of absence of heterozygosity in chromosomes 2 and 8.
Figure 1.
Two-dimensional TTE, suprasternal views obtained preoperatively without (A, B,left) and with (B,right) color-flow Doppler, demonstrates the fourth arch and narrowed fifth arch with their branches; two-dimensional TEE, upper esophageal (C) and two-dimensional epicardial (D) long-axis views with color-flow Doppler obtained postoperatively, demonstrates the unobstructed arch and great vessels. DA, Descending aorta; LCCA, left common carotid artery; LSCA, left subclavian artery; RCCA, right common carotid artery; RPA, right pulmonary artery; RSCA, right subclavian artery.
Figure 2.
Cardiac computed tomography multiplanar reconstruction, oblique sagittal (A), and three-dimensional volume-rendered reconstructions, left lateral (B) and posterior (C) displays, demonstrates cardiac and vascular anatomy including the fourth and fifth arches. DA, Descending aorta; KD, Kommerell diverticulum; LCCA, left common carotid artery; LSCA, left subclavian artery; RCCA, right common carotid artery; RPA, right pulmonary artery; RSCA, right subclavian artery.
The preoperative aortic anatomy was visualized with sweeps through the aortic arches (Videos 1-4). The complex anatomy was further defined by correlating the CCT with the TTE (Figure 3). A right PFAA supplies the descending aorta with focal stenosis proximal to the descending aorta. The true (fourth) arch was moderately hypoplastic, giving rise to the left and right common carotid arteries and the right subclavian artery. The left subclavian artery arises as a fourth branch aberrantly with a Kommerell diverticulum connecting the ligamentum arteriosum to the left pulmonary artery, forming a complete vascular ring. The patient was asymptomatic and was discharged and readmitted for elective repair at 5 weeks of age.
Figure 3.
Axial illustration of the relationship between the vascular structures, the esophagus, and the trachea highlighting the fourth and fifth arches (arrows). Asc. Ao, Ascending aorta; Desc. Ao, descending aorta; KD, Kommerell diverticulum; LA, ligamentum arteriosum; LCCA, left common carotid artery; LPA, left pulmonary artery; LSCA, left subclavian artery; PA, pulmonary artery; RCCA, right common carotid artery; RPA, right pulmonary artery; RSCA, right subclavian artery.
When the patient came for surgery, the immediate preoperative TTE confirmed the above findings and also showed that the patient had a small patent foramen ovale with an otherwise normal intracardiac and segmental anatomy. The fifth aortic arch had narrowed down to 2 mm with a peak pressure gradient of 61 mm Hg and a mean pressure gradient of 22 mm Hg. Intraoperative surgical visual inspection and assessment revealed an atretic connection between the fourth and fifth arches that had not been visualized on preoperative CCT or TTE (Figure 1B, Figure 2A).
The surgical repair was performed via a median sternotomy on full cardiopulmonary bypass at mild hypothermia with cardioplegic arrest and unilateral antegrade cerebral perfusion (Figure 4, Video 5). The cardiopulmonary bypass time was 145 minutes, and the cross-clamp time was 61 minutes. The minimum systemic temperature was 33.2 °C.
Figure 4.
Oblique sagittal illustration of the step-by-step surgical repair starting with the complete vascular ring encircling the trachea and esophagus formed by the aortic arches anteriorly and on the right a retroesophageal Kommerell diverticulum (KD) and a left ligamentum arteriosum (A). To highlight the pathologic vascular anatomy, the pulmonary artery, trachea, esophagus, and left common carotid artery (LCCA) are made transparent (B). After cannulating the distal LCCA and the descending thoracic aorta above the diaphragm, a transverse aortotomy was made, the fifth arch was incised across the stenosis, parallel openings were created between the arches, and the KD was transected (C; green hashed lines); the left ligamentum arteriosum was divided (D); the KD tissue was used to enlarge the narrowed segment of the fifth aortic arch (E); and the 2 arches were connected side-to-side (F), resulting in a new arch (G), which was further augmented with a patch of bovine pericardium (H). The ascending aorta was reconnected (I), and the left subclavian artery (LSCA) was reimplanted to the LCCA (J); the final result was an arch configuration that resembles a right aortic arch with mirror image branching where the first branch is the left innominate artery that gives rise to both the LCCA and the LSCA (K). DA, Descending aorta; RCCA, right common carotid artery; RSCA, Right subclavian artery.
Postoperative transesophageal echocardiography and epicardial echocardiography revealed an unobstructed aortic arch with good biventricular function (Videos 6-8). There was no gradient from the ascending aorta to the femoral arterial line by direct needle measure.
The patient was extubated on postoperative day 1 but remained dependent on continuous positive airway pressure. Rigid bronchoscopy revealed moderate-severe tracheal and right dynamic bronchomalacia and bilateral vocal cord paralysis possibly related to intraoperative tissue manipulation, which has been described with variable frequencies after pediatric cardiac surgery.11 Endoscopic repair of glottic and infraglottic stenosis with left arytenoidpexy and lateralization, posterior cricoid split, and right-sided supraglottoplasty was performed. The patient remained in hospital for 1.5 months and was discharged home on nasogastric tube feeds. On follow-up, the patient underwent G-tube insertion and a revision supraglottoplasty.
Discussion
Fifteen years after its original description in humans, the persistence of the fifth aortic arch postnatally has been labeled the “great pretender” for its mimicry and elusive embryologic origin.2,12 Although this anomaly can be suspected on prenatal ultrasound, as in our case and previous publications, the precise diagnosis often requires multiple postnatal imaging modalities.13 Echocardiography is greatly valuable in the assessment of this anomaly; however, even with the use of specific approaches such as the left ventricular outflow tract and suprasternal views, it remains a screening tool for the diagnosis of PFAA, and further tomographic imaging is usually necessary for confirmation.1 Cardiac computed tomography has been found to be more precise in delineating the vascular tree origins, branching patterns, and arch anomalies with their special orientation compared to echocardiography, but blood flow pattern assessment remains better studied with echocardiography.14 Cardiovascular magnetic resonance can be a great tool in diagnosing vascular and aortic arch anomalies, but its applicability is limited by its availability, expense, and the effects of the heart rate on the imaging quality.14,15
This patient's configuration of PFAA is unique in that the aortic arch is right sided and stenotic and the true fourth arch is interrupted along with an aberrant left subclavian artery. Multimodality imaging along with intraoperative inspection had to be undertaken to fully understand the anatomy. The surgical repair entailed amalgamation of the 2 aortic arches and reimplantation of the aberrant left subclavian artery anteriorly, in essence turning this anatomy into a right-sided aortic arch with mirror image branching in which the first branch is a left innominate artery giving rise to the left carotid and left subclavian arteries, the second branch is a right carotid artery, and the third branch is a right subclavian artery.
Conclusion
We report on a rare variation of PFAA and our repair technique. The PFAA was right sided with distal stenosis, and the true arch was interrupted with aberrant left subclavian artery. Fetal diagnosis was suspected, and the diagnosis was confirmed with echocardiography and computed tomography. An elective repair was performed, which included amalgamating the 2 arches.
Consent Statement
Complete written informed consent was obtained from the patient (or appropriate parent, guardian, or power of attorney) for the publication of this study and accompanying images.
Ethics Statement
The authors declare that the work described has been carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving humans
Funding
The authors declare that this report did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Disclosure Statement
The authors reported no actual or potential conflicts of interest relative to this document.
Footnotes
Supplementary data related to this article can be found at https://doi.org/10.1016/j.case.2026.03.009.
Supplementary Data
Two-dimensional TTE, suprasternal long-axis sweep view obtained preoperatively, demonstrates the fourth arch and narrowed fifth arch and their branches. Asc, Ascending aorta; Des, descending aorta; IV, fourth aortic arch; V, fifth aortic arch.
Two-dimensional TTE, suprasternal long-axis view obtained preoperatively focused on the fourth and fifth arches, demonstrates their parallel arrangement and the great vessels originating from the fourth aortic arch with absence of connection between the 2 arches. Asc, Ascending aorta; IV, fourth aortic arch; V, fifth aortic arch.
Two-dimensional TTE, suprasternal short-axis sweep obtained preoperatively, demonstrates the aorta with the innominate and left common carotid arteries originating from the fourth arch and its relationship with the pulmonary artery. Asc, Ascending aorta; PA, pulmonary artery; IV, fourth aortic arch; V, fifth aortic arch.
Two-dimensional TTE, suprasternal long-axis view obtained preoperatively with color-flow Doppler focused on the fourth and fifth arches, demonstrates narrowing and turbulence between the fifth arch and the descending thoracic aorta. Asc, Ascending aorta; IV, fourth aortic arch; V, fifth aortic arch.
Animated illustration starting with an axial display to demonstrate the complete vascular ring encircling the trachea and esophagus and highlighting the fourth and fifth arches, then in an oblique sagittal display to demonstrate the step-by-step surgical repair strategy with a series of images from echocardiography and CCT for direct comparison. Asc. Ao, Ascending aorta; Desc. Ao, descending aorta; DA, descending aorta; KD, Kommerell diverticulum; LA, ligamentum arteriosum; LCCA, left common carotid artery; LPA, left pulmonary artery; LSCA, left subclavian artery; PA, pulmonary artery; RCCA, right common carotid artery; RPA, right pulmonary artery; RSCA, right subclavian artery.
Two-dimensional TEE, upper esophageal short-axis (0°) view with color-flow Doppler obtained preoperatively, demonstrates the unobstructed arch and great vessels.
Two-dimensional epicardial echocardiography, long-axis view with color-flow Doppler obtained postoperatively, demonstrates the obstructed arch and great vessels.
Two-dimensional TTE, subcostal view with color-flow Doppler, demonstrates the ascending aorta, aortic arch, and descending thoracic aorta without obstruction. Asc, Ascending aorta; Des, descending aorta.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Two-dimensional TTE, suprasternal long-axis sweep view obtained preoperatively, demonstrates the fourth arch and narrowed fifth arch and their branches. Asc, Ascending aorta; Des, descending aorta; IV, fourth aortic arch; V, fifth aortic arch.
Two-dimensional TTE, suprasternal long-axis view obtained preoperatively focused on the fourth and fifth arches, demonstrates their parallel arrangement and the great vessels originating from the fourth aortic arch with absence of connection between the 2 arches. Asc, Ascending aorta; IV, fourth aortic arch; V, fifth aortic arch.
Two-dimensional TTE, suprasternal short-axis sweep obtained preoperatively, demonstrates the aorta with the innominate and left common carotid arteries originating from the fourth arch and its relationship with the pulmonary artery. Asc, Ascending aorta; PA, pulmonary artery; IV, fourth aortic arch; V, fifth aortic arch.
Two-dimensional TTE, suprasternal long-axis view obtained preoperatively with color-flow Doppler focused on the fourth and fifth arches, demonstrates narrowing and turbulence between the fifth arch and the descending thoracic aorta. Asc, Ascending aorta; IV, fourth aortic arch; V, fifth aortic arch.
Animated illustration starting with an axial display to demonstrate the complete vascular ring encircling the trachea and esophagus and highlighting the fourth and fifth arches, then in an oblique sagittal display to demonstrate the step-by-step surgical repair strategy with a series of images from echocardiography and CCT for direct comparison. Asc. Ao, Ascending aorta; Desc. Ao, descending aorta; DA, descending aorta; KD, Kommerell diverticulum; LA, ligamentum arteriosum; LCCA, left common carotid artery; LPA, left pulmonary artery; LSCA, left subclavian artery; PA, pulmonary artery; RCCA, right common carotid artery; RPA, right pulmonary artery; RSCA, right subclavian artery.
Two-dimensional TEE, upper esophageal short-axis (0°) view with color-flow Doppler obtained preoperatively, demonstrates the unobstructed arch and great vessels.
Two-dimensional epicardial echocardiography, long-axis view with color-flow Doppler obtained postoperatively, demonstrates the obstructed arch and great vessels.
Two-dimensional TTE, subcostal view with color-flow Doppler, demonstrates the ascending aorta, aortic arch, and descending thoracic aorta without obstruction. Asc, Ascending aorta; Des, descending aorta.