Transcatheter aortic valve replacement in right aortic arch with mirror image branching

Abstract

Background

A right aortic arch withmirror-image branching is a rare congenital anomaly resulting from the abnormal regression ofthe embryonic left aortic arch. This variant, in which the aortic arch courses to the right of the trachea and gives rise to its branches in a mirrored configuration compared to the standard left-sided arch, can present unique challenges during cardiovascular interventions such as transcatheter aortic valve replacement (TAVR).

Case Report

We describe a 75-year-old male undergoing evaluation for TAVR who was incidentally found to have a right aortic arch with mirror-image branching. This anomaly, characterized by a mirrored branching pattern of the arch vessels, required tailored imaging and procedural considerations. The patient successfully underwent TAVR through the right aortic arch without complications, demonstrating the adaptability of contemporary structural heart interventions.

Conclusions

This patient presented with an embryonic right aortic arch with mirror-image branching (RAA-MIB) and persistence of the left sixth arch. Given the potential technical challenges in catheter navigation that the unique anatomy of this aortic arch poses, it is critical to understand these embryological variations for successful procedural planning and execution. Clinical implications include a potentially increased risk of stroke and dissection. Advances in imaging modalities continue to enhance our ability to diagnose and manage rare aortic arch anomalies, ultimately improving patient outcomes.

Take-Home Messages

TAVR may be feasible in congenitally anomalous arch anatomy but requires careful multidisciplinary approach and planning.

Background

A persistent aortic arch is a rare congenital anomaly caused by the failure of an embryonic aortic arch to regress. According to Rathke’s classic diagram, the aortic arch and great vessels develop from six paired pharyngeal arch arteries connecting the dorsal and ventral aortae. Selective regression and remodeling create the typical left-sided aortic arch [1–4]. Persistent aortic arches may present in infancy with symptoms or may be incidentally detected during imaging studies (echocardiography, CT angiography, or MRI) in asymptomatic individuals [5]. While previous reports have described successful implementation of TAVR in a right aortic arch, this is the first case report that details TAVR in a right aortic arch with mirror-image branching (RAA-MIB) [6].

Case report

A 75-year-old male with severe symptomatic calcific aortic stenosis and moderate aortic regurgitation was evaluated for transcatheter aortic valve replacement (TAVR). The patient had a past medical history of hypertension, hypercholesterolemia, coronary artery disease and has no smoking history. The patient has no family history of valvular disease. The STS Risk for mortality was 2.4% and the STS Risk for morbidity or mortality 11.6%.

Preoperative CT angiography showed aortic valve leaflet thickening and calcification consistent with aortic valve stenosis and concentric left ventricular hypertrophy. There was moderate-grade atherosclerotic changes of the infrarenal aortic without significant stenosis. Aortic dimensions include a proximal aorta of 2.3 × 2.4 cm, mid aorta of 2.2 × 2.0 cm, distal aorta 1.4 × 1.7 cm, right common iliac of 1.2 cm, and left common iliac of 1.1 cm.

An echocardiogram showed preserved LV function, a severely calcified aortic valve, especially at the leaflet tips with reduced mobility. There was also mild-moderate aortic regurgitation. Doppler evaluation shows a mean gradient of 30mmHg, DI < 0.25.

Pre-procedural CT imaging revealed a RAA-MIB [7]. This rare vascular anomaly featured a left brachiocephalic artery arising from the ascending aorta followed by a separate origin of the right carotid artery and finally the right subclavian artery thus mirroring the normal anatomy. The dominant right aortic arch coursed over the right main bronchus and behind the esophagus to a contralateral left-sided descending thoracic aorta (Figs. 1 and 2A) [8]. Additionally, the left vertebral artery was hypoplastic and originated from the left subclavian artery (Video 1).

Fig. 1.

3D-rendered reconstruction of right aortic arch with mirror image branching. Left anterior oblique (LAO) 60-degree projection. The left carotid (green) and the left subclavian (red) arise together as a left brachiocephalic artery (a remnant left fourth embryologic arch) while the right carotid (blue) and right subclavian (yellow) arteries arise from the right aortic arch. The right vertebral artery (purple) arises from the right subclavian. The left vertebral artery was hypoplastic. The distal left sixth arch developed into the left ductus arteriosus, visible as an anteriorly projecting diverticulum under the left subclavian artery origin. See also Video 1. Video 1 demonstrates the role of 3D reconstruction in defining these atypical angulations, which are critical for procedural planning in anomalous arches

Fig. 2.

CT angiography of right aortic arch with mirror image branching. A Asymmetric bilateral carotid and subclavian arteries arising from each ipsilateral arch differentiating from axial symmetry seen in a double arch. B The vascular ring encircling the trachea is incomplete. RCCA – right common carotid artery, LCCA – left common carotid artery, RSA – right subclavian artery, LSA – left subclavian artery

Despite this rare anatomical configuration, imaging demonstrated aortic root and coronary anatomy suitable for TAVR. The patient underwent uneventful transfemoral TAVR using a steerable Commander Delivery System to deploy a 26 mm SAPIEN 3 transcatheter heart valve (THV) and remains well four years after the procedure with excellent THV function.

An echocardiogram four years post-TAVR demonstrated normal left ventricular systolic function (LVEF 60%), stable valve hemodynamics (mean gradient 8 mmHg, peak gradient 15 mmHg), and only mild central aortic insufficiency without valve migration or structural failure. These findings were unchanged from a study two years post-TAVR, indicating stability of valve function and cardiac performance. The ascending aorta measured 3.6 cm (Z-score 1.25) with no evidence of dissection or aneurysmal dilation. No pericardial effusion or thrombus was seen, and right-sided pressures remained normal. Surveillance echocardiography is performed routinely per institutional post-TAVR protocol or as clinically indicated.

Although a cerebral embolic protection device (CEPD) could not be used intra-procedurally, the patient exhibited no clinical evidence of stroke post-operatively. Neuroimaging performed approximately one year later showed no intracranial hemorrhage or infarction. CT angiography demonstrated no acute intracranial pathology, no large-vessel stenosis or occlusion, and only mild atherosclerosis.

We present this case to demonstrate procedural feasibility of TAVR in an anomalous right aortic arch—a consideration inherently focused on the short term. Long-term valve durability is not expected to be influenced by arch anatomy, and indeed our patient’s follow-up demonstrated stable valve hemodynamics, absence of recurrent symptoms, and no cerebrovascular events. While formal quality-of-life questionnaires were not collected, the absence of cardiovascular morbidity over four years supports the safety and durability of TAVR in this rare anatomic context.

Discussion

This case describes a rare congenital anomaly, RAA-MIB, which occurs in less than 0.05% of the population [9]. Embryologically, RAA-MIB arises from regression of the left fourth branchial arch between the left ductus and dorsal aorta, with persistence of the left sixth arch. This diagnosis is distinct from a double aortic arch. In a double arch, two separate arches encircle the trachea and esophagus, each giving rise to the ipsilateral carotid and subclavian arteries, producing the classic ‘four-vessel sign’ and a complete vascular ring. In RAA-MIB, by contrast, there is a single right arch, with the first branch being a left brachiocephalic trunk that divides into the left carotid and subclavian arteries. Although our axial CT showed four head and neck vessels, the asymmetry of their arrangement, absence of a complete ring, and presence of a left brachiocephalic trunk confirmed RAA-MIB rather than double arch. From a procedural standpoint, this branching pattern differs from other right arch variants (e.g., aberrant subclavian origin or Kommerell’s diverticulum) by altering the trajectory of the delivery system through the arch. This necessitates modified fluoroscopic projections and individualized wire/delivery system selection to safely navigate the anatomy. This persistence of the distal left sixth aortic arch, which forms the ductus arteriosus in fetal development, typically becomes the ligamentum arteriosum. In this case, imaging reveals an anteriorly projecting diverticulum beneath the left subclavian artery, suggestive of a ligamentous remnant rather than a true diverticulum (Fig. 1). Persistent remnants of the sixth arch are typically asymptomatic but may rarely calcify or form ductal aneurysms in patients with abnormal blood flow dynamic or hypertension. Occasionally, this results in a mirrored branching pattern, featuring a left brachiocephalic artery, right common carotid, and right subclavian artery (Fig. 1, Video 1). Unlike double aortic arches, which form vascular rings causing compressive symptoms, RAA-MIB typically does not, as the distal left sixth arch forms the left ductus arteriosus projecting anteriorly toward the pulmonary artery (Figs. 1 and 2A). These features likely explain the absence of respiratory or feeding symptoms in this patient. Notably, no associated congenital heart defects, such as tetralogy of Fallot or truncus arteriosus, were identified (Fig. 2B).

The identification of RAA-MIB during pre-procedural imaging was essential for successful TAVR planning. Although isolated RAA-MIB is not associated with aneurysm, dissection, or systemic perfusion abnormalities, its atypical geometry can complicate device navigation. These challenges include altered catheter trajectory and wire bias. While insufficient studies report systematic data to establish whether such anatomy carries higher complication rates, these mechanistic risks highlight the importance of careful pre-procedural imaging, device planning, and multidisciplinary review. In this patient, transfemoral access was feasible; however, in cases where alternative routes such as carotid or axillary access are considered, detailed knowledge of the arch branching pattern and cerebrovascular anatomy becomes especially critical for safe procedural planning. Valve delivery systems that are more flexible or steerable may be more appropriate to be used in such an anatomy. The delivery system must navigate the atypical aortic curve, increasing procedural complexity and risk, especially if significant atherosclerosis of the aorta is present. While crossing the aortic arch, a more acute angle must be negotiated, increasing the risk of wire prolapse or difficulty in positioning the device. As shown in Fig. 1 and Video 1, 3D reconstruction of the aorta can help anticipate challenges and plan the access route. 3D reconstruction was used to identify the specific angulations needed to guide the device safely through the anomalous arch. This allowed us to plan fluoroscopic projections that allowed real-time monitoring of delivery system movement and minimization of arch interaction using wire tension. Such an approach is less feasible with non-steerable, self-expanding systems which rely on a stability layer/stabilizing sheath for deployment, and this consideration contributed to our choice of a steerable, balloon-expandable system in this case. Furthermore, the THV was delivered over an operator-shaped Amplatz Extra Stiff Wire in the LV. While stiffer wires such as Safari or Brecker are commonly used by many operators, our practice is to employ the Amplatz Extra-Stiff wire because it provides support while reducing wire bias and minimizing unfavorable contact forces in angulated anatomy. This approach facilitates delivery and may reduce the risks of complications such as dissection or stroke.

The tortuosity of the aortic arch in this patient with RAA-MIB presented significant challenges for safe device navigation. Based on 3D volume-rendered preprocedural CT, we elected to use a balloon-expandable transcatheter heart valve (SAPIEN 3 Ultra, Edwards Lifesciences) due to its deflectable delivery system, which offered enhanced steerability through the sharply curved right arch. Our selection of a steerable, balloon-expandable delivery system was based on patient-specific 3D CT findings rather than an assumption that right-sided arches are uniformly more angulated. In anatomies with sharp turns or atypical trajectories, a deflectable system enables finer control of catheter path and wire tension, potentially reducing contact forces. In contrast, self-expanding systems with a stability/stiffening layer provide limited steerability and may be less forgiving in tortuous arches. Although operator preference often favors deflectable balloon-expandable systems for their precise positioning, our choice in this case was driven by the 3D reconstruction indicating a challenging arch traversal. Our intent is not to prescribe exact fluoroscopic angles or maneuvers for this unique patient, but rather to highlight a reproducible thought process: careful review of 3D reconstruction to anticipate non-standard projections, deliberate choice of a steerable delivery system to minimize bias, and close monitoring of wire–device interactions throughout. These principles can be generalized to a wide range of anomalous anatomies where operators may face similar, though not identical, challenges.

Although transfemoral access was feasible and selected in this patient, detailed knowledge of the arch anatomy is especially important if alternative access routes must be considered. In this case, a left carotid approach would have been unfavorable, given the origin of the left common carotid from the left brachiocephalic artery at a right angle from the ascending aorta. A right carotid approach might have been technically feasible, albeit tortuous. The anomalous branching pattern also precluded safe use of cerebral embolic protection devices. These considerations emphasize the importance of thorough imaging and anatomical assessment when transfemoral access is not an option. Specific anatomic risks were also evaluated, including the possibility of a Kommerell’s diverticulum - which, while not present in this case, is an important consideration in right arch anomalies. The hypoplastic left vertebral artery would raise concerns about cerebrovascular vulnerability if a carotid approach was selected. CEPD could not be used in this case; nonetheless, anomalous aortic anatomy may increase stroke risk by altering hemodynamics and embolic trajectories. Variants such as RAA-MIB may also coexist with vascular abnormalities such as carotid or subclavian stenosis or kinking, which can further compromise cerebral perfusion [10–12]. Importantly, in this case, CEPD deployment with currently commercially available devices was not technically feasible due to the anomalous branching pattern - highlighting a practical limitation of embolic protection in such anatomies. With careful manipulation and real-time hemodynamic monitoring, the procedure was completed without complication or cerebrovascular events.

Although outcome studies have not identified arch anatomy as an independent predictor of stroke risk [10], these analyses did not consider rare variants such as RAA-MIB. In such anatomies, altered catheter trajectories and wire dynamics may increase embolic potential and lead to unpredictable embolic trajectories, emphasizing the need for careful imaging, delivery system selection, and procedural planning. A limitation of this report is that CT at one year cannot exclude subclinical embolization, which is common after both TAVR and surgical valve replacement. While CEPD are available, routine use is not supported by randomized data, and the anomalous arch branching in this case would have precluded safe deployment. At present, the Sentinel device is the only FDA-approved CEPD system, and no alternatives are available for this anatomy. Stroke-mitigation strategies therefore relied on pre-procedural imaging, selection of a steerable balloon-expandable system, careful wire manipulation, and meticulous de-airing. Due to unusual anatomy, valve malposition can occur, and meticulous attention should be paid to using appropriate fluoroscopic angles for valve delivery.

Conclusion

This case highlights the importance of individualized planning and multidisciplinary evaluation for patients with congenital aortic anomalies undergoing structural heart procedures. In this case, the multidisciplinary team—including interventional cardiology, cardiac surgery, cardiac imaging, and vascular surgery—collaborated to assess anatomical complexity and procedural risk. This approach supported a successful outcome and may serve as a model for similar cases involving anomalous aortic arch anatomy.

Abbreviations

TAVR

Transcatheter aortic valve replacement

RAA-MIB

Right aortic arch with mirror-image branching

THV

Transcatheter heart valve

CEPD

Cerebral embolic protection devices

Authors’ contributions

P.P., W.Q., and N.K. all participated in the drafting and editing of the manuscript.

Funding

There was no funding source for the study.

Data availability

Not applicable to the study.

Declarations

Ethics approval and consent to participate

Please see below.

Consent for publication

As the case report is fully anonymized with no PHI it is except by our UMass Chan IRB from being considered research and requiring specific patient consent. All our patients provide consent for their anonymized data to be used in research and educational purposes. Written informed consent was obtained for the participants based on our institutional guidelines.

Competing interests

The authors declare no competing interests.