Mechanical Thrombectomy for Acute Medium Vessel Occlusion Because of Paradoxical Cerebral Embolism in a Patient with a Right Aortic Arch: A Case Report

Abstract

Objective: Right aortic arch is a rare congenital anomaly. We report a case of mechanical thrombectomy for acute left medium-vessel occlusion due to a paradoxical embolism in a patient with a right aortic arch.

Case Presentation: An 81-year-old woman presented with severe right-sided hemiparesis and aphasia. The National Institutes of Health Stroke Scale score was 16, MRI demonstrated a diffusion-weighted imaging Alberta Stroke Program Early CT score of 7, and MRA revealed left M2 occlusion. CTA revealed a right aortic arch with mirror image branching. Mechanical thrombectomy was conducted using the usual system, and effective recanalization was achieved with a stent retriever and aspiration catheter after 3 passes. CTA revealed pulmonary embolism and deep vein thrombosis (DVT) in the right deep femoral vein, and transesophageal echocardiography demonstrated a patent foramen ovale. Electrocardiography did not reveal atrial fibrillation, and other examinations did not reveal any other cause; therefore, a paradoxical cerebral embolism was diagnosed. After anticoagulant therapy, no recurrence of infarction, pulmonary embolism, or DVT was observed. Severe right hemiparesis and total aphasia did not improve, and the patient was discharged on day 37 after admission with a modified Rankin Scale score of 5.

Conclusion: Access to the left common carotid artery in right aortic arch cases can be anatomically challenging. Preoperative imaging evaluation of the access route is crucial for quick and safe mechanical thrombectomy.

Introduction

The right aortic arch (RAA) is a rare vascular anomaly with an incidence of approximately 0.04%–0.1% in radiology and autopsy series.¹⁾ RAA is linked to abnormal aortic arch development and its branches in fetal life.²⁾ Several studies have reported on RAA; however, few have reported endovascular treatment (EVT) for craniocervical lesions with RAA, particularly in mechanical thrombectomy (MT) for cerebral vessel occlusion. Herein, we report a case of MT for an acute paradoxical cerebral embolism in a patient with an RAA.

Case Presentation

The patient was an 81-year-old woman with a medical history of hypertension and hyperlipidemia. The patient was brought to our hospital with severe right hemiparesis and total aphasia, and the National Institutes of Health Stroke Scale (NIHSS) score at admission was 16. The last known well (LKW) to door time was 12 hours. At our facility, we follow a time-based imaging protocol for acute stroke cases: cases within 4.5 hours from onset undergo CTA first, while cases beyond 4.5 hours are evaluated with MRI first. MRI demonstrated cerebral infarction in the left middle cerebral artery area, and the diffusion-weighted imaging Alberta Stroke Program Early CT Score (DWI ASPECTS) was 7. MRA revealed left M2 segment occlusion. However, findings from the chest X-ray indicated a possible anomaly in the aortic arch, leading us to perform additional CTA to assess the access route for thrombectomy. CTA revealed RAA with mirror-image branching (Fig. 1). The patient did not receive an intravenous recombinant tissue plasminogen activator. Although there is limited evidence supporting MT in such scenarios, we carefully evaluated the patient’s condition based on several factors: the pre-stroke modified Rankin Scale (mRS) was 0, the DWI ASPECTS was 7, and the presentation was a wake-up stroke with a DWI-FLAIR mismatch, suggesting that the actual time from onset might not be as prolonged as indicated by LKW. Additionally, the patient exhibited severe symptoms with an NIHSS score of 16. Based on these factors, we judged that MT was appropriate, as it provided a chance to improve the patient’s outcome.

Fig. 1 MRI and CTA at onset. (A and B) Infarction at the left insular cortex, corona radiata, and M3 and M5 areas in the Alberta Stroke Program Early CT Score. (C) Right aortic arch with mirror image branching and left M2 occlusion. (D) Left first arch defect (dotted circle) and right upper mediastinal anomalous shadow (arrow).

We chose the usual guidance system. A 9-Fr sheath was inserted into the right common femoral artery. A guidewire (Radifocus; Terumo, Tokyo, Japan) and 6-Fr JB2 catheter (Medikit, Tokyo, Japan) were advanced using a 9-Fr OPTIMO balloon guide catheter (Tokai Medical Products, Aichi, Japan).

The guide catheter was advanced from the abdominal aorta in the middle of the spine to the thoracic aorta on the right side of the spine and was easily placed in the left internal carotid artery in the usual way with reference to the CTA (Fig. 2). Left internal carotid angiography revealed a left M2 inferior trunk occlusion. Thrombolysis in the cerebral infarction 2B reperfusion was achieved using Trevo NXT 3 × 32 mm (Stryker, Fremont, CA, USA) and Catalyst 6 (Stryker) after 3 passes (Fig. 3). The time from puncture to recanalization was 61 min (10 min, from puncture to placement of the guide catheter in the left internal carotid artery; 51 min, from placement of the guide catheter to recanalization). Post-procedural CT revealed a small subarachnoid hemorrhage.

Fig. 2 The guide catheter was advanced into the left internal carotid artery. (A) From the abdominal aorta in the middle of the spine to the thoracic aorta on the right side of the spine. (B) Left innominate angiography. (C) A guide catheter was placed in the left internal carotid artery in the usual fashion.

Fig. 3 Left internal carotid angiography. (A) Proximal of the M2 inferior trunk was occluded. (B) Thrombolysis in the cerebral infarction 2B reperfusion was achieved.

Atrial fibrillation was not detected, and whole-body contrast-enhanced CT was performed to further search for the embolic source. Deep vein thrombosis (DVT) and pulmonary embolism (PE) were observed in the right deep femoral vein and both pulmonary arteries, respectively (Fig. 4). Transesophageal echocardiography demonstrated patent foramen ovale (PFO). Despite antinuclear antibodies and coagulability being examined using blood tests, these were not the causes of the cerebral infarction. The pathogenesis of the cerebral infarction was determined as a paradoxical embolism, and apixaban was administered after DVT and PE were revealed. The thrombus in the femoral vein and pulmonary artery almost disappeared, and cerebral infarction did not recur. Right hemiparesis and aphasia persisted, and at discharge, the mRS score was 5.

Fig. 4 Whole-body contrast-enhanced CT. (A) Deep vein thrombosis in the right deep femoral vein. (B and C) Pulmonary embolism in the bilateral pulmonary artery.

Discussion

This is the first reported case of MT for middle vessel occlusion in a patient with RAA and summarizes previously published case reports on the approach and devices used. Additionally, this case is unique, as the pathogenesis was a paradoxical embolism, a rare but significant mechanism in stroke etiology.

RAA results from the persistence of the right fourth aortic arch and the involution of the left between the fourth and fifth weeks of embryonic life.²⁾ Knight and Edwards categorized the relationship between the RAA and the esophagus.³⁾ In one form, the RAA occupies the retroesophageal position. Contrastingly, the RAA maintains the right esophagus without a retroesophageal segment (96%).³⁾ Furthermore, RAA was classified into 3 major groups based on the branching pattern of the arch without a retroesophageal segment: (A) mirror image branching, (B) aberrant left subclavian artery, and (C) isolation of the left subclavian artery.^3,4) Type B is the most common, and type A is next in the RAA. Types A and C are more likely to coexist with congenital heart disease than type B.⁵⁾ Kommerell’s diverticulum at the origin of an aberrant left subclavian artery is related to a substantial risk of rupture and dissection.⁶⁾

We have summarized the RAA types and therapeutic strategies for EVT in 9 previous reports (Table 1). Two and 7 type A and type B, respectively, were found. All patients who required alterations in approach, technique, and devices were type B because of the low left common carotid artery (CCA) bifurcation (Table 1^7–15)). Since the cases reviewed were mainly left-sided lesions, there are limitations in generalizing conclusions regarding the difficulty of type B RAA. In RAA cases, access to the left CCA, which is the furthest from the femoral artery, may be more anatomically difficult than access to the right CCA. Additionally, arterial stiffness and individual differences influence the degree of access difficulty, highlighting the need for further case series. Regardless of which type of RAA is present, access to the left common carotid artery can be difficult; therefore, preoperative CTA is important to evaluate the access route in MT, which requires a rapid procedure. Additionally, in the case of RAA, lack of preoperative imaging evaluation may cause considerable delays in treating the main trunk occlusion, particularly in the posterior circulation, since the origin of the vertebral artery may change depending on the RAA type. Therefore, preoperative evaluation of the aortic arch is crucial. CTA was useful for revealing the type of aortic arch and assessing the access route before the MT procedure. In this case of type A RAA, this allowed rapid recanalization with transfemoral access to be achieved using conventional techniques. However, further case accumulation is needed to generalize that type A RAA is anatomically more advantageous for transfemoral access. Although PFO is the most common defect linked to paradoxical cerebral embolism,¹⁶⁾ no studies mentioning the frequency of co-occurrence of PFO and RAA were observed. Dubiel et al. reported that 69% of 180 patients with a paradoxical embolism exhibited a PFO, 13% demonstrated a PFO-like septal defect, and 17% showed an atrial septal defect.¹⁷⁾ In 195 patients, tetralogy of Fallot was the most common cardiovascular anomaly, and atrial and/or ventricular septal defects were observed in 8 patients (4.1%).⁴⁾ RAA is often associated with congenital heart anomalies like tetralogy of Fallot, which could imply a higher prevalence of PFO in RAA patients. The most common target area was the cerebrum, and the rate of paradoxical cerebral embolism was 37%–58.3% in the paradoxical embolism.^16–18) While we could not identify any literature directly linking PFO and RAA, we noted that RAA is often associated with congenital heart diseases. Considering the high prevalence of PFO in congenital heart anomalies, it is plausible that there may be an association between RAA and PFO. Further case studies are warranted to explore this potential relationship. In our case, the patient demonstrated a type A RAA, and an embolic source search identified DVT and PFO, resulting in a paradoxical embolism diagnosis. After the first paradoxical embolic event, the risk of recurrence is 3.4%–3.8%.¹⁷⁾ Fortunately, no recurrence of cerebral or other emboli has been noticed after initiating direct oral anticoagulation.

Table 1 Summary of the therapeutic strategies for endovascular treatment in patients with right aortic arch

Author (year)	Age (years), sex	Side	Lesion	Treatment	RAA type	Approach	Guiding catheter or sheath	Coaxial catheter	Supplement
Sakamoto et al. (2011)7)	72, M	Left	ICA stenosis	CAS	B	Right transfemoral	9 Fr OPTIMO	Not listed	N/A
Ichinose et al. (2013)8)	60, M	Left	Ruptured MCA aneurysm	Coil embolization	B	Right transfemoral	6 Fr Envoy	5 Fr JB2	N/A
Shitara et al. (2016)9)	68, M	Left	TS dAVF	Coil embolization (TAE)	B	Right transfemoral (failed)	6 Fr Envoy	4 Fr OK2M, Simmons	Only partial occlusion of OA with coils, Direct sinus packing on another day
Ohtani et al. (2016)10)	69, M	Left	ICA pseudo-occlusion	CAS	B	Right transbrachial (transfemoral approach was failed)	6 Fr Axcelguide	6 Fr SY-2	Exchange for the guidewire half-stiff type
Das et al. (2017)11)	Middle age, F	Left	Convexity meningioma	Embolization with PVA	B	Right transfemoral	N/A	Mani (SIM1,2 was failed)	N/A
Kato et al. (2019)12)	80, M	Left	ICA stenosis	CAS	B	Right transbrachial	6 Fr FUBUKI Dilator Kit	6 Fr SY-2	Exchange for the guidewire stiff type, percutaneous manual compression
Furukawa et al. (2021)13)	92, F	Right	Ruptured IC-PC aneurysm	Coil embolization	B	Right transfemoral	6 Fr Flexor Shuttle	4 Fr sidewinder2	Use Cerulean DD6 as an intermediate catheter
Yoshie et al. (2021)14)	70, M	Left	M1 occlusion	MT	A	Right transfemoral	9 Fr Branchor	6 Fr JB2	N/A
Shiraishi et al. (2023)15)	66, M	Right	ICA pseudo-occlusion	PTA, staged CAS	A	Right transfemoral	9 Fr OPTIMO	6 Fr Simmons type	Select the guidewire stiff type
Our case	81, F	Left	M2 occlusion	MT	A	Right transfemoral	9 Fr OPTIMO	6 Fr JB2	N/A

Axcel guide, Medikit, Tokyo, Japan; Branchor, ASAHI INTECC, Aichi, Japan; CAS, carotid artery stenting; dAVF, dural arteriovenous fistula; Envoy, Codman & Shurtleff, Johnson & Johnson, Raynham, MA, USA; F, female; Flexor, Cook Medical, Bloomington, IN, USA; FUBUKI, ASAHI INTECC; IC-PC, internal carotid–posterior communicating artery; ICA, internal carotid artery; JB2, Medikit, Tokyo, Japan; M, male; MCA, middle cerebral artery; MT, mechanical thrombectomy; N/A, not applicable; OA, occipital artery; OK2M, CATHEX, Osaka, Japan; OPTIMO, Tokai Medical Products, Aichi, Japan; PTA, percutaneous transluminal angioplasty; PVA, polyvinyl alcohol; RAA, right aortic arch; sidewinder2, Medikit; Simmons, Medikit; SY-2, Medikit; TAE, transarterial embolization; TS, transverse-sigmoid sinus; Mani, SIM1,2, detailed product information is not available.

Conclusion

In cases of RAA, access to the left CCA may be anatomically challenging, making preoperative assessment of the access route by CTA critical for performing a quick and safe MT.

Acknowledgments

We would like to thank Editage (www.editage.jp) for English language editing.

Disclosure Statement

The authors declare that they have no conflicts of interest.

References

• 1)  Hastreiter AR, D’Cruz IA, Cantez T, et al. Right-sided aorta. I. Occurrence of right aortic arch in various types of congenital heart disease. II. Right aortic arch, right descending aorta, and associated anomalies. Heart 1966; 28: 722–739.
• 2)  Cinà CS, Arena GO, Bruin G, et al. Kommerell’s diverticulum and aneurysmal right-sided aortic arch: a case report and review of the literature. J Vasc Surg 2000; 32: 1208–1214.
• 3)  Knight L, Edwards JE. Right aortic arch. Types and associated cardiac anomalies. Circulation 1974; 50: 1047–1051.
• 4)  Stewart JR, Kincaid OW, Titus JL. Right aortic arch: plain film diagnosis and significance. AJR Am J Roentgenol 1966; 97: 377–389.
• 5)  Türkvatan A, Büyükbayraktar FG, Olçer T, et al. Congenital anomalies of the aortic arch: evaluation with the use of multidetector computed tomography. Korean J Radiol 2009; 10: 176–184.
• 6)  Kim KM, Cambria RP, Isselbacher EM, et al. Contemporary surgical approaches and outcomes in adults with Kommerell diverticulum. Ann Thorac Surg 2014; 98: 1347–1354.
• 7)  Sakamoto S, Shibukawa M, Tani I, et al. Carotid artery stenting in a patient with right-sided aortic arch with an aberrant left subclavian artery. Acta Neurochir (Wien) 2011; 153: 2169–2173.
• 8)  Ichinose N, Kiura Y, Sakamoto S, et al. A case of ruptured cerebral aneurysm with a right-sided aortic arch treated by coil embolization. J Neuroendovasc Ther 2013; 7: 317–322. (in Japanese)
• 9)  Shitara S, Nakazawa T, Nozaki K. A right-sided aortic arch with an aberrant left subclavian artery in a patient with a transverse-sigmoid sinus dural arteriovenous fistula. J Neuroendovasc Ther 2016; 10: 98–99.
• 10)  Ohtani T, Yamazaki T, Ohtaki H, et al. Carotid artery stenting in right-sided aortic arch: a case report. NMC Case Rep J 2016; 3: 9–12.
• 11)  Das D, Kanjilal R, Bhattacharya S. Successful embolisation of an intracranial meningioma via a right-sided aortic arch. BMJ Case Rep 2017; 2017: bcr–2017–222115.
• 12)  Kato T, Aki T, Imai N, et al. Carotid artery stenting via the right brachial artery with right aortic arch. No Kekkannai Chiryo 2019; 4: 77–82. (in Japanese)
• 13)  Furukawa Y, Kikuta H, Iijima A, et al. A case of coil embolization for the ruptured aneurysm with right-sided aortic aorta. Nosotchu 2021; 43: 137–141. (in Japanese)
• 14)  Yoshie T, Suzuki Y, Tatsuno K, et al. Successful endovascular thrombectomy for acute M1 occlusion in a patient with situs inversus: a case report. NMC Case Rep J 2021; 8: 355–358.
• 15)  Shiraishi Y, Kimura H, Chatani M, et al. Case of carotid artery stenting with right aortic arch. Nosotchu No Geka 2023; 51: 28–33. (in Japanese)
• 16)  Zhang H-L, Liu Z-H, Luo Q, et al. Paradoxical embolism: experiences from a single center. Chronic Dis Transl Med 2017; 3: 123–128.
• 17)  Dubiel M, Bruch L, Liebner M, et al. Exclusion of patients with arteriosclerosis reduces long-term recurrence rate of presumed arterial embolism after PFO closure. J Interv Cardiol 2007; 20: 275–281.
• 18)  d’audiffret A, Pillai L, Dryjski M. Paradoxical emboli: the relationship between patent foramen ovale, deep vein thrombosis and ischaemic stroke. Eur J Vasc Endovasc Surg 1999; 17: 468–471.