Feasibility and Safety of Transradial Approach with 8-French Balloon Guide Catheter for Carotid Artery Stenting: Case Series

Abstract

Objective

The use of an 8-French (Fr) balloon guide catheter (BGC) for carotid artery stenting (CAS) using a transradial approach (TRA) has been limited by the small size of the radial artery (RA) and anatomical challenges, including difficulties with catheter navigation and concerns regarding device slippage. This study aimed to evaluate the technical feasibility and safety of TRA-CAS using an 8-Fr BGC.

Methods

We retrospectively reviewed consecutive patients who underwent TRA-CAS with an 8-Fr BGC (Emboguard [Cerenovus, Galway, Ireland], Flowgate2 [Stryker Neurovascular, Fremont, CA, USA], Optimo EPD FLEX [Tokai Medical Products, Aichi, Japan], or Branchor XS/XF [Asahi Intecc, Aichi, Japan]). Introduction of the BGC was performed with either a sheath-based or sheathless approach, selected at the discretion of the operator. Considering the outer diameter of the 8-Fr BGCs, the eligibility criteria included RA diameter ≥2.8 mm on vascular ultrasonography and a waveform other than type D by the BARBEAU test. Patient demographics and procedural and clinical outcomes at 90 days or later were evaluated.

Results

Twenty-one CAS procedures were attempted using an 8-Fr BGC via the TRA; 19 (90.5%) procedures were planned via the conventional RA and 2 (9.5%) via the distal RA. The lesion side was the right side in 14 patients (66.7%) and the left side in 7 (33.3%). Radial access success was achieved in 20 of 21 cases (95.2%); the remaining case required conversion to a transbrachial approach due to access site hematoma. Among the 20 cases with successful radial access, CAS was completed via the TRA/transdistal radial approach without conversion (technical success, 100%). BGC prolapse toward the aortic arch was observed in 6 cases. Balloon inflation was performed to stabilize the BGC in all cases. In 1 of these 6 cases, turnover of the BGC at the aortic valve was additionally required due to prolapse into the aortic arch. One case required device exchange due to BGC kinking. RA occlusion occurred in 1 case (4.8%), with no major complications.

Conclusion

CAS via TRA with an 8-Fr BGC appears feasible and safe in patients with RA diameter ≥2.8 mm, and the balloon properties may improve stability under conditions of challenging anatomy, making this a valuable option for carotid revascularization.

Introduction

In neurointerventional procedures, the transradial approach (TRA) has gained attention as a viable alternative to the conventional transfemoral approach (TFA), offering advantages such as fewer puncture site complications and a shorter hospital stay.¹⁾ In the context of carotid artery stenting (CAS), prevention of distal embolism represents a key concern. The use of balloon guide catheters (BGCs) has proven effective in this respect, particularly for patients with vulnerable plaque or severe stenosis.²⁾ Despite these benefits, the application of BGCs in the TRA for CAS remains uncommon. This is due to several limitations: 1) the small size of the radial arteries (RAs); 2) difficulties with catheter navigation due to anatomical structures; and 3) the risk of BGC prolapse into the aortic arch caused by insufficient stability during stent delivery.^3,4) This study aimed to evaluate the feasibility and safety of performing CAS through the TRA using an 8-Fr BGC.

Materials and Methods

Study design

We performed a retrospective cohort study of databases at 2 institutions in Japan where standard endovascular therapy was performed. Clinical data were obtained from consecutive patients with symptomatic or asymptomatic carotid stenosis in whom a right-side transradial or transdistal radial artery approach was used with BGCs between July 2022 and June 2024. Selection of the TRA was based on 3 preoperative criteria. The 1st criterion was the decision of the operator after evaluating preoperative CTA and/or MRA to assess the aortic arch type, the branching angle between the right subclavian artery and right common carotid artery (CCA) or between the brachiocephalic artery and left CCA, and vessel tortuosity, in addition to patient background such as relevant comorbidities. Branching angles were measured on preoperative CTA or MRA in the projection that best depicted both the access artery and the target CCA. The angle was defined as the smaller angle between the longitudinal axes of the proximal segment of the subclavian or brachiocephalic artery and the target CCA at their junction, according to previously reported measurement methods.⁴⁾ TRA was selected when these features suggested favorable catheter navigation. In line with previous TRA neurointerventional reports, vascular anatomy was regarded as anatomically challenging for TRA-CAS when preoperative CTA or MRA demonstrated an acute branching angle of approximately 30° or less between the access artery and the target CCA and/or marked tortuosity of the proximal CCA (defined as kinking with an angulation of <90°).^4–7) The 2nd criterion was maximum diameter ≥2.8 mm at the puncture site in either the RA or distal RA, as assessed by vascular ultrasonography performed the day before the procedure (Fig. 1). When both the RA and distal RA diameters were ≥2.8 mm, the distal RA was preferentially selected as the access site; otherwise, the conventional RA was used. This threshold for vessel diameter was determined based on the outer diameter (OD) of the BGC with the largest OD among those used in this study: 8-Fr Emboguard (OD, 2.8 mm; Cerenovus, Galway, Ireland), 8-Fr Flowgate2 (OD, 2.7 mm; Stryker Neurovascular, Fremont, CA, USA), 8-Fr Optimo EPD FLEX (OD, 2.78 mm; Tokai Medical Products, Aichi, Japan), or 8-Fr Branchor XS/XF (OD, 2.7 mm; Asahi Intecc, Aichi, Japan). The 3rd criterion was demonstration of a waveform other than type D in the BARBEAU test,⁸⁾ which was performed immediately before the CAS procedure to assess collateral hemodynamics based on the patency of the superficial palmar arch. In this test, a pulse oximeter was placed on the ipsilateral thumb to monitor the plethysmographic waveform, and the RA was manually compressed at 1–2 cm proximal to the planned puncture site; type D indicates no recovery of the waveform within 2 min after compression. If navigating the BGC proved difficult during the TRA procedure, another access site, including the femoral or brachial artery, was selected. All patients received dual antiplatelet therapy for 2 weeks before the procedure, consisting of aspirin (100 mg/day) and either clopidogrel (75 mg/day) or prasugrel (3.75 mg/day); prasugrel was preferentially used in patients with symptomatic carotid stenosis.

Fig. 1. Schematic illustration of the RA (A) at the wrist and the distal RA (B) in the anatomical snuffbox, showing puncture sites and ultrasonographic measurement sites for vessel diameter. Transverse ultrasound images of the RA and distal RA at the corresponding levels, with calipers indicating vessel diameters measured in 2 orthogonal directions, adoption of the larger diameter as the representative value. (Original figure created by the authors.).

RA, radial artery

Technique and endovascular procedure

The right forearm was immobilized using an Arm Rest for Radial Access Small (Siemens Healthineers, Bayern, Germany). The anterior–posterior plane was rotated 12° counterclockwise to facilitate visualization of the right forearm. To prevent vasospasm, heparinized saline (5000 IU/500 mL) mixed with nicardipine (2 mg) was perfused in the BGC in all cases. Following local anesthesia with 1–2 mL of lidocaine, the RA was punctured either 2–3 cm proximal to the wrist crease or in the distal RA from the anatomical snuffbox using a Mini Access KIT (21-gauge needle, 0.018 guidewire, and 4-Fr short sheath; Merit Medical Systems, South Jordan, UT, USA). After achieving arterial access, systemic heparinization (60 U/kg) was initiated, and activated clotting time was maintained between 250 and 350 s. At the discretion of the operator, either the sheathless or sheath-based method was employed to insert the BGC intravascularly.

For the sheath-based approach, the 4-Fr short sheath was exchanged for an 8-Fr peel-off sheath (Medikit, Tokyo, Japan), which was inserted coaxially over the guidewire to a depth of approximately 1 cm beyond the access site. After the inner dilator and guidewire were removed, backflow from the sheath was confirmed, and the peel-off sheath was placed in the RA (Fig. 2A). The BGC was then advanced through the peel-off sheath (Fig. 2B), after which the peel-off sheath was fully withdrawn and peeled away (Fig. 2C). For the sheathless approach, a 0.035-inch, 180-cm Radifocus guidewire (Terumo, Tokyo, Japan) was navigated into the brachial artery through the 4-Fr short sheath. The short sheath was then removed; the puncture site was dilated along the guidewire using a large-bore TMP Dilator (Tokai Medical Products) (Fig. 2D). Subsequently, the BGC mounted on the TMP Dilator I (OD, 6.3 Fr; length, 107.8 cm) was advanced over the guidewire under fluoroscopic guidance (Fig. 2E). If bleeding was observed at the puncture site before the BGC reached the target vessel, manual compression was applied in a manner that did not interfere with catheter manipulation. Once the BGC reached the target vessel, hemostasis at the puncture site was achieved using a half-inflated hemostatic device (TR Band; Terumo or Prelude SYNC Distal; Merit Medical Systems). Subsequent procedural steps were identical regardless of whether the sheathless or sheath-based approach was applied. After insertion of the BGC into the RA, further navigation of the BGC to the CCA on the lesion side was performed using a 6-Fr modified Simmons SY6 135-cm catheter (Gadelius Medical, Tokyo, Japan). Intraoperative radial artery spasm (RAS) was assessed clinically during catheter manipulation. Clinically significant RAS was defined as the occurrence of resistance or difficulty during advancement of the BGC that required additional manipulation, temporary cessation of advancement, or administration of vasodilators. No ultrasonographic or angiographic assessment of RA caliber or flow was performed; the evaluation was based solely on tactile feedback experienced by the operator during the procedure. CAS was performed using a standard technique with the assistance of a BGC and distal embolic protection devices. Following the procedures, the hemostatic device was inflated and managed according to the manufacturer’s instructions.

Fig. 2. Sheath-based approach: (A) Insertion of an 8-Fr peel-off sheath (advanced about 1 cm from the puncture site after exchange from a 4-Fr short sheath). (B) Advancement of the BGC through the sheath. (C) Peel-off of the sheath. Sheathless approach: (D) Dilation with the supplied dilator over a 0.035-inch, 180-cm Radifocus guidewire. (E) Introduction of the BGC with TMP Dilator I over the guidewire.

8-Fr peel-off sheath, Medikit, Tokyo, Japan; BGC, balloon guide catheter; Radifocus guidewire, Terumo, Tokyo, Japan; TMP Dilator I, Tokai Medical Products, Aichi, Japan

Outcome

Procedural success was assessed at 2 levels: access success and technical success. Access success was defined as the successful establishment of RA or distal RA access allowing device introduction. After successful access, technical success was defined as the completion of CAS via TRA or transdistal radial approach without the need to convert to a conventional transbrachial or transfemoral approach. Safety outcomes included radial artery occlusion (RAO), access-site hematoma requiring additional surgical treatment, and local ischemic complications. The occurrence of RAO in each case was evaluated in patients who underwent follow-up by palpation at 90 days or later after treatment.

Ethical considerations

The protocol was reviewed and approved by the Institutional Ethics Committees of Iwate Medical University (approval no. MH2024-101). The need to obtain informed consent was waived based on the retrospective nature of the investigation. Information regarding the study was publicly disclosed by the participating institutions, and patients were provided the opportunity to refuse the use of their clinical data (opt-out). This study was conducted in accordance with the Declaration of Helsinki and reported according to the PROCESS guideline.

Results

The patient selection process and the application of these inclusion and exclusion criteria for TRA-CAS with an 8-Fr BGC are summarized in Fig. 3. During the study period, 21 CAS procedures were attempted via a right-sided RA or distal RA using an 8-Fr BGC. All procedures were initially attempted through the right RA or distal RA; 19 procedures employed the conventional RA and 2 used the distal RA. All procedures were conducted under local anesthesia. All patients treated with TRA were male, with a median age of 75 years (range, 58–87 years). Median diameters of the accessed RA and distal RA were 3.0 mm (range, 2.8–4.3 mm) and 3.4 mm (range, 3.3–3.5 mm), respectively. Sheathless approaches were performed in 13 cases (61.9%), while peel-off sheaths were used in 8 cases (38.1%). The BGC was navigated into the right CCA in 14 cases (66.7%) and the left CCA in 7 cases (33.3%). The type of BGC used was Emboguard (Cerenovus) in 11 cases, Flowgate2 (Stryker Neurovascular) in 5, Branchor XS (Asahi Intecc) in 1, Branchor XF (Asahi Intecc) in 2, and Optimo EPD FLEX (Tokai Medical Products) in 2. Radial access success was achieved in 20 of the 21 cases (95.2%). In the remaining case, the approach was converted to a transbrachial approach because right RA access could not be established after unsuccessful puncture attempts, resulting in hematoma formation, which precluded further cannulation, and CAS was successfully completed. Among the 20 cases with successful radial access, CAS was completed via the TRA/transdistal RA approach without conversion (technical success, 100%). Among the 21 cases, 8 (38.1%) were classified as anatomically challenging. In 4 of these cases (19.0%; 2 left-sided and 2 right-sided), the branching angle between the access artery and target vessel was <30°. In the remaining 4 anatomically challenging cases (3 left-sided and 1 right-sided), a branching angle <30° was accompanied by marked tortuosity at the origin of the CCA. In 6 cases (28.6%; 4 left-sided and 2 right-sided), BGC prolapse toward the aortic arch was observed during navigation of the BGC into the target vessel or stent delivery, all of which were included in the anatomically challenging group. Of these, 5 procedures (3 left-sided, 2 right-sided) were successfully completed by anchoring the BGC with balloon inflation (Fig. 4), and in 1 left-sided CAS case, the BGC was turned over at the aortic valve to achieve sufficient support, resulting in completion of the procedure via TRA (Fig. 5). In 1 left-sided case using the Optimo catheter, kinking of the BGC occurred during stent advancement within the catheter in the setting of severe brachiocephalic artery–left CCA angulation, necessitating a switch to the Flowgate catheter. Balloon rupture occurred in 1 case. No instances of RAS were observed during the procedures. No postoperative complications, such as hematoma, pseudoaneurysm, or ischemic changes that required surgical intervention, were observed at the puncture site. The RA patency rate at 90 days post-procedure was 95.2% (20 cases), with RAO confirmed in 1 case. This RAO case involved a left-sided cervical internal carotid artery (ICA) stenosis with an extremely steep brachiocephalic artery–left CCA branching angle (6°) and marked tortuosity at the origin of the left CCA. The patient reported persistent arm pain beginning on postoperative day 2. However, no ischemic complications of the hand were noted. Clinical data and procedural outcomes are summarized in Table 1.

Fig. 3. Flowchart of patient selection and access route. Participants comprised consecutive patients with symptomatic or asymptomatic cervical ICA stenosis treated with CAS during the study period. Cases allocated to the transfemoral approach were excluded and the remaining cases were allocated to transradial or transdistal radial artery approaches according to RA or distal RA diameter.

BGC, balloon guide catheter; CAS, carotid artery stenting; ICA, internal carotid artery; RA, radial artery; TFA, transfemoral approach; TRA, transradial approach

Fig. 4. Representative case of right transradial CAS with a steep branching angle between the access artery and target vessel. (A) CTA of the right subclavian artery and right CCA demonstrating a branching angle of 15.4°. (B) Lateral angiographic view showing stenosis of the right ICA. (C) Anteroposterior X-ray view during balloon dilatation after stent placement, 8-Fr BGC (white arrow) inflated in the right CCA for catheter stabilization. (D) Post-procedural lateral angiographic view revealing good revascularization.

BGC, balloon guide catheter; CAS, carotid artery stenting; CCA, common carotid artery; ICA, internal carotid artery

Fig. 5. Representative case of transradial CAS with a steep branching angle between the brachiocephalic artery and left CCA. (A) CTA of the brachiocephalic artery and left CCA revealing a branching angle of 16.2° and marked tortuosity at the origin of the left CCA (kinking with an angulation of <90°). (B) Preprocedural lateral angiographic view showing stenosis of the left ICA. (C) Anteroposterior X-ray view after advancement of the BGC into the left CCA, turn-over maneuver of the BGC at the aortic valve (black arrow), and balloon inflation (white arrow) at the CCA origin for catheter stabilization. (D) Post-procedural lateral angiographic view showing good revascularization.

BGC, balloon guide catheter; CAS, carotid artery stenting; CCA, common carotid artery; ICA, internal carotid artery

Table 1. Patient demographics and characteristics.

Median age, years (range)	75 (58–87)
Male sex (%)	21 (100)
Median diameter of accessed artery, mm (range)
Distal RA	3.4 (3.3–3.5)
Conventional RA	3.0 (2.8–4.3)
Access site (%)
Distal RA	2 (9.5)
Conventional RA	19 (90.5)
Insertion method (%)
Peel-off sheath	8 (38.1)
Sheathless	13 (61.9)
BGC used (%)
Emboguard	11 (52.4)
Flowgate2	5 (23.8)
Branchor XS/XF	3 (14.3)
Optimo EPD FLEX	2 (9.5)
Target vessel (%)
Right CCA	14 (66.7)
Left CCA	7 (33.3)
Anatomical challenging cases (%)
Access artery–CCA branching angle <30°	4 (19.0)
Branching angle <30° and CCA tortuosity	4 (19.0)
Procedural success (%)
Access success	20 (95.2)
Technical success	20/20 (100)
Local complications (%)	1 (4.8)
RA spasm during procedures (%)	0 (0)
RA patency beyond 90 days after procedure (%)	20 (95.2)

BGC, balloon guide catheter; Branchor XS/XF, Asahi Intecc, Aichi, Japan; CCA, common carotid artery; Emboguard, Cerenovus, Galway, Ireland; Flowgate2, Stryker Neurovascular, Fremont, CA, USA; Optimo EPD FLEX, Tokai Medical Products, Aichi, Japan; RA, radial artery

Discussion

This study demonstrated the feasibility and safety of using an 8-Fr BGC in CAS using the TRA. Traditionally, CAS via TRA has been limited to selected cases due to constraints related to BGC size, RA diameter, and technical difficulties. However, in the present study, preprocedural assessments of RA diameter and the adoption of technical refinements during the procedure allowed favorable outcomes to be achieved in the majority of cases.

As highlighted in this study, a critical factor in endovascular treatment with an 8-Fr BGC via TRA is ensuring that the RA diameter is sufficient in relation to the OD of the device. In general, the mean RA diameter has been reported as approximately 3.10 ± 0.60 mm in men and 2.8 ± 0.60 mm in women.⁹⁾ Considering the OD of the 8-Fr BGC, patients with a small RA (particularly in women) are often technically challenging. In fact, in this study, all female patients for whom the TRA-CAS was anatomically feasible showed a RA diameter <2.8 mm and were therefore not considered as candidates for TRA. The greatest concern when using an 8-Fr BGC via TRA is the potential risk of procedural failure due to RAS and RAO. Previous studies have demonstrated that the risk of RAS increases with smaller RA diameters and that RAS is closely associated with procedural failure, often necessitating conversion from TRA to TFA.^10–12) Accordingly, preprocedural measurement of the RA diameter is crucial. In this study, by selecting cases with RA diameter ≥2.8 mm relative to the OD of the BGC, mechanical stress on the vascular endothelium could be minimized. Further, to minimize the ratio of the sheath or BGC OD to the RA diameter, we employed 2 strategies: a sheath-based approach, in which only the distal 1 cm of the peel-off sheath was inserted, and a sheathless approach, in which the TMP Dilator (Tokai Medical Products) was connected directly to the 8-Fr BGC to eliminate the ledge effect and advanced into the artery without a sheath. These techniques contributed to minimizing vessel endothelial injury and preventing RAS. In many transradial neuroendovascular and carotid interventions, intra-arterial vasodilator “cocktails” (e.g., verapamil with nitroglycerin, with or without heparin) are administered via the sheath to mitigate RAS. However, in the present study, because we selected patients with an adequate RA diameter at the puncture site and adopted the 2 strategies described above to minimize endothelial stress during catheter introduction, we did not routinely administer additional spasm prophylaxis; accordingly, no intraoperative RAS (as defined in this study) was observed.

Martínez-Galdámez et al. highlighted RAO as another major concern when using 8-Fr BGC in TRA, further emphasizing the importance of careful preprocedural vascular assessment to minimize these complications.¹³⁾ Regarding RAO, prior studies have shown that smaller RA diameters are associated with a higher risk of RAO, with reported rates of 3.1%–28%.^3,14) Despite our preprocedural selection for adequate RA size and the sheath strategies described above, RAO was observed in 1 of 21 patients (4.8%) at follow-up beyond 90 days. In this case, no intraoperative RAS, overt arterial injury, or postprocedural hand ischemia was noted; however, persistent arm pain began on postoperative day 2. In a large multicenter dataset of 1706 transradial catheterizations, RAO was independently associated with moderate-to-severe postprocedural arm pain (odds ratio = 3.35), and the authors suggested that pain accompanying RAO is less likely to be attributable to hand ischemia and may instead reflect arteritis related to thrombus formation following subtle arterial injury during transradial access and/or subsequent hemostasis.¹⁵⁾ In our RAO case, the vascular anatomy was anatomically challenging (6° branching angle with marked proximal CCA tortuosity), and the procedure required prolonged catheter navigation and repeated push–pull manipulations. These factors may have increased the cumulative mechanical burden on the RA wall, resulting in subclinical endothelial micro-injury and subsequent thrombus-related inflammation, which could have contributed to delayed RAO. Therefore, in addition to appropriate device-to-artery sizing and sheath strategies aimed at minimizing mechanical stress on the RA wall, it may be important—particularly in anatomically challenging cases—to plan the procedure so as to avoid unnecessary catheter manipulations and to complete catheter navigation as efficiently as possible. Furthermore, when arm pain persists after the procedure, early assessment of RA patency may be considered with delayed RAO in mind.

Although numerous reports have described neuroendovascular treatment via TRA, a certain proportion of cases required conversion to TFA due to anatomical constraints. Indeed, the reported rate of crossover from TRA to TFA ranges from 4.2% to 9.4%, with anatomical factors accounting for 73%–89% of these cases.^6,11,16) In particular, procedures requiring catheter navigation into the left CCA or ICA are more likely to be challenging. Kim et al. reported that the procedural success rate was significantly lower for left-sided lesions than for right-sided lesions when using TRA, suggesting that this may be attributable to difficulties in guiding and stabilizing the guide catheter.¹⁷⁾ Similarly, Chen et al. described 49 cases of flow diverter stent deployment via TRA, in which treatment was abandoned in 10 cases (20.4%). Eight (16.3%) of those cases were due to acute angulation at the origin of the left CCA or tortuosity of the CCA or ICA.⁷⁾ More recently, Arakawa et al. quantitatively demonstrated that a branching angle of <30° between the subclavian artery and CCA was associated with difficult navigation of a BGC in right-sided TRA-CAS.⁴⁾ Taken together, these reports suggest that sharp branching angles and proximal carotid tortuosity are major anatomical determinants of catheter instability and failure of TRA, particularly when navigating to the left CCA or ICA. In our study, anatomically challenging cases (defined as an access–CCA branching angle <30° and/or kinking at the origin of the CCA with an angulation of <90°) were observed in 8 of 21 cases (38.1%). Catheter instability during navigation or stent delivery was noted in 6 of these 8 cases (75.0%), including 4 left-sided and 2 right-sided lesions; this is consistent with previous reports indicating that left-sided lesions are more likely to be technically demanding in TRA because of unfavorable branching geometry. In 1 left-sided case with severe brachiocephalic–left CCA angulation, catheter kinking occurred during stent advancement, requiring exchange of the BGC. This kinking may be explained by the combination of an extremely acute brachiocephalic–left CCA branching angle creating a short-radius bend at the CCA origin and increased compressive load during stent advancement through the large-bore BGC, leading to catheter kinking. The Optimo EPD FLEX (Tokai Medical Products) is designed with a relatively flexible, multi-segment shaft to enhance trackability, which may be disadvantageous under severe angulation, whereas Flowgate2 (Stryker Neurovascular) incorporates a multi-section shaft with a stainless-steel double-braid structure to improve stability and pushability. Taken together, a steep branching angle between the access artery and the CCA, along with marked proximal CCA tortuosity, may increase the risk of BGC kinking, underscoring the importance of appropriate device selection. More commonly, however, the technical challenge in anatomically difficult cases was catheter instability with a tendency toward BGC prolapse or imminent herniation into the aortic arch during advancement to the target CCA or during stent delivery. In our study, this instability was effectively managed with balloon-assisted maneuvers. Five of the 6 difficult-navigation cases were successfully managed by inflating the BGC balloon within the CCA to anchor the catheter or by partially inflating the balloon to approximately half the vessel diameter and allowing distal advancement with the blood flow, thereby preventing herniation of the catheter into the aortic arch. In the remaining left-sided case with marked tortuosity of the proximal CCA, advancement of the BGC into the distal CCA was not feasible. Instead, catheter stability was achieved by turning the BGC over at the aortic valve in combination with balloon anchoring. These findings indicate that, even in anatomically unfavorable configurations that have traditionally been regarded as unsuitable for TRA, adequate catheter stability can be obtained by appropriately exploiting the balloon and length characteristics of the BGC, allowing safe completion of CAS via TRA without conversion to TFA.

This study has several limitations. First, the investigation was conducted as a retrospective analysis at 2 centers over a short period, with a relatively small sample size. The external validity of the findings is therefore limited, and caution is warranted when interpreting or generalizing the results. Second, the decision to perform TRA was left to the discretion of each operator, which may have introduced selection bias. Third, intraoperative RAS was assessed only by tactile feedback, defined as resistance during catheter advancement, without objective confirmation. The presence or severity of RAS, therefore, may not have been fully characterized. Fourth, RA patency at follow-up was evaluated only by palpation of the radial pulse, a method known to underestimate the true incidence of RAO compared with duplex ultrasonography.¹⁸⁾ Accordingly, the actual rate of RAO in this cohort may have been underestimated.

Further prospective, multicenter studies with larger cohorts and standardized assessment methods are warranted to validate these findings.

Conclusion

In patients with RA diameter ≥2.8 mm, CAS via the TRA using an 8-Fr BGC can be performed safely without serious access site complications. Further, even in cases where catheter manipulation may prove challenging due to anatomical factors, the use of a BGC may contribute to procedural stability and improve the feasibility of the intervention.

Disclosure Statement

The authors declare that they have no conflicts of interest.