Initial clinical experience with the Bendit steerable articulating tip microcatheter for intracranial access and intervention

Abstract

Background

The increasing complexity and sophistication of neurovascular implants and other therapeutic devices depend on access and delivery systems. Advancements in access technologies are required to improve minimally invasive endovascular procedures. Steerable catheters have been available in other disciplines, however, their implementation in neurovascular interventions has been a barrier previously due to issues with miniaturization and vascular caliber/complexity.

Methods

A retrospective review of the neurovascular stroke database was conducted in accordance with local IRB to identify patients that received neurointerventional endovascular procedures using a novel first iteration 0.021'' microcatheter with controlled articulating tip flexion. Indications, management, demographics, comorbidities, and clinical and technical outcomes were recorded and analyzed. Primary operator feedback on the novel catheter was collected and reviewed.

Results

Ten consecutive patients receiving treatment that involved a novel steerable 0.021'' microcatheter were identified and analyzed. No complications were reported. Novel useful features of the catheter were reported on a case-by-case basis.

Conclusions

Initial clinical experience with the controlled articulation that permits flexion at the tip of the microcatheter demonstrated it to be safe. Access to difficult proximal origin curves, and distal clinoidal/ophthalmic segment anatomy may be improved due to the high torque transmission, and acute angulation of this microcatheter. Further experience with the delivery of therapeutic devices will be necessary to better understand the potential role that the present catheter may play in modern neurointerventional procedures.

Background

Both access platforms and delivery devices are crucial components of neurointerventions. ¹ The current generation of flow divertors and intra-saccular devices would likely be less successful if not for robust intermediate catheters that were developed concomitantly with the blossoming of acute stroke interventions. Intermediate catheters allow for aspiration in conjunction with stent retrievers, ² but also provide support and stability for the delivery of increasingly complex endovascular vessel reconstruction devices. ³

Steerable catheters do exist in other specialties, notably in cardiac electrophysiology where such catheters are essential for cardiac circuit mapping and ablation. ⁴ An earlier steerable catheter called Enzo ⁵ was introduced in early 2000s for neurovasculature size profiles but was however discontinued.

With continued miniaturization and development of hypotube and tendon technologies, steerable and torqueable microcatheters are now coming to market. This retrospective review of the first 10 clinical cases at a single high-volume comprehensive stroke center outline observations about the novel Bendit 21 microcatheter (Bendit Technologies, Ltd, Petach Tikva, Israel) which received Food and Drug Administration (FDA) clearance in 2019.^6,7

Methods

Retrospective analysis of all neurovascular interventions at a single center in accordance with the local IRB protocols was performed, with identification of ten such cases which used the Bendit 21 microcatheter. Cases in which the Bendit 21 microcatheter was not used were excluded. Relevant demographics and case information including complications were recorded. Catheter use characteristics were analyzed by three mid-career neurointerventionalists, hailing from radiology, neurosurgery, and neurology backgrounds.

Results

Case summaries were collected and summarized in Table 1. There were three aneurysm embolizations (30%), one middle meningeal artery embolization (10%), five acute stroke thrombectomies (40%), one intracranial atherosclerotic angioplasty with stent deployment (10%), and one venous diagnostic procedure (10%).

Table 1.

Bendit 21 steerable articulating tip microcatheter clinical experience.

Patient	Indication	Comorbidities	Treatment	Bendit 21 role
1. 60 s F	Cerebral aneurysm, left MCA bifurcation 6.6 × 5.9 mm	Renal transplant with lupus	WEB SL 5 × 3 mm	Catheterizing the L M1 and delivering the WEB into the aneurysm
2. 60 s F	Cerebral aneurysm, right ICA terminus 4.1 × 4.0 mm	Hypertension, hyperlipidemia, diabetes	Coil embolization	Catheterizing from the aortic arch to the R ICA supraclinoidal segment
3. 60 s F	Acute stroke, right M1 occlusion	DM, HTN, hyperlipidemia	Aspiration, stentriever	Catheterizing from the aortic arch to the R ICA supraclinoidal segment past the ophthalmic artery
4. 80 s F	Acute stroke, left M2 occlusion	AFIB, HTN, hyperlipidemia	Aspiration, stentriever	Catheterization from aortic arch to L communicating segment
5. 55 s M	Venous manometry for cerebral venous congestion	Vertigo, headaches, visual obscuration, photopsia, CSF leak	N/A	Catheterizing the R IJV and R transverse sinus from the inferior vena cava
6. 40 s M	Acute stroke, right M2 occlusion	Cardiomyopathy, cellulitis, substance abuse, HTN	Aspiration, stentriever	Catheterization from aortic arch to R M1. No recanalization. NIHSS 4->1
7. 80 s F	R occipital SM 4 AVM with large R PCA P3 segment aneurysm	Headaches	Flow diversion and Gamma Knife	Catheterization from the aortic arch to the R P3 segment. Delivery of the flow divertor was with a 0.027'' microcatheter
8. 40 s M	R SDH with R M1 occlusion and Moyamoya collaterals	None	MMA embolization with particles	Catheterization from the aortic arch to the R internal maxillary artery. MMA embolization was with a 0.027'' microcatheter.
9. 80 s M	L ICA terminus occlusion	AFIB, HTN, prior stroke, tall and long torso	Aspiration	R femoral access could not reach the clot with the aspiration catheter and stentriever was unable to open the clot. R brachial access with sharply angled L CCA angle. First attempt with Bendit was successful, deployed within an aspiration catheter and guide. TICI 3. NIHSS 24->2
10. 60 s F	R V4 segment critical stenosis, symptomatic	HTN, hyperlipidemia, L hemiparesis, ataxia, dysarthria	Balloon-mounted stent	R radial access with difficult vertebral origin angulation. 15 min of failed access using other microcatheters and wires was followed by immediate access by Bendit and guide catheter through the difficult vertebral origin.

MCA: middle cerebral artery; WEB: woven EndoBridge device; ICA: internal cerebral artery; DM: diabetes mellitus; HTN: hypertension; AFIB: atrial fibrillation; IJV: internal jugular vein; NIHSS: National Institutes of Health Stroke Scale; SM: Spetzler-Martin; AVM: arteriovenous malformation; SDH: subdural hematoma: MMA: middle meningeal artery; CCA: common carotid artery; TICI: thrombolysis in cerebral infarction; PCA: posterior cerebral artery.

No complications for any of the cases were reported and therefore no complications directly related to this novel microcatheter were observed. The catheter was used in several modes.

0.035'' guide wire substitute. In several of the cases (Cases 2–4, 6–8) the novel microcatheter was used within a guide-sheath and intermediate/aspiration catheter from the aortic arch to the target vessel. In 2 of the cases, no microwire was used (Cases 2, 8), and a heparinized saline flush was used to maintain luminal patency during catheterization.

Microcatheter/obturator for an aspiration catheter and intermediate catheters.^8,9 Intermediate catheters have a ledge or step off that frequently can become stuck on vessel ostia, such as the ophthalmic artery origin beyond the clinoidal loop. The Bendit 21 microcatheter can create a solid curve on the inner curvature that allows the intermediate catheter to adopt the inner curvature and avoid the ophthalmic artery ostium (Cases 3,4,6,9).

Novel use to create a sharply angled “stiff” wire for selection. In these cases, the intermediate catheter was advanced over the pinned Bendit 21 microcatheter at the ostium of the vessel to be selected (Cases 3,4,6,8,9,10).

Delivery of a therapeutic implant. In case 1, an intrasaccular device was successfully delivered into an angled middle cerebral artery (MCA) bifurcation aneurysm for the first time in the US, without any complications.

Case highlights

Case 1

The delivery of the intrasaccular aneurysm device into a left MCA bifurcation aneurysm was successful (Figure 1(a) and (b)), but it was observed that the rigidity of the implant (woven EndoBridge device (WEB), Microvention, Tustin CA USA) partially straightened the curve of the Bendit 21 microcatheter during device delivery. Given the limited experience with the delivery of intrasaccular devices, it is uncertain whether this may help or hinder the effective delivery of rigid therapeutic devices, especially in smaller aneurysms.

Figure 1.

(a) DSA of the L ICA demonstrating 6.6 × 5.9 mm L MCA bifurcation saccular aneurysm. (b) Successful delivery of WEB SL 5 × 3 mm vascular plug into L MCA bifurcation aneurysm using Bendit 21 (arrow). MCA: middle cerebral artery; ICA: internal carotid artery; WEB: woven EndoBridge device.

Case 3

The Bendit 21 was used to angle the intermediate catheter away from the ophthalmic artery origin, allowing smooth passing of the aspiration catheter (Sofia 6, Microvention) to the posterior communicating segment of the right internal carotid artery (ICA) (Figure 2(a) and (b)).

Figure 2.

(a) Bendit 21 tip angled away from the origin of the ophthalmic artery (arrow) allowing for advancement of an intermediate catheter. (b) Aspiration catheter passes smoothly over the intermediate catheter into the posterior communicating segment of the R internal carotid artery (ICA) (arrow).

Case 5

The Bendit 21 was able to traverse the valves of the right internal jugular vein (IJV) and was used to select the contralateral transverse sinus through the torcula (Figure 3). The benefit of in situ angulation is that at times partially disconnected torcular herophili can be hard to navigate due to the large caliber of the dural transverse sinus.

Figure 3.

Bendit 21 traverses through the valves of the R internal jugular vein (IJV) and torcula, allowing for selection of the contralateral transverse sinus.

Case 7

The Bendit 21 with a 0.014'' microwire was able to readily select the left posterior cerebral artery (PCA) and cross the aneurysm neck, but the proximal stiffness of the catheter required active holding of the microcatheter to maintain position, presumably due to vessel tortuosity (Figure 4(a) and (b)).

Figure 4.

(a) Bendit 21 readily selects the L posterior cerebral artery (PCA), (b) and crosses the neck of a large saccular aneurysm.

Case 9

The Bendit 21 was used during brachial access for stroke in a very tall patient where femoral access had failed due to insufficient catheter length. Radial access would provide the same device length challenges. Brachial access through the right side approach at times can render difficult access and angles to the left common carotid artery (CCA). The Bendit 21 was appropriately curved and easily engaged the left CCA (Figure 5), the microwire (Synchro 2, Stryker, Kalamazoo, MI USA) was then advanced into the left CCA, and the aspiration catheter (Sofia 6) was advanced over the Bendit and microwire to rapidly engage the left ICA terminus clot, without the need for exchange maneuvers; resulting in a complete (TICI 3) recanalization of this occlusion.

Figure 5.

Brachial access through a right-sided approach can render difficult access and angles to the L common carotid artery (CCA). Bendit 21 easily engaged the L CCA origin with steerable tip.

Case 10

The Bendit 21 was used during radial access for a symptomatic intracranial V4 segment stenosis that had failed medical therapy. The right vertebral artery origin was severely tortuous and acute. With prolonged attempts using various devices and techniques unsuccessfully, the Bendit 21 was eventually used to cannulate this vessel on the first attempt and within 30 s. Figure 6(a) shows the curvature before torquing the microcatheter. Figure 6(b) shows the position after a turn of the microcatheter. The guide catheter was advanced into the vertebral artery over a pinned Bendit microcatheter with angulation engaged. Figure 6(c) shows the Bendit microcatheter advancing through the guide catheter in the vertebral artery base. This maneuver obviated a potential femoral puncture, and an exchange maneuver.

Figure 6.

(a) DSA of acute severely tortuous R vertebral artery. (b) Bendit 21 cannulates R vertebral artery origin via steerable tip on first attempt (arrow). (c) Bendit 21 advanced further into L vertebral artery.

Discussion

Novel therapeutic devices are only applicable and effective when paired with devices that can deliver them. The development of the class of intermediate catheters ¹⁰ has allowed for acute stroke interventions, primarily clot aspiration,^9,11,12 but also provided stable large lumen access for increasingly complex implanted constructs in the neurovasculature.^13,14 Steerable catheters have been available in other domains^15–18 such as peripheral intervention ¹⁹ and cardiology. ²⁰ The Enzo catheter, which is no longer in production, was marketed for neurovascular uses, ⁵ but had a very wide turn radius and relatively poor torque transmission. While our experience with this device is relatively early in practice, it is likely that, given the stage of miniaturization, more high-performance steerable microcatheters will eventually become available in the near future.

This study is limited by a small number of patients, single-center, and early first experiences. This initial clinical series was however devoid of any complications and demonstrated a quick learning curve over a month with the first 8 cases performed within a week, and the remaining 2 cases shortly thereafter, when the operators judged that the device may have benefits given the anatomy they encountered. The near 1-to-1 torqueability and strong steerability/tip articulation, permitting angulation of this novel microcatheter are technical features that may prove beneficial for the next generation of devices towards ease-of-access and deployments.

In particular, remote intervention with future robotic platforms will probably be best paired with devices that may be more expensive but lend themselves to more quantitative control mechanisms.^21,22 Remote, robotic endovascular interventions, such as mechanical thrombectomy, ²³ will likely have fewer personnel and limited inventory at the remote site. As such, versatile and steerable catheters will likely be essential as switching devices mid-procedure will be much more challenging. The avoidance of exchange maneuvers will be key to robotics success for ischemic stroke and other access challenges. It may also expand possibilities for intrasaccular devices in sidewall aneurysms.

Conclusion

The steerable 0.021'' microcatheter exhibited articulation with tight angulation and excellent torque transmission and was able to assist in access and improve stability in difficult vascular anatomy in some circumstances, and outperforming the initial access platform substantively. Future experience with updated, mature devices will be necessary to better understand the role that this catheter may play in modern and future neurointerventions.