Relationship Between Clot Quality and Microguidewire Configuration During Endovascular Thrombectomy for Acute Ischemic Stroke

Pull the Trigger Sign: A Novel Method to Identify the Clot Position during Acute Endovascular Thrombectomy

Objective

Accurately determining the clot position is highly important for immediate recanalization when endovascular mechanical thrombectomy is performed using a stent retriever and aspiration catheter. We describe a new method that facilitates the precise identification of the clot position called pull the trigger sign (PTS).

Case Presentation

Selective angiography was performed through a 0.027-inch microcatheter that penetrated the clot into the distal lumen. Although the contrast media highlighted the occluded artery, it often stagnated in the distal artery. It was washed away at a certain point when a stent clot retriever was deployed over the potential clot site. We hypothesized that this point represented the exact position of the clot's proximal end and used in vitro analyses to assess this hypothesis. Briefly, a circulation-enabled silicone vascular model in which colored water was used to simulate stagnation beyond a fake clot was developed and utilized to investigate PTS six times. The rate of identifying PTS in the vascular model was 100%. As hypothesized, stagnant fluid was washed away when the deployed stent reached the clot's proximal position. The clinical efficacy of PTS was also confirmed.

Conclusion

PTS was useful in revealing the precise position of clot's proximal end, which enabled safer contact aspiration when using an aspiration catheter. Thus, PTS led to a higher success rate and faster recanalization in the first attempt than conventional methods.

Safety and Effectiveness of a Modified ASAP Technique during Mechanical Thrombectomy for Acute Ischemic Stroke: Initial Clinical Experience

Objectives:

For patients with acute ischemic stroke, various endovascular approaches have been reported with high recanalization rates and good clinical outcomes. However, the best technique for the first attempt at mechanical thrombectomy remains a matter of debate. In this study, we evaluated the efficacy of a modified version of a stent-retrieving into an aspiration catheter with a proximal balloon (ASAP) technique.

Materials and Methods:

Modification 1: After stent deployment, the microcatheter was not removed immediately. Modification 2: After the withdrawal of the stent retriever into an aspirator and its removal from the entire system, we focused on the drainage of fluid into a pump. The aspirator was withdrawn slowly until the fluid appeared to be draining continuously into the pump. Before the removal of the aspirator, we performed angiography through the aspirator. We carried out a retrospective analysis of 30 consecutive patients with acute ischemic stroke caused by occlusion of the anterior circulation who were treated with the modified ASAP technique at our institution.

Results:

A thrombolysis in cerebral infarction score of 2B or 3 was achieved in 29/30 patients (96.7%). The average number of passes was 1.2 ± 0.5. The mean time from puncture to recanalization was 17.6 ± 6.84 min. Twenty-three (76.7%) patients achieved a modified Rankin Scale score of 0–2 at 3 months after the procedure.

Conclusions:

We found that the modified ASAP technique yielded fast recanalization, minimal complications, and good clinical outcomes of mechanical thrombectomy in this case series.

Initial Clinical Experience of Using a Newly Designed Preshaped Microguidewire in Acute Endovascular Thrombectomy

Mechanical thrombectomy has been widely used for the treatment of acute ischemic stroke. During this procedure, operators must navigate the microcatheter with a microguidewire (MGW) into vessels that cannot be visualized on fluoroscopy as rapidly as possible. In this study, we developed a modified pigtail-shaped MGW (MPMGW) for security and controllability. Moreover, the efficacy of the MPMGW for the treatment of acute ischemic stroke was assessed. The MPMGW was designed using 0.014 MGW. Because we created four MPMGWs during a clinical evaluation before the launch in the market, these wires were used in four consecutive patients with acute ischemic stroke in the single institution. The occluded arteries were the basilar artery (n = 1), middle cerebral arteries (M1 and M2, n = 2), and internal carotid artery (n = 1). All four procedures were conducted without any complications. The procedures included navigating the MGW and passing it through the clot. Complete recanalization was achieved in all cases. The average time between femoral artery puncture and recanalization was 15 min. The use of the preshaped MPMGW in acute thrombectomy was effective in terms of both security of procedure and reduction in recanalization time.

Novel Technique for Detection of Actual Position of Clot During Endovascular Clot Retrieval: Assessment of Microcatheter Withdrawing Angiography

BACKGROUND

When endovascular clot retrievals are performed using a stent retriever and/or an aspiration catheter, identifying the accurate position of a clot is extremely important for a successful immediate recanalization. Herein, we report a new technique called microcatheter withdrawing angiography, which facilitates the identification of the precise position of a clot. The negative shadow appearance of the clot on angiography was referred to as the actual crab claw sign.

METHODS

When a 0.027-inch microcatheter penetrated the clot after inserting a 0.014-inch microwire, selective angiography was conducted using the microcatheter. Simultaneously, the microcatheter was slowly withdrawn with continuous contrast media injection, while the microwire was kept in the distal vessel. The precise position of the clot was found, which was referred to as the actual crab claw sign. Next, we conducted in vitro and in vivo analyses.

RESULTS

The actual crab claw sign could be identified in the vascular model and in actual clinical settings. Therefore the sweet spot of the stent retriever could be set over the clot, and an accurate contact aspiration could be performed using an aspirator.

CONCLUSIONS

Microcatheter withdrawing angiography can help identify the actual crab claw sign. This technique has a higher success rate and faster recanalization than conventional strategy, particularly in challenging cases of unsuccessful recanalization during the first attempt.

Ideas Developed from the Routine Use of Problem-solving Skills in Neuroendovascular Therapy

Objective

All physicians should endeavor to perform safe and rapid neuroendovascular operations. We describe the process of identifying novel methods and highlight some representative clinical examples from our practice.

Methods

We made a habit of asking questions regarding problems encountered during operations. Potential solutions are often identified and noted in our smartphones or as memos. These solutions are then evaluated by experiments in vascular models before assessing their efficacy in clinical settings.

Results

Some ideas based on our process of raising problems and finding solutions were published, and found to be relevant to the wider scientific community. Moreover, all ideas were applicable in most settings due to the use of conventional, familiar, and cheap methods and equipment. The paper rail method, modified pigtail shape microguidewire, microcatheter in vivo printing method, microcatheter shaping cast, and wireless trans-cell approach are presented as representative ideas.

Conclusions

We reported methods of neuroendovascular therapy identified through the routine practice of problem-solving by our team.

A Novel Technique for Stent-Assisted Coil Embolization of Intracranial Aneurysms: The Wireless Trans-Cell Approach

Background:

When inserting coils under stent deployment, a jailed microcatheter technique is typically applied as a first line approach. However, the trans cell approach might be required to achieve satisfactory complete occlusion. The trans cell approach occasionally ends in failure because the catheter cannot safely follow a proceeding guidewire into the aneurysm. Here, we report the new wireless trans cell approach (WTA), which allows feasible and safe catheter navigation through the stent strut into the aneurysm, without a proceeding guidewire.

Methods:

A straight tip microcatheter was used, and the tip was shaped as a very small bend of approximately 45°. The side aspect of the catheter tip exhibited a right angled edge, while the front aspect showed a round curve in the advancing direction. We compared the 45° microcatheter with a straight tip microcatheter using a silicon vascular model and then applied the WTA in a case of an unruptured basilar apex aneurysm.

Results:

Catheter navigation through the stent strut was smoother with the WTA than the conventional wire assisted approach. Our case of a basilar apex aneurysm was successfully treated with the dual catheter technique, which involved a jailed catheter and navigation using the WTA. After stent deployment from the right posterior cerebral artery to the basilar artery through the 45° microcatheter, the WTA was applied using the same catheter. No stress was detected during catheter navigation through the stent strut into the aneurysm.

Conclusions:

The WTA is associated with smoother catheter navigation compared with the conventional wire assisted approach in cases of a terminal type aneurysm.

Efficacy and Safety of a Modified Pigtail-Shaped Microguidewire during Endovascular Thrombectomy

A 75-year-old man presented with right-sided hemiplegia and was diagnosed with a left middle cerebral artery occlusion. He underwent endovascular thrombectomy, and a bulge was found. A modified pigtail-shaped microguidewire (MPMGW) proved useful for diagnosis because it allowed differentiation between the occluded artery and a saccular aneurysm as the etiology. When a clot was partially retrieved, a previously unidentified vessel dilatation appeared. The dilatation origin was unclear and could have resulted from either the occluded artery or an unruptured saccular aneurysm. We tried to navigate the MPMGW into the bulging area. The patient showed unusual body movement attributed to pain and the dilatation was diagnosed as an aneurysm. Subsequent 3-dimensional angiography revealed a recanalized artery and the aneurysm. With no subarachnoid hemorrhage or extravasation of the contrast medium. The hemiplegia dramatically improved. An MPMGW may be useful in acute thrombectomy where the target vessel cannot be visualized during the procedure.

Usefulness of modified pigtail-shaped microguidewire guidance for microcatheter navigation in difficult vasculatures during neuroendovascular interventions

We previously reported using a microguidewire with a curved, pigtail-shaped tip as an anchor for navigating a microcatheter. However, we considered that the microcatheter could follow even if the tip of wire did not advance so far distally. The present study assessed the usefulness of a modified version of this pigtail-shaped microguidewire for navigating microcatheters to difficult vasculatures during neurointerventions. The microguidewire was repeatedly evaluated using a silicon tube vascular model. We also employed this method as the first choice for some patients. In both the in vitro tests and clinical use, the round curved tip could be used to position the microguidewire at the entry of a sharply angled vessel or aneurysmal neck, and the following catheter could then be advanced gently and easily. This technique allowed navigation of the microcatheter without inserting the guidewire into the distal vasculature.