Background The Pipeline Embolization Device (PED; Medtronic Neurovascular, Irvine, California, USA) is designed for delivery through a 0.027″ microcatheter. Challenges with the second-generation PED Flex include limited support from the Marksman microcatheter for consistent resheathing and transmission of push forces for device delivery. The VIA27 (Sequent Medical/MicroVention Terumo, Tustin, California, USA) is an alternative 0.027″ microcatheter originally designed for intrasaccular flow diverter delivery. Here we describe our experience with the VIA27 in the delivery of PED Flex.
Methods We retrospectively identified patients who underwent PED Flex treatment with the VIA27 microcatheter at our institution. Patient demographics, aneurysm characteristics, equipment utilized, and procedural details were documented.
Results A total of 127 cases were completed using the VIA27 microcatheter for PED Flex implantation. Mean patient age was 56.8±12.4 years (range 21–86 years). All but one of the cases were treatments for intracranial aneurysms. Average aneurysm size was 6.5±6 mm (range 2–38 mm). Of the 127 cases, 120 (95%) were anterior circulation cases and 7 (6%) were posterior circulation cases. Significant cervical internal carotid artery (ICA) tortuosity was present in 33/120 cases (28%). Moderate to severe cavernous ICA tortuosity was present in 54/120 cases (45%). Mean fluoroscopy time was 34.1±22.7 min. Large diameter PED devices (4.5–5 mm) were used in 42/127 cases (33%). Balloon post-processing of the PED was used in 15/127 cases (12%) to improve vessel wall apposition of the PED.
Conclusions The VIA27 is a microcatheter capable of successful PED Flex delivery in neurointervention. We have shown its utility in enhancing both resheathing and push for optimal PED Flex implantation. The VIA27 microcatheter may be a useful and safe adjunct to the traditional Marksman microcatheter in PED Flex treatment of the cerebrovasculature.
- Flow Diverter
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The Pipeline Embolization Device (PED; Medtronic Neurovascular, Irvine, California, USA) is a braided flow diverter designed for delivery through a 0.027″ microcatheter, specifically the Marksman microcatheter (Medtronic Neurovascular). PED procedures can be challenged with failed opening and delivery of the cobalt-chromium PED implant.1–3
The second-generation PED, named Pipeline Flex (PED Flex), incorporates several design alterations to the delivery system to enhance opening of the PED implant.4 A fundamental modification of PED Flex was a new resheathing feature. Additionally, the pusher wire was changed to a larger laser-cut hypotube for more pushability. These improvements have enhanced the usability and safety profile of the PED system; however, compared to the first-generation PED, PED Flex has an increased stiffness profile. New procedural challenges with PED Flex include limited support from the Marksman microcatheter for consistent resheathing of the device. The lack of support from the Marksman microcatheter also limits the pushability of the PED Flex system for reliable deployment of the implant in tortuous anatomy.
The VIA27 (Sequent Medical/MicroVention Terumo, Tustin, California, USA) is a 0.027″ microcatheter originally designed for the delivery of a braided intrasaccular flow diverter, the Woven EndoBridge (WEB; Sequent Medical/ MicroVention Terumo, Tustin, California, USA).5 Here we describe our experience with the VIA27 microcatheter in the delivery of PED Flex in 127 embolizations of the cerebrovasculature. To our knowledge, this is the first report in the literature of an alternative 0.027″ microcatheter used for PED delivery and its technical nuances.
Patients and methods
We retrospectively reviewed a prospective, single-center neurointerventional database identifying all patients undergoing Pipeline embolization for the treatment of cerebrovascular pathologies. Cases using the VIA27 microcatheter for PED Flex deployment were identified for analysis.
Data were collected with respect to patient demographics, aneurysm characteristics, proximal tortuosity, procedural equipment, and technical details. Factors assessed for proximal tortuosity included cervical internal carotid artery (ICA) tortuosity (defined as a 90° turn, hairpin turn, or corkscrew loop), and cavernous ICA grade.6 Data were presented as counts.
Details regarding the embolization procedure have been previously outlined.4 ,7 Patients were preoperatively treated with aspirin 325 mg daily and clopidogrel 75 mg daily for at least 5 days prior to treatment. The P2Y12 assay for platelet inhibition testing was not routinely performed. Systemic anticoagulation with heparin was given during the embolization. Through an 8F femoral sheath, a triaxial system was used for all procedures and consisted of a long guide sheath, a distal access catheter, and a 0.027″ microcatheter. The guide sheaths utilized included an AXS Infinity 0.088″ inner diameter (ID) (Stryker Neurovascular, Fremont, California, USA), Neuron MAX 0.088″ ID (Penumbra, Alameda, California, USA), and Flexor Shuttle Sheath 0.087″ ID (Cook Medical, Bloomington, Indiana, USA). The distal access catheters utilized included a Navien (Medtronic Neurovascular), Catalyst 5 (Stryker Neurovascular), and InNeuroCo Intermediate Catheter (InNeuroCo, Sunrise, Florida, USA). In three cases, PED deployment was first attempted with either a Marksman microcatheter (two cases) or a Phenom 27 microcatheter (Medtronic Neurovascular). In all cases, the VIA27 (Sequent Medical, Aliso Viejo, California, USA) was used as the PED Flex delivery microcatheter. Parent vessel measurements were made using DSA, and PED deployment occurred under real-time fluoroscopy. Angiography was performed in both an immediate and delayed fashion after deployment to determine adequate PED positioning and parent vessel patency.
Patient and aneurysm characteristics
Twenty-two men and 105 women were treated. The mean patient age was 56.8±12.4 years, ranging from 21 to 86 years. All but one of the patients were treated for an intracranial aneurysm. The average aneurysm size was 6.5±6 mm with a range of 2–38 mm. Ninety-nine of the aneurysms (99/126, 78%) had no prior treatment, 4/126 (3%) were previously clipped, 19/126 (15%) were previously coiled, 4/126 (3%) were previously treated with a flow diverter, and 1/126 (1%) had multiple prior treatments. Of the PED cases, 120/127 (95%) were in the anterior circulation and 7/127 (6%) were in the posterior circulation. The most common PED implantation positions along the ICA were the paraophthalmic/clinoidal segment (50/94, 53%), followed by the supraclinoid/posterior communicating artery (25/94, 26%), the cavernous segment (15/94, 16%), the petrous segment (2/94, 2%), and ICA termination (2/94, 2%). In addition to ICA aneurysms, 23 (19%) anterior cerebral artery aneurysms and 3 (2.5%) middle cerebral artery aneurysms were treated. Of the seven posterior circulation aneurysms treated, the locations included the V3-4 junction (n=3), posterior inferior cerebellar artery (n=2), mid-basilar artery (n=1), and P1 segment (n=1).
Proximal vascular access characteristics
Indicators of proximal access complexity and procedural challenges include cervical ICA tortuosity and cavernous ICA grade. Of the 120 anterior circulation cases, 33 (28%) had significant cervical ICA tortuosity defined as a 90° turn, hairpin turn, or corkscrew loop. A spectrum of cavernous ICA tortuosity was encountered for the anterior circulation cases: 66 patients (55%) had minimal tortuosity (type IA and IB), 21 patients (17%) had moderate tortuosity (type II), and 33 patients (28%) had severe tortuosity (type III and IV). The most common positions of the distal intracranial catheter support were as follows: proximal cavernous (n=61, 48%), distal cavernous (n=35, 28%), and supraclinoid (n=21, 17%).
All 127 cases were completed with successful PED implantation using the VIA27 microcatheter. Mean radiation exposure was 2093±1197 mGy. Mean fluoroscopy time was 34.1±22.7 min. Vasospasm prophylaxis and treatment with IA verapamil infusion delivered through the guide sheath and/or distal access catheter was performed in 20/127 cases (16%). In 3/127 (2%) cases, PED deployment was first attempted with either a Marksman microcatheter (two cases) or a Phenom 27 microcatheter. Corking to remove partially opened PED devices was performed in five cases. PED implantation was subsequently successful in all five of these cases after the VIA27 microcatheter was used. Two of these cases are illustrated in figures 1 and 2.
A mean of 1.2±0.4 devices were implanted in each case. One PED was implanted in 110/127 (87%) cases, two PEDs in 14/127 (11%) cases, and three PEDs in 3/127 (2%) cases. The most common PED diameter used was 4.0 mm (35/127, 28%). In 42/127 (33%) cases, large diameter PED devices (4.5–5 mm) were used. Adjuvant coiling via jailing of the coiling microcatheter was performed in 9/127 (7%) cases at the time of PED treatment. Balloon post-processing of the PED was used in 15/127 cases (12%) to improve vessel wall apposition of the PED. In-stent thrombosis requiring IA ReoPro administration was encountered in 9/127 (7%) cases (eight during the procedure and one after the procedure). The thrombosis resolved in all nine cases without neurological deficits.
In this report, we describe our experience with the VIA27 microcatheter as the workhorse delivery microcatheter in 127 cases of PED embolization in the cerebrovasculature. The PED Flex was successfully implanted using the VIA27 microcatheter in all 127 cases despite significant cervical ICA tortuosity in 28% of the cases, moderate to severe cavernous ICA tortuosity (type II–IV) in 45% of cases, and use of large diameter PED devices (4.5–5 mm) in 33% of cases. To our knowledge, this is the first report describing the use of the VIA27 microcatheter for PED Flex delivery in neurointervention.
PED Flex is a second-generation PED with several delivery system modifications to enhance the opening of the PED implant and to provide resheathability of the device.4 These changes to the PED system have improved the usability and safety profile of the PED, but at the cost of increased stiffness of the PED system compared to the first-generation PED. PED Flex also has a larger pusher wire made of laser-cut hypotube. These features of the PED Flex become challenges particularly in cases of tortuosity, where traditional use of the Marksman microcatheter for PED delivery often fails to provide the necessary support for delivery of the PED Flex, reliable deployment of the implant, or consistent resheathing of the device. In these circumstances, the trackability of the Marksman becomes a liability for deployment in tortuosity as demonstrated in the illustrated case (figure 2).
Successful use of VIA27 microcatheter in the PED Flex cases described in this report is attributable to the microcatheter construction offering a superior support profile compared to other available 0.027″ microcatheters. The VIA line of microcatheters were initially designed for use with the WEB device, a type of braided intrasaccular flow diverter.5 Compared to traditional endoluminal flow diverters such as the PED, intrasaccular flow diverters are less compressible and require delivery microcatheters resistant to compression. The VIA microcatheters were constructed with more robust column strength and a higher stiffness profile to provide the support needed for deploying and resheathing braided devices such as the WEB.
Compared to the Marksman microcatheter designed with a distal flexible tip of 2.8F outer diameter (OD) and a proximal shaft of 3.2F OD, the VIA27 microcatheter has a larger OD distal flexible tip of 3.0F with a similar proximal shaft OD of 3.2F. The larger OD of the distal flexible tip contributes to the stability and pushability of the VIA27. This decreased size difference between the proximal and distal OD of the VIA27 also contributes to the support profile of the microcatheter. These features of the VIA27 allow for its success as a more supportive delivery microcatheter for PED Flex, which has a higher stiffness profile compared to the first-generation PED.
In the cases presented in this report, we observed that the added support offered by the VIA27 provides consistent transmission of the push forces required for delivering the PED Flex to the target landing zone. Additionally, the larger and more stable design of this microcatheter allows the pushability of the PED Flex system to be harnessed more safely, and in turn improves the opening of the PED implant. A further advantage of the VIA27 design for PED Flex cases is the distal tip stability that provides more reliable performance when retrieving the device. Compared to the Marksman microcatheter, we observed a smaller accordion effect of the distal tip when resheathing the PED Flex. The two cases with the Marksman delivery catheter where PED Flex failed to open presented the initial opportunities for trying the VIA27 microcatheters for PED deployment. Both these cases had significant access challenges in cavernous ICA tortuosity. Given our consistent success with PED Flex deployment with the VIA27, we have only used the Marksman microcatheter in 12 cases in this past year when the VIA27 was in limited supply.
The enhanced support profile of the VIA27 microcatheter does come at a trade-off of decreased trackability of the microcatheter. This is particularly notable when navigating the larger OD distal tip of the VIA27 across the ophthalmic shelf. The reduced trackability of the VIA27 can be overcome with a more distal intracranial position of the intermediate catheter to provide added support prior to navigating the microcatheter beyond the ophthalmic segment.
The VIA27 microcatheter can be used safely for PED Flex. The supportive nature of the microcatheter enhances the pushability of the PED Flex system for optimal device delivery and deployment. The resheathing performance of PED Flex is also augmented with the VIA27.
Contributors LML drafted the manuscript and critically revised it for important intellectual content. GPC assisted in critically revising the manuscript. MB and RX assisted with data collection and analysis. ALC conceived of the manuscript and critically reviewed the important intellectual content. All authors read and approved the final manuscript.
Competing interests ALC is a proctor for the Woven EndoBridge (WEB) device (Sequent Medical, Aliso Viejo, California, USA), a proctor for the Surpass device (Stryker Neurovascular, Fremont, California, USA) and a consultant for Stryker Neurovascular, a proctor for the Pipeline Embolization Device (Medtronic Neurovascular, Irvine, California, USA) and a consultant for Medtronic Neurovascular, and a proctor for the FRED device (MicroVention, Tustin, California, USA) and consultant for MicroVention. GPC is a consultant for Medtronic Neurovascular and MicroVention. LML is a proctor for the Pipeline Embolization Device (Medtronic Neurovascular, Irvine, California, USA) and a consultant for MicroVention. The other authors have no conflict of interest. No author received financial support in conjunction with the generation of this submission.
Provenance and peer review Not commissioned; externally peer reviewed.
Ethics approval This research was approved by the Johns Hopkins institutional review board.