Ex Vivo Release of Pipeline Embolization Device Polytetrafluoroethylene Sleeves: A Technical Note

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1 DOI: /jnet.tn Ex Vivo Release of Pipeline Embolization Device Polytetrafluoroethylene Sleeves: A Technical Note Yu Takahashi, Kenji Sugiu, Jun Haruma, Satoshi Murai, Naoya Kidani, Shingo Nishihiro, Masafumi Hiramatsu, Tomohito Hishikawa, and Isao Date Objective: A method to deal with situations in which the protective sleeves of the Pipeline Flex embolization device (Medtronic, Minneapolis, MN, USA) cannot be released in its placement due to strong resistance to the delivery wire is presented. Case Presentation: The patient was a 60-year-old woman with symptomatic aneurysm in the cavernous portion of the left internal carotid artery. We attempted to navigate the Pipeline Flex to, and place it in, the target vessel, but the resistance to the delivery wire in the microcatheter was so strong that it was totally impossible to expose the Pipeline Flex from the catheter tip. Therefore, we expanded the tip of the Pipeline Flex ex vivo, resheathed it after releasing the protective sleeves, and attempted to place the device again with success. Conclusion: While this method cannot be recommended, it may be effective if there is strong resistance in releasing the protective sleeves. Keywords Pipeline Flex, polytetrafluoroethylene sleeves, ex vivo release Introduction The Pipeline embolization device (PED, Medtronic, Minneapolis, MN, USA) has become a useful option for the treatment of large/giant intracranial aneurysm of the internal carotid artery (ICA), 1,2) which used to be difficult to treat. In Japan, the Pipeline Flex with improved manipulability due to modifications of the tip protective function and delivery wire compared with the previous Pipeline classic type was approved in October With increases in cases treated using the Pipeline Flex, reports of its safety and efficacy are also increasing. 3,4) However, technical problems may arise in its clinical use, but reports concerning Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Okayama, Japan Received: September 21, 2017; Accepted: March 12, 2018 Corresponding author: Kenji Sugiu. Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Shikata-cho, Kita-ku, Okayama, Okayama , Japan ksugiu@md.okayama-u.ac.jp This work is licensed under a Creative Commons Attribution-NonCommercial- NoDerivatives International License The Japanese Society for Neuroendovascular Therapy technical tips are scarce. We encountered a case of left ICA-cavernous portion (cav) aneurysm in which the resistance to the delivery wire in the microcatheter was so strong that the deployment of the PED was difficult, but the device could be deployed after releasing the polytetrafluoroethylene (PTFE) protective sleeves ex vivo. This case is reported with a review of the literature. Case Presentation The patient was a 60-year-old woman presenting with diplopia as the primary complaint. She had a history of ovarian cystectomy at the age of 43 years. History of the present illness: The patient consulted a local doctor as she noted double vision when she looked to the left. She was found to have unruptured aneurysm in the left internal carotid artery cavernous portion (ICA-cav) on head MRI and referred to our department for treatment. Neurologic findings: Neurologic examination revealed left abducens nerve palsy. Imaging findings: Head MRI showed an aneurysm in the left IC-cav without findings of thrombus formation. On DSA, an aneurysm 14 mm 12 mm 11 mm with a neck about 7.4 mm long was observed in the left ICA from C5 to the curved portion of C4 (Fig. 1A and 1B). On balloon test occlusion (BTO) of the left ICA, no neurologic deficits 1

2 Takahashi Y, et al. A B C D E Fig. 1 A 60-year-old woman suffered from diplopia due to the left abducens nerve palsy. DSA on AP view (A) and 3D imaging on lateral view (B) showed an aneurysm of cavernous portion of the left ICA. (C) Pipeline Flex 5.0/35 mm (Medtronic, Minneapolis, MN, USA) was introduced into the microcatheter (Marksman; Medtronic) which was navigated into M1 portion of the left middle cerebral artery. Because it was very hard to advance the PED, we retrieved the system including the microcatheter and PED. Note the waving tip of the delivery wire in the microcatheter (arrows), which indicates strong resistance in the system. (D) We successfully deployed the PED from C3 to petrous portion of ICA. (E) Final angiography on lateral view. DSA after the procedure showing eclipse sign (contrast stagnation) (arrowhead). AP: anterior posterior; ICA: internal carotid artery; PED: pipeline embolization device appeared during 30-minute occlusion, and a rich cross flow from the posterior communicating artery was noted, but Single Photon Emission Computed Tomography (SPECT) during BTO showed a slight decrease in the blood flow of the left hemisphere. Periprocedural management: Oral administration of aspirin at 100 mg and clopidogrel at 75 mg was initiated 10 days before the procedure, and the VerifyNow (Medico s Hirata Inc, Osaka, Japan) test was performed 2 days before the procedure. Since the effect of clopidogrel was slightly insufficient, the dose of clopidogrel was increased to 150 mg on the same day. Endovascular treatment: Under general anesthesia, an 8 Fr sheath introducer was placed in the right femoral artery. Heparin was intravenously injected at a loading dose of 5000 U, and the activated clotting time (ACT) was adjusted thereafter at 2 3 times the baseline value by administering 1000 U at 1-hour intervals. An 8 Fr guiding catheter (GC) (Launcher; Medtronic) was placed in the left ICA, and a distal access catheter (Navien 5.4 Fr; Medtronic) was navigated to the closest possible point to the aneurysm. Then, a micro-catheter (MC) for stent navigation (Marksman; Medtronic) was advanced to the M1. The PED was planned to be placed from the C3 to C5 portion, and a PED 5 mm 35 mm was selected because the diameter of the ICA was 4.6 mm in the distal portion, 5.3 mm at the neck, and 5.0 mm in the proximal portion. We first attempted to release the protective sleeves in the M1 but could not advance the PED due to very strong resistance to the delivery wire in the MC. Therefore, to increase the support force, the Navien was navigated to the terminal portion of the ICA, but the reattempt to deploy the PED failed again (Fig. 1C). When the PED was retrieved with the MC, part of the MC was found to be collapsed like an accordion, and the delivery wire was completely stuck even ex vivo. The system was replaced with a new one, and in vivo 2

3 Ex Vivo Release of Pipeline Flex A B C D E 1cm Fig. 2 (A) We inserted the introducer sheath into the microcatheter (arrow) with the tip of it attached to saline. (B) and (C) We pushed the delivery wire until the PTFE sleeves (arrowhead) were released. (D) and (E) We carefully resheathed the PED into the microcatheter as not to enter air into it. PED: pipeline embolization device; PTFE: polytetrafluoroethylene deployment was attempted again, but the insertion was similarly prevented by strong resistance. We judged that the deployment of the PED would be impossible by repetition of similar attempts and also retrieved this system. Since the PED was the largest and longest model, we suspected that the resistance was intensified by marked curving of the ICA. Therefore, we decided to reduce the resistance in pushing out the PED by releasing the protective sleeves ex vivo and to place the PED primarily by withdrawing the MC. While the tip of the MC was immersed in saline ex vivo, the PED was expanded under direct visual observation until the protective sleeves were released, and, with caution not to aspirate air and not to allow the sleeves to get stuck at the tip of the MC, the PED was resheathed with the tip of the wire exposed by about 2 cm (Fig. 2). This maneuver could be easily performed ex vivo. Since the Navien stood ready in the terminal portion of the ICA, the MC could be readily guided to the distal part of the aneurysm. When the placement of the PED was initiated from the terminal portion of the ICA, the delivery wire could be pushed this time with less resistance, and the tip of the PED could be deployed. It was repositioned to the intended position by pulling back the entire system and could be placed with sufficient anchoring (Fig. 1D). On the final angiography, the eclipse sign (niveau formed by stagnation of the contrast medium in the aneurysm due to the flow diverting effect) was confirmed (Fig. 1E). No clear neurologic symptoms were noted after the procedure, and the patient was discharged, capable of unassisted ambulation. Discussion In the Pipeline Flex, there have been improvements in the protective mechanism for the main body of the device, mechanism for its transmission, and delivery wire compared with the Pipeline Classic, which have not only facilitated the deployment and placement of the device but also made resheathing of the device possible. The protective mechanism was changed from a platinum protective coil to two feather-like PTFE sleeves. In the previous Pipeline Classic, a twist-stopper, which was the protective mechanism, was attached to the tip of the delivery system, and twisting of the wire clockwise released the lock on the tip and allowed it to expand. However, the resistance of the wire was strong, and there were times when the tip would not expand despite repeated attempts to twist or when the stent twisted itself and came off unintendedly. 5) In the Pipeline Flex, on the other hand, as the protective sleeves are released spontaneously by the radial force of the stent itself, allowing the device to expand, the device can be deployed more easily by simpler manipulation than the previous model. In addition, the delivery wire was also changed to a thicker one in the Pipeline Flex, leading to improvements in the support ability and 3

4 Takahashi Y, et al. (A) (E) Aneurysm introducer sheath (B) microcatheter PTFE sleeves (F) (C) (D) microcatheter Fig. 3 Christoph s method. (A) and (B) First, we push the delivery wire until the PTFE sleeves are released from the introducer sheath. (C) Next, we resheath the PED into the introducer sheath. (D) and (E) Finally, we insert the PED into the microcatheter which is placed at the distal portion of the aneurysm and (F) deploy the PED. PED: pipeline embolization device; PTFE: polytetrafluoroethylene pushability. With these improvements, the procedure time has been markedly shortened, and the accuracy of its positioning has been improved. According to the report of the use of the Pipeline Classic by Lin et al., 6) it was necessary to retrieve the device due to poor deployment in 14.3%, but Pereira et al., 3) who used the Pipeline Flex, reported that retrieval was unnecessary in all patients. Also, Le et al. 7) reported that the operation time was shortened by 44 minutes with decreases in the radiation dose for fluoroscopy and the dose of the contrast agent in patients treated with the Pipeline Flex than in those treated with the Pipeline Classic. Moreover, they reported that failure in PED deployment also decreased from 23% to 7%. Concerning complications of Pipeline placement, the morbidity and mortality were 5.6% and 8.4%, respectively, and the incidence of ischemic complications was 4.7%, in PUFs 1) and InterPED, 8) in which the Pipeline Classic was used, but the morbidity and mortality were improved to 0% and 6.7%, respectively, in recent studies using the Pipeline Flex. 3,4) However, despite the improvements in the device, strong resistance is felt in pushing the delivery wire, making the deployment of the PED difficult in not a few instances. According to our experience, the greatest resistance is felt in expanding the tip of the PED and releasing the protective sleeves, and we have the impression that the resistance is stronger as the PED is larger and longer and as the proximal portion of the vessel in which the device is placed is more tortuous. We have also experienced that, while the PED had been partially expanded, the protective sleeves could not be released, preventing expansion of the distal end of the PED. In this event, it is recommended to remove the protective sleeves by resolving twisting of the PED and stimulating the distal end by repeated resheathing. 5) However, this increases the risk of thrombus formation or vascular damage as well as complications such as breakage of the PED itself. In addition, Tan et al. 9) reported that complications increased with prolongation of the procedure time. In our patient, the resistance was so strong that we could not even advance the delivery wire let alone attempt the maneuver to release the protective sleeves. Martínez-Galdámez et al. 10) recommended to recover the entire system if more resistance is felt in the manipulation of the delivery wire than usual. However, the PED is an expensive device, and repeated trials should be avoided also from the viewpoint of medical economy. In our patient, therefore, we attempted to place the PED after releasing the protective sleeves ex vivo and reducing the resistance in expanding the distal end of the device. Griessenauer et al. 11) reported that 25 PEDs could be safely and accurately placed in all 21 aneurysms by releasing the sleeves ex vivo. They placed PEDs after releasing the protective sleeves ex vivo only in cases that required accurate placement due to a very short distal landing zone. The protective sleeves cover the end of the PED and keep it closed to protect it from damages while the device is advanced in the MC. Therefore, if the sleeves are removed ex vivo, the tip may be damaged while it is advanced in the MC. Unlike our method, they first expanded PED from the accompanying introducer sheath ex vivo, released the protective sleeves, resheathed the device with the same introducer sheath, and advanced it in the MC by the usual 4

5 Ex Vivo Release of Pipeline Flex (A) (E) Aneurysm introducer sheath (B) microcatheter distal access catheter (C) (F) PTFE sleeves (D) Fig. 4 Our method. (A) and (B) First, we insert the PED into the microcatheter. (C) Next, we push the delivery wire until the PTFE sleeves are released from the microcatheter and (D) resheath the PED into the microcatheter. (E) Finally, we insert the microcatheter into the distal access catheter which is placed at the distal portion of the aneurysm and (F) deploy the PED. PED: pipeline embolization device; PTFE: polytetrafluoroethylene method (Fig. 3). For this reason, the device is advanced without the protection of the PTFE sleeves as mentioned above at the risk of damaging the tip. By our method, on the other hand, the protective sleeves are released after the PED is passed through the MC ex vivo, and the device is resheathed (Fig. 4). Then, the PED, inserted in the MC, is advanced in the Navien, so the possibility of damaging the tip is extremely low. Since the protective sleeves also serve as a mechanism that prevents expansion of the PED at an unintended site, caution is needed in advancing the device in the Navien. However, this risk is considered to be controlled by careful fixation with a torque device attached to the Y-connecter part of the delivery wire. However, since this technique requires ascending of the MC with the PED inserted, the micro wire cannot be used. Therefore, it is necessary to place the Navien at a site sufficiently distal to the aneurysm in advance. Since this procedure of navigating the Navien involves the risk of complications, such as vascular damage, it must be performed with sufficient caution. Our patient was free of this problem because the Navien had been inserted safely to the terminal portion of the ICA for the IC-cav aneurysm. Lastly, this method is not recommended by the manufacturer, and there has been no report concerning its safety. Also, as there is a possibility of unexpected complications, it cannot be recommended invariably. It should be regarded as an option for limited cases such as those that show strong resistance in advancing the delivery wire and difficulty in releasing the protective sleeves or, as reported by Griessenauer et al., those that require accurate placement due to an extremely short distal landing zone. 11) Conclusion In a case in which strong resistance to the delivery wire was felt in PED placement, the PED could be placed safely and without resistance by releasing the protective sleeves ex vivo in advance. This method is not recommended by the manufacturer and lacks reports concerning the safety. Therefore, it cannot be recommended to all cases but is considered effective when there is strong resistance in releasing the protective sleeves. Disclosure Statement Neither the first author nor any of the coauthors have any conflicts of interest. References 1) Becske T, Kallmes DF, Saatci I, et al: Pipeline for uncoilable or failed aneurysms: results from a multicenter clinical trial. Radiology 2013; 267: ) Nelson PK, Lylyk P, Szikora I, et al: The pipeline embolization device for the intracranial treatment of aneurysms trial. AJNR Am J Neuroradiol 2011; 32: ) Pereira VM, Kelly M, Vega P, et al: New pipeline flex device: initial experience and technical nuances. J Neurointerv Surg 2015; 7: ) Martínez-Galdámez M, Pérez S, Vega A, et al: Endovascular treatment of intracranial aneurysms using the pipeline flex embolization device: a case series of 30 consecutive patients. J Neurointerv Surg 2016; 8:

6 Takahashi Y, et al. 5) Miyachi S, Ishii A: Development of a pipeline-classic type to flex: points of improvement and precautions for use. JNET 2017; 11: ) Lin LM, Colby GP, Kim JE, et al: Immediate and follow-up results for 44 consecutive cases of small (<10 mm) internal carotid artery aneurysms treated with the pipeline embolization device. Surg Neurol Int 2013; 4: ) Le EJ, Miller T, Serulle Y, et al: Use of pipeline flex is associated with reduced fluoroscopy time, procedure time, and technical failure compared with the first-generation Pipeline embolization device. J Neurointerv Surg 2017; 9: ) Kallmes DF, Hanel R, Lopes D, et al: International retrospective study of the pipeline embolization device: a multicenter aneurysm treatment study. AJNR Am J Neuroradiol 2015; 36: ) Tan LA, Keigher KM, Munich SA, et al: Thromboembolic complications with pipeline embolization device placement: impact of procedure time, number of stents and preprocedure P2Y12 reaction unit (PRU) value. J Neurointerv Surg 2015; 7: ) Martínez-Galdámez M, Gil A, Caniego JL, et al: Preliminary experience with the pipeline flex embolization device: technical note. J Neurointerv Surg 2015; 7: ) Griessenauer CJ, Gupta R, Moore J, et al: Ex-vivo release of pipeline embolization device polytetrafluoroethylene (PTFE) sleeves for improved distal landing zone accuracy in-vivo: a technical note. Interv Neuroradiol 2016; 22: