Peer-Review ReportCurrent Status of Pipeline Embolization Device in the Treatment of Intracranial Aneurysms: A Review
Introduction
The treatment of endovascular aneurysm has evolved considerably during the past two decades, with coiling emerging as the treatment of choice for a significant proportion of saccular aneurysms (17). The International Study of Subarachnoid Aneurysm Treatment (24) and the Barrow Ruptured Aneurysm Trial (23) have established the advantages of endovascular treatment in selected clinical scenarios. However, a considerable number of aneurysms are not amendable to coiling.
Balloon remodeling and stent-assisted techniques were developed in mid-1990s and early 2000, rendering more feasible the treatment of aneurysms with more complex morphology (17).
Despite the technological advances, wide-neck and giant saccular or fusiform aneurysms present considerable challenges for the operator (13). Parent artery occlusion is one of the earliest endovascular techniques that showed efficacy treatment for unclippable giant aneurysms. However, parent artery occlusion depends on patient tolerance to occlusion, and reliable predictors for ischemic events are lacking. (13) Furthermore, successful balloon occlusion test does not preclude delayed ischemic complications that occur between 4% and 15% of cases. (13) Endovascular treatments frequently fail to produce complete occlusion in such aneurysms (1).
Recurrence of the treated aneurysm postendovascular treatment occurs in 9% to 34% cases 1, 3, 4, 5, 25, 30. Incomplete occlusion, larger (>10 mm) aneurysm size, and neck size are risk factors for recurrence 1, 3, 4, 5, 25, 30. These aneurysms are prone to coil compaction and recanalization, even when complete or near-complete occlusion has been achieved after the initial embolization, and require extended imaging surveillance and the possibility of retreatment 12, 24, 25, 35. Failure of endovascular techniques to achieve a complete and durable occlusion of aneurysms has been attributed to several factors, including limitations with respect to the volumetric packing of the aneurysm sac with coils, inherent difficulties associated with achieving a continuous reconstruction of large complex aneurysm neck defects with coils, and finally a fundamental failure of the endovascular strategy to address the underlying diseased parent vessel (9).
Section snippets
Literature Review
A search for published articles on pipeline embolization devices (PED) in PubMed between 2000 and February 2012 was performed. A total of 210 patients with 241 aneurysms treated with PED were identified in five reported case series. A detail review on the indications, therapeutic results, and technical and safety issues of PED was performed.
Principle of Flow Diversion
Flow diversion offers a fundamentally novel treatment approach. This approach potentially represents a more physiologic treatment of intracranial aneurysms
PED
PED (ev3, Irvine, California, USA) is a flexible self-expanding, microcatheter-delivered, high-metal-surface-area coverage, stent-like device designed to achieve aneurysm occlusion through the endoluminal reconstruction of the diseased segment of the parent artery that gives rise to the aneurysm (Figure 1). Composed of 48 individual cobalt chromium and platinum strands, it provides 30% to 35% metal surface area coverage when fully deployed (10), in comparison with only 6% to 9.5% coverage with
Aneurysm Selection and Limitations
With larger patient series being published recently, confirming the efficacy of the device and its safety profile, the use of PED has transformed during the past few years from a novel, investigational device reserved for otherwise-untreatable lesions to a more established alternative technique that is being integrated into routine cerebrovascular practice (6). A transition in the use of PED in treating large and giant aneurysms to include small- to medium-sized aneurysms has been observed.
Conclusion
PED offers an alternative to endovascular coiling for aneurysms with complex morphology. The indication for its use has evolved from giant aneurysms with wide necks to small aneurysms. The safety profile of PED is comparable with or possibly superior to balloon-remodeling or stent-assisted coil embolization in specific circumstances. However, questions remain regarding the long-term safety, treatment results, and clinical outcomes. Continued ongoing research and monitoring of the usage of PED
References (36)
- et al.
Pipeline flow-diverter stent for endovascular treatment of intracranial aneurysms: preliminary experience in 20 patients with 27 aneurysms
World Neursurg
(2011) - et al.
Holman: International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: A randomized trial
J Stroke Cerebrovasc Dis
(2002) Flow diverter stents in treatment of intracranial aneurysm. Where are we?
J Neuroradiol
(2011)- et al.
Retreatment of ruptured cerebral aneurysms in patients randomized by coiling or clipping in the International Subarachnoid Aneurysm Trial (ISAT)
Stroke
(2007) - et al.
Aneurysm rupture following treatment with flow-diverting stents: computational hemodynamics analysis of treatment
Am J Neuroradiol
(2011) - et al.
Clinical and angiographic long-term follow-up of completely coiled intracranial aneurysms using endovascular technique
J Neurosurg
(2010) - et al.
Coiling of intracranial aneurysms: a systematic review on initial occlusion and reopening and retreatment rates
Stroke
(2009) - et al.
Late reopening of adequately coiled intracranial aneurysms: frequency and risk factors in 400 patients with 440 aneurysms
Stroke
(2011) Pipeline in clinical practice in 2011
Neuroradiology
(2012)- et al.
Very late thrombosis of a Pipeline embolization device construct: case report
Neurosurgery
(2010)
Curative reconstruction of a giant midbasiar trunk aneurysm with the Pipeline embolization device
Neurosurgery
Curative cerebrovascular reconstruction with the Pipeline embolization device: the emergence of definitive endovaswith the Pipeline embolization device: the emergence of definitive endovascular therapy for intracranial aneurysms
J Neurointerv Surg
Definitive reconstruction of circumferential, fusiform intracranial aneurysms with the pipeline embolization device
Neurosurg
Aguilar Perez M, Schmid E, Hopf N, Bäzner H, Henkes H: Pipeline embolization device (PED) for neurovascular reconstruction: initial experience in the treatment of 101 intracranial aneurysms and dissections
Neuroradiology
Guglielmi detachable coil treatment of ruptured saccular cerebral aneurysms: Retrospective review of a 10-year single center experience
Am J Neuroradiol
Challenges in the endovascular treatment of giant intracranial aneurysms
Neurosurgy
A new endoluminal, flow-disrupting device for treatment of saccular aneurysm
Stroke
A second-generation, endoluminal, flow-disrupting device for treatment of saccular aneurysms
Am J Neuroradiol
Cited by (29)
Evolution of open surgery for unruptured intracranial aneurysms over a fifteen year period–increased difficulty and morbidity
2023, Journal of Clinical NeuroscienceMagnetic Resonance Imaging Safety of Retained Tip and Protective Coils after Faulty Deployment of an Intracranial Pipeline Embolization Device: A Case Report
2019, World NeurosurgeryCitation Excerpt :With the advent of new endovascular devices and techniques, the treatment of intracranial aneurysms remains an ever-evolving field, and coiling has become a feasible treatment option for most saccular aneurysms.1
Predicting Successful Treatment of Intracranial Aneurysms with the Pipeline Embolization Device Through Meta-Regression
2018, World NeurosurgeryCitation Excerpt :While examining hemodynamics of SAC for the containment of coils within the dome of challenging IA morphologies and for the prevention of coil herniation into parent arteries, researchers discovered, by chance, that placement of a stent by itself can lead to flow diversion and eventual obliteration of the IA.2,4 Conventional self-expanding stents previously designed to assist with mechanical retention of coils within IAs (Neuroform [Stryker, Kalamazoo, Michigan, USA], Enterprise [Codman & Shurtleff, Raynham Massachusetts, USA]) were limited in terms of flow-diverting capacity because of their high porosity and were not effective as stand-alone devices.1,5 However, when combinations of stents were used to decrease stent porosity and increase metal surface area, a significant hemodynamic effect was observed.1
Treatment of large and giant intracranial aneurysms: Cost comparison of flow diversion and traditional embolization strategies
2014, World NeurosurgeryCitation Excerpt :There are several other factors that should be taken into account when comparing relative costs of PED therapy with traditional embolization strategies. Aneurysms treated with flow diverters achieve a much higher rate of complete angiographic obliteration and are less likely to require further intervention compared with standard endovascular techniques (7, 10, 13). This would unquestionably translate to long-term cost savings for those treated with the PED.
Development of normal pressure hydrocephalus after the placement of a pipeline embolization device for the treatment of a large aneurysm: Case report
2014, Clinical Neurology and NeurosurgeryCitation Excerpt :The major complications reported have included intracranial hemorrhage, thromboembolic events, perforator occlusion, in-stent thrombosis, mechanical delivery problems and aneurysm rupture [2,4–7,13,14]. However, PED is now widely used in other patients who do not strictly match the criteria of PUFS study [5,7,8]. Recent reports have mentioned unique and unusual complications, such as embolic retinal venous occlusion and shortening/migration of the PED itself [8,9].
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.