Endovascular Metal Devices for the Treatment of Cerebrovascular Diseases

Abstract

Cerebrovascular disease involves various medical disorders that obstruct brain blood vessels or deteriorate cerebral circulation, resulting in ischemic or hemorrhagic stroke. Platinum coils with or without biological modification have become routine embolization devices in the cerebral aneurysm sac to reduce the risk of bleeding. Many intracranial stents, flow diverters and stent retrievers have been invented with uniquely designed structures. To accelerate the translation of these devices into clinical usage, an indepth understanding of the mechanical and material performance of these metal-based devices is critical. However, considering the more distal location and tortuous anatomic characteristics of cerebral arteries, present devices still risk failing to arrive at target lesions. Consequently, more flexible endovascular devices and novel designs are under urgent demand to overcome the deficiencies of existing devices. Herein, we discuss the pros and cons of the current structural designs when these devices are applied to the treatment of diseases ranging broadly from hemorrhages to ischemic strokes, in order to encourage further development of such kind of devices and investigation of their use in the clinic. Moreover, novel biodegradable materials and drug elution techniques, and the design, safety and efficacy of personalized devices for further clinical applications in cerebral vasculature are discussed.

Advances in endovascular aneurysm management: coiling and adjunctive devices

“…Balloon remodelling during endovascular coiling involves the temporary inflation of a balloon catheter across the aneurysm neck during the placement of coils 5 14. The balloon catheter increases coil packing density and is removed towards the end of the procedure.…”

“…Originally, balloon remodelling used a single low-compliance balloon and was limited to sidewall aneurysms. More compliant balloons are now available, and those commonly used for balloon-assisted coiling include Hyperform and HyperGlide (single lumen), TransForm (single lumen) and Scepter (dual lumen) 5 15 16. Some of the safety concerns associated with balloon remodelling is the possibility of blood stasis increasing the risk of thrombus formation and thromboembolic events, as well as platelet aggregation of the parent artery during balloon inflation.…”

“…The Analysis of Treatment by Endovascular Approach of Non-ruptured Aneurysms (ATENA) study involving 547 patients found a similar rate of complications comparing balloon remodelling coiling (11.7%) and standard coiling (10.8%) for use in unruptured aneurysms. Most of the balloons used were HyperForm and HyperGlide 5 18. In the Clinical and Anatomy Results in the Treatment of Ruptured Intracranial Aneurysms (CLARITY) study, balloon remodelling was performed in 792 patients with ruptured intracranial aneurysms in this multicentre prospective study.…”

“…Endovascular coiling remains a feasible and effective treatment option for the treatment of ruptured and unruptured aneurysms, especially as an alternative to surgical clipping in most cases, which is associated with higher morbidity and mortality rates. Devices to augment coil embolisation now include balloon-assist techniques and intracranial stents to increase coil packing and parent artery patency, as well as reduce the risk of coil herniation 5. Significant changes in coil properties have also been made to increase the aneurysm occlusion rates 6…”

“…Balloon-assisted coil embolisation reduces the risk of coil prolapse into the parent artery and can provide immediate proximal control with balloon inflation in case of intraprocedural aneurysm rupture. Similarly, stent-assisted coiling allows for increased coil packing density, critical for the treatment of wide-necked, large and giant aneurysms, thereby significantly improving obliteration rate and reducing aneurysm recurrence rate 5 9–11…”