Bioresorbable flow diverters for the treatment of intracranial aneurysms: review of current literature and future directions

Abstract

The use of flow diverters is a rapidly growing endovascular approach for the treatment of intracranial aneurysms. All FDA-approved flow diverters are composed of nitinol or cobalt-chromium, which will remain in the patient for the duration of their life. Bioresorbable flow diverters have been proposed by several independent investigators as the next generation of flow diverting devices. These devices aim to serve their transient function of occluding and healing the aneurysm prior to being safely resorbed by the body, eliminating complications associated with the permanent presence of conventional flow diverters. Theoretical advantages of bioresorbable flow diverters include (1) reduction in device-induced thrombosis; (2) reduction in chronic inflammation and device-induced stenosis; (3) reduction in side branch occlusion; (4) restoration of physiological vasomotor function; (5) reduction in imaging artifacts; and (6) use in pediatric applications. Advances made in the similar bioresorbable coronary stenting field highlight some of these advantages and demonstrate the feasibility and safety of bioresorbable endovascular devices in the clinic. The current work aims to review the progress of bioresorbable flow diverters, identify opportunities for further investigation, and ultimately stimulate the advancement of this technology.

Thrombogenicity of biodegradable metals

“…Future work will be required to confirm the mechanisms involved in Mg metal prevention of FXII activation and delay of fibrin generation. Previous work with a porcine whole blood shunt model also suggested that Mg alloys have low thrombogenicity compared to SS [ 59 ], and clinical trials have shown limited thrombogenicity on Mg alloys; however, these clinical trials use antiplatelet therapies, making direct comparison challenging [ 60 , 61 ]. It is interesting to note the lack of differences between the types of metals that were seen for the downstream platelet, thrombosis, and inflammation markers in this work.…”

“…A limitation of this study is the focus on the acute response to biomaterials only. Future work is needed to evaluate materials over the course of healing and the body's immune response, particularly with the biodegradable metals, which need thorough biological characterization throughout the degradation timeframe of 6–12 months [ 11 , 61 ]. However, the strict and highly thrombogenic nature of the ex vivo model mimics longer term thrombosis risk by eliminating the effects of anticoagulant and anti-platelet medications, which are often used in animal work.…”

Bioresorbable Poly (L-Lactic Acid) Flow Diverter Versus Cobalt-Chromium Flow Diverter: In Vitro and In Vivo Analysis

“…Bioresorbable coronary scaffolds with polymer or magnesium have been applied in clinical practice. 27 Oliver et al 28 reported that metals such as iron or magnesium would be ideal for the material of bioresorbable FDs in terms of mechanical strength and biocompatibility. However, the number of reports regarding bioresorbable FD is limited.…”

Medical Imaging Compatibility of Magnesium- and Iron-Based Bioresorbable Flow Diverters

“…33 A major direction for the field is to determine the optimal device resorption rate that allows the device to maintain structural integrity long enough for the aneurysm to heal before notable resorption. 10 The medical imaging characteristics of the MgBRFD and FeBRFD relative to a control FD will also be assessed using animal models. Blinded interventional neuroradiologists will assess the deployability and image quality of the MgBRFDs and FeBRFDs relative to the control FDs using Likert scales.…”

“…Bioresorbable flow diverters (BRFDs) are emerging as the next generation of FD technology to mitigate these complications. 10 BRFDs aim to serve their transient function of healing and occluding the aneurysm and subsequently to be safely resorbed into the body. BRFDs show promise in reducing metal-induced image artifacts for 2 reasons: First, before any resorption, the innate material properties of many bioresorbable materials induce fewer metal artifacts than conventional FD materials.…”