New Concept of Patient-specific Flow Diversion Treatment of Intracranial Aneurysms : Design Aspects and in vitro Fluid Dynamics

Initial Experience with the New DERIVO® Mini Embolisation Device for the Treatment of Intracranial Aneurysms

The aim of this study is to present the outcomes of cerebral aneurysm treatment with the DERIVO® mini Embolisation Device (DMD), which is compatible with microcatheters with 0.021-inch inner diameters. Consecutive patients treated with DMD were identified retrospectively. Patient and aneurysm characteristics, procedural findings, clinical outcomes and follow-up imaging results were evaluated. A total of 44 target aneurysms in 30 patients were treated with DMD. The mean age of the patients was 49.9 (range, 4-77 years). Four patients with five aneurysms presented with acute subarachnoid hemorrhage. The mean aneurysm size was 6.8 mm (range, 1.5-22 mm). In 29 (65.9%) aneurysms, adjunctive devices were used for endovascular treatment. The overall mortality rate was 3.3% and procedure-related mortality was 0%. Overall neurologic morbidity was 6.6% and none of the patients had a permanent sequela secondary to the procedure. The mean clinical follow-up period was 20.9 months (range, 3 days-46 months) and the mean DSA follow-up period was 10.9 months. A total of 37 (84.1%) aneurysms demonstrated total occlusion (Raymond-Roy [RR 1]); 3 (6.8%) aneurysms had a neck remnant or infundibular filling at the origin of the jailed side branch (RR 2), 4 (9.1%) aneurysms had residual aneurysm filling (RR 3). For those aneurysms treated with bare DMD, the total occlusion rate was 73.3% at a mean follow-up of 16.1 months. In this initial clinical single-center experience, DMD had a good safety profile and efficacy comparable with the currently used flow diverters.

Fabrication, characterization and numerical validation of a novel thin-wall hydrogel vessel model for cardiovascular research based on a patient-specific stenotic carotid artery bifurcation

In vitro vascular models, primarily made of silicone, have been utilized for decades for studying hemodynamics and supporting the development of implants for catheter-based treatments of diseases such as stenoses and aneurysms. Hydrogels have emerged as prominent materials in tissue-engineering applications, offering distinct advantages over silicone models for fabricating vascular models owing to their viscoelasticity, low friction, and tunable mechanical properties. Our study evaluated the feasibility of fabricating thin-wall, anatomical vessel models made of polyvinyl alcohol hydrogel (PVA-H) based on a patient-specific carotid artery bifurcation using a combination of 3D printing and molding technologies. The model's geometry, elastic modulus, volumetric compliance, and diameter distensibility were characterized experimentally and numerically simulated. Moreover, a comparison with silicone models with the same anatomy was performed. A PVA-H vessel model was integrated into a mock circulatory loop for a preliminary ultrasound-based assessment of fluid dynamics. The vascular model's geometry was successfully replicated, and the elastic moduli amounted to 0.31 ± 0.007 MPa and 0.29 ± 0.007 MPa for PVA-H and silicone, respectively. Both materials exhibited nearly identical volumetric compliance (0.346 and 0.342% mmHg-1), which was higher compared to numerical simulation (0.248 and 0.290% mmHg-1). The diameter distensibility ranged from 0.09 to 0.20% mmHg-1 in the experiments and between 0.10 and 0.18% mmHg-1 in the numerical model at different positions along the vessel model, highlighting the influence of vessel geometry on local deformation. In conclusion, our study presents a method and provides insights into the manufacturing and mechanical characterization of hydrogel-based thin-wall vessel models, potentially allowing for a combination of fluid dynamics and tissue engineering studies in future cardio- and neurovascular research.

Design of Personalized Devices—The Tradeoff between Individual Value and Personalization Workload

Personalized medical devices adapted to the anatomy of the individual promise greater treatment success for patients, thus increasing the individual value of the product. In order to cater to individual adaptations, however, medical device companies need to be able to handle a wide range of internal processes and components. These are here referred to collectively as the personalization workload. Consequently, support is required in order to evaluate how best to target product personalization. Since the approaches presented in the literature are not able to sufficiently meet this demand, this paper introduces a new method that can be used to define an appropriate variety level for a product family taking into account standardized, variant, and personalized attributes. The new method enables the identification and evaluation of personalizable attributes within an existing product family. The method is based on established steps and tools from the field of variant-oriented product design, and is applied using a flow diverter—an implant for the treatment of aneurysm diseases—as an example product. The personalization relevance and adaptation workload for the product characteristics that constitute the differentiating product properties were analyzed and compared in order to determine a tradeoff between customer value and personalization workload. This will consequently help companies to employ targeted, deliberate personalization when designing their product families by enabling them to factor variety-induced complexity and customer value into their thinking at an early stage, thus allowing them to critically evaluate a personalization project.