Study explores impact of more uniform distribution of endovascular coils


A study published in the June edition of the Journal of NeuroInterventional Surgery highlights that a more uniform distribution of endovascular coils may help in the treatment of cerebral aneurysms. Deltapaq endovascular microcoils from Codman were used in the study. 


The study set out to investigate the impact of coil design on the distribution of the coil mass in a controlled in vitro experiment. A secondary objective, wrote the authors, was to study the relationship between angiographic occlusion, packing density and coil mass uniformity.


Mehra et al found that the novel triangular primary wind design of Deltapaq endovascular microcoils achieved a tighter packing density and a more uniform distribution of the coil mass across the aneurysm dome in comparison with helical and complex endovascular microcoils.

Deltapaq coils were also more likely to have the highest rate of angiographic occlusion.


The results of the study showed that the wind design of Deltapaq achieved a more homogenous distribution of coils within the aneurysm dome compared with the helical and complex microcoil systems (p=0.018). In the in vitro study, Deltapaq coils were more uniformly distributed in the dome of the aneurysm than were the complex (Cashmere) and helical (Helipaq) coils.


The average packing density for Deltapaq (39.1%) was significantly higher than the complex (35.2%) and helical (32.2%) coil systems. In addition, Deltapaq had the highest rate of angiographic occlusion (Class 1) based on the Raymond score, a qualitative measure of permeability. Researchers concluded that the evaluation of emerging coil technologies with respect to treatment durability may be well served by an assessment of their uniformity of distribution within an aneurysm, in addition to the traditional packing density and angiographic occlusion scoring methods. 


“This study suggests that the uniformity across the dome of the aneurysm may play an important role in enhancing the durability of endovascular treatment and is an important area for further study and confirmation,” said Bernard R Bendok, study co-author and associate professor of Neurological Surgery and Radiology at Northwestern University’s Feinberg School of Medicine. “The application of a coil uniformity model may provide valuable design information.”


Researchers’ views


Two of the study investigators Matthew Gounis, director, New England Center for Stroke Research (NECStR), director of Scientific Affairs, Advanced MRI Center (AMRIC) and assistant professor, Department of Radiology, University of Massachusetts, USA, and  Bernard R Bendok, Neurovascular and skull base surgeon, director, Neurointerventional Surgery Program, Northwestern Memorial Hospital and Northwestern Medical Faculty Foundation, USA, answered some questions from NeuroNews.


Why are these results important?


As the concept of changing the way coils are made, starting with the primary coil wind and then designing techniques for secondary shaping, the possibilities of altering coil properties expands exponentially. Thus, having benchtop techniques to properly characterise the way these devices will perform clinically becomes of paramount importance. This is the first study that demonstrates how coil design ultimately impacts the manner in which the coils distribute in an aneurysm phantom, essentially the ability of a coil to find voids and reduce permeability of the coil mass.


Could you give us perspective on the issue?


Robust scientific method needs to be applied in order to understand the advantages of a given neurointerventional device. The manner in which this study was conducted, multicentre and multidisciplinary collaboration, may serve as a viable model for thoughtful research into important questions in neurointerventional surgery.


What would you recommend on the basis of these findings to your interventional colleagues?


In an era of flow diverters and surface modified embolic coils, the role of platinum embolic coils remains the first line for the endovascular treatment of most brain aneurysms. Continued research into improving the detachable coil remains important area, as this technology has secured its place in the treatment of brain aneurysms for the foreseeable future.


What are the limitations of this study?


The true clinical significance of this finding has yet to be confirmed clinically. This could be an opportunity for future research.