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Clot friction variation with fibrin content; implications for resistance to thrombectomy
  1. Gillian M Gunning1,
  2. Kevin McArdle1,
  3. Mahmood Mirza1,
  4. Sharon Duffy1,2,
  5. Michael Gilvarry1,
  6. Patrick A Brouwer3
  1. 1Neuravi Ltd, Galway, Ireland
  2. 2Department of Mechanical and Industrial Engineering, Galway-Mayo Technologies Centre, Galway-Mayo Institute of Technology, Galway, Ireland
  3. 3Department of Neuroradiology, Karolinska University Hospital, Stockholm, Sweden
  1. Correspondence to Dr Patrick A Brouwer, Neuroradiology Department, Karolinska University Hospital, Solna, SE171 76 Stockholm, Sweden; patrickbrouwermd{at}


Background Despite significant advancements in the procedural efficacy of mechanical thrombectomy in patients with ischemic stroke in recent years, there still remains a portion of the population that does not achieve good recanalization. The reasons for this may be varied. We hypothesized that static friction between the clot and the vessel, or catheter wall might contribute to the difficulty in removing the clot.

Objective To determine if there is a relationship between clot composition and the resistance to sliding (friction) which might contribute to resistance to clot removal.

Methods As clot composition can vary significantly, we investigated five different types of clot in order to measure their respective frictional properties. To do this, a custom-made testing apparatus was created, consisting of various replaceable low-friction surfaces on which the clots could be placed. The surface was then gradually tilted until the clots began to slide; the angle at which this occurred is related to the coefficient of friction of the clots. The experiment was repeated on a bovine aortic surface in order to confirm the results.

Results We found that fibrin-rich clots (<20% red blood cell content) have a significantly higher coefficient of friction than clots with a red blood cell content >20%. This result was confirmed by repeating the experiment on a bovine aortic surface as a representation of the interaction between clots and the arterial wall.

Conclusions The friction properties of clots were found to be related to the content ratio of fibrin to red blood cells. Future imaging techniques that could show fibrin and red blood cell content might help us to predict the ‘stickiness’ of a clot.

  • Stroke
  • Thrombectomy

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  • GMG and KM contributed equally.

  • Contributors GMG: data analysis and interpretation, as well as manuscript writing. KM: experimental conception and design, the preparation of clots, data collection, analysis, and interpretation. MM: testing and data collection. SD: clot preparation, data collection, and data analysis. MG: experimental conception and design, data interpretation, and manuscript drafting and editing. PAB: experimental conception, testing, data interpretation, and manuscript drafting and editing. All authors provided suggestions and feedback and approved the final manuscript.

  • Funding This work was supported by Neuravi Ltd.

  • Competing interests GMG, KM, MM, SD, and MG: other work from Neuravi Ltd, outside the submitted work. PAB: personal fees from Neuravi, Stryker, Codman DePuy Synthes and Medtronic, outside the submitted work.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Please contact the corresponding author with data sharing requests.