Limitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters

Ronald A Robinson, Luke H Herbertson, Srilekha Sarkar Das, Richard A Malinauskas, William F Pritchard, Laurence W GrossmanOffice of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD, USAAbstract: The purpose of this s...

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Autores principales:	Robinson RA, Herbertson LH, Sarkar Das S, Malinauskas RA, Pritchard WF, Grossman LW
Formato:	article
Lenguaje:	EN
Publicado:	Dove Medical Press 2013
Materias:	Medical technology R855-855.5
Acceso en línea:	https://doaj.org/article/2ea0ff157014409ba38e83e861608a32
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spelling	oai:doaj.org-article:2ea0ff157014409ba38e83e861608a322021-12-02T01:36:54ZLimitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters1179-1470https://doaj.org/article/2ea0ff157014409ba38e83e861608a322013-05-01T00:00:00Zhttp://www.dovepress.com/limitations-of-using-synthetic-blood-clots-for-measuring-in-vitro-clot-a13020https://doaj.org/toc/1179-1470Ronald A Robinson, Luke H Herbertson, Srilekha Sarkar Das, Richard A Malinauskas, William F Pritchard, Laurence W GrossmanOffice of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD, USAAbstract: The purpose of this study was first to evaluate the clot capture efficiency and capture location of six currently-marketed vena cava filters in a physiological venous flow loop, using synthetic polyacrylamide hydrogel clots, which were intended to simulate actual blood clots. After observing a measured anomaly for one of the test filters, we redirected the focus of the study to identify the cause of poor clot capture performance for large synthetic hydrogel clots. We hypothesized that the uncharacteristic low clot capture efficiency observed when testing the outlying filter can be attributed to the inadvertent use of dense, stiff synthetic hydrogel clots, and not as a result of the filter design or filter orientation. To study this issue, sheep blood clots and polyacrylamide (PA) synthetic clots were injected into a mock venous flow loop containing a clinical inferior vena cava (IVC) filter, and their captures were observed. Testing was performed with clots of various diameters (3.2, 4.8, and 6.4 mm), length-to-diameter ratios (1:1, 3:1, 10:1), and stiffness. By adjusting the chemical formulation, PA clots were fabricated to be soft, moderately stiff, or stiff with elastic moduli of 805 ± 2, 1696 ± 10 and 3295 ± 37 Pa, respectively. In comparison, the elastic moduli for freshly prepared sheep blood clots were 1690 ± 360 Pa. The outlying filter had a design that was characterized by peripheral gaps (up to 14 mm) between its wire struts. While a low clot capture rate was observed using large, stiff synthetic clots, the filter effectively captured similarly sized sheep blood clots and soft PA clots. Because the stiffer synthetic clots remained straight when approaching the filter in the IVC model flow loop, they were more likely to pass between the peripheral filter struts, while the softer, physiological clots tended to fold and were captured by the filter. These experiments demonstrated that if synthetic clots are used as a surrogate for animal or human blood clots for in vitro evaluation of vena cava filters, the material properties (eg, elastic modulus) and dynamic behavior of the surrogate should first be assessed to ensure that they accurately mimic an actual blood clot within the body.Keywords: blood clot, elastic modulus, polyacrylamide hydrogel, in vitro testing of vena cava filtersRobinson RAHerbertson LHSarkar Das SMalinauskas RAPritchard WFGrossman LWDove Medical PressarticleMedical technologyR855-855.5ENMedical Devices: Evidence and Research, Vol 2013, Iss default, Pp 49-57 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medical technology R855-855.5
spellingShingle	Medical technology R855-855.5 Robinson RA Herbertson LH Sarkar Das S Malinauskas RA Pritchard WF Grossman LW Limitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters
description	Ronald A Robinson, Luke H Herbertson, Srilekha Sarkar Das, Richard A Malinauskas, William F Pritchard, Laurence W GrossmanOffice of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD, USAAbstract: The purpose of this study was first to evaluate the clot capture efficiency and capture location of six currently-marketed vena cava filters in a physiological venous flow loop, using synthetic polyacrylamide hydrogel clots, which were intended to simulate actual blood clots. After observing a measured anomaly for one of the test filters, we redirected the focus of the study to identify the cause of poor clot capture performance for large synthetic hydrogel clots. We hypothesized that the uncharacteristic low clot capture efficiency observed when testing the outlying filter can be attributed to the inadvertent use of dense, stiff synthetic hydrogel clots, and not as a result of the filter design or filter orientation. To study this issue, sheep blood clots and polyacrylamide (PA) synthetic clots were injected into a mock venous flow loop containing a clinical inferior vena cava (IVC) filter, and their captures were observed. Testing was performed with clots of various diameters (3.2, 4.8, and 6.4 mm), length-to-diameter ratios (1:1, 3:1, 10:1), and stiffness. By adjusting the chemical formulation, PA clots were fabricated to be soft, moderately stiff, or stiff with elastic moduli of 805 ± 2, 1696 ± 10 and 3295 ± 37 Pa, respectively. In comparison, the elastic moduli for freshly prepared sheep blood clots were 1690 ± 360 Pa. The outlying filter had a design that was characterized by peripheral gaps (up to 14 mm) between its wire struts. While a low clot capture rate was observed using large, stiff synthetic clots, the filter effectively captured similarly sized sheep blood clots and soft PA clots. Because the stiffer synthetic clots remained straight when approaching the filter in the IVC model flow loop, they were more likely to pass between the peripheral filter struts, while the softer, physiological clots tended to fold and were captured by the filter. These experiments demonstrated that if synthetic clots are used as a surrogate for animal or human blood clots for in vitro evaluation of vena cava filters, the material properties (eg, elastic modulus) and dynamic behavior of the surrogate should first be assessed to ensure that they accurately mimic an actual blood clot within the body.Keywords: blood clot, elastic modulus, polyacrylamide hydrogel, in vitro testing of vena cava filters
format	article
author	Robinson RA Herbertson LH Sarkar Das S Malinauskas RA Pritchard WF Grossman LW
author_facet	Robinson RA Herbertson LH Sarkar Das S Malinauskas RA Pritchard WF Grossman LW
author_sort	Robinson RA
title	Limitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters
title_short	Limitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters
title_full	Limitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters
title_fullStr	Limitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters
title_full_unstemmed	Limitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters
title_sort	limitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters
publisher	Dove Medical Press
publishDate	2013
url	https://doaj.org/article/2ea0ff157014409ba38e83e861608a32
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Limitations of using synthetic blood clots for measuring in vitro clot capture efficiency of inferior vena cava filters

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