Journal article 1271 views 143 downloads
Integrated geometric and mechanical analysis of an image-based lymphatic valve
Journal of Biomechanics, Volume: 64, Pages: 172 - 179
Swansea University Authors:
Igor Sazonov , Raoul van Loon
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DOI (Published version): 10.1016/j.jbiomech.2017.09.040
Abstract
Lymphatic valves facilitate the lymphatic system’s role in maintaining fluid homeostasis. Malformed valves are found in several forms of primary lymphœdema, resulting in incurable swelling of the tissues and immune dysfunction. Their experimental study is complicated by their small size and operatio...
Published in: | Journal of Biomechanics |
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ISSN: | 00219290 |
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2017
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2020-07-14T14:24:51.5428719 v2 35694 2017-09-28 Integrated geometric and mechanical analysis of an image-based lymphatic valve 05a507952e26462561085fb6f62c8897 0000-0001-6685-2351 Igor Sazonov Igor Sazonov true false 880b30f90841a022f1e5bac32fb12193 0000-0003-3581-5827 Raoul van Loon Raoul van Loon true false 2017-09-28 AERO Lymphatic valves facilitate the lymphatic system’s role in maintaining fluid homeostasis. Malformed valves are found in several forms of primary lymphœdema, resulting in incurable swelling of the tissues and immune dysfunction. Their experimental study is complicated by their small size and operation in low pressure and low Reynolds number environments. Mathematical models of these structures can give insight and complement experimentation. In this work, we present the first valve geometry reconstructed from confocal imagery and used in the construction of a subject-specific model in a closing mode. A framework is proposed whereby an image is converted into a valve model. An FEA study was performed to identify the significance of the shear modulus, the consequences of smoothing the leaflet surface and the effect of wall motion on valve behaviour. Smoothing is inherent to any analysis from imagery. The nature of the image, segmentation and meshing all cause attenuation of high-frequency features. Smoothing not only causes loss of surface area but also the loss of high-frequency geometric features which may reduce stiffness. This work aimed to consider these effects and inform studies by taking a manual reconstruction and through manifold harmonic analysis, attenuating higher frequency features to replicate lower resolution images or lower degree-of-freedom reconstructions. In conclusion, two metrics were considered: trans-valvular pressure required to close the valve, ΔPc, and the retrograde volume displacement after closure. The higher ΔPc, the greater the volume of lymph that will pass through the valve during closure. Retrograde volume displacement after closure gives a metric of compliance of the valve and for the quality of the valve seal. In the case of the image-specific reconstructed valve, removing features with a wavelength longer than four μm caused changes in ΔPc. Varying the shear modulus from 10kPa to 60kPa caused a 3.85 fold increase in the retrograde volume displaced. The inclusion of a non-rigid wall caused ΔPc to increase from 1.56 to 2.52 cmH2O. Journal Article Journal of Biomechanics 64 172 179 00219290 Lymphatic; Valve; Harmonic manifold analysis; Segmentation; FEA 31 12 2017 2017-12-31 10.1016/j.jbiomech.2017.09.040 COLLEGE NANME Aerospace Engineering COLLEGE CODE AERO Swansea University 2020-07-14T14:24:51.5428719 2017-09-28T09:07:05.5846748 Faculty of Science and Engineering School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Aerospace Engineering Daniel J. Watson 1 Igor Sazonov 0000-0001-6685-2351 2 David C. Zawieja 3 James E. Moore 4 Raoul van Loon 0000-0003-3581-5827 5 0035694-09102017091451.pdf watson2017.pdf 2017-10-09T09:14:51.8400000 Output 1371157 application/pdf Accepted Manuscript true 2018-10-07T00:00:00.0000000 true eng |
title |
Integrated geometric and mechanical analysis of an image-based lymphatic valve |
spellingShingle |
Integrated geometric and mechanical analysis of an image-based lymphatic valve Igor Sazonov Raoul van Loon |
title_short |
Integrated geometric and mechanical analysis of an image-based lymphatic valve |
title_full |
Integrated geometric and mechanical analysis of an image-based lymphatic valve |
title_fullStr |
Integrated geometric and mechanical analysis of an image-based lymphatic valve |
title_full_unstemmed |
Integrated geometric and mechanical analysis of an image-based lymphatic valve |
title_sort |
Integrated geometric and mechanical analysis of an image-based lymphatic valve |
author_id_str_mv |
05a507952e26462561085fb6f62c8897 880b30f90841a022f1e5bac32fb12193 |
author_id_fullname_str_mv |
05a507952e26462561085fb6f62c8897_***_Igor Sazonov 880b30f90841a022f1e5bac32fb12193_***_Raoul van Loon |
author |
Igor Sazonov Raoul van Loon |
author2 |
Daniel J. Watson Igor Sazonov David C. Zawieja James E. Moore Raoul van Loon |
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Journal of Biomechanics |
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10.1016/j.jbiomech.2017.09.040 |
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Faculty of Science and Engineering |
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description |
Lymphatic valves facilitate the lymphatic system’s role in maintaining fluid homeostasis. Malformed valves are found in several forms of primary lymphœdema, resulting in incurable swelling of the tissues and immune dysfunction. Their experimental study is complicated by their small size and operation in low pressure and low Reynolds number environments. Mathematical models of these structures can give insight and complement experimentation. In this work, we present the first valve geometry reconstructed from confocal imagery and used in the construction of a subject-specific model in a closing mode. A framework is proposed whereby an image is converted into a valve model. An FEA study was performed to identify the significance of the shear modulus, the consequences of smoothing the leaflet surface and the effect of wall motion on valve behaviour. Smoothing is inherent to any analysis from imagery. The nature of the image, segmentation and meshing all cause attenuation of high-frequency features. Smoothing not only causes loss of surface area but also the loss of high-frequency geometric features which may reduce stiffness. This work aimed to consider these effects and inform studies by taking a manual reconstruction and through manifold harmonic analysis, attenuating higher frequency features to replicate lower resolution images or lower degree-of-freedom reconstructions. In conclusion, two metrics were considered: trans-valvular pressure required to close the valve, ΔPc, and the retrograde volume displacement after closure. The higher ΔPc, the greater the volume of lymph that will pass through the valve during closure. Retrograde volume displacement after closure gives a metric of compliance of the valve and for the quality of the valve seal. In the case of the image-specific reconstructed valve, removing features with a wavelength longer than four μm caused changes in ΔPc. Varying the shear modulus from 10kPa to 60kPa caused a 3.85 fold increase in the retrograde volume displaced. The inclusion of a non-rigid wall caused ΔPc to increase from 1.56 to 2.52 cmH2O. |
published_date |
2017-12-31T03:44:29Z |
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1763752090458390528 |
score |
11.021648 |