The engineering foundation for novel approaches for the repair of congenital defects that involve the main pulmonary artery (PA) must rest on an understanding of changes in the structure-function relationship that occur during postnatal maturation. In the present study, we quantified the postnatal growth patterns in structural and biomechanical behavior in the ovine PA in the juvenile and adult stages. The biaxial mechanical properties and collagen and elastin fiber architecture were studied in four regions of the PA wall, with the collagen recruitment of the medial region analyzed using a custom biaxial mechanical-multiphoton microscopy system. Circumferential residual strain was also quantified at the sinotubular junction and bifurcation locations, which delimit the PA. The PA wall demonstrated significant mechanical anisotropy, except in the posterior region where it was nearly isotropic. Overall, we observed only moderate changes in regional mechanical properties with growth. We did observe that the medial and lateral locations experience a moderate increase in anisotropy. There was an average of about 24% circumferential residual stain present at the luminal surface in the juvenile stage that decreased to 16% in the adult stage with a significant decrease at the bifurcation, implying that the PA wall remodels toward the bifurcation with growth. There were no measurable changes in collagen and elastin content of the tunica media with growth. On average, the collagen fiber recruited more rapidly with strain in the adult compared to the juvenile. Interestingly, the PA thickness remained constant with growth. When this fact is combined with the observed stable overall mechanical behavior and increase in vessel diameter with growth, a simple Laplace Law wall stress estimate suggests an increase in effective PA wall stress with postnatal maturation. This observation is contrary to the accepted theory of maintenance of homeostatic stress levels in the regulation of vascular function and suggests alternative mechanisms regulate postnatal somatic growth. Understanding the underlying mechanisms, incorporating important structural features during growth, will help to improve our understanding of congenital defects of the PA and lay the basis for functional duplication in their repair and replacement.
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February 2013
Research-Article
Regional Structural and Biomechanical Alterations of the Ovine Main Pulmonary Artery During Postnatal Growth
Bahar Fata,
Bahar Fata
1
1For this work, Dr. Fata won second place in the Ph.D. student paper competition in the “Cardiovascular solid mechanics” category at the 2012 summer bioengineering conference.
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Christopher A. Carruthers,
Christopher A. Carruthers
Department of Bioengineering,
Pittsburgh,
University of Pittsburgh
,Pittsburgh,
PA 15219
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Simon C. Watkins,
Simon C. Watkins
Center for Biologic Imaging,
University of Pittsburgh
,Pittsburgh, PA 15219
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John E. Mayer,
John E. Mayer
, Jr.
Department of Cardiac Surgery,
Boston,
Boston Children's Hospital and Harvard Medical School
,Boston,
MA 02481
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Michael S. Sacks
Michael S. Sacks
2
Professor of Biomedical Engineering,
Department of Biomedical Engineering,
University of Texas,
e-mail: msacks@ices.utexas.edu
Department of Biomedical Engineering,
Institute for Computational Engineering and Science
,University of Texas,
Austin, TX 78712
e-mail: msacks@ices.utexas.edu
2Corresponding author. Present address: Institute for Computational Engineering and Sciences (ICES), The University of Texas at Austin, 201 East 24th Street, ACES 5.438, 1 University Station, C0200, Austin, TX 78712-0027.
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Christopher A. Carruthers
Department of Bioengineering,
Pittsburgh,
University of Pittsburgh
,Pittsburgh,
PA 15219
Simon C. Watkins
Center for Biologic Imaging,
University of Pittsburgh
,Pittsburgh, PA 15219
John E. Mayer
, Jr.
Department of Cardiac Surgery,
Boston,
Boston Children's Hospital and Harvard Medical School
,Boston,
MA 02481
Michael S. Sacks
Professor of Biomedical Engineering,
Department of Biomedical Engineering,
University of Texas,
e-mail: msacks@ices.utexas.edu
Department of Biomedical Engineering,
Institute for Computational Engineering and Science
,University of Texas,
Austin, TX 78712
e-mail: msacks@ices.utexas.edu
1For this work, Dr. Fata won second place in the Ph.D. student paper competition in the “Cardiovascular solid mechanics” category at the 2012 summer bioengineering conference.
2Corresponding author. Present address: Institute for Computational Engineering and Sciences (ICES), The University of Texas at Austin, 201 East 24th Street, ACES 5.438, 1 University Station, C0200, Austin, TX 78712-0027.
Contributed by the Bioengineering Division of ASME for publication in the JOURNAL OF BIOMECHANICAL ENGINEERING. Manuscript received December 1, 2012; final manuscript received December 27, 2012; accepted manuscript posted January 18, 2013; published online February 7, 2013. Editor: Victor H. Barocas.
J Biomech Eng. Feb 2013, 135(2): 021022 (11 pages)
Published Online: February 7, 2013
Article history
Received:
December 1, 2012
Revision Received:
December 27, 2012
Accepted:
December 27, 2012
Citation
Fata, B., Carruthers, C. A., Gibson, G., Watkins, S. C., Gottlieb, D., Mayer, J. E., and Sacks, M. S. (February 7, 2013). "Regional Structural and Biomechanical Alterations of the Ovine Main Pulmonary Artery During Postnatal Growth." ASME. J Biomech Eng. February 2013; 135(2): 021022. https://doi.org/10.1115/1.4023389
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