Research Papers

Regional Structural and Biomechanical Alterations of the Ovine Main Pulmonary Artery During Postnatal Growth

[+] Author and Article Information
Christopher A. Carruthers

Department of Bioengineering,
University of Pittsburgh,
Pittsburgh, PA 15219

Simon C. Watkins

Center for Biologic Imaging,
University of Pittsburgh,
Pittsburgh, PA 15219

John E. Mayer

Department of Cardiac Surgery,
Boston Children's Hospital and Harvard Medical School,
Boston, MA 02481

Michael S. Sacks

Professor of Biomedical Engineering,
Department of Biomedical Engineering,
Institute for Computational Engineering and Science,
University of Texas,
Austin, TX 78712
e-mail: msacks@ices.utexas.edu

1 For 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 135(2), 021022 (Feb 07, 2013) (11 pages) Paper No: BIO-12-1591; doi: 10.1115/1.4023389 History: Received December 01, 2012; Accepted December 27, 2012; Revised December 27, 2012

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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Adatia, I., Kothari, S. S., and Feinstein, J. A., 2010, “Pulmonary Hypertension Associated With Congenital Heart Disease: Pulmonary Vascular Disease: The Global Perspective,” Chest, 137(6 Suppl), pp. 52S–61S. [CrossRef] [PubMed]
Tulloh, R. M., 2005, “Congenital Heart Disease in Relation to Pulmonary Hypertension in Paediatric Practice,” Paediatr. Respir. Rev., 6(3), pp. 174–180. [CrossRef] [PubMed]
Deterling, R. A., Jr., and Clagett, O. T., 1947, “Aneurysm of the Pulmonary Artery: Review of the Literature and Report of a Case,” Am. Heart J., 34(4), pp. 471–499. [CrossRef] [PubMed]
Kutty, S., Kaul, S., Danford, C. J., and Danford, D. A., 2010, “Main Pulmonary Artery Dilation in Association with Congenital Bicuspid Aortic Valve in the Absence of Pulmonary Valve Abnormality,” Heart, 96(21), pp. 1756–1761. [CrossRef] [PubMed]
Patnaik, A. N., Barik, R., Babu, S., and Gullati, A. S., 2012, “A Rare Case of Left Lung Hypoplasia Associated With Congenital Pulmonary Artery Aneurysm and Ventricular Septal Defect,” Pediatr. Cardiol. (in press).
Greenwald, S. E., Johnson, R. J., and Haworth, S. G., 1984, “Pulmonary Vascular Input Impedance in the Newborn and Infant Pig,” Cardiovasc. Res., 18, pp. 44–50. [CrossRef] [PubMed]
Lammers, S. R., Kao, P. H., Qi, H. J., Hunter, K., Lanning, C., Albietz, J., Hofmeister, S., Mecham, R., Stenmark, K. R., and Shandas, R., 2008, “Changes in the Structure-Function Relationship of Elastin and Its Impact on the Proximal Pulmonary Arterial Mechanics of Hypertensive Calves,” Am. J. Physiol. Heart Circ. Physiol., 295(4), pp. H1451–H1459. [CrossRef] [PubMed]
Kogon, B. E., Patel, M., Pernetz, M., Mcconnell, M., and Book, W., 2009, “Late Pulmonary Valve Replacement in Congenital Heart Disease Patients Without Original Congenital Pulmonary Valve Pathology,” Pediatr. Cardiol., 31(1), pp. 74–79. [CrossRef] [PubMed]
Ono, M., Goerler, H., Kallenbach, K., Boethig, D., Westhoff-Bleck, M., and Breymann, T., 2007, “Aortic Valve-Sparing Reimplantation for Dilatation of the Ascending Aorta and Aortic Regurgitation Late After Repair of Congenital Heart Disease,” J. Thorac. Cardiovasc. Surg., 133(4), pp. 876–879. [CrossRef] [PubMed]
Rosenberg, H. G., Williams, W. G., Trusler, G. A., Higa, T., and Rabinovitch, M., 1987, “Structural Composition of Central Pulmonary Arteries. Growth Potential After Surgical Shunts,” J. Thorac. Cardiovasc. Surg., 94(4), pp. 498–503. [PubMed]
Mayer, J. E., Jr., 1995, “Uses of Homograft Conduits for Right Ventricle to Pulmonary Artery Connections in the Neonatal Period,” Semin. Thorac. Cardiovasc. Surg., 7(3), pp. 130–132. [PubMed]
Cho, S. W., Kim, I. K., Kang, J. M., Song, K. W., Kim, H. S., Park, C. H., Yoo, K. J., and Kim, B. S., 2009, “Evidence for In Vivo Growth Potential and Vascular Remodeling of Tissue-Engineered Artery,” Tissue Eng. Part A, 15(4), pp. 901–912. [CrossRef] [PubMed]
Hoerstrup, S. P., Cummings Mrcs, I., Lachat, M., Schoen, F. J., Jenni, R., Leschka, S., Neuenschwander, S., Schmidt, D., Mol, A., Gunter, C., Gossi, M., Genoni, M., and Zund, G., 2006, “Functional Growth in Tissue-Engineered Living, Vascular Grafts: Follow-up at 100 Weeks in a Large Animal Model,” Circulation, 114(1 Suppl), pp. I159–I166. [CrossRef] [PubMed]
Shinoka, T., Shum-Tim, D., Ma, P. X., Tanel, R. E., Isogai, N., Langer, R., Vacanti, J. P., and Mayer, J. E., Jr., 1998, “Creation of Viable Pulmonary Artery Autografts Through Tissue Engineering,” J. Thorac. Cardiovasc. Surg., 115(3), pp. 536–546. [CrossRef] [PubMed]
Mol, A., Smits, A. I., Bouten, C. V., and Baaijens, F. P., 2009, “Tissue Engineering of Heart Valves: Advances and Current Challenges,” Expert Rev. Med. Devices, 6(3), pp. 259–275. [CrossRef] [PubMed]
Huang, Y., Guo, X., and Kassab, G. S., 2006, “Axial Nonuniformity of Geometric and Mechanical Properties of Mouse Aorta is Increased During Postnatal Growth,” Am. J. Physiol. Heart Circ. Physiol., 290(2), pp. H657–H664. [CrossRef] [PubMed]
Sugimoto, T., Miyazaki, H., and Hayashi, K., 2003, “Age-Related Changes in the Morphology and Mechanics of Arterial Wall in the Rat,” JSME Int. J., 46(4), pp. 1312–1320. [CrossRef]
Wells, S. M., Langille, B. L., and Adamson, S. L., 1998, “In Vivo and In Vitro Mechanical Properties of the Sheep Thoracic Aorta in the Perinatal Period and Adulthood,” Am. J. Physiol., 274(43), pp. H1749–H1760. [PubMed]
Wells, S. M., Langille, B. L., Lee, J. M., and Adamson, S. L., 1999, “Determinants of Mechanical Properties in the Developing Ovine Thoracic Aorta,” Am. J. Physiol., 277(4), pp. H1385–H1391. [PubMed]
Haskett, D., Johnson, G., Zhou, A., Utzinger, U., and Vande Geest, J., 2010, “Microstructural and Biomechanical Alterations of the Human Aorta as a Function of Age and Location,” Biomech. Model. Mechanobiol., 9(6), pp. 725–736. [CrossRef] [PubMed]
Bruel, A., and Oxlund, H., 1996, “Changes in Biomechanical Properties, Composition of Collagen and Elastin, and Advanced Glycation Endproducts of the Rat Aorta in Relation to Age,” Atherosclerosis, 127(2), pp. 155–165. [CrossRef] [PubMed]
Gaballa, M. A., Jacob, C. T., Raya, T. E., Liu, J., Simon, B., and Goldman, S., 1998, “Large Artery Remodeling During Aging: Biaxial Passive and Active Stiffness,” Hypertension, 32(3), pp. 437–443. [CrossRef] [PubMed]
Boumaza, S., Arribas, S. M., Osborne-Pellegrin, M., Mcgrath, J. C., Laurent, S., Lacolley, P., and Challande, P., 2001, “Fenestrations of the Carotid Internal Elastic Lamina and Structural Adaptation in Stroke-Prone Spontaneously Hypertensive Rats,” Hypertension, 37(4), pp. 1101–1107. [CrossRef] [PubMed]
Gottlieb, D., Kunal, T., Emani, S., Aikawa, E., Brown, D. W., Powell, A. J., Nedder, A., Engelmayr, G. C., Jr., Melero-Martin, J. M., Sacks, M. S., and Mayer, J. E., Jr., 2010, “In Vivo Monitoring of Function of Autologous Engineered Pulmonary Valve,” J. Thorac. Cardiovasc. Surg., 139(3), pp. 723–731. [CrossRef] [PubMed]
Gottlieb, D., Fata, B., Powell, A. J., Cois, A., Annese, D., Tandon, K., Stetten, G., Mayer, J. E., Jr., and Sacks, M. S., “Pulmonary Artery Dimensional Changes in a Growing Ovine Model: Comparisons With the Ascending Aorta,” J. Heart Valve Dis. (in-press).
Fata, B., Gottlieb, D., Mayer, J. E., and Sacks, M. S., “Postnatal In Vivo Surface Growth Deformation Patterns of the Ovine Main Pulmonary Artery and Ascending Aorta,” J. Biomech. Eng. (submitted).
Grashow, J., 2005, “Evaluation of the Biaxial Mechanical Properties of the Mitral Valve Leaflet Under Physiological Loading Conditions,” Ph.D. thesis, University of Pittsburgh, Pittsburgh, PA.
Han, H. C., and Fung, Y. C., 1996, “Direct Measurement of Transverse Residual Strains in Aorta,” Am. J. Physiol., 270(2 Pt 2), pp. H750–H759. [PubMed]
Meijering, E., Jacob, M., Sarria, J. C. F., Steiner, P., Hirling, H., and Unser, M., 2004, “Design and Validation of a Tool for Neurite Tracing and Analysis in Fluorescence Microscopy Images,” Cytometry, Part A, 58A(2), pp. 167–176. [CrossRef]
Hill, M. R., Duan, X., Gibson, G. A., Watkins, S., and Robertson, A. M., 2012, “A Theoretical and Non-Destructive Experimental Approach for Direct Inclusion of Collagen Orientaiton and Recruitment Into Mechanical Models of the Artery Wall,” J. Biomech., 45(5), pp. 762–771. [CrossRef] [PubMed]
Courtney, T., Sacks, M. S., Stankus, J., Guan, J., and Wagner, W. R., 2006, “Design and Analysis of Tissue Engineering Scaffolds That Mimic Soft Tissue Mechanical Anisotropy,” Biomaterials, 27(19), pp. 3631–3638. [CrossRef] [PubMed]
Vande Geest, J. P., Di Martino, E. S., Bohra, A., Makaroun, M. S., and Vorp, D. A., 2006, “A Biomechanics-Based Rupture Potential Index for Abdominal Aortic Aneurysm Risk Assessment: Demonstrative Application,” Ann. N. Y. Acad. Sci., 1085, pp. 11–21. [CrossRef] [PubMed]
Gozna, E. R., Marble, A. E., Shaw, A., and Holland, J. G., 1974, “Age-Related Changes in the Machanics of the Aorta and Pulmonary Artery of Man,” J. Appl. Physiol., 36(4), pp. 407–411. [PubMed]
Vande Geest, J. P., Sacks, M. S., and Vorp, D. A., 2004, “Age Dependency of the Biaxial Biomechanical Behavior of Human Abdominal Aorta,” J. Biomech. Eng., 126(6), pp. 815–822. [CrossRef] [PubMed]
Choudhury, N., Bouchot, O., Rouleau, L., Tremblay, D., Cartier, R., Butany, J., Mongrain, R., and Leask, R. L., 2009, “Local Mechanical and Structural Properties of Healthy and Diseased Human Ascending Aorta Tissue,” Cardiovasc. Pathol., 18(2), pp. 83–91. [CrossRef] [PubMed]
Patel, D. J., Schilder, D. P., and Mallos, A. J., 1960, “Mechanical Properties and Dimensions of the Major Pulmonary Arteries,” J. Appl. Physiol., 15(1), pp. 92–96. [PubMed]
Drexler, E. S., Quinn, T. P., Slifka, A. J., Mccowan, C. N., Bischoff, J. E., Wright, J. E., Ivy, D. D., and Shandas, R., 2007, “Comparison of Mechanical Behavior Among the Extrapulmonary Arteries from Rats,” J. Biomech., 40(4), pp. 812–819. [CrossRef] [PubMed]
Hunter, K. S., Albietz, J. A., Lee, P. F., Lanning, C. J., Lammers, S. R., Hofmeister, S. H., Kao, P. H., Qi, H. J., Stenmark, K. R., and Shandas, R., 2010, “In Vivo Measurement of Proximal Pulmonary Artery Elastic Modulus in the Neonatal Calf Model of Pulmonary Hypertension: Development and Ex Vivo Validation,” J. Appl. Physiol., 108(4), pp. 968–975. [CrossRef] [PubMed]
Chesler, N. C., Thompson-Figueroa, J., and Millburne, K., 2004, “Measurements of Mouse Pulmonary Artery Biomechanics,” J. Biomech. Eng., 126(2), pp. 309–314. [CrossRef] [PubMed]
Patel, D. J., Freitas, F. M. D., and Mallos, A. J., 1962, “Mechanical Function of the Main Pulmonary Artery,” J. Appl. Physiol., 17(2), pp. 205–208. [PubMed]
Chuong, C. J., and Fung, Y. C., 1986, “On Residual Stress in Arteries,” J. Biomech. Eng., 108, pp. 189–192. [CrossRef] [PubMed]
Fung, Y. C., 1990, Biomechanics: Motion, Flow, Stress, and Growth, Springer, New York, p. 569.
Vaishnav, R. N., and Vossoughi, J., 1983, “Estimation of Residual Strains in Aortic Segments,” Biomechanical Engineering II, Recent Developments, Pergamon, New York, pp. 330–333.
Jiang, Z. L., Kassab, G. S., and Fung, Y. C., 1994, “Diameter-Defined Strahler System and Connectivity Matrix of the Pulmonary Arterial Tree,” J. Appl. Physiol., 76(2), pp. 882–892. [PubMed]
Fung, Y. C., 1991, “What Are the Residual Stresses Doing in Our Blood Vessels?,” Ann. Biomed. Eng., 19(3), pp. 237–249. [CrossRef] [PubMed]
Liu, S. Q., and Fung, Y. C., 1992, “Changes in the Rheological Properties of Blood Vessel Tissue Remodeling in the Course of Development of Diabetes,” Biorheology, 29(5-6), pp. 443–457. [PubMed]
Zou, Y., and Zhang, Y., 2009, “An Experimental and Theoretical Study on the Anisotropy of Elastin Network,” Ann. Biomed. Eng., 37(8), pp. 1572–1583. [CrossRef] [PubMed]
Lillie, M. A., Shadwick, R. E., and Gosline, J. M., 2010, “Mechanical Anisotropy of Inflated Elastic Tissue From the Pig Aorta,” J. Biomech., 43(11), pp. 2070–2078. [CrossRef] [PubMed]
Roach, M. R., and Burton, A. C., 1957, “The Reason for the Shape of the Distensibility Curves of Arteries,” Can. J. Biochem. Physiol., 35, pp. 681–690. [CrossRef] [PubMed]
Hill, M., 2011, “A Novel Approach for Combining Biomechanical and Micro-Structural Analyses to Assess the Mechanical and Damage Properties of the Artery Wall,” Ph.D. thesis, University of Pittsburgh, Pittsburgh, PA.
Keyes, J. T., Lockwood, D. R., Utzinger, U., Montilla, L. G., Witte, R. S., and Vande Geest, J. P., 2012, “Comparisons of Planar and Tubular Biaxial Tensile Testing Protocols of the Same Porcine Coronary Arteries,” Ann. Biomed. Eng. (in press).
Keyes, J. T., Haskett, D. G., Utzinger, U., Azhar, M., and Vande Geest, J. P., 2011, “Adaptation of a Planar Microbiaxial Optomechanical Device for the Tubular Biaxial Microstructural and Macroscopic Characterization of Small Vascular Tissues,” J. Biomech. Eng., 133(7), p. 075001. [CrossRef] [PubMed]
Hollander, Y., Durban, D., Lu, X., Kassab, G. S., and Lanir, Y., 2011, “Experimentally Validated Microstructural 3d Constitutive Model of Coronary Arterial Media,” J. Biomech. Eng., 133(3), p. 031007. [CrossRef] [PubMed]
Hollander, Y., Durban, D., Lu, X., Kassab, G. S., and Lanir, Y., 2011, “Constitutive Modeling of Coronary Arterial Media–Comparison of Three Model Classes,” J. Biomech. Eng., 133(6), p. 061008. [CrossRef] [PubMed]
Freed, A. D., and Doehring, T. C., 2005, “Elastic Model for Crimped Collagen Fibrils,” J. Biomech. Eng., 127(4), pp. 587–593. [CrossRef] [PubMed]
Prot, V., Skallerud, B., Sommer, G., and Holzapfel, G. A., 2010, “On Modelling and Analysis of Healthy and Pathological Human Mitral Valves: Two Case Studies,” J. Mech. Behav. Biomed. Mater., 3(2), pp. 167–177. [CrossRef] [PubMed]
Ooi, C. Y., Wang, Z., Tabima, D. M., Eickhoff, J. C., and Chesler, N. C., 2010, “The Role of Collagen in Extralobar Pulmonary Artery Stiffening in Response to Hypoxia-Induced Pulmonary Hypertension,” Am. J. Physiol. Heart Circ. Physiol., 299(6), pp. H1823–H1831. [CrossRef] [PubMed]
Tozzi, C. A., Christiansen, D. L., Poiani, G. J., and Riley, D. J., 1994, “Excess Collagen in Hypertensive Pulmonary Arteries Decreases Vascular Distensibility,” Am. J. Respir. Crit. Care Med., 149(5), pp. 1317–1326. [PubMed]
Poiani, G. J., Tozzi, C. A., Yohn, S. E., Pierce, R. A., Belsky, S. A., Berg, R. A., Yu, S. Y., Deak, S. B., and Riley, D. J., 1990, “Collagen and Elastin Metabolism in Hypertensive Pulmonary Arteries of Rats,” Circ. Res., 66(4), pp. 968–978. [CrossRef] [PubMed]
Berry, C. L., Looker, T., and Germain, J., 1972, “The Growth and Development of the Rat Aorta. I. Morphological Aspects,” J. Anat., 113(Pt 1), pp. 1–16. [PubMed]
Leung, D. Y. M., Glagov, S., and Mathews, M. B., 1977, “Elastin and Collagen Accumulation in Rabbit Ascending Aorta and Pulmonary Trunk During Postnatal Growth. Correlation of Cellular Synthetic Response With Medial Tension,” Circ. Res., 41(3), pp. 316–323. [CrossRef] [PubMed]


Grahic Jump Location
Fig. 3

The miniature biaxial stretching device combined with MPM system. Specimen's reflection in mirror captured by camera underneath the device stage (bottom).

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Fig. 2

(a) Collagen (red) and elastin (green) of a proximal section of tunica media shown on left with each fiber population individually displayed in middle. (b) A depiction of orientation analysis of elastin fibers is demonstrated through superimposed regional fiber orientation vectors (white arrows) with corresponding normalized fiber orientation distribution graph.

Grahic Jump Location
Fig. 1

(a) Anterior view of the ascending aorta (AA) and pulmonary trunk (PT) with medial aspect outlined (dashed square), showing the sinotubular junction (STJ) and bifurcation (BFN), which define the main pulmonary artery (PA). (b) Locations of biaxial testing samples excised from the PA's anterior (A), medial (M), posterior (P), and lateral (L) walls. Also shown are the estimated change in the PA circumference with growth (circumferential growth stretch, λθ) from Ref. [26], highlighting regions of large and small growth deformations, used to guide the specimen selection locations. (c) Sample unloaded ring (top) and stress-free (bottom) states shown for circumferential luminal and abluminal residual strain measurements at the STJ and BFN.

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Fig. 4

Results from the equibiaxial stress protocol for each of four regions displayed for juvenile (circles) and adult (triangles) groups. Responses demonstrated mild nonlinearity and were circumferentially stiffer than longitudinally in all regions except the posterior wall, which was nearly isotropic in both age groups. The longitudinal compliance (maximum measured deformation) of lateral wall increased significantly with growth.

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Fig. 5

(a) Ratio of maximum longitudinal to circumferential stretch of equi-biaxial stress protocol in four regions of PA with growth. Here, the anisotropy of the medial wall increased substantially during postnatal growth while it was maintained in the other regions. (b) Circumferential residual strains at the luminal and abluminal surfaces in juvenile and adult ovine PA. Larger residual strain values were measured on abluminal surface than luminal surface in both age groups; BFN residual strain decreased considerably over time while it was maintained at STJ.

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Fig. 6

MPM image set showing different layer structures of PA. The top image is a montage of a transverse image sections of PA anterior wall with each layer labeled. MPM images of representative en-face sections of intimal, medial, and adventitial layers (bottom) displaying collagen (red) and elastin (green) structure and content in each layer: Collagen was relatively thin and had fine crimp structure in media and formed into thicker fiber bundles in adventitia; relative elastin content of media (62 ± 1%) was significantly larger than collagen while collagen was dominant fiber in adventitia (63 ± 2%).

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Fig. 7

(a) Thicknesses (in mm) of excised specimens of adult and juvenile PA. Anterior and posterior samples were consistently thicker than the medial and lateral samples. (b) Relative thickness of each arterial layer in transverse section of PA wall: media is substantially thicker than the intima and adventitia.

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Fig. 8

Regional variations in mean elastin fiber orientation and NOI from the PA wall with growth. (a) Elastin alignment in medial wall did not change significantly with growth, whereas the anterior and medial wall elastin fiber alignment was significantly closer to circumferential direction than posterior wall. (b) NOI of lateral wall was less than other regions in juvenile stage. In lateral wall, significant increase in circumferential mean orientation of elastin fibers with growth (from 23 ± 6 deg to 1 ± 7 deg) was associated with a significant drop in NOI from 60 ± 3% to 46 ± 4%. Overall, only the lateral region demonstrated statistically significant growth changes in both mean fiber direction and NOI.

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Fig. 9

The mean collagen (red) and elastin (green) fiber orientation histograms at peak physiological stretch in the juvenile and adult medial PA wall quantified in the MPM-biaxial-deformation experiments. Also shown for the elastin are the histogram results at low stretch, which were similar to the peak stretch results, supporting the assumption that equi-biaxial stretch induced no change in fiber alignment.

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Fig. 10

Growth adaptations in collagen fiber (a) tortuosity and (b) recruitment behavior of medial aspect of PA wall measured at different equibiaxial deformation levels. Overall, the adult group demonstrated greater initial tortuosity and recruitment rate compared to the juvenile state. (c) Biaxial stress-stretch behavior of medial aspect of adult PA wall near physiological biaxial stress levels demonstrated near equibiaxial deformation.



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