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Ascending aortic aneurysm biomechanical properties are variable depending on aortic valve morphology

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Ascending aortic aneurysm biomechanical properties are variable depending on aortic valve morphology Joseph Muthu, ME,MS, Julie Philippi, PhD, Thomas Gleason, MD ... – PowerPoint PPT presentation

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Title: Ascending aortic aneurysm biomechanical properties are variable depending on aortic valve morphology


1
Ascending aortic aneurysm biomechanical
properties are variable depending on aortic valve
morphology
  • Joseph Muthu, ME,MS, Julie Philippi, PhD, Thomas
    Gleason, MD, David A. Vorp, PhD

2
Introduction
  • Biomechanical models of wall strength are being
    developed to better predict Ascending Aortic
    Aneurysm (TAA) dissection or disruption as
    compared to diameter criterion
  • TAA dissection/disruption represents a mechanical
    failure of the diseased aortic wall, and has been
    associated with diminished tensile strength.
  • BAV patients are predisposed to TAA formation
  • The correlation of variable TAA wall strength
    with aortic valve morphology is unknown

3
Purpose of This Study
  • Determine whether differences in wall tensile
    strength exist between BAV and TAV TAAs
  • Determine whether tensile strength depends on
    location and orientation of the tissue
  • Evaluate biomechanical model differences in BAV
    and TAV

4
Methods
  • Rectangular tissue specimens from TAA patients
    with BAV and TAV were harvested in
    circumferential and longitudinal orientations,
    and tested in uniaxial tensile test machine
    within 48 hrs.
  • The specimens were preconditioned for 10 cycles
    of loading and unloading
  • After preconditioning, the tissues were stretched
    at the rate of 8.5 of its initial gauge length
    until its failure
  • The Cauchy stress and strain were derived from
    force displacement data and initial tissue
    dimensions

5
Uniaxial Tensile Testing (LONG)
Ultimate Tensile Strength
6
Uniaxial Tensile Testing (CIRC)
Ultimate Tensile Strength
7
(No Transcript)
8
P 0.29
P 0.004
P0.0001
P0.009
9
Histology Collagen (Trichrome staining)
40X Brightfield Trichrome stain 5 µm paraffin
sections
Bluecollagen Red cytoplasm
10
Diameter
11
Conclusion
  • The average strength of aneurysmal wall in the
    circumferential direction was significantly
    higher than that of the longitudinal direction
    within the groups exhibiting anisotropic nature
    of the wall.
  • Wall strength of BAV may be stronger than TAV in
    both the orientations
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