Is the Structure of the Vessel Wall a Generator of Spiral Flow? A - - PowerPoint PPT Presentation

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Is the Structure of the Vessel Wall a Generator of Spiral Flow? A - - PowerPoint PPT Presentation

Mar 26, 2023 104 likes •212 views

Is the Structure of the Vessel Wall a Generator of Spiral Flow? A Cadaveric Histological Study Heire P 1 , Wilton J 1 , Jacques S 1 , Marie Y 2 , Jones R 3 , N Inston 2 1 Department of Anatomy, School of Immunity and Infection, College of Medical

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SLIDE 1

Is the Structure of the Vessel Wall a Generator of Spiral Flow? A Cadaveric Histological Study

Heire P1, Wilton J1, Jacques S1, Marie Y2, Jones R3, N Inston2

1Department of Anatomy, School of Immunity and Infection, College of Medical and Dental Sciences, University of

Birmingham, Birmingham, UK

2Department of Renal Surgery, Queen Elizabeth Hospital, University Hospitals Birmingham, Edgbaston, Birmingham, B15

2WB, UK

3Department of Radiology, Queen Elizabeth Hospital, University Hospitals Birmingham, Edgbaston, Birmingham, B15 2WB,

UK

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Background

  • In healthy individuals flow

patterns in the arterial tree have a spiral vector (Spiral Laminar Flow, SLF)

▫ Peripheral arteries with angioscopy (Stonebridge and Brophy 1991) ▫ Normal physiological finding (Houston et al 2003, Kilner et al 1993)

  • Spiral laminar flow may be

preventative against the development of atherosclerosis by:

▫ Reducing the laterally directed forces on the vessel wall and stabilising flow (Stonebridge et al 2004) ▫ Inhibiting the expression of genes involved in atherosclerosis (Chen 2002) ▫ Inhibiting the expression of adhesion molecules (Chappelle et al 1998) ▫ Loss of spiral flow associated with vascular disease (Houston et al 2004)

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SLIDE 3

Background

  • Spiral flow is seen in the cephalic vein in brachiocephalic

arteriovenous fistulas (Marie et al 2012) This implies that the vessel (artery and vein) must be capable

  • f generating spiral flow
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SLIDE 4

Aims

  • Assess the anatomical structure of artery and

vein (muscle fibre orientation) as a potential generator of spiral flow

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SLIDE 5

Methods

  • 4 brachial arteries and 4

cephalic veins taken from embalmed cadavers.

  • Sectioned in 2 angles (0˚ and

20˚)

  • Mounted on slides and stained

using H&E

  • Region of the vessel tunica

media chosen at random and all cell nuclei measured within that region

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Methods – angular sectioning

  • Assessment of smooth

muscle pitch

  • Dimensions of vascular

smooth muscle cell nucleus 37µm by 2µm (Walmsley and Canham 1979)

  • Size of nucleus in cross-

section will depend on angle at which it is sectioned.

Adapted from Canham (1977)

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Results

Section angle 0˚ (n=798) 20˚ (n=1945) Median nucleus length (μm) (CI interval) 16.32 (15.67-17.00) 7.54 (7.39-7.74)

Brachial artery

Section angle 0˚ (n=328) 20˚ (n=548) Median nucleus length (μm) (CI interval) 10.72 (9.76-11.92) 5.33 (5.16-5.65)

Cephalic vein Smooth muscle pitch = 6.04˚ to 6.28˚ Smooth muscle pitch = 1.37˚ to 9.33˚

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SLIDE 8

Artists impression

Illustration Aimee Jewitt Harris

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Discussion

  • Conflicting evidence describing the orientation of

fibres within the arterial and venous tunica media

Artery:

  • Circumferential – Walmsley et al

(1983), Wolinsky & Glagov (1963), Arner & Uvelius (1982), Dingemans (2000), O’Connell (2008)

  • Spiral – Todd et al (1983), Herlihy

& Murphy (1973), Borovic et al (2010), Fujiwara and Uehara (1992) Vein:

  • Spiral – Todd et al (1983) *portal vein*
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SLIDE 10

Summary

  • Blood vessels are capable of generating spiral flow
  • The alignment of muscle fibres is angular and

might be the mechanism

  • This should be considered in design of vascular

devices