Measurement in vitro of pulsatile arterial diameter using a helium-neon laser

Brant, Arthur; Rodgers, G. J.; Borovetz, Harvey S.

doi:10.1152/jappl.1987.62.2.679

Cited by 26 publications

(18 citation statements)

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“…Our laboratory's well established, validated EVPS has been used for over two decades to study the mechanopathobiological responses of intact blood vessel segments to accurately simulated physiologic biomechanical signals [3,39,[244][245][246][247][248][249]. The EVPS used in this study has gone through several iterations to improve its functionality and is described in detail below.…”

Section: History Of Ex Vivo Vascular Perfusionmentioning

confidence: 99%

“…The EVPS used in this study has gone through several design iterations to improve its functionality and diversity [3,39,[244][245][246][247]. The previous generation EVPS, upon which the current design was based, is shown schematically in Several other groups have designed specialized EVPSs for studying biochemical responses of blood vessel segments to imposed biomechanical stresses.…”

Section: The Concept Of Ex Vivo Perfusion Was Originally Investigatedmentioning

confidence: 99%

“…The unpressurized dimensions were measured from rings which had been cut, at the time of harvest, proximally and distally to the PCA segment that was implanted into the EVPS. The rings were individually placed into a custom built holder [245] that allowed the unpressurized thickness, as well as the unpressurized inner and outer diameters to be measured via a helium-neon laser micrometer. A linear variation in dimensions was assumed along the longitudinal axis of the implanted PCA segment so that the dimensions could be estimated at any point along the length.…”

Section: Cws and Shear Stress Control Signal Calculationsmentioning

confidence: 99%

“…Vein segments with and without the wrap were mounted in our well established, validated earlier version EVPS (not the version described in Chapter 2.0) [3,39,245,246,248,249,273,275]. Hz as described in Section 2.3.3. pO 2 , pCO 2 , pH, perfusate temperature, and bathing media temperature were measured within each loop of the paired EVPS every hour.…”

Section: Ex Vivo Perfusion Conditionsmentioning

confidence: 99%

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In Situ Bioengineering of Arterial Vein Grafts

El-Kurdi

Morelli

Hong

et al. 2008

ASME 2008 Summer Bioengineering Conference, Parts a and B

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The autogenous saphenous vein remains the graft of choice for both coronary (500,000 annually in the US) and peripheral (80,000 annually) arterial bypass procedures. Failure of arterial vein grafts (AVGs) remains a major problem, and patients with failed grafts will die or require reoperation. Intimal hyperplasia (IH) accounts for 20% to 40% of all AVG failures. It is believed that this adverse pathological response by AVGs is largely due to their abrupt exposure to the significantly elevated circumferential wall stress (CWS) associated with the arterial system. We believe that if an AVG is given an ample opportunity to adapt and remodel to the stresses of its new environment, cellular injury may be reduced, thus limiting the initiating mechanisms of IH.The goal of this work was to develop a new mechanical conditioning paradigm, in the form of a peri-adventitially placed, biodegradable polymer wrap, to safely and functionally "arterialize" AVGs in situ. The polymer wrap was tuned so that as it degraded over a desired period of time, the mechanical support offered by it was reduced and the vein was exposed to gradually increasing levels of CWS in situ.To investigate the effects of mechanical conditioning on AVGs, we utilized both our well established, validated ex vivo vascular perfusion system (EVPS) as well as an appropriate preclinical animal model. The "engineering" component of this bioengineering study was to enhance our EVPS capabilities. Enhancements were made in the form of rigorous mathematical modeling, via subspace system identification, and automatic feedback control, via proportional iv integral and derivative control, of the arterial CWS and shear stress waveform generation capabilities of the EVPS. Pairs of freshly harvested porcine internal jugular veins (PIJVs) were perfused ex vivo under several biomechanical conditions. The acute hyperplastic response of PIJVs abruptly exposed to arterial hemodynamic conditions was compared to PIJVs perfused under normal venous conditions. In an attempt to attenuate this acute hyperplastic response, an ex vivo mechanical conditioning paradigm was imposed onto the PIJVs both via manual adjustment of EVPS parameters and via an adventitially placed tuned electrospun biodegradable polymer wrap. Early markers of IH were evaluated post-perfusion, and they included vascular smooth muscle cell apoptosis, proliferation, and phenotypic modulation. Quantification of these markers via immunohistochemical techniques provided the foundation for the final stage of this work. To assess the efficacy of the tuned electrospun biodegradable polymer wrap in attenuating the development of intimal hyperplasia in AVGs, a series of preclinical studies was performed in a pig model. PIJVs abruptly exposed to arterial levels of CWS showed a significant increase in apoptosis and in the number of synthetic smooth muscle cells, as well as a decrease in proliferation. Mechanical conditioning, via both manual adjustment of the EVPS parameters and placement of the biodegradable adventitial wra...

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Section: History Of Ex Vivo Vascular Perfusionmentioning

confidence: 99%

Section: The Concept Of Ex Vivo Perfusion Was Originally Investigatedmentioning

confidence: 99%

Section: Cws and Shear Stress Control Signal Calculationsmentioning

confidence: 99%

Section: Ex Vivo Perfusion Conditionsmentioning

confidence: 99%

See 2 more Smart Citations

In Situ Bioengineering of Arterial Vein Grafts

El-Kurdi

Morelli

Hong

et al. 2008

ASME 2008 Summer Bioengineering Conference, Parts a and B

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“…Concurrent with further research into anastomotic compliance mismatch (Kidson, 1983;Kinley and Marble, 1980;Seifert et al, 1979) the need for an in vitro method to test biomechanical parameters was recognized and apparatus was developed to measure biomechanics in artery, vein or graft material (Brant et al, 1987;Rodgers et al, 1986). This methodology, based on measuring external diameter change with a lasertechnique, permits in vitro testing of graft materials and anastomotic suture techniques under both physiological and pathophysiological hemodynamic conditions.…”

Section: Introductionmentioning

confidence: 99%

Rotational in vitro compliance measurement of diverse anastomotic configurations: a tool for anastomotic engineering

Knez

Nelson

Hakimi

et al. 2004

Journal of Biomechanics

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Spatial and temporal changes in compliance following implantation of bioresorbable vascular grafts

Greisler

Joyce

Kim

et al. 1992

J. Biomed. Mater. Res.

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Compliance matching between the host vessel and vascular grafts used for small-diameter arterial replacements is thought to be important for long-term patency. However, currently available grafts elicit fibroplastic reactions, resulting in decreasing compliance with time after implantation. Bioresorbable prostheses elicit ingrowth of myofibroblasts containing abundant contractile elements. This led us to investigate whether compliance of implanted bioresorbable prostheses decreased as a function of time and if the kinetics of change correlated with the progression of tissue ingrowth. Woven polyglactin 910 prostheses (10 mm x 4 mm i.d.) were implanted into adult NZW rabbit infrarenal aortas and replicates were harvested serially through 8 months. Control grafts were implanted, and immediately resected. Dynamic compliance was measured at 1-mm axial increments along each explant using a pulse duplicator apparatus which exposed the harvested samples to realistic pulsatile hemodynamics. Compliance was calculated for proximal, mid, and distal segments of each graft and averaged at each time point by grouping into control (zero time, n = 3), early (1-4 weeks, n = 13), and late (6-36 weeks, n = 9) explant periods. At late explant periods both proximal and distal compliance were significantly greater than mid graft compliance (p < .02 and p < .03, respectively). There was a significant increase in proximal compliance between early and late explant times (p < .01). Measured increases in mid and distal segment compliance over time did not reach statistical significance. Myofibroblast laden tissue ingrowth into the inner capsule followed macrophage phagocytosis and was nearly complete prior to the time that an increase in compliance was demonstrated. Thus since the major histologic episodes precede the change in compliance, these are not likely initiated by this biomechanical change. We hypothesize the graft resorption coupled with the ingrowth of more compliant tissue likely leads to the increased compliance of the graft material.

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Measurement in vitro of pulsatile arterial diameter using a helium-neon laser

Cited by 26 publications

References 0 publications

In Situ Bioengineering of Arterial Vein Grafts

In Situ Bioengineering of Arterial Vein Grafts

Rotational in vitro compliance measurement of diverse anastomotic configurations: a tool for anastomotic engineering

Spatial and temporal changes in compliance following implantation of bioresorbable vascular grafts

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