Effective hemodynamic diameter: An intrinsic property of vein grafts with predictive value for patency

Meyerson, Shari L.; Moawad, John; Loth, Francis; Skelly, Christopher L.; Bassiouny, Hisham S.; McKinsey, James F.; Gewertz, Bruce L.; Schwartz, Lewis B.

doi:10.1067/mva.2000.105957

Cited by 16 publications

(17 citation statements)

References 31 publications

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“…Z L was determined based on the summation of the longitudinal impedance moduli, , for each harmonic n = 1 to 8 Hz, where . This methodology is based on the vein graft patency studies by Meyerson et al [42] and Skelly et al [43] and utilized in the thesis work of Kalata [44].…”

Section: Methodsmentioning

confidence: 99%

The Impact of Spinal Cord Nerve Roots and Denticulate Ligaments on Cerebrospinal Fluid Dynamics in the Cervical Spine

et al. 2014

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Cerebrospinal fluid (CSF) dynamics in the spinal subarachnoid space (SSS) have been thought to play an important pathophysiological role in syringomyelia, Chiari I malformation (CM), and a role in intrathecal drug delivery. Yet, the impact that fine anatomical structures, including nerve roots and denticulate ligaments (NRDL), have on SSS CSF dynamics is not clear. In the present study we assessed the impact of NRDL on CSF dynamics in the cervical SSS. The 3D geometry of the cervical SSS was reconstructed based on manual segmentation of MRI images of a healthy volunteer and a patient with CM. Idealized NRDL were designed and added to each of the geometries based on in vivo measurments in the literature and confirmation by a neuroanatomist. CFD simulations were performed for the healthy and patient case with and without NRDL included. Our results showed that the NRDL had an important impact on CSF dynamics in terms of velocity field and flow patterns. However, pressure distribution was not altered greatly although the NRDL cases required a larger pressure gradient to maintain the same flow. Also, the NRDL did not alter CSF dynamics to a great degree in the SSS from the foramen magnum to the C1 level for the healthy subject and CM patient with mild tonsillar herniation (∼6 mm). Overall, the NRDL increased fluid mixing phenomena and resulted in a more complex flow field. Comparison of the streamlines of CSF flow revealed that the presence of NRDL lead to the formation of vortical structures and remarkably increased the local mixing of the CSF throughout the SSS.

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Section: Methodsmentioning

confidence: 99%

The Impact of Spinal Cord Nerve Roots and Denticulate Ligaments on Cerebrospinal Fluid Dynamics in the Cervical Spine

et al. 2014

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“…The zero-eth harmonic was not included as the focus of this study was on unsteady resistance. The above methodology is based on a similar calculation performed in vein graft patency studies by Meyerson, et al and Skelly, et al [29], [30]. A similar method has also been employed to understand the hemodynamic impact of proximal aortic grafts [31].…”

Section: Methodsmentioning

confidence: 99%

Hydrodynamic and Longitudinal Impedance Analysis of Cerebrospinal Fluid Dynamics at the Craniovertebral Junction in Type I Chiari Malformation

Martin

Kalata²,

Shaffer

et al. 2013

PLoS ONE

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Elevated or reduced velocity of cerebrospinal fluid (CSF) at the craniovertebral junction (CVJ) has been associated with type I Chiari malformation (CMI). Thus, quantification of hydrodynamic parameters that describe the CSF dynamics could help assess disease severity and surgical outcome. In this study, we describe the methodology to quantify CSF hydrodynamic parameters near the CVJ and upper cervical spine utilizing subject-specific computational fluid dynamics (CFD) simulations based on in vivo MRI measurements of flow and geometry. Hydrodynamic parameters were computed for a healthy subject and two CMI patients both pre- and post-decompression surgery to determine the differences between cases. For the first time, we present the methods to quantify longitudinal impedance (LI) to CSF motion, a subject-specific hydrodynamic parameter that may have value to help quantify the CSF flow blockage severity in CMI. In addition, the following hydrodynamic parameters were quantified for each case: maximum velocity in systole and diastole, Reynolds and Womersley number, and peak pressure drop during the CSF cardiac flow cycle. The following geometric parameters were quantified: cross-sectional area and hydraulic diameter of the spinal subarachnoid space (SAS). The mean values of the geometric parameters increased post-surgically for the CMI models, but remained smaller than the healthy volunteer. All hydrodynamic parameters, except pressure drop, decreased post-surgically for the CMI patients, but remained greater than in the healthy case. Peak pressure drop alterations were mixed. To our knowledge this study represents the first subject-specific CFD simulation of CMI decompression surgery and quantification of LI in the CSF space. Further study in a larger patient and control group is needed to determine if the presented geometric and/or hydrodynamic parameters are helpful for surgical planning.

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“…Smaller length suggests a more preserved venous segment with an optimal distal diameter. Meyerson et al [23] showed that diameter of graft smaller than 3.6 mm predicts impairment of patency and if established, a different alternative should be chosen. In a multi segmental spread of the disease, especially when the runoff arteries are partially involved, longer grafts are necessary [29], which accounts for the higher rate of the failure of bypasses with a bigger length over patent ones irrespective of their greater diameter (over 3.5 mm) by 28%.…”

Section: Discussionmentioning

confidence: 99%

“…The size of the graft and its quality are also major determinants of the long-term success of intrainguinal reconstructions. The exact measurement of the internal venous diameter is difficult due to the different wall thickness and conical narrowing [23]. Wengerter et al [24] demonstrate a model of increasing patency in venous grafts ranging from 3.0 mm to 4.0 mm, and Idu et al [25] consider only a venous graft diameter below 3.5 mm important for the development of stenoses.…”

Section: Introductionmentioning

confidence: 99%

Clinical Significance of Venous Graft Size and Run-Off Segment for Peripheral Bypass Patency

Jordanov¹

2015

J Vasc Med Surg

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Aim: To analyze the one-year-patency of infrainguinal arterial reconstructions in relation to venous graft diameter and length and the run-off segment, when arteries above the proximal anastomosis of the reconstruction are not diseased.Material and Methods: We compared retrospectively for two-year period the diameter, the length of the used vein and the run-off segment in 107 consecutively constructed infrainguinal autovenous bypasses -54 patent (not less than 1 year) and 53 failed bypasses Diameter of the vein was measured at the narrowest part of the vein (in all cases this was the area of the distal anastomosis). Аll bypassеs are made with translocated nonreversed vein and the length of the vein was measured after the completion of reconstruction. Volume and pressure of blood flow were measured below the distal anastomosis by the means of ultrasound transit-time flowmetry. For the assessment of run-off segment Fourier analyses of flow and pressure were used and alteration of the amplitudes after intragraft infusion of Prostaglandines was calculated.Results: We compared the alteration in amplitudes in failed and patent for at least 1 year bypasses and estimated that ratio below 2 before and after medicamentous vasodilatation, sets the reconstruction in the group of threatened, as well as graft diameter below 3.5 mm and length over 40 cm.Conclusion: Hemodynamic assessment of blood flow below distal anastomosis defines the necessary vein lenght, that is why run-off segment has the most important significance for the patency of the infrainguinal autovenous reconstructions. Shorter grafts with diameter over 3.5 mm do not guarantee longer patency if distal anastomosis is constructed above diseased run-off segment.

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Effective hemodynamic diameter: An intrinsic property of vein grafts with predictive value for patency

Abstract: An EHD is a unique parameter that quantifies conduit size and has a significant impact on vein graft patency. An EHD less than 3.6 mm portends graft failure.

Cited by 16 publications

References 31 publications

The Impact of Spinal Cord Nerve Roots and Denticulate Ligaments on Cerebrospinal Fluid Dynamics in the Cervical Spine

The Impact of Spinal Cord Nerve Roots and Denticulate Ligaments on Cerebrospinal Fluid Dynamics in the Cervical Spine

Hydrodynamic and Longitudinal Impedance Analysis of Cerebrospinal Fluid Dynamics at the Craniovertebral Junction in Type I Chiari Malformation

Clinical Significance of Venous Graft Size and Run-Off Segment for Peripheral Bypass Patency

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