Abstract 13903: Application of in vivo Tissue-engineered, Autologous “Biotube” Vascular Grafts, Prepared Using a Less Invasive Device, for Hemodialysis Access in a Canine Model

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Maya Furukoshi ◽  
Yasuhide Nakayama
Keyword(s):  
Blood Flow ◽  
Vascular Access ◽  
Vascular Grafts ◽  
Canine Model ◽  
Invasive Technique ◽  
Internal Diameter ◽  
External Diameter ◽  
Av Fistula ◽  
Av Shunt

Purpose: When arteriovenous (AV) fistula is not feasible for vascular access in most patients on hemodialysis, the second choice is interposition AV fistula using synthetic graft. However, the grafts pose risks such as infection and low patency. Therefore, we created in vivo tissue-engineered “Biotube” vascular grafts formed with autologous tissue, based on the tissue encapsulation phenomenon. Previously, we confirmed that vascular-like structure was reconstructed in implanted Biotubes with year-ordered patency in vivo. In this study, we evaluated whether Biotubes could replace vascular access grafts for hemodialysis in the cervical vessels of beagles. Methods and Results: The mold for Biotube preparation was assembled by inserting a silicone rod (external diameter 4 mm; length 50 mm) into an acrylate tubular cover (internal diameter 6 mm; length 50 mm with several longitudinal slits). The molds were embedded into the dorsal subcutaneous pouches of beagles (n=3) for 4 weeks, after which they were harvested by a minimally invasive technique from the same incision (width ca. 20 mm). After removing the molds, Biotubes formed by tissue migration to a silicone surface through the mold slits (internal diameter 4 mm; length 45 mm; wall thickness ca. 1 mm) were obtained. Biotubes were then bypassed between the carotid artery (side-to-end anastomosis) and jugular vein (end-to-end anastomosis) of anesthetized beagles. Following placement of Biotubes, continuous thrill was felt by palpation and ultrasound showed turbulent blood flow. After one month, angiography showed no stenosis, elongation, or hemorrhage in any Biotubes. Percutaneous puncturing with a needle, blood removal and resupply from the needle, and astirction within several minutes were feasible. Conclusions: In our beagle model, Biotubes successfully created an AV shunt that maintained steady blood flow, suggesting that Biotubes have potential clinical use in maintaining vascular access for hemodialysis.

scholarly journals Histological Reactions and the In Vivo Patency Rates of Small Silk Vascular Grafts in a Canine Model

2017 ◽  
Vol 10 (2) ◽  
pp. 132-138 ◽  
Author(s):  
Makoto Haga ◽  
Satoshi Yamamoto ◽  
Hiroyuki Okamoto ◽  
Katsuyuki Hoshina ◽  
Tetsuro Asakura ◽  
...  
Keyword(s):  
Vascular Grafts ◽  
Canine Model ◽  
Histological Reactions

Measurements of Hemodialysis Catheter Blood Flow in Vivo

2002 ◽  
Vol 25 (4) ◽  
pp. 276-280 ◽  
Author(s):  
Z. J. Twardowski ◽  
J. D. Haynie
Keyword(s):  
Blood Flow ◽  
Average Length ◽  
Internal Diameter ◽  
Hemodialysis Catheter ◽  
Blood Flows ◽  
Catheter Design ◽  
Poiseuille’S Equation ◽  
Different Diameters ◽  
The Relationship

The relationship between the blood flow and inflow and outflow pressures was determined in PermCath, dual lumen catheters during regular hemodialyses in vivo in eight patients with average hematocrit of 38%. From the luer lock connector the catheters had an average length of 32 cm to the outflow tip and 30 cm to the inflow tip. The catheters had an internal diameter of 0.2 cm and were straight before implantation. Dialyses were performed on Fresenius 2008 D or E machines with ReadySet™ blood lines with an 8 mm ID pump segment and a noncollapsible arterial chamber. Pressures and blood flows were measured at pump speeds from 50 to 500 ml/min in increments of 50 ml/min with lines in normal configuration. Blood flow was measured continuously using ultrasound. The correlations between pressures and flows are not linear. The best correlations are according to the Stirling model of exponential growth category equation. Inflow pressure = -9.07–0.4865*(exp(0.0020*blood flow)-1)/0.0020 Outflow pressure = -28.14+0.5002*(exp(0.0015*blood flow)-1/0.0015 Based on these results and Poiseuille's equation a table was developed for the optimal relationship between catheter length and diameter to achieve standardized (average, low and high) blood flows regardless of the lengths of the catheters. The diameter/length relationships are based on theoretical considerations. Because resistances depend on the material and shape of the tubing, the actual measurements of flow/pressure relationships should be done once tubings of different diameters are manufactured, and final catheter design has to be based on these measurements.

Effects of vasopressin and oxytocin on canine cerebral circulation in vivo

1992 ◽  
Vol 77 (3) ◽  
pp. 424-431 ◽  
Author(s):  
Yoshio Suzuki ◽  
Shin-ichi Satoh ◽  
Masaaki Kimura ◽  
Hirofumi Oyama ◽  
Toshio Asano ◽  
...  
Keyword(s):  
Blood Flow ◽  
Neuropeptide Y ◽  
Vertebral Artery ◽  
Cerebral Circulation ◽  
Internal Diameter ◽  
Artery Blood Flow ◽  
Bolus Infusion ◽  
Arterial Blood ◽  
Basilar Arteries

✓ In vivo experiments on the vasoactive effects of vasopressin and oxytocin on cerebral circulation were carried out in anesthetized dogs, using an electromagnetic flowmeter to measure vertebral blood flow and angiography to measure the internal diameter of the basilar artery. Direct bolus infusion of 1 pmol to 1 nmol of vasopressin or 10 pmol to 10 nmol of oxytocin into a femoral-vertebral artery shunt produced a dose-dependent decrease in vertebral artery blood flow without significantly affecting mean arterial blood pressure. Vasopressin was more potent than endothelin and neuropeptide Y, which have also been demonstrated to induce long-lasting decreases in vertebral artery blood flow. However, direct bolus infusion of vasopressin (100 pmol and 1 nmol) or oxytocin (1 nmol and 10 nmol) into the vertebral artery dilated major vessels including the vertebral, anterior spinal, and basilar arteries, as well as the circle of Willis and its main branches, while endothelin (1 nmol) and neuropeptide Y (5 nmol) caused no change in the diameters of major cerebral arteries. The V1 antagonist d(CH2)5tyrosine(methyl) arginine vasopressin suppressed the effects of both vasopressin and oxytocin. Vasopressin was over 10 times as potent as oxytocin in both assays. The vasodilatory effect of vasopressin, which may be mediated by an endothelium-dependent mechanism, was functionally damaged in dogs after experimental subarachnoid hemorrhage. These data suggest regional differences in the sensitivity and responsiveness of vasculature to vasopressin and oxytocin, and specifically that both peptides act through V1 receptors to decrease the resistance of large vessels and increase the resistance of small vessels.

scholarly journals 2-D Kasai velocity estimation for Doppler optical coherence tomography / by Darren Morofke.

2021 ◽  
Author(s):  
Darren Morofke
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Frequency Estimation ◽  
Doppler Frequency ◽  
Velocity Estimation ◽  
Low Flow ◽  
Invasive Technique ◽  
Optical Coherence ◽  
Detection Range

Optical Coherence Tomography (OCT) is a high-resolution, non-invasive technique to image subsurface tissue and tissue functions. A broadband light source illuminates an object and the reflected photons are processed using an interferometer, demodulated into inphase and quadrature components and then digitized. The captured data contains information about the velocity of the moving scatterers but current Doppler estimation algorithms have a limited velocity detection range. Here we demonstrate Doppler OCT (DOCT) detection of in vivo of blood flow in a rat aorta with over 1 m/s peak velocity through an esophageal DOCT probe using a new processing technique. Previous methods have used a transverse Kasai (TK) autocorrelation estimation to estimate the velocity. By calculating the Kasai autocorrelation with a lag in the depth or axial direction, backscattered frequency information is obtained. Through subtraction with stationary backscattered information, the Doppler shift is obtained by the axial Kasai (AK) technique. Maximum non-aliased Doppler frequency estimation using a time domain DOCT system increased from +/-4 kHz to =+/-1.6 MHz. The TK has better velocity resolution in the low flow rate range and when combined with the AK we demonstrate a dynamic frequency range over 100 dB with a velocity detection range from 10 [micro]m/s to over 1 m/s. This velocity range spans from microcirculation to cardiac blood flow velocities.

scholarly journals Bioactive coating for tissue-engineered smalldiameter vascular grafts

2021 ◽  
Vol 23 (4) ◽  
pp. 119-131
Author(s):  
V. A. Surguchenko ◽  
E. A. Nemets ◽  
V. Yu. Belov ◽  
V. I. Sevastianov
Keyword(s):  
Vascular Grafts ◽  
Small Diameter ◽  
Internal Surface ◽  
Internal Diameter ◽  
Bioactive Coating ◽  
Human Endothelial Cell Line ◽  
Copolymer Poly ◽  
Biopolymer Scaffolds

Objective: to develop a method for modifying composite small-diameter porous tubular biopolymer scaffolds based on bacterial copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and gelatin modified with a double-layered bioactive coating based on heparin (Hp) and platelet lysate (PL) that promote adhesion and proliferation of cell cultures.Materials and methods. Composite porous tubular biopolymer scaffolds with 4 mm internal diameter were made by electrospinning from a 1 : 2 (by volume) mixture of a 10% solution of poly(3-hydroxybutyrateco- 3-hydroxyvalerate) copolymer, commonly known as PHBV, and a 10% solution of gelatin, respectively, in hexafluoro-2-propanol. The structure of the scaffolds was stabilized with glutaraldehyde vapor. The scaffolds were modified with a bioactive Hp + PL-based coating. The surface morphology of the samples was analyzed using scanning electron microscopy. Biological safety of the modified scaffolds in vitro (hemolysis, cytotoxicity) was evaluated based on the GOST ISO 10993 standard. Interaction with cultures of human endothelial cell line (EA. hy926) and human adipose-derived mesenchymal stem cells (hADMSCs) was studied using vital dyes.Results. We developed a method for modifying small-diameter composite porous tubular biopolymer scaffolds obtained by electrospinning from a mixture of PHBV and gelatin modified with double-layered bioactive coating based on covalently immobilized Hp and human PL. The modified scaffold was shown to have no cytotoxicity and hemolytic activity in vitro. It was also demonstrated that the developed coating promotes hADMSC adhesion and proliferation on the external surface and EA.hy926 on the internal surface of the composite porous tubular biopolymer scaffolds in vitro.Conclusion. The developed coating can be used for the formation of in vivo tissueengineered small-diameter vascular grafts.

Application of in-body tissue architecture–induced Biotube vascular grafts for vascular access: Proof of concept in a beagle dog model

2019 ◽  
Vol 21 (3) ◽  
pp. 314-321 ◽  
Author(s):  
Maya Furukoshi ◽  
Eisuke Tatsumi ◽  
Yasuhide Nakayama
Keyword(s):  
Vascular Access ◽  
Body Tissue ◽  
Internal Diameter ◽  
Proof Of Concept ◽  
Beagle Dogs ◽  
Tissue Architecture ◽  
First Choice ◽  
Type 3

Introduction: The first choice of vascular access for hemodialysis is an autogenous arteriovenous fistula, because prosthetic arteriovenous grafts have a high probability of failure. In this study, Biotubes, in-body tissue architecture–induced autologous collagenous tubes, were evaluated for their potential use as vascular access grafts. Three animal implantation models were developed using beagle dogs, and the in vivo performance of Biotubes was observed after implantation in the acute phase as a pilot study. Methods: Biotubes (internal diameter ca. 4.0 mm, length ca. 5.0 cm, and wall thickness ca. 0.7 mm) were prepared through subcutaneous embedding of specially designed molds in beagle dogs for 8 weeks. The Biotubes were then implanted between the common carotid artery and the jugular vein of beagles via three methods, including side-to-side (in) -end-to-end (out) as type 1 (n = 4), side-to-side (both) as type 2 (n = 4), and side-to-end (in) -end-to-side (out) as type 3 (n = 1 using a composite Biotube). Results: Although two cases in type 1 and 2 resulted in Biotube deformation, all cases were patent for 4 weeks and maintained a continuous turbulent flow. At 4 weeks after implantation, percutaneous puncture could be performed repeatedly without aneurysm formation or hemorrhage. Conclusion: Within a short implantation period, with limited animal numbers, this proof-of-concept study showed that Biotubes may have a high potential for use in vascular access.

scholarly journals 2-D Kasai velocity estimation for Doppler optical coherence tomography / by Darren Morofke.

2021 ◽  
Author(s):  
Darren Morofke
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Frequency Estimation ◽  
Doppler Frequency ◽  
Velocity Estimation ◽  
Low Flow ◽  
Invasive Technique ◽  
Optical Coherence ◽  
Detection Range

Optical Coherence Tomography (OCT) is a high-resolution, non-invasive technique to image subsurface tissue and tissue functions. A broadband light source illuminates an object and the reflected photons are processed using an interferometer, demodulated into inphase and quadrature components and then digitized. The captured data contains information about the velocity of the moving scatterers but current Doppler estimation algorithms have a limited velocity detection range. Here we demonstrate Doppler OCT (DOCT) detection of in vivo of blood flow in a rat aorta with over 1 m/s peak velocity through an esophageal DOCT probe using a new processing technique. Previous methods have used a transverse Kasai (TK) autocorrelation estimation to estimate the velocity. By calculating the Kasai autocorrelation with a lag in the depth or axial direction, backscattered frequency information is obtained. Through subtraction with stationary backscattered information, the Doppler shift is obtained by the axial Kasai (AK) technique. Maximum non-aliased Doppler frequency estimation using a time domain DOCT system increased from +/-4 kHz to =+/-1.6 MHz. The TK has better velocity resolution in the low flow rate range and when combined with the AK we demonstrate a dynamic frequency range over 100 dB with a velocity detection range from 10 [micro]m/s to over 1 m/s. This velocity range spans from microcirculation to cardiac blood flow velocities.

scholarly journals Accuracy Of Spiral Laminar Flow, Spectral Broadening And Murmur / Thrill As Av-Shunt Maturuty Predictors In Dr. Mohammad Hoesin Hospital Palembang

2020 ◽  
Vol 3 (2) ◽  
pp. 138-150
Author(s):  
Kemas Muhammad Dahlan ◽  
Sefta Jaka ◽  
Jaka Fahmi ◽  
Erial Bahar
Keyword(s):  
Kidney Disease ◽  
Laminar Flow ◽  
Sensitivity And Specificity ◽  
Vascular Access ◽  
High Sensitivity ◽  
Spectral Broadening ◽  
Av Fistula ◽  
End Stage ◽  
Av Shunt ◽  
Very High

Background : Hemodialysis is a therapy for end-stage cornic kidney disease (ESRD) which is most often used as renal replacement therapy. Vascular access for hemodialysis is essential in the management of patients with chronic kidney disease. One type of vascular access is av fistula. A well-matured AVF is needed in order to function optimally during the hemodialysis process. The study of Srivastava et al. In India examined a predictor parameter of the maturation of AVF using Doppler ultrasound. The parameters studied were Spiral Laminar Flow (SLF), Spectral Broadening and Murmur / thrill. The results of this study state that SLF is the most important and early predictor of AVF maturation.5 Research on the accuracy of spiral laminar flow, spectral broadening and murmur / thrill as predictors of av-shunt maturity has never been carried out in Indonesia. This encourages this research to be carried out. Method : This type of research is the prognostic test. The study was conducted in the vascular and endovascular subdivisions from July - September 2020 or until the number of research samples is met. Result : There were 30 samples in this study, Murmur / thrill had high sensitivity and specificity values ​​on day 21 while SLF and spectral broadening had very high sensitivity and specificity values ​​in predicting AVF maturase from day 7th and 21th, also had a significant association with AVF maturase (p < 0.001). Conclusion : Murmur / thrill on 21th day can be a perdictor for maturity of AVF

Regional Blood Flow to the Canine Vocal Fold Rest and during Phonation

1989 ◽  
Vol 98 (10) ◽  
pp. 796-802 ◽  
Author(s):  
David P. Arnstein ◽  
Terrence K. Trapp ◽  
Gerald S. Berke ◽  
Manuel Natividad
Keyword(s):  
Blood Flow ◽  
Left Atrium ◽  
Lamina Propria ◽  
Vocal Fold ◽  
Regional Blood Flow ◽  
Canine Model ◽  
Tissue Oxygen ◽  
Indirect Measures ◽  
Surface Technique

Recent reports have suggested that blood flow to the vocal fold decreases during phonation. However, these studies relied on indirect measures of blood flow, such as tissue oxygen tension. Among the differing methods of measuring blood flow, one of the most sensitive is the microsphere surface technique. This technique has been effective in assessing the overall and regional blood flow to a number of different organs, including the cochlea. Employing an in vivo canine model, we injected microspheres into the left atrium. From there, they were distributed and became entrapped in the tissues in proportion to blood flow. We measured the blood flow to the entire vocal fold, as well as the lamina propria and muscularis layers. The results revealed a statistically significant (p<.002) increase in blood flow on phonation. The increase, however, was due to increased flow to the muscularis layer. The flow to the lamina propria remained unchanged during phonation.

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