Compliant design of artificial graft: Compliance determination by new digital X‐ray imaging system‐based method

Abstract

The development of an artificial graft requires formulation of biomechanical design criteria. The compliance of artifical grafts, based on the intraluminal pressure-internal diameter (Pi-Di) relationship, was measured by a novel method using a digital X-ray imaging system coupled with an edge detection algorithm and a pressure transducer. The Pi-Di values were obtained from digital angiographic images under continuous inflation of a canine femoral artery anastomosed with an expanded poly(tetrafluoroethylene) (ePTFE) vascular graft as a model vessel with a pressurized contrast medium. The Di at Pi using an NIH Image software specially programmed for the entropy filter method, which enables the detection of the edge of the vessel phantoms of the images, was determined. The Pi-Di relationships showed a "J-shape" curve for the artery, a steeper line with a very low pressure-dependent distensibility for the ePTFE graft, and an intermediate curve for the anastomosis protion. The two indices for the vessel compliance, the stiffness parameter (beta value) and the diameter compliance (Cd), both of which were calculated from the Pi-Di relationships, were 10.6 and 6.8%/mmHg x 10(-2) for the artery, 164 and 0.51%/mmHg x 10(-2) for the ePTFE, and 14.4 and 5.5%/mmHg x 10(-2) for the anastomosis portion, respectively. This method can measure compliance at any portions of the sampling vessel in a single experiment on a real-time basis with very high accuracy, compared with conventional methods, and even in cases of intimal thickening and/or connective tissues-adhered vessels, and may serve to provide information on compliant design criteria of artificial and tissue-engineered graft.

Hydroxylapatite nanoparticles: fabrication methods and medical applications

“…After adsorption of HAp nanocrystals and reaction at the interface between HAp nanocrystals and substrate surfaces, the HAp-nanocrystal-coated substrates retained the mechanical properties of the substrates and showed improved cell adhesion properties owing to the presence of HAp crystals on the surface [349][350][351][352][353]355]. The HAp nanocrystal coating is applied to percutaneous devices [349,356], artificial blood vessels [357,358] and stents [352].…”

Coaxial double‐tubular compliant arterial graft prosthesis: Time‐dependent morphogenesis and compliance changes after implantation

“…17 Briefly, one end of a vessel segment was cannulated to a fixed stainless steel connector for pressure loading and the other to a sliding connector, and the vessel was restored to in situ length in a bath filled with Krebs-Ringer solution held at 37°C. The vessel was gradually inflated with a pressurized contrast medium (Iomeron 350, Eisai Co., Ltd., Tokyo, Japan) using a syringe pump, recording the intraluminal pressures from 0 to ϳ200 mmHg.…”

“…The details of the procedure were described in our previous article. 17 Compliance changes were evaluated with the stiffness parameter (␤ value) determined from the following equation 18,19 : Figure 4. Operative findings of the coaxial double-tubular grafts.…”

Construction of Small-Caliber, Polydiaxanone Cyclohexanone Vascular Stents

“…Furthermore, these parameters are significantly higher than those of the commonly used dacron and Grafts were implanted subcutaneously for 2 weeks. a Granulocyte infiltration was observed in the graft implantation area (97,000), b collagen fibril was produced by fibroblasts (95,000), c particle of degradation were observed in macrophage cytoplasm (97,000), d particle of degradation and myelinoid bodies were observed in macrophage cytoplasm (98,000) TEM: transmission electron microscopy ePTFE grafts, which have a reported compliance of (1.9 ± 1.2)%/100 mmHg and (0.9 ± 0.1)%/100 mmHg, respectively [26,27]. Therefore, the vessels developed in this study show promise for clinical application as they are physically strong, and although their flexibility is still lower than the physiological blood vessels, the stress-strain curve results show that these artificial stents are still close to the values seen with natural vessels.…”