Surgical results using ultrafine polyester fiber graft (TORAY GRAFT)in patients with abdominal aortic aneurysm were examined. From January 1992 to May 1996, vascular replacement using this graft were performed in 54 cases. The surgical mortality was 19% and 3% in cases undergoing emergency surgery and elective surgery, respectively.No death was related to the graft.During an average follow-up period of 2.8 years, the cumulative survival rate was 93% at 1 year and 85% at 2 years.Results of computed tomography and digital subtraction angiography during the late phase showed that the internal diameter of the graft extended by 10% compared with the standerd size and regenerative intima-like hypertrophy was observed on CT images in 27.7% of the cases.

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Differentiation and apotosis were regulated by immobilized nerve growth factor (NGF) and tumor necrosis factor (TNF), respectively. They were pattern-immobilized on a cell culture polystyrene plate by photolithographic technique. The pattern-immobilization was confirmed by immuno-fluorescence micriscopy. PC12 cells formed neurocites only on the NGF-immobilized regions. In addition, the neurocites direction was regulated by immobilized NGF. On the other hand, A673 cells were apotosized only on the TNF-immobilized regions.

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In order to examine the mechanism of calcification which thought to be one of the major factors to deteriorate the durability of Jellyfish valve, the strain aging on valve membrane at its closed position under the static pressure was analyzed using finite element method(FEM), focusing on changes in mechanical characteristics. Material properties of valve membrane were obtained from the uniaxial tensile test, and the static pressure was 90mmHg which denoted physiological mean aortic pressure. Using isoparametric membrane element with four nodes, FEM analysis was performed on the one-twelfth model of Jellyfish valve taking symmetry of valve shape into consideration The result exhibited that strain concentration was observed at two areas. Then, in order to examine the strain distribution toward membrane thickness-wide direction, analysis was performed on the simplified model using isoparametric hexahedron element with eight nodes. The results exhibited that high tensile strain areas by analysis were corresponding to the locations of calcification in the animal trial. Based upon the results above, it was clarified that high tensile strain would have a major role to increase a calcification.

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Effective and concentrated investment and distribution of national fund are essential for the development of Japanese artificial organs especially based on big projects such as implantable device for long-term use. To establish proper strategy in terms of effective distribution of national fund, investigation of clinical needs and collection of clinical data such as market research is mandatory. From our experiences of the cooperative development of artificial organs with Japanese manufactures such as IABP balloon of Tokai Medical Products, Terumo centrifugal pump and emergency PCPS system, and membrane oxygenator with silicon coated hollow fiber, important key factors were summarized as follows. 1) Size reduction to match Japanese small body size, 2) Quick response to the clinical needs and requests, 3) Collection of clinical data and its feed back to manufacturers, 4) Cost effectiveness analysis, 5) Analysis of patient view such as improved quality of life or minimally invasive treatment.

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Various innovative totally implantable artificial hearts have been studied and developed in Japan. They are an electrohydraulic total artificial heart (TAH) using a regenerative pump, an undulation pump TAH, a linear motor-driven TAH, and a ball screw-driven assist heart. The followings are original rotary pumps; a magnetically suspended centrifugal pump, a centrifugal pump with a central balancing hole in the impeller, a monopivot, agnetic suspension blood pump, and a vibrating flow pump. A transcutaneous transformer made of ferromagnetic materials aand optical information transmission are Japanese original ideas. Good animal experiment results have been obtained with these systems. Japanese totally implantable artificial hearts are available m near future.

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Thirty patients who underwent cardiac surgery were randomly assigned to three groups (groups N, H, and L). Patients in group N were perfused with the usual cardiopulmonary bypass (CPB) circuit, and those in groups H and L, with heparin-coated circuits. Patients received high-(300 U/kg; groups N and H) or low-dose (150 U/kg; group L) systemic heparin. In all patients, granulocyte elastase (GEL), C3a, interleukin-6 (IL-6), and interleukin-8 (IL-8) were measured from before the operation until 24 h after the end of CPB. The serum levels of GEL and C3a during CPB were significantly higher in group N than in the other two groups, and no significant difference was found between groups H and L at any time point. The serum levels of IL-6 and IL-8 during CPB were higher in group N, and after the end of CPB, these levels were significantly lower in group L than in the other two groups. In summary, heparin-coated CPB with low systemic heparin maintains biocompatibility and allows reduced protamine administration, thus decreases systemic inflammatory responses.

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We developed a model of an integrated non-roller extracorporeal circulation system (NR-ECC) according to the basic concept of a roller-less system. Characteristics of NR-ECC are (1) prevention of hemolysis, (2) easiness to operate, (3) safety, (4) compactness, and (5) low cost. In this study, the prevention of hemolysis of NR-ECC was examined by a mock experiment. A pool for the mock experiment was prepared, extracorporeal channels were assembled using an NR-ECC and a conventional roller pump. Aspiration was made through 4 routes, and each channel was filled with blood obtained from the same cow, extracorporeal circulation was performed simultaneously for 5h, and changes in the free hemoglobin level were compared. The free hemoglobin level increased to 0.415±0.157 mg/dl/min with the roller type system and to 0.215±0.105 mg/dl/min with NR-ECC; the increase in free hemoglobin was significantly smaller with NR-ECC (p=0.0479). Therefore, NR-ECC is considered to have a significant prevention of hemolysis.

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Adsorption characteristics of the direct hemoperfusion column (Lixelle) for treatment of dialysis-rebated amyloidosis (DRA) were evaluated in vitro. (1) The adsorbent mainly adsorbed peptides or proteins whose molecular weight (MW) ranged from 4, 000 to 20, 000 daltons. (2) The adsorption capability for peptides or proteins decreased with a decrease of MW lower than 4, 000 daltons and with an increase of MW higher than 20, 000 daltons. (3) The adsorbent did not significantly adsorb low-MW substances and electrolytes whose MW are lower than 1, 000 daltons. It was also found that the adsorbent adsorbed inflammatory cytokines related to pathogenesis of DRA. These results suggest that Lixelle can be a useful device to remove middle MW substances efficiently from DRA patients in combination with hemodialysis treatment.

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CAPIOX EBS is a newly developed heparin-coated system for percutaneous cardiopulmonary support. Ten patients were assisted by this system after cardiac surgery because of low cardiac output syndrome in our institute, and 18 kits of CAPIOX EBS were installed in these patients. Non of the 18 kits showed any troublesome within 24 h of circulatory assist, but 6 kits were replaced over 36 h of circulatory assist because of hemolysis, annoying noise from the pump, or impaired oxygenation. Out of these 6 kits, two pumps revealed blood clot formation at the outlet and another two oxygenators showed plasma leakage. The mean running period of the other twelve kits was 142h (2-194h), and they did not show any functional waning. We needed 5 to 10 min for kit exchange, and hemodynamic deterioration during the procedure was minimal, and all patients requiring a new kit regained stable hemodynamic state immediately after kit exchange.

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