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Biomedical subjects

Kenji Okada

Publications and source records attributed to Kenji Okada.

60 records · Page 4Linked to original sources
PubMed2002

Reconstruction of right ventricular outflow tract with stentless xenografts in Ross procedure.

To investigate whether the use of a stentless porcine aortic xenograft can be an alternative for right ventricular outflow tract (RVOT) reconstruction during the Ross procedure, 9 patients underwent the Ross procedure and RVOT reconstruction with a stentless xenograft since January 2000. After the aortic valve was replaced with a pulmonary autograft, a stentless xenograft with a xeno- pericardial roll was implanted in the RVOT. One patient required subsequent aortic valve replacement because of severe regurgitation of the pulmonary autograft. All patients recovered well from the operation. The right ventricle-pulmonary arterial pressure gradient was 18 +/- 7 mm Hg at discharge and was not significantly increased during the 2-year follow-up period. Although 1 patient died of ventricular arrhythmia 5 months after, his cardiac function was normal, and transpulmonary valve pressure was 19 mm Hg in the follow-up. The other 7 patients are currently in New York Heart Association functional Class I. Although long-term follow-up is required to explain the durability, the stentless xenograft with a pericardial roll is considered to be an alternative for reconstruction of the RVOT within 2 years after the Ross procedure.

Adolescent↗
PubMed2000

Clonal spread of an invasive strain of Haemophilus influenzae type b among nursery contacts accompanied by a high carriage rate of non-disease-associated strains.

Haemophilus influenza carriage was examined in unvaccinated nursery contacts of a patient with H. influenzae type b (Hib) meningitis and isolates were typed by pulsed-field gel electrophoresis (PFGE). Nasopharyngeal isolates were classified into eight PFGE patterns. Seven Hib carriers were found among 15 nursery contacts. The isolates from the carriers showed a PFGE pattern identical to that of the meningitis strain. The carrier rate of non-disease-associated strains was also high (47%, 7 of 15). This study suggests that the clonal spread of invasive (serotype b) H. influenzae strains is accompanied by a high carriage rate of non-disease-associated strains.

Carrier State↗
PubMedDate not supplied

Hybrid small-caliber vascular prosthesis for coronary artery bypass grafting: a preliminary study of plasmin-treated fibrin-coated vascular prosthesis.

The potential use of plasmin-treated fibrin-coated vascular prosthesis (PF-V) for coronary artery bypass grafting (CABG) in animal models was investigated. PF-V grafts, 3 mm in internal diameter, were studied on 5 sheep in off-pump CABG model and on 18 rabbits in abdominal aortic bypass grafting (AABG) model. Patency, blood flow, angiography, Indium-111 platelet scintigraphy, and histology of the graft were evaluated. In the sheep CABG model, the PF-V grafts were patent for a range of 12 to 22 days without postoperative antiplatelet therapy. Graft flows ranged 58 to 90 ml/min until the day before graft occlusion by thrombus. In rabbit AABG model, the fibrin coating of the PF-V grafts was completely absorbed and replaced with neofibrin net between 7 and 14 days after implantation. Platelet depositions on the graft between 7 and 14 days after implantation were significantly higher than those at other periods (p < 0.05). The small-caliber PF-V graft in sheep CABG model had a good blood flow with high antithrombogenicity in acute phase, but occluded over 2 to 3 weeks without antiplatelet agents after implantation. The current problem of the PF-V graft was a thrombus formation at the time of the degradation of fibrin coating. Further improvements are needed.

Animals↗
PubMedDate not supplied

Indium-111-oxine-labeled platelet scintigraphic images in the assessment of thrombogenicity in small-caliber prosthetic vascular grafts.

Anti-thrombogenicity is one of the essential factors for successful development of small-caliber prosthetic vascular grafts, and its accurate evaluation is important. The purpose of this study was to investigate the efficacy of indium-111-oxine-labeled (In) platelet scintigraphic images in the assessment of graft thrombogenicity. Fibrin-coated knitted polyester vascular prostheses, 2 mm in diameter and 2 cm in length, were implanted in the bilateral common carotid arteries of 18 Japanese white rabbits. The grafts were explanted on postoperative days 1, 3, 7, 10, 14, and 30 (six grafts on each of the days), and In platelet scintigraphy was performed with visual, semiquantitative, and quantitative analysis. The relationships among the three analyses were evaluated. Platelet depositions on the luminal surface were clearly visualized with In-platelet scintigraphy if the number of In platelets was more than 4.8 x 10 counts per minute, even if a macroscopic thrombus formation was not observed. There was a highly significant correlation between the graft region of interest on the images and the total platelet deposition (p<.0001). The images in the thrombotic grafts have shown a very strong In-platelet accumulation, but there were some limitations in the In-platelet scintigraphic images. In-platelet scintigraphic images are useful for evaluating platelet deposition in small-caliber vascular prostheses if they are performed with a proper understanding of their limitations.

Animals↗