Browsing by Author "BHUVANESHWAR, GS"

Now showing 1 - 4 of 4
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    CHITRA HEART-VALVE PROSTHESIS
    (ARTIFICIAL ORGANS, 1987) BHUVANESHWAR, GS; VALIATHAN, MS; RAMANI, AV; LAL, GAV; KUMAR, RS
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    EVALUATION OF MATERIALS FOR ARTIFICIAL-HEART VALVES
    (BULLETIN OF MATERIALS SCIENCE, 1991) BHUVANESHWAR, GS; Muraleedharan, CV; RAMANI, AV; VALIATHAN, MS
    The heart of a normal human being beats about 38 million cycles every year. An artificial heart valve, to perform at this rate in the adverse conditions inside the heart for 20 years or more, should be highly wear-resistant with excellent fatigue strength. Thus, the study of mechanical and physical properties of the materials intended for use in artificial valves becomes an inseparable part of the valve development process itself. The physical and mechanical requirements of the materials used in the Chitra heart valve have been evaluated by studying their water absorption, adhesive wear and abrasive properties. The mechanical durability of the device has been assessed by accelerated life cycle testing. The test systems developed for the above are described here. The results show UHMW-PE to be a highly wear-resistant material suitable for the occluder. The accelerated wear tests show that the valve with Haynes-25 alloy cage and UHMW-PE disc has durability in excess of 50 years.
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    PREVENTION OF CALCIFICATION OF TISSUE VALVES
    (ARTIFICIAL ORGANS, 1994)
    In this study an attempt was made to find an optimum method of chemical treatment to prevent the calcification of bioprosthetic heart valves. Bovine pericardium was washed in a 5% sodium chloride solution followed by trypsin (Tr) treatment and was kept in 0.1% glutaraldehyde (GA) with a gradual increase in concentration up to 0.25% GA and finally posttreated with a 4% chitosan (Ch) solution. Fresh, 0.2% GA, 0.625% GA, and sodium chloride-Tr-GA treated pericardial samples were taken for comparative study. Tensile testing showed comparable strength and elongation at the breaking point for all groups. The thermal shrinkage studies indicated merit of the proposed treatment (5% sodium chloride-trypsin-glutaraldehyde treated pericardia with chitosan and without chitosan posttreatment). Collagenase assay showed that all differently treated (GA) materials were equally resistant to collagenase. All samples were implanted subcutaneously in rats for 2, 4, 8, or 12 weeks for calcification study. Morphological and mineral analyses showed complete prevention of calcification in sodium chloridetrypsin-GA-chitosan treated pericardium (Ca was 1.1 +/- 0.27 mg/g, von Kossa 0) at the 12th week of implantation.
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    USE OF GLUTARALDEHYDE-GENTAMICIN-TREATED BOVINE PERICARDIUM AS A WOUND DRESSING
    (BIOMATERIALS, 1994) CHANDA, J; RAO, SB; MOHANTY, M; Muraleedharan, CV; ARTHUR, VL; BHUVANESHWAR, GS; VALIATHAN, MS
    Glutaraldehyde (GA)-pretreated gentamicin post-fixed bovine pericardium has been evaluated as a wound dressing in this study. Two excisions approximately 7 x 4cm, each of full thickness skin, from the upper and lower parts down to, but not including, the panniculus carnosus were made from the back of the guinea pig. The skin excised from the upper part was placed on the wound bed of the lower part as an autograft, whereas the upper wound was closed using 5% sodium chloride-trypsin-0.1% GA-0.048% gentamicin-treated bovine percardium and sutured for comparative study. The wounds were inspected every 3-6 d for infection and exudation. Histopathological studies were performed at weekly intervals in the post-operative period. At the fifth week, a very thin linear scar on the epidermal aspect without remarkable contracture was observed and histopathology showed the completion of epithelization across the wounds in all cases. This study demonstrates that GA-pretreated, gentamicin-post-fixed bovine pericardium may be used as an alternative biological dressing in the case of large wounds.