G S Bhuvaneshwar

Publications of G S Bhuvaneshwar

• The toxicological quandary in the use of plasticizers in medical devices.

  Authors: V Kalliyana Krishnan, G S Bhuvaneshwar

  The Indian journal of medical research. 05/2004; 119(4):vi-viii.

• Long term tissue response to titanium coated with diamond like carbon.

  Authors: M Mohanty, T V Anilkumar, P V Mohanan, C V Muraleedharan, G S Bhuvaneshwar, F Derangere, Y Sampeur, R Suryanarayanan

  Biomolecular engineering. 09/2002; 19(2-6):125-8.

  Diamond like carbon (DLC) coatings were deposited on to Ti substrates by plasma enhanced chemical vapor deposition technique. Ti and DLC/Ti samples were implanted in skeletal muscle of rabbits. TheDiamond like carbon (DLC) coatings were deposited on to Ti substrates by plasma enhanced chemical vapor deposition technique. Ti and DLC/Ti samples were implanted in skeletal muscle of rabbits. The samples were explanted after 1, 3, 6 and 12 months and the tissue-cell interaction was studied. Our data indicate both DLC/Ti and bare Ti to be compatible with skeletal muscle.

• Quantitation of platelet adhesion to Ti and DLC-coated Ti in vitro using (125)I-labeled platelets.

  Authors: L K Krishnan, N Varghese, C V Muraleedharan, G S Bhuvaneshwar, F Derangère, Y Sampeur, R Suryanarayanan

  Biomolecular engineering. 09/2002; 19(2-6):251-3.

  Measurement of platelet adhesion in vitro is a good indicator of its reactivity to implant devices in vivo. Platelets were labeled with I-125 without affecting its normal morphology and function andMeasurement of platelet adhesion in vitro is a good indicator of its reactivity to implant devices in vivo. Platelets were labeled with I-125 without affecting its normal morphology and function and the labeled platelets were suspended in platelet poor plasma and exposed to Ti and diamond like carbon-coated (DLC) Ti discs, under dynamic conditions, using a parallel plate flow chamber. The test materials were washed, dried, exposed to a phosphor screen and scanned to get the images. The number of platelets that adhered to Ti was found to be higher than those that adhered to DLC coated Ti sample, irrespective of the shear stress which was varied between 2 and 16 dynes/cm(2).

• In vitro cytocompatibility studies of Diamond Like Carbon coatings on titanium.

  Authors: T V Kumari, P R Anil Kumar, C V Muraleedharan, G S Bhuvaneshwar, Y Sampeur, F Derangere, R Suryanarayanan

  Bio-medical materials and engineering. 02/2002; 12(4):329-38.

  Diamond like carbon (DLC) films were deposited on to titanium (Ti) substrates by Plasma Enhanced Chemical Vapour Deposition (PECVD) process. The quality of the films were checked by Raman spectra andDiamond like carbon (DLC) films were deposited on to titanium (Ti) substrates by Plasma Enhanced Chemical Vapour Deposition (PECVD) process. The quality of the films were checked by Raman spectra and nano-hardness tests. The cytocompatibility of titanium and DLC coated titanium were studied using continuous cell lines of mouse fibroblast cells ( L-929), Human Osteoblast cells (HOS) and primary human umbilical cord vein endothelial cells (HUVEC). The cellular responses to the materials were assessed both quantitatively and qualitatively. The adhesion and spreading of cells on materials were compared using Ti as a control. Present study indicates an improved cytocompatibility of DLC coated Ti in comparison to bare Ti.

• Chitra heart valve: results of a multicenter clinical study.

  Authors: R Sankarkumar, G S Bhuvaneshwar, R Magotra, S Muralidharan, R S Rajan, D Saha, K S Subba Rao, M S Valiathan, S Radhakrishna, A V Ramani

  The Journal of heart valve disease. 10/2001; 10(5):619-27.

  BACKGROUND AND AIM OF THE STUDY: The Chitra tilting disc valve was developed in India to meet the need for a low-cost cardiac valve. The valve has an integrally machined cobalt-based alloy cage, anBACKGROUND AND AIM OF THE STUDY: The Chitra tilting disc valve was developed in India to meet the need for a low-cost cardiac valve. The valve has an integrally machined cobalt-based alloy cage, an ultra-high molecular-weight polyethylene disc, and a polyester suture ring. An important feature of this valve is its soft closing sound, by virtue of a plastic occluder. METHODS: Between December 1990 and January 1995, 306 patients underwent isolated aortic (AVR, n = 101) or mitral valve replacement (MVR, n = 205) at six institutions in India. The early mortality rate was 6.9% (seven after AVR; 14 after MVR). A total of 285 survivors was followed up until September 1998; total follow up was 1212 patient-years (pt-yr) (AVR, 445 pt-yr; MVR, 767 pt-yr). RESULTS: There were 52 late deaths (4.3%/pt-yr; AVR 2.2%/pt-yr; MVR 5.5%/pt-yr). Thirty-five deaths were valve-related (23 were due to unknown causes). One AVR patient (0.2%/pt-yr) and 12 MVR patients (1.6%/pt-yr) developed valve thrombosis, and embolic episodes occurred in 25 patients (seven after AVR, 1.6%/pt-yr; 18 after MVR, 2.4%/pt-yr). Bleeding events and infectious endocarditis occurred infrequently (AVR 0.9 and 0.7%/pt-yr; MVR 0.4 and 0.5%/pt-yr, respectively). There was no incidence of paravalvular leak or structural dysfunction of the valve. Actuarial survival rates at seven years were 82.4+/-4.0% for AVR and 65.2+/-5.0% for MVR. During the same interval, thrombus-free and embolism-free survival after AVR and MVR occurred in 98.9+/-1.1% and 94.1+/-1.9%, and 92.3+/-2.8% and 82.1+/-5.7% of patients, respectively. Freedom from all valve-related mortality and morbidity at seven years was 81.5+/-4.1% after AVR, and 64.2+/-5.1% after MVR. CONCLUSION: The Chitra valve appears to be safe and to have performance comparable with that of other currently used tilting disc valves. This valve costs substantially less than other valves, and is therefore within reach of a larger subset of Indian patients.

• Development of the Chitra tilting disc heart valve prosthesis.

  Authors: G S Bhuvaneshwar, C V Muraleedharan, G A Vijayan, R S Kumar, M S Valiathan

  The Journal of heart valve disease. 08/1996; 5(4):448-58.

  BACKGROUND AND AIMS OF THE STUDY: The high prevalence of rheumatic valvular disease in the young population and the high cost of imports necessitated the development of an Indian valve. TheBACKGROUND AND AIMS OF THE STUDY: The high prevalence of rheumatic valvular disease in the young population and the high cost of imports necessitated the development of an Indian valve. The development of a tilting disc prosthesis was successfully concluded in February 1995, when the third model completed its clinical trial. The tilting disc valve has an integrally machined cobalt alloy cage, an ultra high molecular weight polyethylene disc and a polyester suture ring. The choice of design was based on its superior hydrodynamics and the age distribution of patients, the majority of whom were below 30 years. The polymer-metal combination was selected for its extremely low wear rate and proven durability in the human body. MATERIALS AND METHODS: The hydrodynamic performance was tested under steady and pulsatile flow conditions. The accelerated durability of nine test valves was evaluated at 800-840 cycles/min for over 350 million cycles each. Size 23 mm valves mere implanted in the mitral position of five sheep. In a clinical trial, 306 patients with isolated mitral or aortic valve replacements were followed up for a total of 371 patient years (mean 1.37 years and range 0-4 years). RESULTS: The hydrodynamic performance was comparable to that of proven clinical models. The accelerated testing indicated lifetimes in excess of 50 years and the animal trials showed the valve to be safe. In the clinical trial, there was no incidence of structural failure or paravalvular leak. The linearized rate of late thromboembolism was 6.2%/patient-year (pty), anticoagulant related hemorrhage 0.54%/pty and infective endocarditis 0.54%/pty. At two years, the total actuarial survival was 89.5%. The higher incidence of thromboembolism and the very low incidence of anticoagulant related hemorrhage illustrate the difficulty in the management of anticoagulant therapy in a developing country, while the low incidence of endocarditis reflects their greater resistance to infection. CONCLUSION: These data clearly showed the valve to be safe and comparable to other similar valves in clinical use.

• Impedance measurement system for concentric needle electrodes

  Authors: N.D. Khambete, J. Shashidhara, G.S. Bhuvaneshwar, R. Sivakumar

  Engineering in Medicine and Biology Society, 1995 and 14th Conference of the Biomedical Engineering Society of India. An International Meeting, Proceedings of the First Regional Conference., IEEE; 03/1995

  Electromyographic recordings are significantly affected by electrode characteristics and associated instrumentation. This paper describes a system developed for measuring the interface impedanceElectromyographic recordings are significantly affected by electrode characteristics and associated instrumentation. This paper describes a system developed for measuring the interface impedance of concentric needle electrodes in normal saline at constant current density and over a frequency range of 10 Hz to 10 kHz. Five commercially available electrodes, having platinum as the core wire material were tested and the impedance was found to reduce exponentially with frequency according to an empirical equation Z=Kf^-m. The value of K, a measure of magnitude, was 1309 kohm/Hz^m and that of m was 0.75. The system was used to study the effect of electrolytic treatment on the electrode impedance. Considerable reduction was observed in the impedance magnitude (K=245 kohm/Hz^-m) and its variation with frequency (m=0.58), but only for short duration. The system can be effectively used to optimise various parameters for achieving desired impedance characteristics of the electrode

• Failure mode and effect analysis of Chitra heart valve prosthesis

  Authors: C.V. Muraleedharan, G.S. Bhuvaneshwar

  Engineering in Medicine and Biology Society, 1995 and 14th Conference of the Biomedical Engineering Society of India. An International Meeting, Proceedings of the First Regional Conference., IEEE; 03/1995

  Artificial heart valves are devices used for replacing diseased natural valves of the human heart. The failure of such a device to perform to its requirements can lead to serious complications,Artificial heart valves are devices used for replacing diseased natural valves of the human heart. The failure of such a device to perform to its requirements can lead to serious complications, even threatening the life of the recipient. There are many and varied modes of valve failure that can lead to departure from specifications. These failure mechanisms can be broadly classified into (1) intrinsic factors, like prosthesis design, materials and fabrication processes, and (2) extrinsic factors due to remodelling of the heart and lungs subsequent to valvular disease and valve replacement. This failure mode and effect analysis (FMEA) is an attempt to identify the various possible failure modes of the Chitra heart valve prosthesis

• PC based instrumentation as an economic method for quality assurance-an experience based on development of hydrocephalus shunt test system

  Authors: D.S. Nagesh, S.K. Srinivasan Nair, C.V. Muraleedharan, G.S. Bhuvaneshwar

  Engineering in Medicine and Biology Society, 1995 and 14th Conference of the Biomedical Engineering Society of India. An International Meeting, Proceedings of the First Regional Conference., IEEE; 03/1995

  A PC based system is an attractive alternative to conventional methods of industrial quality assurance for its high reliability at lower cost. A custom assembled system with user friendly softwareA PC based system is an attractive alternative to conventional methods of industrial quality assurance for its high reliability at lower cost. A custom assembled system with user friendly software is ideal for industries, especially when the quantity requirement is small. This concept is illustrated with an example of the development of a PC based test system for the quality assurance of hydrocephalus shunt-a neurosurgical implant. During the technology transfer of the device, a 16 channel PC controlled test system has been developed for classifying the device according to their pressure-flow characteristics. Here, the speed of the multichannel peristaltic pump is controlled for various flow rates ranging from 5 ml/hour to 50 ml/hour and the corresponding pressure drop sensed by the transducer is amplified, digitized and monitored. Depending on the measured values, the software classifies all the accepted devices in appropriate ranges and rejects the rest. The test results are printed out in proper format. All the subsystems and components used are in modular form and are standard products of leading manufacturers, enabling the user industry to operate and maintain the system without the help of the developer

• Prevention of calcification of tissue valves.

  Authors: J Chanda, S B Rao, M Mohanty, A V Lal, C V Muraleedharan, G S Bhuvaneshwar, M S Valiathan

  Artificial organs. 11/1994; 18(10):752-7.

  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 chlorideIn 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 chloride-trypsin-GA-chitosan treated pericardium (Ca was 1.1 +/- 0.27 mg/g, von Kossa 0) at the 12th week of implantation.

• Use of glutaraldehyde-gentamicin-treated bovine pericardium as a wound dressing.

  Authors: J Chanda, S B Rao, M Mohanty, C V Muraleedharan, V L Arthur, G S Bhuvaneshwar, M S Valiathan

  Biomaterials. 02/1994; 15(1):68-70.

  Glutaraldehyde (GA)-pretreated gentamicin post-fixed bovine pericardium has been evaluated as a wound dressing in this study. Two excisions approximately 7 x 4 cm, each of full thickness skin, fromGlutaraldehyde (GA)-pretreated gentamicin post-fixed bovine pericardium has been evaluated as a wound dressing in this study. Two excisions approximately 7 x 4 cm, 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 pericardium 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.

• A preliminary report on the development of an arterial prosthesis.

  Authors: G S Bhuvaneshwar, M S Valiathan, G A Lal, C C Kartha

  The Indian journal of medical research. 11/1983; 78:556-63.

• Development of textile fabrics for surgical application.

  Authors: G S Bhuvaneshwar, V.S. Venkatesan, V L Pattankar, C C Kartha, V A Lal, M S Valiathan

  The Indian journal of medical research. 11/1981; 74:580-5.

• Use of glutaraldehyde-gentamicin-treated bovine pericardium as a wound dressing

  Authors: J. Chanda, S.B. Rao, M. Mohanty, C.V. Muraleedharan, V.L. Arthur, G.S. Bhuvaneshwar, M.S. Valiathan

  Biomaterials.

  Glutaraldehyde (GA)-pretreated gentamicin post-fixed bovine pericardium has been evaluated as a wound dressing in this study. Two excisions approximately 7 × 4cm, each of full thickness skin, fromGlutaraldehyde (GA)-pretreated gentamicin post-fixed bovine pericardium has been evaluated as a wound dressing in this study. Two excisions approximately 7 × 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.

• Cardiac valvular prosthesis: an indigenous approach to development.

  Authors: M S Valiathan, G S Bhuvaneshwar

  Indian heart journal. 34(6):387-90.