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M S Valiathan

Publications and source records attributed to M S Valiathan.

At least 19 recordsLinked to original sources
PubMed2001

Chitra heart valve: results of a multicenter clinical study.

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, 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.

Adolescent↗
PubMed1997

Cerium levels are elevated in the serum of patients with endomyocardial fibrosis (EMF).

The geochemical hypothesis on endomyocardial fibrosis (EMF) links causation of the disease to increased levels of cerium in the heart. Since cardiac tissues are not easily accessible from patients, we explored whether cerium can be detected in the serum using neutron activation analysis (NAA). Cerium levels in serum of EMF patients were significantly elevated (p < 0.05) compared to controls.

Adolescent↗
PubMed1996

Levels of cerium in the tissues of rats fed a magnesium-restricted and cerium-adulterated diet.

Cerium, a lanthanide, is the most abundant rare earth element present in monazite and is biologically active. It has been postulated that cerium toxicity in conjunction with magnesium deficiency causes tropical endomyocardial fibrosis, a restrictive human cardiomyopathy (Valiathan et al. 1989; Valiathan and Kartha 1990). Generally, lanthanides are known to be poorly absorbed (Durbin et al. 1956; Evans 1990). The present study was carried out to ascertain whether magnesium deficiency promotes accumulation of cerium in various organs of rats.

Animals↗
PubMed1996

Structural studies on bovine bioprosthetic tissues and their in vivo calcification: prevention via drug delivery.

Cardiovascular calcification, the formation of calcium phosphate deposits in cardiovascular tissue, is a common end-stage phenomenon affecting a wide variety of bioprostheses. To study the process of calcification in tissue prosthetics, glutaraldehyde-treated bovine pericardium, dura mater and fascialata were implanted subcutaneously in rats and retrieved 21 days later and thereby morphological findings were correlated with biochemically determined levels of calcium. Transmission electron microscopy showed that calcification primarily involved the surface of collagen fibrils and the interfibrillar spaces. The deposition of calcium was higher with dura and fascia prostheses compared to pericardium. However, the release of Fe3+ ions from chitosan matrix had substantially inhibited the deposits of calcium in all implanted tissues. It seems that the structural and anatomical features of the tissue is one of the important factors for tissue-associated calcification. It is also confirmed that glutaraldehyde-preserved pericardium is the most suitable material for the development of cardiac prosthesis, with an appropriate drug combination therapy for prevention of pathological calcification.

Animals↗
PubMed1996

Development of the Chitra tilting disc heart valve prosthesis.

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. 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.

Adult↗
PubMed1994

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

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, 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.

Animals↗
PubMed1994

Prevention of calcification of tissue valves.

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

Animals↗
PubMed1992

Paradoxical effect of cerium on collagen synthesis in cardiac fibroblasts.

The present study examined the effect of cerium on collagen synthesis in cultured cardiac fibroblasts and explants. At 100 nM, a concentration comparable with that found in the cardiac tissue of patients with endomyocardial fibrosis, the element was found to enhance the incorporation of tritiated proline into collagen and non-collagen proteins while at 10 microM, it had an inhibitory effect. Cerium was found to have no effect on rates of DNA synthesis in fibroblasts at 100 nM. However, at this concentration, the element markedly enhanced the incorporation of tritiated uridine into RNA, suggesting that cerium may act at the level of transcription to stimulate collagen and non-collagen protein syntheses. The stimulatory action of very low levels of cerium on collagen synthesis may contribute to the accumulation of collagen seen in endomyocardial fibrosis.

Animals↗
PubMed1989

Surgical management of aortopulmonary septal defect.

Fourteen patients with malseptation of the aortopulmonary trunk underwent operative repair from 1978 to 1988. Age ranged from 1 year to 35 years (mean age, 9.6 years). Five patients had type I, 6 had type II, and 3 had type III lesions. The hemodynamic disturbance in all patients was the consequence of a large left-to-right shunt (mean pulmonary/systemic flow ratio, 2.38:1) with increased pulmonary vascular resistance (mean value, 4.47 units/m2). Our initial surgical experience with closure under cardiopulmonary bypass through the transaortic route in 3 patients and the transpulmonary approach in two patients resulted in 3 deaths. In the 9 subsequent patients, division and repair of the defect in the great vessels yielded uniformly good results. During follow-up, which ranged from 3 months to 2 years, all 11 survivors had good clinical improvement and none showed residual defects on restudy. Pulmonary artery pressure and pulmonary vascular resistance decreased in all patients except 1.

Adult↗
PubMed1989

A geochemical basis for endomyocardial fibrosis.

Analysis of hearts of patients dying from endomyocardial fibrosis showed a significantly greater concentration of cerium, a lanthanide present in leafy vegetables and root tubers, than in control hearts. This may be important in the pathogenesis of the disease and provides a geographical basis for the prevalence of the disease in the tropics.

Cerium↗
PubMed1989

Clinical course of endomyocardial fibrosis.

The survival pattern, morbidity, and clinical course of 145 patients with endomyocardial fibrosis who were followed up between November 1975 and June 1987 were studied. The diagnosis was confirmed in all cases by cardiac angiography, or echocardiography, or necropsy. Percentage survival at the end of one and 9.5 years was 76.11 and 26.35 respectively. History, physical examination, electrocardiography, and cardiac catheterisation were studied at the first presentation. The determinants of early mortality were studied by univariate Kaplan-Meier estimates compared by the log rank test and Cox proportional hazards multiple regression analysis. Significant univariate predictors of early mortality were QRS axis above +90 degrees, intraventricular conduction delay (QRS duration greater than 0.12 s), duration of symptoms before presentation, New York Heart Association functional classes III and IV, presence of embolic episodes, right atrial mean pressures greater than 20 mm Hg, right ventricular end diastolic pressure greater than 20 mm Hg, and aortic oxygen saturation less than 85%. The significant multivariate predictors of mortality were cyanosis, New York Heart Association functional class at first presentation, and right atrial mean pressure greater than 20 mm Hg. The bleak prognosis of endomyocardial fibrosis did not substantially improve despite advances in the medical management of congestive cardiac failure during the period of the study.

Adult↗
PubMed1988

Unusual manifestation of valvular vegetations.

Mitral obstruction due to a large vegetation of bacterial endocarditis occurred in a 30 year old man. 2-D echocardiogram revealed an echodense mass obstructing the mitral valve. The patient was successfully treated by mitral valve replacement.

Adult↗