Indigenous heart valve makes a difference

School children participate in a rally to create awareness about heart ailments on the World Heart Day in Amritsar. In India, large numbers of people suffer heart valve damage as a result of rheumatic heart disease.  

In his khaki shirt, Rameshnath looks no different from any other autorickshaw driver in Thiruvananthapuram. But he has been able to work for the last 15 years only because a damaged valve in his heart could be replaced with an artificial one. That valve was developed at the Sree Chitra Tirunal Institute for Medical Sciences and Technology, a speciality hospital and medical research centre in the same city.

The lower cost of the indigenous valve has given tens of thousands of people in the country, like 55-year-old Mr. Rameshnath, access to life-saving surgery over the course of nearly 20 years. With states like Andhra Pradesh and Tamil Nadu starting health insurance schemes for the poor, the demand for such a valve is set to grow.

In India, large numbers of people suffer heart valve damage as a result of rheumatic heart disease. This condition is produced when some bacterial throat infections, especially in children, evoke a severe immune response known as rheumatic fever. The body’s immune system may then turn on its own tissues, including the heart.

Rheumatic heart disease can affect the valves of the heart, which are then unable to function properly. In such cases, the unfortunate individual is unable to tolerate much exertion and quickly becomes tired and short of breath. Without valve replacement, these people risk heart failure and death.

The Indian Council of Medical Research has estimated that six out of every 1,000 children between the ages of five and 15 in the country suffer from rheumatic fever. Over one million children in the country could therefore be at risk of developing valvular disease.

Rheumatic fever and rheumatic heart disease are closely associated with overcrowding and poor living conditions. As a result, these ailments are more common among the poor, who often have limited access to medical care and cannot afford expensive surgery.

“Nothing was more painful or more cruel than the denial of a surgical procedure to a patient on the ground that a life saving device was beyond his or her means,” wrote M.S. Valiathan, who headed the Sree Chitra Tirunal Institute for two decades, in reminisces published in the Journal of Biosciences last year.

In 1976, with a project funded by the Department of Science and Technology, he initiated efforts to make heart valves within the country. (Four years later, the Institute, which had been started by the Kerala Government, was taken over by the Central Government.)

It was decided that the indigenous valve would be a mechanical device, not one that used human or animal tissue, said G.S. Bhuvaneshwar, who came to the institute as a young engineer and was given the task of developing the valve.

Tissue vs mechanical valves

One important reason for that choice was that mechanical heart valves last much longer than tissue-based ones. In India, the majority of valve replacements occur in those less than 30 years of age and so the artificial valve needed to function for several decades. Besides, mechanical valves were also cheaper, he pointed out.

(Tissue valves, on the other hand, have the advantage that those who get them do not need to be on drugs that reduce their blood’s ability to clot.)

The Sree Chitra team opted for a design where a metal ring with struts holds a tilting disc, which opens and closes, in place. The entire course of development of the valve was both a fascinating study of material science as well as a hugely challenging effort, pointed out A.V. Ramani in a paper published in 1991. Mr. Ramani headed Sree Chitra’s Biomedical Technology Wing while the valve was being developed.

The artificial valve must withstand the stress of opening and closing some 40 million times a year. The materials used for the valve have to be compatible with blood and human tissues. When open, the valve should allow the blood to flow smoothly through. Once closed, the back flow of blood had to be minimal.

The setbacks in developing the valve were many. A particularly bad moment came when a model that had passed all the laboratory tests failed when it was implanted in sheep. The tilting disc of synthetic sapphire had broken and the search for a material to replace it had to start anew.

Finally, a new model, with the disc made of a particularly tough and wear-resistant type of plastic, cleared laboratory tests and animal trials. In December 1990, after clearance was obtained from the Institute’s ethics committee, the first Chitra valve was implanted in a patient. After successful trials in the Institute, the valve went through further clinical trials at five more hospitals in various parts of the country.

Over 40,000 of the indigenous valves have gone into patients with success rates comparable to those of other mechanical heart valves on the international market today, said Dr. Bhuvaneshwar who now heads the Biomedical Technology Wing. An improved version of the valve is getting ready for clinical trials.

In late 1991, TTK Healthcare, one of the constituents of the TTK group, took the technology for the manufacture of the valve.

The valve is being used at around 275 medical centres across the country, said K.Sunil, vice-president of the company’s heart valve division. The Indian market for heart valves was about 30,000 a year and a sizeable portion of that is being met by the TTK-Chitra valves. These valves are being made at a state-of-the-art manufacturing facility that was recently commissioned in Thiruvananthapuram, he added.

The burden of rheumatic disease and rheumatic heart disease appears to have declined in many urban areas and states like Kerala and Tamil Nadu where human development had taken place, observed R. Krishna Kumar and his colleagues at the Amrita Institute of Medical Sciences and Research Centre at Kochi in a paper published recently in the journal Current Science. But “there are many areas [of the country] where the disease burden may be high.”

Where these diseases were widely prevalent, even young children would turn up requiring valve replacement, Dr. Krishna Kumar, a paediatric cardiologist, told this correspondent. Several children had received the TTK-Chitra valve at the Amrita Institute and follow-up studies indicated that it provided a safe, effective and inexpensive replacement.

But typically it was young men and women in their twenties who needed an artificial valve put in as a result of rheumatic heart disease, he added.

In 2007, the Andhra Pradesh government launched ’Aarogyasri’, a community health insurance scheme for the poor. It has opened the doors for those who once could not have afforded valve replacement surgery.

Under this scheme, the hospitals received a fixed amount for valve replacement operations, according to Rekha Matta, a cardiothoracic surgeon at the Narayana Medical College Hospital in Nellore, Andhra Pradesh. As the Indian valve was up to Rs. 10,000 cheaper than imported ones, it enjoyed a commercial advantage.

Besides, the TTK-Chitra valve was “definitely excellent” and as good as any similar valve made abroad, said Dr. Matta, who trained at the Sree Chitra Tirunal Institute and was even involved in the animal trials of the valve.

This year, Tamil Nadu launched the “Kalaignar’s Insurance Scheme for Life Saving Treatments” for families with an annual income less than Rs. 72,000.

The incidence of rheumatic heart disease seemed to be coming down in Tamil Nadu, observed Dr. S. Muralidharan, chief cardiothoracic surgeon at the G. Kuppuswamy Naidu Memorial Hospital in Coimbatore. There were fewer young patients needing valve replacement and more older people coming in for the operation. Rheumatic heart disease was usually the problem in the former while degenerative processes that affected the valve were common in latter.

The use of tissue valves had grown. The TTK-Chitra valve, imported mechanical valves and tissue valves had roughly equal share in the 150-200 heart valves being used in the hospital each year, he added.

Apart from its use in India, the TTK-Chitra valve is also being exported to countries such as Thailand, Myanmar and Kenya, remarked Mr. Sunil.

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Printable version | Jun 18, 2021 7:14:08 PM |

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