Cyro-preservation of heart valves from cadavers

The State’s first-ever project launched by Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST) for setting up a Homograft Valve Bank, involving the harvesting and cryo-preservation of human heart valves from cadavers for use in place of costly artificial heart valves, has been flagging as there is little public awareness of cadaveric valve donation.

With at least a hundred patients with congenital heart diseases — all children and young adults — on the surgery waiting list at the SCTIMST, there is an urgent need to create public awareness.

It was in 2006 that the SCTIMST entered into a Memorandum of Understanding with the Department of Forensic Medicine, Thiruvananthapuram Medical College Hospital, for harvesting heart valves from cadavers that reach the post mortem table.

The harvested valves can be processed and can be preserved for later use in the Homograft Valve Bank.

These processed, cryo-preserved human valves, can replace the costly artificial or bio prosthetic valves that are required for patients who need to undergo valve replacement surgeries. Artificial (mechanical) valves cost anywhere between Rs.35,000 and Rs.50,000 or upward. The homograft will be supplied free at the SCTIMST or the MCH. With nearly 2,500 patients coming to the SCTIMST every year with valvular diseases and a majority of them requiring valve replacement surgeries, the Homograft Valve Bank is expected to bring about major gains to patients because of the reduced treatment costs and because of the inherent advantages in opting for a homograft.

But the supply of valves for harvesting has been dwindling because of the problems involved in getting consent from the relatives of dead individuals. The growing waiting list of patients requiring heart valves at the SCTIMST has thus been quite worrying, says K. Jayakumar, the Head of Cardiovascular Thoracic Surgery (CVTS), SCTIMST.

In the initial years of the project, the human valves harvested were used up for laboratory studies and for perfecting the process of cryo- preservation. The first homograft valve was implanted in November 2011. Till date, SCTIMST has implanted 22.

There are many patients in whom artificial valves cannot be used for various reasons and the only option is a homograft. Homograft offers improved quality of life to patients; it can bring down treatment costs and the anti-coagulant therapy required for those implanted with artificial valves can be done away with.

“Though we have a medico-social worker who visits the mortuary to meet the relatives of a dead individual and to counsel them about donating the heart valves and related humanitarian aspects, the yield of valves has been very poor. Because close relatives are usually never present at the mortuary to give consent and we are also constrained by the fact that the valves have to be removed within 24 hours of the time of death. Despite the promotion of organ donation in recent times, we still have problems convincing people that heart valves can be donated for a good cause,” Dr. Jayakumar says.

Heart valves cannot be harvested if cause of death is due to poisoning or if the patient died of cancer. Valves can be harvested from children or adults less than 55 years, who died due to road traffic accidents or by hanging.

“Given the number of road traffic accidents and suicides in the State, we should have been able to ensure sufficient stock of valves in the Valve Bank. A homograft is different from a transplant because once the valves are processed and de-cellularised, there is no need for even blood compatibility for it to be implanted in a patient. But we are now down to just four or five valves and a waiting list running to 100 patients,” says Baiju S. Dharan, Associate Professor, division of Congenital Heart Surgery in the Dept of CVTS.

  • 100 young adults, children awaiting surgery at SCTIMST

  • SCTIMST gets 2,500 cases with valvular problems annually