Mitral Valve Replacement
There are two main types of prosthetic valves. They are-
- Mechanical or metal valves
- Tissue or bioprosthetic valves
Bioprosthetic valves lasts about 10-15 years. These are usually obtained from animals or human organ donors.
Human Valves are referred as Homograft or allograft. Valves from pigs (porcine) or cows (bovine) can be used and are referred as heterograft or Xenograft. Both these valves have a metal wire or stent in the middle and have a similar design. Stentless valves are also present but are hard to implant.
Tissue valves seem to improve the patient’s hemodynamics, but tend to stiffen in 10-15 years and calcify causing a stenotic valve.
An organ donor’s valve is cryopreserved in liquid nitrogen and used when there is a requirement for the valve. Patients’ chances of rejecting the valve are low. It shows good durability and hemodynamics.
Mechanical valves are purely metal and lasts a lifetime. Complications of blood clots and emboli are common in patients with a mechanical valve. So patients take Coumadin or blood thinners all their life.
The most commonly used valve in the United States is a bileaflet valve called as “ST. Jude”. Incidence of thrombosis in this valve is low.
“Starr-Edwards” is a caged ball valve, which has very long durability but high incidences of thromboembolism.
Since 1952, 30 different valves have been used worldwide and the recent one being a bileaflet valve. The bileaflet valve does not close completely and allows back flow of blood to an extent and therefore is not ideally used.
TTK chitra valve is the only Indian made valve. It is a tilting disc valve, durable and highly cost effective.