In this medical health video learn about the On-X Heart Valve: Longevity With Less Reliance on Coumadin.
Read the full transcript »
The On-X Heart Valve: Longevity With Less Reliance on Coumadin: Dr. John Puskas: The On-X valve reduces a need for Coumadin, we believe in three ways. First it's made of pure carbon, that is 100% pure carbon. It has no silicon in it. So it is polished to a surface that when you look at it on microscope, it is smoother than any other surface from an older generations of valves. So that's the first thing, it's smoother so clots are less common there. Dr. Allen Graeve: They worked for decades to try to come up with a purely -- a pure pyrolytic carbon leaflet. At first they were stymied. They had to use silicon to I believe stabilize the leaflet and make it smooth, but now they have found the process by which they can remove all silicon. Dr. John Puskas: The smoother the surface on the mechanical valve, the less likely blood is to clot on it. Blood will clot on a shaggy or rough surface very quickly and does not clot very quickly on very smooth surfaces if the blood is flowing past it. So we want to have our mechanical valves made of the smoothest possible material and as we are implanting these valves, we take exquisite care to avoid scratching or damaging them. We want them to be implanted in a pristine condition. The material that the valve is made of matters. Almost all the presently available mechanical valves are made of a substance called pyrolytic carbon and it's about 6% or 8% silicon within the carbon that makes up this pyrolytic carbon. That means that when they polish this material very smooth, you can see little tiny microscopic pits where the silicon is. So if you look at the valves of this older generation, a valve manufacturers with electronic microscope, we can see little tiny pits. Whereas if you look at the newer valve this is On-X valve, that is pure carbon, it achieves a smoother surface. We believe that, that would be associated with less clotting risk. Dr. Allen Graeve: Secondly, the company decided that they would make the housing height along physical principles to reduce the turbulence of the blood going through the actual valve. Dr. John Puskas: Now there are two really interesting features of the design. The inlet of the On-X valve has a flair like the inlet of a rocket engine and blood enters this trumpet shaped flair and flows through it in a very laminar, even way. So the flow through the valve is smoother. Less turbulence produces less likelihood of clotting. The third way is how the leaflets are designed. The leaflet themselves open to 90° that the flow down the middle of the channel of the valve is not disturbed by the leaflets and the hinge points of the leaflets are designed to have a washing function to prevent clots from forming at the hinge points. Dr. Allen Graeve: They changed the canter of the leaflets slightly, so that it would also reduce turbulence and they gave a slight flair to the inlet of valve which is part of their design, which is not seen with other manufacturers. Dr. John Puskas: One of the problems with mechanical valves or any abnormal valve is tearing up blood as a blood flows through it. If blood passes over rough or turbulent surfaces, the cells in the blood can be physically damaged, bang against each other and torn up. Well that requires of the body, make new blood cells. This is a wear and tear on the blood function that is undesirable. We can measure how much wear and tear on the blood there is by sampling substances in the bloodstream. They tell us about broken red blood cells. We know that with this new valve; the On-X valve, those levels in the bloodstream are much lower than they are with the older design valves. Dr. Allen Graeve: They made several design changes all meant to be the best physical -- with the best physical evidence that they could come up with. Dr. John Puskas: So there are some materials differences, the substance from which the valve is constructed and also the design differences that we think make this valve more effective and safer than the