Peter Easton Thread
Peter Easton Thread
Thus, you are introduced (see Nancy's last post) to the famous "Peter Easton Thread," a monument at its time (less than four years ago), excellent and thoughtful arguments.
There are cautions that must now go with the thread, though. In this short period of time, many improvements have occured in all segments of valve replacements.
Results for Ross procedures are now separated by the type of surgery done, as a different method of implantation has proven much more succcessful than the original method whose numbers were still in use then.
Mechanical valves have improved in terms of hemodynamics, with better bloodflows, less damage to blood cells (hemolysis), even lower clotting potential for some types. Actual mechanical failures of mechanical valves are extremely rare now.
Xenograft (a.k.a. biological) valves have improved immensely, with major preservation and anticalcification improvement introductions, even in the last eighteen months.
While these changes are for the good, they do change the essential balance of the equations so carefully considered then as they are now.
For example, the figures given for mechanical valve/Anticoagulation Therapy (ACT) morbidity in the article in the link given by Peter ( http://www.hsforum.com/stories/storyReader$1472 ) are 4% - 8%. I doubt you'd get much agreement with those figures now. You're likely to get more concurrence when you describe a combined mechanical valve/ACT rate somewhere in the 2% - 4% level, depending on how the figures are compiled.
The rate is combined mortality, mostly from thromboses thrown by the mechanical valve despite warfarin therapy and from bleeding events attributed to warfarin therapy. This is one of the reasons that it is improper - although we frequently do it - to focus on the Coumadin end of the equation, when more than half of the problems are actually due to what happens in spite of the warfarin, rather than because of it.
But this, too, is changing, because of apparently lower surface reactivity and design improvements in some new models of mechanical valves (e.g. the On-X). These improvements are not in the numbers yet. Plus, we will begin to see a new series of statistics begin to show. While traditionally staged to a younger age group for avoidance of reoperations, mechanical valves have been so viable in patients that we will see the general population of mechanical valvers age significantly over the next decade. This is good, inthat it means that these people are a living success story. But it will change some numbers and comparisons, particularly in relation to biologicals, which have traditionally been placed in an older population.
Xenografts are generally described in the Easton thread as showing significant deterioration at the ten-year mark. That research data was actually old even then, and is no longer the case (with the probable exception of younger patients, for whom we still await documentation). Even the previous version of the bovine valve has a track record that averages its useful life at 18-22 years, and the top porcines at 15-18 years.
So, take in the sense of the thread, but be cautious of the numbers.
It seems as if every time we turn a page or click on a link, something new is being added to the valve replacement lexicon, something has been substantially improved, or something has been obviated. Because of the nature and rapidity of these changes, our discourse here today on valve choices, as earnest, heartfelt, hopefully accurate, and truly necessary as it is, will likely be just so much heat on the page in only a few years.
And then we'll do it all over again.
Until then, here's to learning, discussion, understanding, choice, and most of all to support of those who have had, shared in, or will undergo this life-changing, life-saving surgery. Solidarnosc!
Best wishes,
