While I applaud the efforts of people trying to improve health care throughout the world, such as those in "Two Vein Attempts that Succeeded" (People and Innovations, September), I think it is important to keep the proper perspective in mind.

The material developed by Dr. Lyman has had extremely limited animal testing and virtually no clinical usage thus far. The article ignores the fact that expanded polytetrafluoroethylene grafts, Dacron grafts, and human umbilical vein grafts have been in use for more than a decade in more than a million patients and that they have provided patency and efficacy throughout this time. New products deserve proper evaluation by the medical community, but, in my opinion, they must prove their merit before they are worthy of such publicity.

As far as the Xenotech product is concerned, the history of biological implants from other species has been unsatisfactory in the opinion of most people. Obviously, the long-term clinical results will finally determine the success or failure of these products.