Current state of in vivo preclinical heart valve evaluation.

The use of animals to predict prosthetic valve performance in humans has now been in operation for over 25 years. Studies have focused on improvements in structural integrity, anti-thrombogenicity and anticalcification, and provide extensive in vivo analysis and validation of a valve before its clinical evaluation. Many animal models have been developed for such investigations, including calves, goats, pigs, baboons, dogs and adult sheep. Recent models used to assess prosthetic mitral valves have involved site-specific testing in several species; the present study represents the largest series of orthotopically implanted stentless bioprosthetic aortic valves and the first to utilize a juvenile sheep model for the aortic position.