Determinants of pannus formation in long-surviving artificial heart calves, and its prevention

In a group of 76 calves maintained with Jarvik-5 and Jarvik-7 artificial hearts, pannus formation in the atrial location was evaluated retrospectively using a grading system based on measurement of the pannus tissue. Pannus was present in 87% of the calves surviving one to 7 mos with an old-style inflow quick-connect design utilizing polyester felt surfaces. This design had a suboptimal hemodynamic flow path. Using a new design of quick-connect with an improved hemodynamic flow path and a Biomer blood-contacting surface, pannus occurred only in 17% of calves surviving one to 9 mos. Furthermore, the pannus formation with the new design was mild in the 2 cases where it occurred, whereas the pannus formation in animals with the old cuffs was frequently severe. One calf survived 9 mos with no pannus formation utilizing our new quick-connect system, and we conclude that pannus is no longer a problem in our experiments. We also reviewed the relation of pannus to anticoagulant regimens and found that Persantine, Coumadin, and aspirin were not effective in preventing pannus when the inflow cuff design was conducive to its development.