Pseudointima in inflow conduits of left ventricular assist devices

Background. Explant analysis of left ventricular assist systems (LVAS) shou ld permit a better evaluation of long-term evolution of materials and tissu e healing in patients supported by mechanical devices and a precise underst anding of embolic phenomena, observed clinically. Methods. Five Novacor LVAS and their conduits have been explanted after 156 days (range 61-226 days) of mechanical support. The pseudo-intima (PI) dev eloped in the inflow and outflow conduits was characterized microscopically , using monoclonal antibodies. Results. The morphological aspects of PI were quite different in the inflow and outflow conduits. Blood coagulation between the basal surface of the P I and the Dacron tube, irregular collagen type I matrix with plasma infiltr ation, macrophages, and neutrophil granulocyte elastase characterized the n onadherent, loose, and potentially thrombogenic PI growth in the inflow con duit. The PI from collagen types I and IV with circumferentially oriented a lpha-smooth muscle cell actin-positive cells was anchored to the outflow co nduits. Conclusions. The observations, which have to be confirmed by a more extensi ve study on a larger number of specimens, suggest the role of the biomateri al itself, as well as the configuration, physical characteristics, and rheo logy in the conduit. They also suggest that thromboembolic complications of LVAS may eventually be related to this host tissue response. (C) 1999 by T he Society of Thoracic Surgeons.