Volume compensation for left ventricle assist systems (LVAS): 18 month in vivo evaluation.

The smooth surface cycled chambers, both Biomer and silicone rubber, developed thick tissue capsules and exhibited persistent active tissue reactions at the diaphragm-capsule interface. Textured surface chambers (dacron velour), both the cycled and control, developed a thin, stable capsule, with no active tissue reaction. Textured surface chambers have been explanted and examined after 210 and 494 days. One experiment is continuing, approaching 2 yrs in vivo with good performance. Although the number of textured surface compliance chamber studies as yet is limited, the dramatic improvement in performance and tissue response between the smooth and textured surface studies demonstrates the biological feasibility of this method of variable volume compensation for use in completely intracorporeal LVAS.