SHORT-TERM EFFECTS OF DIMINISHED PULSATILE PERFUSION ON ARTERIAL STRUCTURAL PROTEIN CONTENT

Continuous flow ventricular assist devices (CFVADs) could revolutionize the industry, but effects on the vasculature are not well understood. The purpose of this work was to examine the effects of diminished pulse on arterial microstructure. Arterial segments were removed at the time of implantation (baseline: n=5) of a CFVAD into male dairy calves (flow was maintained at ± 50% of cardiac output). Another arterial segment was removed after 30 days (necropsy: n=3). Rings, of 2 mm width, were cut from the end of each vessel, embedded in freezing medium and frozen. The remaining segment was used for mechanical and vasoresponse testing (previously reported). Once frozen, five 6-micron sections were cut from each ring so that the staining could be repeated five times for each sample. Images were taken at 10x magnification and analyzed using Bioquant Nova software. Collagen and elastin content were recorded as a percentage of total cross-sectional area and each result reported as the average of the five measured values for each sample. Our results did not indicate significant differences between baseline and necropsy in either collagen (35.12+-10.8% vs 38.59+-1.8%, p<0.52) or elastin (10.67+-3.5% vs 13.85+-2.2%, p<0.16) content. This finding supports our previous result that there were no significant differences in the mechanical properties or vasoresponse between baseline and necropsy. Studies are ongoing to examine long-term (120 days) implantation effects, where direct correlations will be made between changes in arterial microstructure and changes in mechanical properties and vasoresponse.