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Show 141 school of medicine and health sciences UNDERGRADUATE RESEARCH ABSTRACTS Left ventricular assist devices (LVADs) are used clinically to "bridge" end-stage heart failure patients during the period (~ 238 days) required to obtain a viable donor heart. In some cases, LVADs can be used as a per-manent i.e., destination therapy. LVADs significantly lower mechanical loading associated with heart failure and beneficial structural alterations have been reported. We sought to determine the impact of continu-ous- flow LVAD therapy on coronary vascular function. Rationale for this inquiry is that unlike the pulsatile nature of blood flow experienced by the endothelial cells lining coronary arteries of a normal functioning heart, some LVADs generate constant flow. Myocardial tissue was obtained from 17 males (57±4 y) at the time of LVAD implantation. Arteries (n=29; 155±13 μm i.d.) were isolated and function was assessed using isometric tension techniques. After Lmax tension was determined for each vessel, contraction-response curves to potassium chloride (KCl, 10-100 mM) were performed. To determine endothelium-dependent and -independent vasorelaxation, respectively, concentration-response curves to bradykinin (BK, 10-6-10- 10 M) and sodium nitroprusside (SNP, 10-4-10-9 M) were completed on vessels precontracted to ~65% of maximal KCl-evoked tension development. Maximal KCl-evoked contraction was 0.51± 0.09 mg tension / μm vessel length; maximal BK-evoked vasorelaxation was 85±3%; and maximal SNP-evoked vasorelax-ation was 80±4%. Of these 17 patients, three (51 ± 14 y) received heart transplants after being "bridged" via the LVAD for 116 ± 7 days. Maximal KCl-evoked contraction (0.51± 0.26 and 0.53± 0.15 mg tension development / μm vessel length), maximal BK-evoked vasorelaxation (98±3% and 90±7%), and maximal SNP-evoked vasorelaxation (103±8% and 93±4%), was similar in vessels at the time of LVAD implant (n=4 arteries, 131±12 μm i.d) and LVAD removal (n=8 arteries, 241±12 μm i.d.), respectively. "Control" responses were obtained using arteries (n=9; 167±16 μm i.d.) from 3 patients (42 y) that did not have heart disease, but whose health status precluded their ability to donate an organ. Maximal KCl-evoked contraction was 0.86± 0.13 mg tension / μm vessel length, maximal BK-evoked vasorelaxation was 92± 12%, and maximal SNP-evoked vasorelaxation was 99±8%. These preliminary data indicate that LVAD implantation does not alter coronary vascular function. THE INFLUENCE OF LEFT VENTRICULAR ASSIST DEVICE IMPLANTATION ON CORONARY VASCULAR FUNCTION Quinn Shelton, Lyman Wood, Robert Calvert (Stavros Drakos, Nikos Diakos, Omar Wever Pinzon, Dean Li, J. David Symons). College of Health, Division of Endocrinology, Metabolism and Diabetes University of Utah Quinn Shelton Lyman Wood J. David Symons |