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Show SCHOOL OF MEDICINE AND HEALTH SCIENCES UNDERGRADUATE RESEARCH ABSTRACTS CORONARY ARTERIAL FUNCTION IS NOT IMPAIRED IN PATIENTS FOLLOWING CONTINUOUS-FLOW LEFT VENTRICULAR ASSIST DEVICE IMPLANTATION Elizabeth Johnson (J. David Symons) Division of Endocrinology, Metabolism and Diabetes University of Utah Continuous-flow left ventricular assist devices (LVADs) are used in advanced heart failure patients either to bridge them to transplantation or as a permanent-destination therapy. W e sought to determine whether chronic exposure to non-pulsatile blood flow and acute increases in coronary perfusion pressure associated with LVAD implantation attenuate arterial function. A transmural biopsy of the left-ventricle was obtained from seven male patients (53±6 years old) at the time of LVAD implant (pre) and 128±17 days later (post) upon LVAD explant. Arteries were dissected free and function was assessed using isometric tension techniques. First, Lmax tension was determined on each vessel. Next, contraction-response curves to potassium chloride (KCI, 10-100 m M ) were performed.To determine endothelium-dependent and -independent vasorelaxation, respectively, concentration-response curves to bradykinin (BK, 106 to 1010 M) and sodium nitroprusside (SNP, lO^to 10~9 M) were completed on vessels pre-contracted to - 6 5 % of maximal tension development. Maximal KCI-evoked contraction (0.93±0.17 and 0.57±0.12 m g tension development / p m vessel length), maximal BK-evoked vasorelaxation (62±10% and 65±9%), and maximal SNP-evoked vasorelaxation (83±7% and 84±5%), was similar in arteries obtained from pre (n=17 arteries, 219±36 p m i.d.) and post (n=19 arteries, 341 ±36 p m i.d.) transmural biopsy samples, respectively. These preliminary data indicate that coronary vascular function is not attenuated by LVAD implantation. £ 1.4 at | 1-2 E,,( = 0.8 §0.6 W 0.4 C « 0.2 |»0.0 A. non-receptor mediated vasocontraction -30 S o x J5 30 9 implant v - v explant 60 90 B. endothelium-dependent vasorelaxation •-• implant v - v explant 20 40 60 80 100 potassium chloride, m M 10 9 8 7 6 [bradykinin], -log M -30 -I i o ts *Z 60 90 C. endothelium-independent vasorelaxation implant v - v explant 4 5 6 7 8 9 [sodium nitroprusside], -log M Elizabeth Johnson J. David Symons 121 |
