Aspirate from stented aortocoronary saphenous vein grafts reduces coronary flow and left ventricular pressure in an isolated perfused rat hearts

Abstract

BackgroundStent implantation into aortocoronary saphenous vein grafts (SVG) releases not only particular debris but also soluble factors which compromise coronary blood flow: using rat mesenteric arteries as bioassay, we have identified serotonin as the main vasoconstrictor. We now addressed the effects of aspirate on the coronary microcirculation and left ventricular function.MethodsIn 16 patients with significant SVG stenoses, arterial plasma was withdrawn before stent implantation and aspirate was retrieved after stent implantation under protection with a distal occlusion/aspiration device. Isolated rat hearts were perfused at constant pressure with Krebs‐Henseleit buffer containing 4% bovine albumin. Plasma was infused (2ml/min) into rat hearts (± NOS‐inhibition: L‐NAME 100µM; ± serotonin receptor blockade: ketanserin (10‐6 M) and pindolol (10‐7 M)). Changes of coronary flow (CF) and left ventricular pressure (LVP) are expressed relative to baseline before plasma application.ResultsAspirate plasma reduced CF and LVP more than arterial plasma, however, only during NOS‐inhibition (arterial vs. aspirate plasma; CF [Δml/min]: ‐1.2±0.3 vs. ‐1.6±0.6, LVP [ΔmmHg]:‐11±2 vs.‐15±‐3). Effects of aspirate on CF and LVP were largely attenuated by serotonin receptor blockade.ConclusionIn isolated rat hearts with impaired endothelial function, soluble factors within coronary aspirate, notably serotonin, compromise coronary microcirculation and left ventricular function.