Coronary artery stent implantation alters wall shear stress during maximal vasodilation

Endovascular stents improve resting blood flow and increase flow reserve in the presence of coronary stenoses, but the impact of these devices on fluid dynamics during profound coronary vasodilation is largely unknown. We tested the hypothesis that stent implantation affects adenosine-induced alterations in coronary hemodynamics and arterial wall shear stress in barbiturate-anesthetized dogs (n=6) instrumented for measurement of hemodynamics including mean arterial pressure, left anterior descending coronary artery (LAD) blood flow, velocity, diameter, and radius of curvature. Indices of fluid dynamics and shear stress were determined before and after placement of a slotted-tube stent in the absence and presence of an adenosine infusion (1.0 mg/min). Adenosine decreased heart rate and mean arterial pressure and increased LAD blood flow, Reynolds and Dean numbers (Re and De, respectively), and global and oscillatory shear stress (τ and τ_os, respectively) concomitant with reductions in LAD vascular resistance in dogs before stent implantation. Increases in LAD blood flow, Re, De, and indices of shear stress were observed with no change in systemic hemodynamics after stent deployment (P<0.05). Adenosine-induced increases in coronary blood flow and reserve, Re, De, τ, and τ_os and decreases in coronary vascular resistance were attenuated after the stent was implanted. The results indicate that stent implantation blunts alterations in fluid dynamics during profound coronary vasodilation in vivo.