In Vitro Evaluation of the Effect of Stenting on Hematological, Hemorheological and Hemodynamic Parameters, in Various Stent Configurations and Flow Conditions.

Purpose: Percutaneous coronary intervention is used extensively for the restoration of blood flow in diseased arteries. The influence of stent implantation on the physiology and flow of blood is an important and still not fully understood issue. The current work evaluated possible stent-induced changes in hematological, hemorheological and hemodynamic parameters.

Methods: Experiments were performed for blood flow in single and overlapping stent configurations, in both straight and curved tube geometries, in order to reproduce various stented coronary artery morphologies. Two different flow regimes were utilized to reflect a range of physiological and more intense flow conditions. Blood samples were obtained from a healthy human population and commercially available stents were inserted in clear perfluoroalkoxy alkane tubing, connected to a syringe/syringe-pump/pressure-sensor setup. Hematological measurements, red blood cell (RBC) deformability and aggregation, and whole blood viscosity tests were performed using standard techniques. The pressure drop across the stented area was measured via an in-line pressure sensing setup.

Results: In terms of hematology, RBC count, hematocrit, and mean corpuscular volume show a slight influence from the longer exposure to elevated stresses. Regarding hemorheology, the most profound effect was observed on RBC aggregation, with an increasing trend primarily in the female population of the study. Further, differences were found in the hemodynamics of the flow, as the pressure drop was altered according to the stent configuration. The viscosity of the blood samples is also found affected in the higher flow rate cases.

Conclusions: The presence of the stent was found to have a distinct effect on specific hemorheological and hemodynamic parameters according to the setup and stent configuration.