Influence of Pathologic Blood Cell Microrheology on Myocardial Microcirculation in Cardiac Surgery Using Cardiopulmonary Bypass

Abstract

A possible link between blood trauma and the myocardial microcirculation was prospectively studied in 27 patients undergoing cardiac surgery. Blood trauma was assessed microrheologically by analysis of gross red cell filtration rate (RFR) and plasma white cell filtration rate (p-WFR). Laser Doppler flow metry (LDF) was used to assess microflow in the myocardium before and after coronary bypass grafting. The LDF% was significantly reduced in the ischemic parts of the myocar dium, by 25% compared with 52% in the nonischemic myocardium (p < 0.01). After grafting, the grafted ischemic myocardium increased the LDF to 55% (p < 0.001) to levels comparable to those of the nonischemic myocardium, but the normal nonischemic, nongrafted myocardium reduced its microflow to 42% (p < 0.02). The RFR taken simultaneously showed a significant reduction by 34% from 45 to 30μL/sec (p < 0.001). The p-WFR fell significantly by 39% from 33 to 20 μL/sec (p < 0.05). The type of operation did not significantly influence the RFR and p-WFR values. There was a positive correlation between the LDF and RFR (r=0.86, p < 0.01) and between LDF and p-WFR (r=0.77, p < 0.01). Surgery with cardiopulmonary bypass (CPB) reduces the microcirculation in the myocardium. The rheology of blood cells is reduced during CPB. Studies to preserve the blood cells and the microcirculation during and after CPB are required.