Significantly increased low shear rate viscosity, blood elastic modulus, and RBC aggregation in adults following cardiac surgery

Yi-Fan Wu,Pin-Cheng Pan,Yeng-Long Chen,Chien-Sung Tsai,Po-Shun Hsu

doi:10.1038/s41598-018-25317-8

Abstract

Open heart surgeries are common for treating ischemic and heart valve disease. During cardiac surgery, cardiopulmonary bypass (CPB) can temporarily take over the function of heart and lungs. However, elevated red blood cell (RBC) aggregation may lead to the common side-effects such as microinfarction. We investigated blood physical properties changes and the correlation between blood microstructure, viscoelastic response and biochemical changes following surgery with CPB. We examined shear-rate dependent blood viscosity, elasticity and RBC aggregate size in the pre-surgery disease state, post-surgery state and long-term recovery state of cardiac surgical patients. Within a week following surgery, the patient hematocrit was significantly lower due to CPB. Despite lower RBC concentration, the RBC aggregate shape became larger and more rounded, which is correlated to the elevated plasma fibrinogen related to systemic inflammatory response. During the same period, the hematocrit-adjusted low shear rate viscosity increased significantly, as did the yield stress, indicating more solid-like behavior for blood. Six months to one year later, all the physical and biochemical properties measured returned to baseline.

Highlights

Cardiovascular disease (CVD) is the most common cause of death worldwide, with the total number of CVD deaths increasing by 40% between 1990 and 20131
To reduce these post-operative complications, hemodilution is applied during surgeries using cardiopulmonary bypass (CPB) to lower blood hematocrit and viscosity, increasing blood fluidity during and after the cardiac surgical procedure
Fib and C-reactive protein (CRP) are protein factors commonly sensitive to red blood cell (RBC) aggregation, as they both correlate with infection, trauma, and inflammation[48]

Summary

Introduction

Cardiovascular disease (CVD) is the most common cause of death worldwide, with the total number of CVD deaths increasing by 40% between 1990 and 20131. The surgical treatment causes side-effects that include systemic inflammation[2], thrombotic responses, endothelial cell activation[3] and tissue damage[4] Other complications such as cerebral ischemia and microinfarction could result in symptoms of impaired cognition or memory deficits, and they have been the focus for several recent studies[5,6,7,8]. Many studies have focused on complications such as cerebral ischemia, memory deficits cognitive loss and neurologic injury in post-surgical patients[5,6] To reduce these post-operative complications, hemodilution is applied during surgeries using cardiopulmonary bypass (CPB) to lower blood hematocrit and viscosity, increasing blood fluidity during and after the cardiac surgical procedure. The results may assist in the evaluation of post-surgical treatments, recovery, and differentiate between heart disease patients and normal subjects

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Results

Conclusion