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PubMed · 6162435

Effect of blood viscosity decrease on exercise ST segment depressions in hyperlipidemia.

A G Olsson·M Blombäck·L G Ekelund
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Abstract

In order to study the possible relation between blood viscosity and exercise ST segment depressions in hyperlipidemia the former was lowered by infusion of dextran and by treatment with clofibrate 1 g twice daily. Acute decrease of blood viscosity with dextran infusion in two cases increased the ST segment depressions during work. Nine subjects with asymptomatic hyperlipidemia, hyperfibrinogenemia and exercise ST segment depressions were treated with clofibrate in order to lower plasma fibrinogen and serum lipids. This did not influence the area of ST segment depression with either Frank leads or CH leads as determined by computer estimation. As the plasma fibrinogen level is of major importance for the blood viscosity it is concluded that the ischaemic ST segment depression seen in hyperlipidemia is not due to increased blood viscosity but more likely to a premature subclinical coronary atherosclerosis.

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Blood ViscosityClinical Trials as TopicClofibrateDextransExercise TestFibrinogenHumansHyperlipidemiasLipoproteinsClinical TrialJournal ArticleResearch Support, Non-U.S. Gov't

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A G Olsson, M Blombäck, L G Ekelund. 1980. Effect of blood viscosity decrease on exercise ST segment depressions in hyperlipidemia.. https://pubmed.ncbi.nlm.nih.gov/6162435/

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PubMed1992

Role of plasma viscosity in platelet adhesion.

Platelet adhesion to the vessel wall is initiated by transport of blood platelets from the bulk flow to the wall. The process of diffusion and convection of the platelets is affected by rheological conditions such as well shear rate, red blood cell (RBC) deformability, and viscosity of the medium. To study the effect of plasma viscosity on platelet adhesion, perfusion experiments with a rectangular perfusion chamber were performed. Reconstituted blood, consisting of washed platelets and washed RBCs, was circulated through this chamber for 5 minutes at a wall shear rate of 300 s-1. Different albumin concentrations were made, to obtain different medium viscosities (0.89 to 1.85 mPa.s). Platelet adhesion decreased with increasing medium viscosity up to viscosities of 0.95 mPa.s, but increased with medium viscosity above this value. Instead of human albumin solution, different plasma viscosities were obtained by dilution of Waldenström plasma with buffer. Plasma was depleted of fibronectin, which gave a final plasma viscosity of 2.0 mPa.s, and was dialyzed against HEPES buffer and subsequently diluted with the dialysis buffer in different fractions (0.89 to 2.00 mPa.s). Perfusions were performed over a purified von Willebrand factor coating on glass, or over an endothelial cell matrix, preincubated with von Willebrand factor. With both surfaces, platelet adhesion was dependent on the plasma viscosity in a similar way: at low plasma viscosities, adhesion was decreased with increasing plasma viscosity, while at higher plasma viscosities, adhesion increased with plasma viscosity. Adhesion values at higher plasma viscosity or at higher human albumin concentrations could be explained by effects of the medium on the rigidity of the RBCs, since platelet adhesion is known to be increased by enhanced RBC rigidity. Effects of the medium on the deformability of the RBCs were measured separately with the laser diffraction method. These experiments confirmed that presence of human albumin or plasma in the measuring suspension increased the rigidity of RBCs. To prevent influence of the medium on the RBCs in perfusion experiments, the RBCs were fixated with glutaraldehyde. Perfusion experiments with fixated RBCs in plasma over a von Willebrand factor preincubated endothelial cell matrix, showed a consequent decrease in adhesion with increasing plasma viscosity, according to the diffusion theories, whereas the increase of adhesion at high plasma viscosities was lacking. This suggests that the latter effect was entirely due to increased transport of platelets by more rigid RBCs.

Blood Viscosity↗