Chronic blood hyperviscosity in subjects with acute stroke, transient ischemic attack, and risk factors for stroke.

Abstract

The origin and significance of blood hyperviscosity in subjects with acute stroke has been controversial. It has been argued that viscous abnormalities simply reflect either elevated hematocnt or an acute-phase response to the stroke itself. To address these issues, we measured the factors that determine blood viscosity in a cross-sectional study of 430 subjects, including 135 with acute stroke, 89 with acute transient ischemic attacks of the brain, 115 with recognized risk factors for stroke, and 91 healthy controls. The at-risk group was balanced with the acute stroke group for types of risk factors and medication usage, and all four groups were balanced for age. The viscosity of whole blood at low rates of shear and the plasma viscosity were significantly elevated in both groups with cerebrovascular symptoms and in the at-risk group compared with the healthy controls. The severity of hyperviscosity was stroke group > transient ischemic attack group > at-risk group > healthy controls. Increased viscosity of whole blood was associated with an elevated plasma fibrinogen concentration and with a decreased albumin/ globulin ratio. This study provides evidence that blood hyperviscosity is present not only in subjects with acute brain infarction, but also in those with risk factors for stroke, and that these abnormalities are, to a considerable degree, chronic (Stroke 1991^2:162-168)

Cushing`s disease: Fibrinogen and D-dimer levels fail to normalize despite early postoperative remission — a prospective, controlled study

“…High fibrinogen levels have been observed in patients with myocardial infarction, stroke, and transient ischaemic attacks, i.e. in conditions characterised by an undeniable thrombotic aspect [18][19][20][21]. Fibrinogen levels have been demonstrated to be higher with age, in smokers, in the obese, in diabetes, and in hypertension [18,19].…”

“…The pathophysiological mechanisms involved in this effect include its impact on platelet aggregation and vascular endothelial function. Fibrinogen also affects the fluidity of blood by increasing blood viscosity and platelet aggregation [18][19][20][21]23].…”

The effects of weight loss due to gastric banding and lifestyle modification on red blood cell aggregation and deformability in severe obese subjects

“…12 Increased blood viscosity is responsible for a greater blood-flow resistance, this effect being most marked in the microcirculation, and especially in capillaries measuring 4-8 m in diameter. 5,13 In various diseases including heart disease 14 and cerebral stroke, 15,16 an increased blood viscosity has been reported, probably linked to an increase in the number of RBCs and the concentration of some plasma proteins (especially fibrinogen and globulins). These rheological alterations induce an increased erythrocyte aggregation and reduced deformation.…”

Fasudil (a Rho Kinase Inhibitor) Specifically Increases Cerebral Blood Flow in Area of Vasospasm After Subarachnoid Hemorrhage

“…Blood viscosity is elevated in patients with acute cerebral infarction (Coull et al, 1991). However, it is not clear if this reflects a pre-existing risk factor or an acute phase response to the stroke itself or both.…”