The role of chronic hyperviscosity in vascular disease

Abstract

BackgroundThe pathogenesis of vascular disease is complex and as of yet not totally understood. Conventional wisdom suggests that atherosclerotic cardiovascular disease is caused by the accumulation of lipid molecules in the arterial luminal wall. Various therapeutic modalities have been proposed; however, current treatment with cholesterol-lowering drugs has not completely solved this problem. Risk factors aiding in the development of atherosclerotic disease have been long promoted, such as genetics, dyslipidemia, hypertension, smoking, lack of adequate exercise, metabolic syndrome, and obesity. However, 50% of myocardial infarctions occur in subjects without overt hyperlipidemia, and 20% of myocardial infarctions occur in the absence of any classic risk factors [Ridker and Libby, 2011].The reason why the pathogenesis of chronic vascular diseases, including atherosclerosis, hypertension, and the metabolic syndrome, is not fully understood by the mainstream is because the role of blood viscosity has been ignored. Most physicians are aware of acute hyperviscosity syndromes as can be seen in Waldenstrom's macroglobulinemia, polycythemia vera, and leukemia, which require immediate intervention. In these conditions, blood viscosity is in the range of 60 millipoise or greater at a shear rate of 94.5/s. However, chronic lesser elevations of viscosity do occur (roughly, 50-56 millipoise at 94.5/s, normal being 37-49 millipoise at the same shear rate) [Antonova and Velcheva, 1999;Velcheva et al. 2008]. Rosenson and colleagues reported a normal value of 32.6 millipoise at a shear rate of 100/s [Rosenson et al.1996].States of chronic, lower elevations of viscosity are clinically less obvious, and left unappreciated, can ultimately shorten one's lifespan by contributing to cardiovascular disease. In the study of Antonova and Velcheva, viscosities in the range referred to here as 'chronic hyperviscosity' were associated with chronic cerebral infarctions, transient ischemic attacks, and risk factors for stroke [Antonova and Velcheva, 1999]. In Velcheva and colleagues' work, chronic hyperviscosity was associated with transient ischemic attacks and unilateral cerebral infarctions [Velcheva et al. 2008].It should be noted that the reference ranges for blood viscosity are tentative, and work remains in standardizing the reporting and measuring of blood viscosity. Hopefully, a collaboration similar to the Reference Values for Arterial Stiffness'The role of chronic hyperviscosity in vascular disease Gregory Sloop, Ralph E. Holsworth Jr, Joseph J. Weidman and John A. St Cyr Abstract: The pathogenesis of several major cardiovascular diseases, including atherosclerosis, hypertension, and the metabolic syndrome, is not widely understood because the role of blood viscosity is overlooked. Low-density lipoprotein accelerates atherosclerosis by increasing blood viscosity in areas of low flow or shear, predisposing to thrombosis. Atherosclerotic plaques are organized mural thrombi, as proposed by Duguid in the midtwentieth century. High-de...

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