Blood rheology alterations in cardiovascular disease

Abstract: This thesis deals with the haemorheological aspects of cardiovascular diseases. The resistance of blood to flow is determined by the rheological properties of blood as well as by organic stenoses and regulatory tonus changes in the vessels. Three idiopathic cardiovascular diseases with a reduced ability to increase blood flow in response to demand were studied. Blood rheology was impaired in a way which could contribute to the reduced coronary blood flow reserve and the myocardial perfusion disturbances in syndrome X (paper I) and in idiopathic dilated cardiomyopathy (paper II). In primary pulmonary hypertension (paper III) the severly increased blood viscosity was estimated to have increased pulmonary vascular resistance to about 140-150% of what it would have been with normal blood viscosity. Furthermore, the blood haemoglobin concentration at the time of percutaneous transluminal coronary angioplasty (PTCA) was associated with the risk of subsequent symptomatic restenosis, which occured in 24.8 % of the patients with median haemoglobin concentration above the median 144 g/l but in only 9.3 % of the patients below the median (paper V). Like in earlier studies, restenosis was more common in men, but multivariate analysis indicates that the higher haemoglobin concentrations in men rather than the male gender per se is associated with an increased restenosis risk. The blood haemoglobin concentration correlates well with the blood viscosity (paper IV). Impaired blood rheology is a characteristic feature also of several other restenosis risk factors, e.g. diabetes mellitus, continued smoking, and unstable angina. It may thus be speculated that altered blood rheology could be of importance in the restenosis process.