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Blood rheology in hypertension and hypertensive heart disease
Insights
Blood viscosity is elevated in hypertensive patients, even those without coronary artery disease (CAD). This increased blood viscosity may contribute to angina and reduced coronary reserve in hypertension.
Area of Science:
- Cardiovascular Physiology
- Hematology
Background:
- Essential hypertension and renoparenchymal hypertension present distinct rheological profiles.
- Coronary artery disease (CAD) complicates essential hypertension, influencing blood rheology.
Purpose of the Study:
- To investigate and compare blood rheology in patients with essential hypertension, renoparenchymal hypertension, and normotensive controls.
- To differentiate rheological findings based on the presence or absence of coronary artery disease in hypertensive patients.
Main Methods:
- Blood rheology was assessed in 50 essential hypertensive patients (with and without CAD), 17 renoparenchymal hypertensive patients, and 34 normotensive controls.
- Coronary angiography was used to exclude CAD in normotensive individuals and to categorize essential hypertensive patients.
- Key rheological parameters measured included plasma viscosity, whole blood viscosity at varying shear rates, fibrinogen levels, and red blood cell aggregation.
Main Results:
- Renoparenchymal hypertension showed increased plasma viscosity and elevated fibrinogen levels.
- Whole blood viscosity and elastic component of blood were higher in renal hypertension compared to essential hypertension.
- Essential hypertensive patients with CAD exhibited higher plasma viscosity and fibrinogen than those without CAD.
- Hypertensive patients without CAD still displayed significantly higher plasma viscosity, red blood cell aggregation, and whole blood viscosity than normotensive controls.
Conclusions:
- Elevated blood viscosity, including plasma viscosity and red blood cell aggregation, is a characteristic of hypertension, independent of coronary artery disease.
- Increased blood viscosity in hypertensive patients, even with normal coronary arteries, may play a role in the development of angina pectoris and reduced coronary reserve.
Abstract:
Blood rheology was studied in 50 patients with a long history of essential hypertension, together with severe left heart hypertrophy (mass-volume relationship greater than 1.6) and angina pectoris, as well as in 17 patients with renoparenchymal hypertension. The rheologic findings were compared with those of 34 normotensive patients in whom coronary artery disease (CAD) was excluded by coronary angiography. Based on angiographic findings, the patients with essential hypertension could be differentiated into two groups: 20 hypertensive patients with normal coronary arteries and 30 hypertensive patients with coexistent CAD. In renoparenchymal hypertension, increased plasma viscosity (1.39 +/- 0.08 mPas) secondary to elevated fibrinogen levels (406.8 +/- 84.6 mg/100 ml) was found. Whole blood viscosity at low and high shear rates and the elastic component of blood were significantly more elevated in patients with renal hypertension than in patients with essential hypertension. In 30 patients with essential hypertension and coexistent CAD, higher levels of plasma viscosity (1.37 +/- 0.08 mPas, p less than 0.05) and fibrinogen (294.1 +/- 55.1 mg/100 ml, p less than 0.02) were found than in patients with essential hypertension and normal coronary arteries (1.32 +/- 0.07 mPas and 259.8 +/- 44.9 mg/100 ml, respectively). Hypertensive patients with normal coronary arteries, however, showed significantly higher levels of plasma viscosity, red blood cell aggregation, and whole blood viscosity than did normotensive controls. It is conceivable that increased blood viscosity in hypertensive patients with normal coronary arteries contributes to angina pectoris and to the reduction in coronary reserve that is observed in hypertensive patients (1).