Related Experiment Videos
Blood rheology as a contributing factor in reduced coronary reserve in systemic hypertension
1Department of Medicine, Heinrich-Heine University of Duesseldorf, Federal Republic of Germany.
Insights
Essential hypertension is linked to poorer blood flow and reduced coronary reserve. Blood fluidity abnormalities, including higher hematocrit and plasma viscosity, significantly impact coronary reserve in hypertensive patients.
Area of Science:
- Cardiovascular Physiology
- Rheology
- Hypertension Research
Background:
- Essential hypertension is a major risk factor for cardiovascular disease.
- Coronary reserve, a measure of blood flow capacity in the heart, can be impaired in hypertensive individuals.
- Blood fluidity (rheology) may play a role in cardiovascular health, but its specific impact on coronary reserve in hypertension needs further investigation.
Purpose of the Study:
- To investigate the relationship between blood fluidity parameters and coronary reserve in patients with essential hypertension.
- To compare blood fluidity in hypertensive patients with normal coronary arteries to normotensive controls.
- To determine if rheological abnormalities contribute to impaired coronary reserve in essential hypertension.
Main Methods:
- Coronary reserve was assessed by measuring the ratio of coronary vascular resistance at rest to that after dipyridamole administration.
- Blood fluidity parameters including hematocrit, plasma viscosity, plasma fibrinogen, and whole blood viscosity were measured.
- Hypertensive patients were categorized based on the severity of their coronary reserve impairment.
Main Results:
- Hypertensive patients exhibited significantly lower coronary reserve compared to normotensive controls (2.4 +/- 0.8 vs 4.1 +/- 1.5).
- Hypertensive patients showed significantly higher hematocrit and plasma viscosity compared to normotensive controls.
- Impaired coronary reserve in hypertensive patients correlated inversely with parameters of blood fluidity, suggesting a role for rheological abnormalities.
Conclusions:
- Rheological abnormalities, characterized by poorer blood fluidity, are prevalent in patients with essential hypertension.
- These blood fluidity abnormalities are significantly associated with impaired coronary reserve in hypertensive individuals.
- Abnormalities in blood fluidity represent a key factor contributing to reduced coronary reserve in essential hypertension.
Abstract:
The influence of blood fluidity on coronary reserve in patients with essential hypertension and normal coronary arteries was examined. The coronary reserve, expressed as the ratio of coronary vascular resistance under resting conditions to the coronary vascular resistance after administration of dipyridamole, was 4.1 +/- 1.5 in 10 normotensive patients with normal coronary arteries, whereas the mean value was only 2.4 +/- 0.8 in 35 hypertensive patients. When compared with the normotensive control group the 35 hypertensive patients had significantly higher levels of hematocrit (45.9 +/- 3.7 vs 42.3 +/- 3.6; p less than or equal to 0.01) and plasma viscosity (1.39 +/- 0.07 vs 1.32 +/- 0.06 mPas; p less than 0.01). Plasma fibrinogen (291 +/- 67 vs 251 +/- 25 mg/dl) and whole blood viscosity at a shear rate of 2 s-1 (7.77 +/- 1.1 vs 7.21 +/- 1.28 mPas) and at a high shear rate of 100 s-1 (4.23 +/- 0.57 vs 3.91 +/- 0.64 mPas) demonstrated a trend without statistical significance toward higher values in hypertensive patients. When the hypertensive group was further divided according to the coronary reserve (less than 2.5, severely impaired coronary reserve; greater than 2.5 less than 3.8, moderately impaired coronary reserve), the parameters of blood fluidity clearly correlated inversely with coronary reserve. This suggests a major importance of rheologic abnormalities on impaired coronary reserve in hypertensive patients.