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Essential hypertension in black and white subjects. Hemodynamic findings and fluid volume state
Insights
Systemic hemodynamics and intravascular volume were similar in black and white patients with essential hypertension. These findings challenge the notion that hypertension pathophysiology differs between races.
Area of Science:
- Cardiovascular Physiology
- Hypertension Research
- Racial Health Disparities
Background:
- Essential hypertension is a complex condition with varying prevalence and clinical presentation across racial groups.
- Understanding the underlying pathophysiology of hypertension in different populations is crucial for effective treatment.
- Previous clinical observations suggested potential differences in hypertension between black and white patients.
Purpose of the Study:
- To compare systemic hemodynamics and intravascular volume between black and white patients with essential hypertension.
- To investigate potential racial differences in the pathophysiology of hypertension.
- To determine if clinical impressions of racial differences in hypertensive vascular disease are supported by objective physiological data.
Main Methods:
- Measured systemic hemodynamics (cardiac output, intraarterial pressure, total peripheral resistance) and intravascular volume (plasma volume, red cell mass).
- Studied 126 patients (51 borderline, 75 established essential hypertension) and 29 age-matched normotensive controls, encompassing both black and white individuals.
- Analyzed correlations between hemodynamic parameters, blood volume, age, and race.
Main Results:
- No significant racial differences were found in cardiac index, total peripheral resistance, plasma volume, or total blood volume.
- Cardiac index positively correlated with plasma and total blood volume across all groups.
- Total peripheral resistance negatively correlated with plasma and total blood volume, with similar regression lines in both races.
Conclusions:
- Systemic hemodynamics and intravascular volume are comparable between black and white patients with essential hypertension, irrespective of age or arterial pressure.
- The study's findings do not support the clinical impression of differing basic pathophysiology or hypertensive vascular disease between black and white patients.
- This research highlights the importance of objective physiological data in evaluating racial disparities in disease.
Abstract:
Systemic hemodynamics (cardiac output, intraarterial pressure, total peripheral resistance) and intravascular volume (plasma volume and red cell mass) were measured in a population of 126 black and white patients, 51 with borderline hypertension and 75 with established essential hypertension. The findings were compared with those in 29 age-matched normotensive control subjects of both races. The white patients with established hypertension demonstrated a faster heart rate than the black patients (less than 0.05); this difference was more pronounced during upright tilt (p less than 0.02). No significant difference in cardiac index, total peripheral resistance, plasma volume or total blood volume was found between the two racial populations. Cardiac index correlated directly with plasma and total blood volume in black patients (r = 0.32, p less than 0.05) and white patients (r = 0.35, p less than 0.001) as well as in the whole study population (r = 0.36, p less than 0.001). The regression lines were similar in the two races. Further, a negative correlation was observed between the total peripheral resistance and plasma volume (r = -0.31, p less than 0.001) or total blood volume (r = -0.34, p less than 0.001), and it was similar in both races (blacks r = -0.48, p less than 0.01; whites r = -0.25, p less than 0.05). Age correlated significantly with total peripheral resistance in the white patients (r = 0.35, p less than 0.001) and in the total study population (r = 0.28, p less than 0.001). We conclude that, for every given age or level of arterial pressure, systemic hemodynamics are similar for the black and white patients with essential hypertension. These data, therefore, do not support the clinical impression that basic pathophysiology and hypertensive vascular disease are different in the black patient with essential hypertension.