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Blood pressure in the 'low-pressure system' and cardiac performance in essential hypertension
Insights
Essential hypertension involves increased central venous pressure, not due to heart function issues or excess blood volume. This elevation is linked to reduced venous bed or left ventricle compliance.
Area of Science:
- Cardiovascular Physiology
- Hypertension Research
Background:
- Essential hypertension is a prevalent cardiovascular condition.
- Understanding hemodynamic alterations in hypertension is crucial for management.
Purpose of the Study:
- To investigate central venous pressure and cardiac hemodynamics in hypertensive men.
- To assess the response to volume expansion in essential hypertension.
Main Methods:
- Compared central venous pressure, cardiac hemodynamics, and volume expansion response in 49 hypertensive men and 27 normotensive controls.
- Utilized iso-oncotic dextran for rapid volume expansion.
Main Results:
- Hypertensive subjects exhibited elevated central venous pressure (CVP) with normal cardiac index and reduced blood volume.
- A positive correlation was observed between CVP, age, arterial pressure, and pulmonary wedge pressure.
- Volume expansion revealed normal cardiac output-CVP relationship but reduced blood volume-CVP relationship, indicating decreased venous compliance.
Conclusions:
- Elevated CVP in hypertension is not due to cardiac pump dysfunction or hypervolemia.
- Reduced venous bed or left ventricular compliance likely contributes to increased CVP.
- Venous system disturbances in hypertension correlate with age, similar to arterial changes.
Abstract:
Determinations of central venous pressure, cardiac haemodynamics and rapid volume expansion using iso-oncotic dextran were made in 49 men with sustained, uncomplicated essential hypertension and compared with those in 27 normotensive subjects of the same age and sex. In the hypertensives, central venous pressure was significantly increased in basal conditions while the cardiac index was normal and total blood volume was reduced. There was a positive and significant correlation of central venous pressure with age, arterial pressure and pulmonary wedge pressure. After rapid volume expansion, the slope of the curve relating cardiac output to central venous pressure was within the normal range, while the slope of the curve relating blood volume to central venous pressure was significantly reduced. The study provided evidence that in hypertensives: central venous pressure as well as arterial pressure is increased, the elevated central venous pressure is not due to an alteration in the cardiac 'pump function' or to hypervolaemia but rather to a decrease in the compliance of the venous bed or the left ventricle or both, and the strong correlation with age of the venous disturbances is similar to that found for the arterial side of the circulation.