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The regulation and measurement of plasma volume in heart failure
Paul R Kalra1, Constantinos Anagnostopoulos, Aidan P Bolger
1Clinical Cardiology, National Heart and Lung Institute, London, United Kingdom. p.kalra@ic.ac.uk
Insights
Plasma volume, the fluid in blood vessels, can change significantly in chronic heart failure (CHF) patients. Stable CHF patients on therapy may have lower plasma volumes than commonly believed, impacting treatment strategies.
Area of Science:
- Cardiology
- Physiology
Background:
- Plasma volume is tightly regulated by neurohormonal systems controlling sodium and water balance.
- Chronic heart failure (CHF) involves neurohormonal activation, but plasma volume changes under treatment are less understood.
- Edematous decompensated heart failure (HF) shows expanded plasma volume, contrasting with stable CHF.
Purpose of the Study:
- To evaluate plasma volume status in patients with chronic heart failure (CHF) under conventional therapy.
- To investigate the dynamic changes in plasma volume during treatment intensification or transition in heart failure.
- To assess the clinical utility of plasma volume measurement in decompensated heart failure (HF).
Main Methods:
- Plasma volume measurement using standard dilution techniques.
- Utilizing radiolabeled tracer molecules for accurate quantification.
- Clinical assessment of plasma volume in relation to extracellular fluid volume.
Main Results:
- Stable CHF patients on conventional therapy may exhibit contracted plasma volume, challenging the hypervolemia assumption.
- Significant plasma volume shifts can occur during treatment adjustments or state transitions in HF.
- Decompensated HF patients can present with contracted plasma volume despite increased total extracellular fluid volume.
Conclusions:
- The common belief of long-term hypervolemia in CHF may not hold true for stable patients on therapy.
- Plasma volume assessment is crucial during HF treatment, especially in decompensated states.
- In contracted plasma volume HF, inotropes or renal vasodilators might be more beneficial than diuretics alone.
Abstract:
Plasma volume, the intravascular portion of the extracellular fluid volume, can be measured using standard dilution techniques with radiolabeled tracer molecules. In healthy persons, plasma volume remains relatively constant as a result of tight regulation by the complex interaction between neurohormonal systems involved in sodium and water homeostasis. Although chronic heart failure (CHF) is characterized by activation of many of these neurohormonal systems, few studies have evaluated plasma volume in this condition under treatment. Untreated edematous decompensated heart failure (HF) is associated with a significant expansion of plasma volume. Patients with stable CHF, receiving conventional therapy, appear to have a contracted plasma volume, a concept that is in contrast to the widely held belief that CHF is associated with long-term hypervolemia. It is likely that significant changes in plasma volume occur during intensification of medical therapy or during transition from the edematous to the stable state. Clinical assessment of plasma volume may be of particular value during treatment in patients with decompensated HF, in whom the plasma volume is contracted despite an increase in total extracellular fluid volume. Under these circumstances, treatment with inotropes or renal vasodilators may be more appropriate than intravenous diuretics alone. Further studies evaluating plasma volume in HF may help to improve our understanding of the pathophysiologic mechanisms occurring in the development and progression of this complex condition.