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Large A-V fistula: pathophysiological consequences and therapeutic perspectives
Zaid A Abassi1, Joseph Winaver, Aaron Hoffman
1Department of Physiology and Biophysics, The Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, P.O.B. 9649, 31096 Haifa, Israel.
Current Vascular Pharmacology
|August 24, 2004
Summary
Large arteriovenous fistulae (AVF) can cause heart failure by disrupting hormonal balances. Medications targeting the Renin-angiotensin system may help restore this balance and improve sodium excretion in affected patients.
Area of Science:
- Cardiology
- Nephrology
- Endocrinology
Background:
- Large arteriovenous fistulae (AVF) increase cardiac output, potentially leading to congestive heart failure.
- This condition involves complex neurohormonal system imbalances, with increased vasoconstrictor activity (Renin-angiotensin system, Sympathetic nervous system, Endothelin, Arginine vasopressin) and compensatory vasodilating systems (Atrial natriuretic peptide, Nitric oxide).
- Urinary sodium excretion is critically influenced by the balance between sodium-retaining and natriuretic hormonal systems.
Purpose of the Study:
- To investigate the hormonal mechanisms governing sodium and water excretion in the context of large AVF and congestive heart failure.
- To explore the potential therapeutic benefits of modulating these hormonal systems, specifically the Renin-angiotensin system, in managing AVF-associated heart failure.
Main Methods:
- Review of previous laboratory data and clinical studies on hormonal regulation in AVF.
- Analysis of the interplay between vasoconstrictor/sodium-retaining systems (RAS, endothelin, SNS) and vasodilatory/natriuretic systems (ANP, NO).
- Consideration of pharmacological interventions targeting hormonal imbalances.
Main Results:
- In decompensated patients, heightened activity of sodium-retaining systems overrides natriuretic effects, reducing sodium and water excretion.
- Compensation requires natriuretic mechanisms to dominate, promoting renal excretion.
- Clinical and experimental evidence suggests pharmacological interventions can correct these imbalances.
Conclusions:
- A shift favoring natriuresis, achieved by enhancing natriuretic factors or reducing antinatriuretic systems, is crucial for compensation in AVF.
- Angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin II (ATII) blockers may offer a beneficial therapeutic strategy for managing large AVF by rebalancing hormonal systems.