Pathogenesis and management of sodium and water retention in cardiac failure and cirrhosis.

The kidneys play the crucial role in the maintenance of the body fluid volume homeostasis. Several hypotheses have been introduced to explain sodium and water retention leading to edematous states in such pathologic conditions as congestive heart failure (CHF) and cirrhosis. We have suggested a unifying arterial underfilling hypothesis, explaining the development of edema in these conditions. Arterial underfilling, caused by decreased cardiac output or peripheral arterial vasodilation, leads to activation of the sympathetic nervous system, renin-angiotensin-aldosterone system, and nonosmotic vasopressin release. This review discusses the pathophysiologic mechanisms resulting in renal sodium and water retention, impaired mineralocorticoid escape, and resistance to atrial natriuretic peptide in patients with CHF and cirrhosis. Furthermore, the basis of current therapies in these disorders is discussed, including beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin-receptor blockers, aldosterone antagonists, and diuretics in CHF and cirrhosis, as well as new approaches to treatment of water retention with vasopressin V(2) receptor antagonists.