Renal and cardiac function during alpha1-beta-blockade in congestive heart failure

The kidney and the neurohormonal systems are essential in the pathogenesis of congestive heart failure (CHF) and the physiologic response. Routine treatment of moderate to severe CHF consists of diuretics, angiotensin-converting enzyme (ACE) inhibition and beta-blockade. The need for control of renal function during initiation of ACE-inhibition in patients with CHF is well known. The aim of this study was to investigate whether supplementation by a combined alpha1-beta-blockade to diuretics and ACE-inhibition might improve cardiac function without reducing renal function.

Fourteen patients treated for moderate to severe CHF with diuretics and ACE inhibitors were investigated at baseline, after 4 months of maximum carvedilol treatment and after withdrawal of carvedilol.

Carvedilol lowered blood pressure and heart rate but increased left and right ventricular ejection fractions without changing cardiac output or pulmonary blood volume. At the same time, a minor fall was seen in glomerular filtration rate (GFR). but renal blood flow was unchanged and effective renal plasma flow slightly increased. Carvedilol also lowered the plasma levels of angiotensin II and aldosterone. All changes were reversed after withdrawal of carvedilol.

Carvedilol augments ACE-inhibitor-induced vasodilation by lowering blood pressure, and angiotensin II beside reducing heart rate. The heart adapts to the haemodynamic alterations without changes in cardiac output and pulmonary blood volume. GFR is slightly lowered despite no changes in renal blood flow and a slight increase in effective renal plasma flow. The study emphasizes the need for control of renal function during treatment with carvedilol in patients with CHF.