Changes in circulating norepinephrine with hemofiltration in advanced congestive heart failure.

Area of Science:

• Cardiology
• Nephrology
• Physiology

Background:

• Congestive heart failure (CHF) is associated with elevated circulating norepinephrine.
• The mechanisms driving increased plasma norepinephrine in chronic CHF remain unclear.
• Hemofiltration is a known intervention that decreases norepinephrine in CHF.

Purpose of the Study:

• To investigate the mechanisms responsible for increased plasma norepinephrine in chronic congestive heart failure.
• To determine if hemofiltration-induced norepinephrine reduction is linked to sympathetic neural inhibition.

Main Methods:

• Hemofiltration was performed on 23 patients with advanced CHF.
• Plasma norepinephrine levels were measured before and after hemofiltration.
• Hemodynamic parameters, including cardiac output, aortic pressure, and systemic vascular resistance, were monitored.
• Other related parameters like plasma renin and various pressures were also assessed.

Main Results:

• Hemofiltration significantly decreased plasma norepinephrine by 515 +/- 444 pg/ml.
• This reduction was prompt, persistent, and not associated with changes in cardiac output or vascular resistance.
• The norepinephrine decrease was independent of sympathetic activity markers and hemofiltration parameters.
• Hemofiltration increased diuresis, which inversely correlated with norepinephrine changes, suggesting a link between fluid balance and norepinephrine levels.

Conclusions:

• The findings do not support neural sympathetic inhibition as the primary cause of norepinephrine decrease during hemofiltration in CHF.
• Fluid retention in CHF may be linked to elevated norepinephrine.
• In advanced CHF, circulating norepinephrine may be an unreliable indicator of sympathetic neural activity due to fluid retention and congestion.