[Hemofiltration and the neurohumoral system in patients with severe heart failure]

6 fluid overloaded patients with congestive heart failure, NYHA classification IV, resistant to drug therapy, were treated by pump driven venovenous hemofiltration. The sympathetic nervous system measured by plasma norepinephrine concentration was stimulated in all patients. 4 of 6 patients had a markedly enhanced plasma renin activity. Between 7 and 20 l of fluid were removed by hemofiltration. The expected increase of plasma norepinephrine did not occur in 4 out of 6 patients. The improvement of cardiac pump function by hemofiltration could be an explanation for this apparent paradoxical regulation. Patients who had almost a normal plasma renin activity prior to hemofiltration showed a marked increase after the procedure. In patients with extremely high levels of plasma renin activity we noted a decrease after hemofiltration. Almost in every patient with a serum sodium concentration lower or equal 132 mmol/l the plasma renin activity was markedly elevated. Patients with normal serum sodium concentrations exhibited only slightly elevated plasma renin activity. Therefore, a hyponatremia in patients with heart failure can be used as a marker for high plasma renin activity. All patients had a significant improvement of the clinical state after hemofiltration. 3 patients, however, showed deterioration within a few weeks, due to the severity of the disease. Their plasma norepinephrine levels remained high or had a tendency to increase.