Sympathetic responsiveness and plasma norepinephrine during therapy of chronic congestive heart failure with captopril

Abstract

The interaction of cardiac function and sympathetic tone in severe chronic heart failure was evaluated in 24 patients by assessing the cardiac index/plasma norepinephrine relationship. Potential changes were assessed during first-dose and long-term captopril therapy including sympathetic responsiveness to the gravitational stress of head-up tilt. Because cardiac index and norepinephrine levels demonstrated a significant inverse correlation (r = -0.640, p less than 0.001). Norepinephrine decreased from 803 +/- 116 to 635 +/- 76 pg/ml following first-dose captopril therapy (p less than 0.02), with overall hemodynamic improvement. However significant first-dose correlations were not observed. During long-term therapy, norepinephrine decreased from 694 +/- 118 to 457 +/- 106 pg/ml, associated with improvement of symptoms and exercise tolerance. The extent of cardiac index increase was matched by norepinephrine reduction, so that their correlation was maintained (r = -0.540, p less than 0.02). First-dose and long-term therapy were associated with improved responsiveness of sympathetic tone to the reduction of cardiac index induced by the gravitational stress of tilt. In summary, sympathetic tone was increased in severe heart failure, correlating inversely with cardiac function. Although there was improvement of cardiac function with first-dose captopril therapy, significant correlations of supine improvement with reduction of sympathetic tone were noted primarily with long-term therapy. Responsiveness of sympathetic tone to the stress of tilt however, was evident during first-dose and long-term therapy.