Atrial natriuretic peptide augments the variability of sympathetic nerve activity in human heart failure

Objectives Activation of the sympathetic nervous system, decreased heart ra te variability (HRV), and loss of modulation of muscle sympathetic nerve ac tivity (MSNA) within the low frequency (LF, 0.05-0.15 Hz) range are three a dverse features of advanced congestive heart failure (CHF). In healthy men, atrial natriuretic peptide (ANP) infusion attenuates reflex increases in M SNA and reduces LF components of HRV spectral power. Sympathoinhibitory act ions have also been documented in CHF, but effects on the variability of MS NA and HRV have not been described. Design and methods Heart rate and MSNA were recorded in 10 men (aged 39 +/- 3 years, mean +/- SE) with dilated cardiomyopathy (mean EF 20 +/- 4%) trea ted with angiotensin converting enzyme (ACE) inhibitors. Subjects received i.v. ANP (50 mug bolus then 50 ng/kg/min) and nitroglycerin (NTG, 8 mg/min) as a hemodynamic control. Signals at baseline, and 13-20 min into each inf usion were submitted to spectral analysis. Results ANP had no effect on HRV, but increased MSNA LF (from 7.9 +/- 1.5 t o 12.1 +/- 2.6 U-2; P < 0.02) and total spectral power (from 47.9 <plus/min us> 5.4 to 61.9 +/- 6.8 U-2; P < 0.05). NTG had no effect on the variabilit y of MSNA or HRV. Conclusions In CHF patients receiving ACE inhibitors, ANP (i) does not supp ress HRV and (ii) enhances the modulation of MSNA, particularly within the LF range. This latter action is not observed with NTG, These findings sugge st beneficial actions of exogenous ANP on neurogenic circulatory control.