Dynamics of muscle sympathetic nerve activity in advanced heart failure patients.
Muscle sympathetic nerve activity (MSNA) is increased in patients with heart failure compared with healthy subjects. We applied spectral and correlation techniques to determine if qualitative as well as quantitative differences in MSNA differentiate heart failure patients from healthy subjects. We recorded MSNA, heart rate, and respiration in 11 heart failure patients and 10 healthy humans. Our results are as follows. 1) Statistically significant low-frequency modulation of MSNA at 0.029 +/- 0.002 Hz (mean +/- SE; range 0.026-0.038 Hz) was found in 10 of 11 heart failure patients but in only 2 of 10 healthy controls (differences between groups, P < 0.01; chi 2 test). 2) Heart rate and respiration also demonstrated significant low-frequency modulation in a similar range. 3) Spectral and correlation techniques revealed that low-frequency modulation of MSNA was highly correlated with low-frequency modulation of respiration in heart failure patients, but not in healthy subjects. In contrast, low-frequency modulation of MSNA did not correlate well with low-frequency modulation of heart rate. In summary, low-frequency modulation of respiration is coupled to low-frequency modulation of MSNA in heart failure patients, but not in normal subjects. We speculate that this low-frequency modulation of respiration may represent subclinical Cheyne-Stokes breathing, which has marked qualitative effects on MSNA in patients with heart failure.
Nguyen
A H
AH
Division of Cardiology, University of California Los Angeles (UCLA) School of Medicine 90095, USA.
Garfinkel
A
A
Walter
D O
DO
Hamilton
M A
MA
Fonarow
G C
GC
Moriguchi
J D
JD
Hage
A
A
Weiss
J N
JN
Middlekauff
H R
HR
D000293:Adolescent; D000328:Adult; D000368:Aged; D002303:Cardiac Output, Low / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000294:innervation*; D010507:Periodicity; D012119:Respiration; D013564:Sympathetic Nervous System / Q000503:physiopathology*