Determinants of cardiac autonomic dysfunction in ESRD.
OBJECTIVE
Cardiovascular events are common in patients with ESRD. Whether sympathetic overactivity or vagal withdrawal contribute to cardiovascular events is unclear. We determined the general prevalence and clinical correlates of heart rate variability in patients on hemodialysis.


METHODS
We collected baseline information on demographics, clinical conditions, laboratory values, medications, physical performance, left ventricular mass (LVM), and 24-hour Holter monitoring on 239 subjects enrolled in the Frequent Hemodialysis Network Daily Trial.


RESULTS
The mean R-R interval was 812 ± 217 ms. The SD of R-R intervals was 79.1 ± 40.3 ms. Spectral power analyses showed low-frequency (sympathetic modulation of heart rate) and high-frequency power (HF; vagal modulation of heart rate) to be 106.0 (interquartile range, 48.0 to 204 ms(2)) and 42.4 ms(2) (interquartile range, 29.4 to 56.3 ms(2)), respectively. LVM was inversely correlated with log HF (-0.02 [-0.0035; -0.0043]) and the R-R interval (-1.00 [-1.96; -0.032]). Physical performance was associated with mean R-R intervals (1.98 [0.09; 3.87]) and SD of R-R intervals (0.58 [0.049; 1.10]). After adjustment for age, race, ESRD vintage, diabetes, and physical performance, the relationship between log HF and LVM (per 10 g) remained significant (-0.025 [-0.042; -0.0085]).


CONCLUSIONS
Holter findings in patients on hemodialysis are characterized by sympathetic overactivity and vagal withdrawal and are associated with higher LVM and impaired physical performance. Understanding the spectrum of autonomic heart rate modulation and its determinants could help to guide preventive and therapeutic strategies.
Chan
Christopher T
CT
Department of Medicine, University Health Network, Toronto, Ontario, Canada. christopher.chan@uhn.on.ca
Levin
Nathan W
NW
Chertow
Glenn M
GM
Larive
Brett
B
Schulman
Gerald
G
Kotanko
Peter
P
D000328:Adult; D002318:Cardiovascular Diseases / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D002986:Clinical Trials as Topic; D003430:Cross-Sectional Studies; D015716:Electrocardiography, Ambulatory; D005260:Female; D006321:Heart / Q000294:innervation*; D006339:Heart Rate; D006352:Heart Ventricles / Q000473:pathology; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D007676:Kidney Failure, Chronic / Q000150:complications / Q000473:pathology / Q000503:physiopathology* / Q000628:therapy; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D018570:Risk Assessment; D012307:Risk Factors; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D014630:Vagus Nerve / Q000503:physiopathology*