Changes in heart rate variability in chronic uremic patients during ultrafiltration and hemodialysis.
BACKGROUND
The analysis of heart rate variability (HRV) is a useful tool to evaluate cardiac autonomic modulation, which is frequently impaired in chronic uremia.


OBJECTIVE
The aim of this study was to evaluate HRV in chronic uremics and to separately investigate the acute changes induced by volume depletion and solute removal during a hemodialysis session.


METHODS
Fourteen uremic patients (8 males and 6 females, aged 50 +/- 15 years) on maintenance hemodialysis and 14 sex- and age-matched healthy controls were studied. Both groups underwent ambulatory electrocardiogram monitoring to evaluate the HRV time and frequency domain indices. The hemodialysis session was performed by 1 h of high-rate isolated ultrafiltration followed by 3 h of bicarbonate diffusive procedure.


RESULTS
In uremic patients, the overall variability in the frequency [low-frequency power (LF): 505 +/- 473, vs. 1,446 +/- 654; high-frequency power (HF): 133 +/- 162 vs. 512 +/- 417; p < 0.001] and time domain indices (standard deviation of normal R-R intervals: 101.9 +/- 33.3 vs. 181.7 +/- 44.1 ms; p < 0.001) was markedly reduced compared to controls, whereas mean heart rate (83 +/- 12.4 vs. 60.9 +/- 8.8 bpm; p < 0.001) and LF/HF ratio (5.8 +/- 3.5 vs. 2.2 +/- 0.8; p < 0.001) were increased. Isolated ultrafiltration produced a marked further decrease in HRV indices, but the subsequent diffusive hemodialysis procedure, with a low ultrafiltration rate, made HRV increase again.


CONCLUSIONS
Chronic uremics showed abnormal autonomic modulation with sympathetic-vagal imbalance. The unbalanced hypersympathetic response to body fluid depletion is related to the ultrafiltration rate. Low interdialytic weight gain and a low ultrafiltration rate, associated with adequate hemodialysis, should be the preferable strategy for uremic patients with autonomic dysfunction.
Galetta
F
F
Department of Internal Medicine, University of Pisa, Italy. fgaletta@int.med.unipi.it
Cupisti
A
A
Franzoni
F
F
Morelli
E
E
Caprioli
R
R
Rindi
P
P
Barsotti
G
G
D000328:Adult; D000368:Aged; D001774:Blood Chemical Analysis; D001810:Blood Volume; D016022:Case-Control Studies; D002908:Chronic Disease; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D017583:Hemodiafiltration / Q000009:adverse effects / Q000379:methods* / Q000592:standards; D006801:Humans; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D014462:Ultrafiltration; D014511:Uremia / Q000503:physiopathology / Q000628:therapy*