LINEAR AND NON-LINEAR HEART RATE VARIABILITY INDICES AT REST AND IN RESPONSE TO PHYSICAL AND MENTAL STRESS: A COMPARATIVE STUDY BETWEEN HEMODIALYSIS AND PERITONEAL DIALYSIS PATIENT

Abstract

Objective: Cardiac arrhythmias and sudden death are the leading causes of cardiovascular mortality in end-stage-kidney-disease(ESKD). Autonomic dysfunction contributes to the arrhythmogenic background of ESKD patients. This is the first study to compare linear and non-linear heart-rate-variability(HRV) indices between hemodialysis(HD) and peritoneal(PD) patients, both at rest and in response to mental- and physical-stimulation maneuvers. Design and method: Thirty-four HD and 34 PD patients matched for age, sex, and dialysis-vintage, as well as 17 age- and sex-matched controls were studied. Autonomic function was examined by linear and non-linear-HRV indices. Heart-rate was recorded continuously with Finometer-PRO at rest and during orthostatic, mental-arithmetic, sit-to-stand, and handgrip-exercise tests. Results: No significant between-group differences were observed in resting HRV indices(RMSSD: HD:57.1 ± 81.1 vs PD:69.6 ± 113.4ms; p = 0.792) except for DFA-a1 index(HD:0.87 ± 0.40 vs PD:0.70 ± 0.20, p = 0.047). All HRV indices during the mental arithmetic test (RMSSD HD:128.2 ± 346.0 vs PD:87.5 ± 150.0ms; p = 0.893) and the physical stress tests were similar between HD and PD patients. Both dialysis groups presented similar patterns of HRV responses to orthostatic and handgrip exercise tests; however, after the sit-to-stand test RMSSD, SD1, SD2 and DFA-a2 indices were higher compared to rest only in HD patients(RMSSD: 57.1 ± 81.1 vs 126.7 ± 185.7ms, p = 0.028), suggesting a greater difficulty of HD patients in recovering normal ANS function following a physical stress-test. Conclusions: HRV indices at rest and after mental and physical stimulation did not differ between HD and PD patients, however the ANS response following the sit-to-stand test was more impaired in HD. These findings suggest that ANS dysfunction is not largely affected by dialysis modality but small differences in normal ANS recovery may exist.