Investigation of heart rate variability and heart rate turbulence in chronic hypotensive hemodialysis patients

Background Sudden cardiac death is the leading cause of cardiac-related death in hemodialysis patients. Hypotensive episodes in pre-, intra-, and post-dialytic periods can present serious clinical challenges that affect a patient's quality of life and prognosis. The aim of the present study was to evaluate cardiac autonomic control and arrhythmogenic risk by analyzing 24-h heart rate variability (HRV) and heart rate turbulence (HRT) in hypotensive hemodialysis patients. Methods A total of 79 patients on maintenance hemodialysis treatment, 39 normotensive and 40 with frequent hypotension episodes during non-dialysis periods, were included in the study. Dialysis-free periods were recorded with a 24-h Holter rhythm and ambulatory blood pressure monitor device. The time-domain parameters of HRV and HRT, including turbulence onset (TO) and turbulence slope (TS), were calculated. Results Values for SDNN (105.5 +/- 7.02, 127.6 +/- 6.2 p < 0.001), SDANN (95.1 +/- 5.9, 111.8 +/- 5.01 p < 0.001), and SDNN index (50.04 +/- 2.7, 55.6 +/- 3.7 p = 0.03), in the hypotensive group were significantly lower than in the normotensive group, respectively. Values for RMSSD (26.5 +/- 2.5, 27.3 +/- 2.7 p = 0.178), pNN50 (17 +/- 1.7, 55.6 +/- 3.7 p = 0.03), and TI (35.1 +/- 3.1, 34.7 +/- 2.6 p = 0.542) in both groups were not significantly different; however, there was a significant difference between HRT parameters, TO (- 1.8 +/- 0.37, - 2.4 +/- 0.39 p < 0.001) and TS (6.9 +/- 0.71, 8.2 +/- 0.97 p < 0.001), respectively, hypotensive and normotensive group. Conclusion Dialysis patients that experience frequent hypotensive episodes may also undergo significant changes in HRT and HRV which may be indicative of serious cardiac sequela. Thus, in such cases, a complete cardiologic evaluation is warranted.