Heart rate variability as an independent predictor for 8-year mortality among chronic hemodialysis patients.

The repeated measurements of heart rate variability (HRV) is more relevant than a single HRV measurement in predicting patient prognosis but is less addressed previously. This prospective study aimed to investigate the association between repeated measurements of HRV and long-term mortality in chronic hemodialysis patients. The 164 patients (65.0 ± 13.1 years; woman, 57.3%) were enrolled from June 1, 2010, to August 31, 2010, and received four HRV measurements (before and during the index hemodialysis session) after the enrollment. The baseline characteristic and clinical variables, including mortality, were documented. The joint modeling method and Cox regression were used for statistical analyses. After an 8-year follow-up, 79 patients expired, and 85 patients survived. We found that higher normalized high-frequency (nHF) (hazard ratio [HR] 1.033) as well as lower very-low-frequency (HR 0.990), Variance (HR 0.991), normalized low-frequency (HR 0.999, P = 0.006), and low-frequency/high-frequency ratio (HR 0.796) were independent predictors for cardiovascular mortality. Whereas the independent predictors for infection-associated mortality included higher nHF (HR 1.033) as well as higher age (HR 19.29) and lower serum albumin (HR 0.01, P = 0.001). (all P < 0.001 unless otherwise stated) In conclusion, HRV measurement predicts long-term mortality among hemodialysis patients.

Correction: Heart rate variability during hemodialysis is an indicator for long-term vascular access survival in uremic patients.

[This corrects the article DOI: 10.1371/journal.pone.0172212.].

Heart rate variability during hemodialysis is an indicator for long-term vascular access survival in uremic patients.

BACKGROUND: Vascular access (VA) is the lifeline of hemodialysis patients. Although the autonomic nervous system might be associated with VA failure (VAF), it has never been addressed in previous studies. This study aimed to evaluate the predictive values of the heart rate variability (HRV) indices for long-term VA outcomes. METHODS: This retrospective study was conducted using a prospectively established cohort enrolling 175 adult chronic hemodialysis patients (100 women, mean age 65.1 ± 12.9 years) from June 2010 to August 2010. Each participant received a series of HRV measurements at enrollment. After a 60-month follow-up period, we retrospectively reviewed all events and therapeutic procedures of the VAs which existed at the enrollment and during the follow-up period. RESULTS: During the 60-month follow-up period, 37 (26.8%) had VAF but 138 (73.2%) didn't. The values of most HRV indices were statistically increased during hemodialysis since initiation in the non-VAF group, but not in the VAF group. Among all participants, the independent indicators for VAF included higher normalized high-frequency (nHF) activity [hazard ratio (HR) 1.04, p = 0.005], lower low-frequency/high-frequency (LF/HF) ratio (HR 0.80, p = 0.015), experience of urokinase therapy (HR 11.18, p = 0.002), percutaneous transluminal angioplasty (HR 2.88, p = 0.003) and surgical thrombectomy (HR 2.36, p = 0.035), as well as higher baseline serum creatinine (HR 1.07, p = 0.027) and potassium level (HR 1.58, p = 0.037). In subgroup analysis, a lower sympathetic activity indicated by lower LF/HF ratio was an independent indicator for VAF (HR 0.61, p = 0.03) for tunneled cuffed catheter, but conversely played a protective role against VAF (HR 1.27, p = 0.002) for arteriovenous fistula. CONCLUSIONS: HRV is a useful tool for predicting long-term VAF among hemodialysis patients.

Impact of metabolic syndrome and its components on heart rate variability during hemodialysis: a cross-sectional study.

BACKGROUND: Both uremia and metabolic syndrome (MetS) affect heart rate variability (HRV) which is a risk factor of poor prognoses. The aim of this study was to evaluate the impact of MetS on HRV among chronic hemodialysis patients. METHODS: This cross-sectional study was carried out in a teaching hospital in Northern Taiwan from June to August, 2010. Adult patients on chronic hemodialysis without active medical conditions were enrolled. HRV were measured for 4 times on the index hemodialysis day (HRV-0, -1, -2, and -3 at before, initial, middle, and late phases of hemodialysis, respectively), and the baseline demographic data and clinical parameters during the hemodialysis session were documented. Then we evaluated the impacts of MetS and its five components on HRV. RESULTS: One hundred and seventy-five patients (100 women, mean age 65.1 ± 12.9 years) were enrolled and included those with MetS (n = 91, 52 %) and without MetS (n = 84, 48 %). The patients with MetS(+) had significantly lower very low frequency, total power, and variance in HRV-0, total power and variance in HRV-2, and variance in HRV-3. (all p ≦ 0.05) When using the individual components of MetS to evaluate the impacts on HRV indices, the fasting plasma glucose (FPG) criterion significantly affected most indices of HRV while other four components including "waist circumference", "triglycerides", "blood pressure", and "high-density lipoprotein" criteria exhibited little impacts on HRV. FPG criterion carried the most powerful influence on cardiac ANS, which was even higher than that of MetS. The HRV of patients with FPG(+) increased initially during the hemodialysis, but turned to decrease dramatically at the late phase of hemodialysis. CONCLUSIONS: The impact of FPG(+) outstood the influence of uremic autonomic dysfunction, and FPG criterion was the most important one among all the components of MetS to influence HRV. These results underscored the importance of interpretation and management for abnormal glucose metabolism.

Heart rate variability is an indicator for intradialytic hypotension among chronic hemodialysis patients.

BACKGROUND: Intradialytic hypotension (IDH) carries adverse impact. Heart rate variability (HRV) represents autonomic cardiac regulation which influences intradialytic blood pressure. We aimed to evaluate the association between IDH and HRV. METHODS: This prospective study was carried out in a teaching hospital in Taiwan from June to August 2010. Adult patients on chronic hemodialysis without active medical conditions were enrolled and received HRV measurements for 4 times (before and during an index hemodialysis session). Patients were categorized by the changes of systolic blood pressure during the index hemodialysis into Group 1 (elevation >20 mmHg), Group 2 (decrease >20 mmHg), and Group 3 (others). Then we compared HRV indices among the three groups, and determined the indicators for IDH. RESULTS: One hundred and seventy-one patients (96 women, mean age 64.9 years) were enrolled and categorized into Group 1 (n = 47, 27.5 %), Group 2 (n = 45, 26.3 %) and Group 3 (n = 79, 46.2 %). Comparing with Group 1 and/or Group 3, Group 2 had significantly higher blood pressure at hemodialysis initiation (most p < 0.001) and statistically lower levels of HRV indices including variance, total power, very low-frequency, low-frequency and high-frequency since the middle phase of the hemodialysis. By logistic regression method, higher systemic blood pressure [odds ratio (OR) 1.048; p < 0.001], heart rate (OR 1.093; p = 0.021), low-frequency/high-frequency ratio (OR 1.715; p = 0.022), as well as lower variance (OR 0.639; p = 0.048) at hemodialysis initiation were independently associated with intradialytic blood pressure changes. CONCLUSIONS: HRV is a useful indicator for IDH among hemodialysis patients.