Abstract
BackgroundBoth 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.MethodsThis 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.ResultsOne 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.ConclusionsThe 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.
Highlights
Both uremia and metabolic syndrome (MetS) affect heart rate variability (HRV) which is a risk factor of poor prognoses
Among the frequency domain indices, very low frequency (VLF) is thought to be influenced by the thermoregulation of vasomotor tone; low-frequency (LF) activity is widely recognized to reflect a mixture of both the sympathetic and parasympathetic tone; high-frequency (HF) activity has been linked to parasympathetic nervous activity, which is associated with the vagal-medicated modulation of heart rate; LF/HF ratio is an index of sympathovagal balance and of autonomic status or sympathetic nervous activities; total power (TP) can be estimated with the sum of the frequencies; whereas variance of the R–R interval values (Var) reflects all the cyclic components responsible for variability in the period of recording [10,11,12,13,14,15]
According to the definitions of MetS and its components, 91 (52.0 %) patients were diagnosed with MetS (MetS(+)), while 79 (45.1 %) patients were waist circumference (WC)(+), 128 (73.1 %) were blood pressure (BP)(+), 65 (37.1 %) were fast‐ ing plasma glucose (FPG)(+), 63 (36.0 %) were TG(+), and 125 (71.4 %) were high-density lipoprotein (HDL)(+)
Summary
Both uremia and metabolic syndrome (MetS) affect heart rate variability (HRV) which is a risk factor of poor prognoses. Among the frequency domain indices, very low frequency (VLF) is thought to be influenced by the thermoregulation of vasomotor tone; low-frequency (LF) activity is widely recognized to reflect a mixture of both the sympathetic and parasympathetic tone; high-frequency (HF) activity has been linked to parasympathetic nervous activity, which is associated with the vagal-medicated modulation of heart rate; LF/HF ratio is an index of sympathovagal balance and of autonomic status or sympathetic nervous activities; total power (TP) can be estimated with the sum of the frequencies; whereas variance of the R–R interval values (Var) reflects all the cyclic components responsible for variability in the period of recording [10,11,12,13,14,15]
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