Heart Rate Variability in Patients with Diabetic Nephropathy
ABSTRACT BackgroundPatients with diabetic nephropathy are likely to have neurological complications including cardiovascular autonomic dysfunction,
which is related to increased risk of mortality and it probably had an earlier onset and may precede the appearance of autonomic
symptoms. The aim of this study was to assess cardiovascular autonomic functions by using heart rate variability analysis and its relationship
with left ventricular function in type 2 diabetic patients with and without nephropathy.
Materials and MethodsThis study was conducted on 45 diabetic patients, 15 without nephropathy, 15 with nephropathy and 15 diabetic nephropathy
on hemodialysis, as well as 15 age- and sex-matched healthy controls. All of them were subjected to analysis of heart rate
variability (HRV) by Holter ECG, Echocardiography, and analysis of the lipid profile.
ResultsAll time domain and frequency domain measures of HRV were significantly reduced in diabetic patients with and without nephropathy
compared to healthy controls (p < 0.0001). There was a significant decrease in ejection fraction (EF) and increase in left ventricular mass index (LVMI)
in diabetic patients with and without nephropathy compared to healthy controls (p < 0.0001). Also there was a significant increase in cholesterol, triglycerides and LDL with significant decrease in HDL in
diabetic patients with and without nephropathy compared to healthy controls (p < 0.0001).
ConclusionCardiac autonomic dysfunction (as manifested by decreased HRV) was demonstrated in diabetic patients and its degree was enhanced
in patients with nephropathy than in those without.
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ABSTRACT: Prolongation of the QT interval and increased QT dispersion are associated with a poor cardiac prognosis. The goal of this study was to assess the long-term influence of the autonomic nervous system on the heart rate dependence of ventricular repolarization in patients with diabetic autonomic neuropathy (DAN). We studied 27 subjects (mean age 51.8 years) divided into three age- and sex-matched groups: nine control subjects, nine diabetic subjects with DAN (mostly at a mild stage; DAN+), and nine diabetic subjects without DAN (DAN-). DAN was assessed on heart rate variations during standard maneuvers (Valsalva, deep-breathing, and lying-to-standing maneuvers). No subject had coronary artery disease or left ventricular dysfunction or hypertrophy, and no subject was taking any drugs known to prolong the QT interval. All subjects underwent electrocardiogram and 24-h Holter recordings for heart rate variations (time and frequency domain) and QT analysis (selective beat averaging QT/RR relation, nocturnal QT lengthening). Rate-corrected QT intervals (Bazett formula) did not differ significantly between the three groups. The diurnal and nocturnal levels of low frequency/high frequency, an index of sympathovagal balance, were significantly reduced in DAN+ subjects. Using the selective beat-averaging technique, a day-night modulation of the QT/RR relation was evidenced in control and DAN- subjects. This long-term modulation was significantly different in DAN+ subjects, with a reversed day-night pattern and an increased nocturnal QT rate dependence. In diabetic patients with mild parasympathetic denervation, QT heart rate dependence was found to be impaired, as determined by noninvasive assessment using Holter data. Analysis of ventricular repolarization could represent a sensitive index of the progression of neuropathy. The potential prognostic impact of a reversed day-night pattern with steep nocturnal QT/RR relation still remains to be defined.Diabetes Care 06/2002; 25(5):918-23. · 7.74 Impact Factor
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ABSTRACT: Heart rate variability (HRV) is an important tool to analyze the autonomic function. It therefore has a special interest for early detection and ensuing treatment of autonomic neuropathy in diabetic patients. The aim of this work is to present a brief historical review of HRV, as well as a technical review of the most common methods to measure it. In this work is presented a system that performs three measurements of HRV. An overview of methodologies developed to quantify HRV is presented; this technical review covers the most common time and frequency domain techniques, for short and long periods of time, with comments about clinical utility of these tests. A system performing three standard tests of HRV, Anscore Health Management System, is presented. This system performs metronomic breathing (MT), the Valsalva Test (VT), and the Stand Test (ST). A normal range study with 212 healthy subjects in three centers (ages 20-80 years, with even age distribution, and even male and female distribution) was conducted. A subset of 45 subjects from the total number of subjects was selected for the reproducibility study, consisting of three measurements of each test. The normal range study showed a decrease in all the ratios with age and, for the Valsalva test, a difference among genders; 5th percentiles were calculated. The reproducibility study results, expressed as mean CV%, were 4.30% for the MT, 6.26% for the VT, and 6.66% for the ST. HRV is the most reliable measurement of autonomic function; when controlled maneuvers like MT, VT, and ST are performed, high reproducibility is obtained, with results comparable to that observed for nerve conduction studies. Such reproducibility makes autonomic function testing more feasible as a test component in multicenter studies of different neurological disorders.Diabetes Technology & Therapeutics 02/2001; 3(1):63-76. · 2.21 Impact Factor
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ABSTRACT: Autonomic nervous system (ANS) dysfunction and peripheral neuropathy occur in patients with chronic renal insufficiency. Adequate renal replacement therapy should prevent development or correct these abnormalities. We studied retrospectively ANS and peripheral neuropathy in 32 patients with chronic uraemia who received either haemodialysis (16) or peritoneal dialysis (16) therapy, and compared the observed dialysis efficiency with changes in neurological function. Heart rate variability (HRV) time domain indices and peripheral sensory nerve conduction studies were followed for a mean of 2.9 years. The adequacy of haemodialysis (HD) efficiency was estimated by Kt/V, an index of fractional urea clearance. Adequacy of continuous ambulatory peritoneal dialysis (CAPD) was estimated on the basis of the patient's wellbeing and nutritional status as excellent, satisfactory or poor. Based on observed changes in HRV time domain measures, the observations were divided in three subgroups: improved, unchanged or deteriorated. The peripheral sensory nerve conduction studies were abnormal in 38% of the patients and did not change significantly during the study. Improvement in HRV time domain measures occurred in HD patients with mean Kt/V > 1.20 or in CAPD patients with satisfactory or excellent response to dialysis treatment. Values of Kt/V < 0.85 in HD patients were associated with progressive deterioration of autonomic neuropathy. Diabetic patients (n = 4) differed from others as their HRV was grossly abnormal and did not improve. The adequacy of haemodialysis is a predictor of improvement of cardiac autonomic nervous function in chronic uraemia. The same trend of improvement was seen also in CAPD patients.Journal of Internal Medicine 07/2000; 248(1):21-6. · 6.46 Impact Factor