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. · 8.57 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. · 5.79 Impact Factor
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ABSTRACT: Type 2 diabetes and impaired glucose metabolism (IGM) are associated with an increased cardiovascular disease (CVD) risk. Increased left ventricular mass (LVM) is thought to increase CVD risk through several unfavorable cardiac changes. Type 2 diabetes and IGM are associated with increased LVM, but the underlying mechanism is unclear. We investigated the association between glucose tolerance status (GTS) and LVM and explored whether any such association could be mediated through increased arterial stiffness, impaired endothelial function, or the presence of atherosclerosis. We used ultrasound to measure LVM, carotid and femoral stiffness, carotid-femoral transit time, and flow-mediated vasodilation (FMD) and tonometry to estimate compliance and augmentation index. The study population (n = 780) consisted of 287 individuals with normal glucose metabolism (NGM), 179 with IGM, and 314 with type 2 diabetes, and the mean age was 68.4 years. In women, after adjusting for age, height, BMI, and mean arterial pressure, LVM increased significantly with deteriorating GTS (LVM 157 g in NGM, 155 g in IGM, and 169 g in type 2 diabetes; P for trend <0.018). Additional adjustment for arterial stiffness, FMD, or the presence of atherosclerosis did not materially alter the results, even though these variables were significantly associated with both GTS and LVM. Indexes of hyperglycemia/-insulinemia or insulin resistance explained at most 7% of the association between GTS and LVM. In men, no statistically significant associations were observed. Our data expand the conceptual view of the pathogenesis of GTS-related changes in LVM because we show that the increase in LVM in women is independent of increased arterial stiffness, impaired FMD, or the presence of atherosclerosis. In addition, we show that this increase in LVM is only minimally explained by indexes of hyperglycemia/-insulinemia or insulin resistance. Our data may, in part, explain the increased CVD risk seen in women with deteriorating GTS.Diabetes Care 03/2004; 27(2):522-9. · 8.57 Impact Factor