Differences in heart rate variability parameters during the post-dialytic period in type II diabetic and non-diabetic ESRD patients

Background. Heart rate variability parameters were evaluated in 10 healthy subjects, 10 type II diabetic patients and 20 end-stage renal disease (ESRD) patients (11 non-diabetic and nine type II diabetic) undergoing chronic haemodialysis. The study was divided in two phases. Methods. In the first phase all subjects underwent electrocardiograph (ECG) recording under baseline conditions. In the second phase only ESRD patients underwent haemodialysis and ECG recording. On the day of dialysis and ECG recording the ECG recording was started Ih before the haemodialysis session (pre-dialytic period), and continued throughout the dialysis (dialytic period), until the morning after (post-dialytic period). Results. Compared with ESRD patients, non-ESRD patients showed the lowest cardiac sympathetic activity. Diabetic patients compared to non-diabetic patients showed a prevalence of cardiac sympathetic activity in the pre-dialytic period (P<0.01). During the dialytic period in comparison with the pre-dialytic one, a further increase in cardiac sympathetic activity was observed in both diabetic and non-diabetic ESRD patients (P<0.001). However, in the postdialysis period the cardiac autonomic nervous system activity remained at the pre-dialytic condition in the diabetic group. In contrast, in the non-diabetic group the cardiac autonomic balance shifted towards a parasympathetic prevalence in the post-dialytic period (P < 0.01). In addition, a significant correlation was found between changes in heart rate variability and changes in plasma urea concentration in the nondiabetic group only (r =0.65; P<0.03). Conclusions. Non-insulin-dependent diabetic uraemic patients undergoing a chronic haemodialysis programme have a severe impairment of heart rate variability. This is probably due to autonomic neuropathy related to the effects of both diabetes and chronic uraemic conditions. In non-diabetic haemodialysis patients uraemia causes similar but reversible changes in heart rate variability compared with the changes caused by diabetes.