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 h aemodialysis. 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 patient s underwent haemodialysis and ECG recording. On the day of dialysis and ECG recording the ECG recording was started Ih before the haemodialysis sessio n (pre-dialytic period), and continued throughout the dialysis (dialytic pe riod), until the morning after (post-dialytic period). Results. Compared with ESRD patients, non-ESRD patients showed the lowest c ardiac sympathetic activity. Diabetic patients compared to non-diabetic pat ients showed a prevalence of cardiac sympathetic activity in the pre-dialyt ic period (P<0.01). During the dialytic period in comparison with the pre-d ialytic one, a further increase in cardiac sympathetic activity was observe d in both diabetic and non-diabetic ESRD patients (P<0.001). However, in th e postdialysis period the cardiac autonomic nervous system activity remaine d at the pre-dialytic condition in the diabetic group. In contrast, in the non-diabetic group the cardiac autonomic balance shifted towards a parasymp athetic prevalence in the post-dialytic period (P < 0.01). In addition, a s ignificant 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 c hronic haemodialysis programme have a severe impairment of heart rate varia bility. This is probably due to autonomic neuropathy related to the effects of both diabetes and chronic uraemic conditions. In non-diabetic haemodial ysis patients uraemia causes similar but reversible changes in heart rate v ariability compared with the changes caused by diabetes.