Assessment of Cardiac Autonomic Nervous Activities by Means of ECG R‐R Interval Power Spectral Analysis and Cardiac Depolarization‐Repolarization Process

Abstract

Background: Cardiac autonomic dysfunction is prevalent in diabetic patients and associated with prolongation of myocardial repolarization period. It was speculated that changes in autonomic nervous system activity, particularly the sympatho‐vagal balance contributes to the prolongation of myocardial repolarization.Methods: Ten patients with ischemic heart disease (IHD), thirty patients with diabetes mellitus, and ten control subjects (CONT) volunteered for this study. The patients with diabetes mellitus were further divided into three subgroups according to the severity of neuropathy: patients without any neuropathy (NO), with peripheral neuropathy (N1) and with autonomic neuropathy (N2). ECG activation time (AT), activation recovery interval (ARI), and recovery time (RT) was measured and ECG R‐R spectral analysis was performed.Result: There were significant decreases (P < 0.01) in RTc in N1, N2, and IHD as compared with CONT and NO. In addition, HI of R‐R interval power spectrum were significantly decreased (P < 0.01) in N1, N2, and IHD than those in CONT and NO.Conclusion: We have successfully developed and adapted a new computer system for simultaneous ECG RT measurements and ECG R‐R power spectral analysis, a putative index of autonomic dysfunction and risk for sudden cardiac death, to study patients with ischemic heart disease and with varying degrees of diabetic autonomic neuropathy. Those with little HI power, which reflects more severe diabetic neuropathy and a high risk of sudden cardiac death, had significantly longer RTc, which is consistent with sympatho‐vagal imbalance toward parasympathetic denervation.