HEART-RATE-VARIABILITY IN PATIENTS WITH SECONDARY AMYLOIDOSIS

Heart rate variability (HRV) is increasingly being used to evaluate th e funciton of the autonomic nervous system. Although autonomic dysfunc tion has been described in primary amyloidosis patients, this has not been established for patients with secondary amyloidosis. This study e xamines the autonomic function of 23 biopsy-proven secondary amyloidos is patients (10 male, 13 female) and compares it with 19 healthy (8 ma le, 11 female) sex-and age-matched controls (Group III), using frequen cy-and time-domain HRV analysis. The study group was further divided a ccording to renal function; Group I (14 nonuremic patients with serum creatinine level <1.4 mg/dl) and Group II (9 uremic patients with seru m creatinine level >1.4 mg/dl). In time domain analysis, standard devi ation and mean of the standard deviation of all normal R to R interval s, and standard deviation of the average normal R to R interval were s ignificantly lower in Groups I and II as compared to Group III. In fre quency domain analysis, low frequency power (LF), representing sympath etic function, was significantly lower in Groups I and II as compared to Group III, but high frequency power (HF), representing parasympathe tic function, and the LF/HF ratio, as an index of sympathovagal balanc e, were not different among the groups. In conclusion, in patients wit h secondary amyloidosis, sympathetic components of heart rate variable s decreased before the onset of uremia and the changes became more pro minent with the appearance of uremia despite not reaching statistical significance.