Sympathetic Nervous System Function and Dysfunction in Chronic Hemodialysis Patients

Abstract

Adequate sympathetic nervous system activation is essential for the compensatory mechanisms of blood pressure maintenance during the hemodialysis (HD) procedure. Chronic sympathetic nervous system overactivity, however, may lead to the development of hypertension and cardiovascular disease in HD patients. The present review focuses on recent findings on the sympathetic nervous system activity in these patients. Sympathetic overactivity has been demonstrated directly by muscle sympathetic nerve activity recordings (MSNA) in chronic renal disease, but only rarely in HD patients. In the latter, sympathetic activity has mostly been assessed using indirect methodology. Decreased heart rate variability, increased blood pressure variability (BPV), and suppressed baroreflex function are believed to represent chronic sympathetic overactivity in HD patients. The HD procedure and ultrafiltration are associated with enhanced sympathetic activity and baroreflex activation. During most episodes of intradialytic hypotension, the baroreflex is adequately activated; sympathetic withdrawal with bradycardia, however, has been reported during excessive hypovolemia. Sympathetic overactivity is also believed to be a mechanism associated with intradialytic hypertensive episodes and refractory hypertension. While successful renal transplantation is associated with improvement of heart rate variability (HRV), improvement and restoration of baroreflex function, persistent sympathetic overactivity has been documented in transplanted patients using MSNA recordings. Decreased HRV and baroreflex function have been reported to be associated with increased mortality and morbidity in HD patients. The predictive value of sympathetic outflow assessed by MSNA has yet to be determined. Optimization of HD treatment, pharmacological interventions, and renal sympathetic denervation are several approaches targeting sympathetic overactivity to improve cardiovascular morbidity and mortality.

Heart rate variability during hemodialysis in patients with chronic renal disease

“…Our findings showed that patients with kidney disease have improved cardiac autonomic regulation during hemodialysis, supporting Rubinger et al [10] in which they reported that hemodialysis treatment induced a lower risk of sudden death or other cardiovascular aggravating event and consequently better control autonomic in chronic renal disease patients [7].…”

“…During hemodialysis, adequate stimulation of sympathetic nervous system is crucial for the beginning and preservation of compensatory mechanisms to maintain blood pressure, especially peripheral vasoconstriction and an increase in heart rate [7,10].The results found in our studysuggest a lower risk of a negative cardiovascular event during the hemodialysis procedure.…”

“…This result demonstrates that the parasympathetic modulation of the heart increased during hemodialysis. The concept of paradoxical withdrawal of sympathetic reflex vasoconstriction with bradycardias as one of the most important mechanisms of cardiovascular responsesinduced by hemodialysis [10,12,20] may be suggested as a mechanism involved in the responses of the parasympathetic modulation of the heart.…”

Effect of hemodialysis on intraocular lens power calculation

“…Adequate sympathetic nervous system activation is essential for hypotension compensatory mechanisms, which help maintain blood pressure during HD sessions. 19,20 We found that HD had no statistically significant effect on IOP or CCT. However, the effect of HD on IOP is somewhat controversial, with some studies reporting significant IOP changes during HD sessions.…”

Heart rate variability - current diagnosis of the cardiac autonomic neuropathy. A review

“…It refers to Parkinson's disease, Alzheimer's dementia 59,60 , haematological malignancies (amyloidosis) (ref. 61 ), patients in chronic hemodialysis 62 , systemic inflammatory diseases 63 . As a diagnostic auxiliary tool HRV can be used in testing the patients with syncope 64 , sleep apnea 65 , in psychiatry in diagnosis and during treatment of depression 66 .…”