title: Heart rate response to blood pressure variations: sympathetic activation versus baroreflex response in patients with end-stage renal disease.
abstract: BACKGROUND
  Continuous systolic blood pressure (SBP) and interbeat intervals (IBI) recordings reveal sequences of consecutive beats in which SBP and heart rate change in opposite direction, representing negative feedback baroreflex mechanisms, as well as sequences in which SBP and heart rate change in the same direction (non-baroreflex), believed to represent feedforward control mechanisms. The present study was undertaken to assess the relationship between baroreflex and non-baroreflex sequences in end stage renal insufficiency.
  
  
  RESULTS
  Continuous beat-to-beat SBP and IBI monitoring was performed in patients on chronic hemodialysis (HD, n=72), in age-matched patients after renal transplantation (TX, n=41) and healthy (control) individuals (C, n=34). The proportion of baroreflex and nonbaroreflex episodes and the b coefficients (the regression line slope of SBP-IBI correlation) were determined using a newly developed 1 minute sliding window method, the classical sequence technique and the "Z" coefficient method. Analysis using the 1 minute sliding window showed an increased proportion of baroreflex episodes in controls and HD, and predominance of nonbaroreflex episodes in TX. An increased proportion of nonbaroreflex episodes in TX patients relative to HD was also revealed by the "Z" method. Baroreflex and nonbaroreflex b coefficients obtained by all methods were markedly decreased in HD. This alteration was reversed at least partly in TX. In HD, both baroreflex and nonbaroreflex b coefficients were inversely correlated to age and CRP levels; in TX, the nonbaroreflex b coefficient was influenced by the type of calcineurin inhibitor.
  
  
  CONCLUSIONS
  Renal status affects the contribution of baroreflex and nonbaroreflex mechanisms and the strength of SBP-IBI relationship. The predominant contribution of nonbaroreflex mechanisms in TX may be suggestive of enhanced central sympathetic control. Our data may be relevant for understanding of the pathogenesis and selection of appropriate treatment of post-transplant hypertension.
authors.affiliation: Nephrology and Hypertension Services, Department of Medicine, Hadassah Hebrew University Medical Center, Jerusalem, Israel.
authors.forename: Dan
authors.initials: D
authors.lastname: Sapoznikov
authors.forename: Michal
authors.initials: M
authors.lastname: Dranitzki Elhalel
authors.forename: Dvora
authors.initials: D
authors.lastname: Rubinger
mesh_terms: D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000494:pharmacology; D017704:Baroreflex / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D019703:Calcineurin / Q000378:metabolism; D065095:Calcineurin Inhibitors; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007676:Kidney Failure, Chronic / Q000503:physiopathology* / Q000628:therapy; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D012307:Risk Factors; D016559:Tacrolimus / Q000494:pharmacology; D013997:Time Factors; D014666:Vasomotor System / Q000187:drug effects
chemical_list: D000959:Antihypertensive Agents; D065095:Calcineurin Inhibitors; D019703:Calcineurin; D016559:Tacrolimus