title: Comparison of different interdialytic intervals among hemodialysis patients on their echocardiogram-based cardiovascular parameters.
abstract: BACKGROUND
  Although cardiovascular events in hemodialysis (HD) patients are the most frequent on the day after a long (2 days) interdialytic interval (IDT), it has been uncertain whether accumulation or elimination of large extracellular fluid volume, electrolyte, and/or uremic substances is the culprit for this. We sought to test our hypothesis that the long IDT alters echocardiographic parameters at rest and during exercise in stable maintenance HD patients compared with other IDTs.
  
  
  METHODS
  We performed a cross-sectional comparison using 1-way repeated analysis of variance or Friedman test of echocardiograms at 3 different IDTs, just after HD, after short IDT (1 day), and after long IDT, among 80 stable Japanese outpatients (age 61 ± 9 years, 60 males) on thrice weekly maintenance. End-systolic elastance (Ees), arterial elastance (Ea), and pressure-volume area (PVA) were estimated using a noninvasive single-beat technique. Ventricular-arterial coupling was assessed by Ea/Ees ratio. Measurements were repeated after 2-minute handgrip stress to evaluate cardiac reserve.
  
  
  RESULTS
  Resting left ventricular end-diastolic volume index and stroke volume index were significantly larger after a 1-day IDT compared with just after HD and even more after a 2-day IDT. Although Ees, Ea, and Ea/Ees ratio at rest remained similar between short and long intervals, stroke work (SW) and PVA were higher after the long interval. During handgrip stress, a significant increase in Ea without corresponding rise in Ees was observed only after long IDT, resulting in decreased stroke volume index, SW, and SW/PVA efficiency.
  
  
  CONCLUSIONS
  In a selective Japanese outpatient population on maintenance HD, there were no differences in resting cardiovascular function measured by echocardiography at 3 different IDTs. However, exercise-induced afterload mismatch assessed by the changes in Ea, SV, SW, and SW/PVA efficiency was most pronounced in individuals after the long IDT compared with other IDTs. Our findings report potential pathophysiologic echocardiographic parameters that attempt to explain why cardiovascular events are highest on the day after the long IDT compared to other IDTs in dialysis patients.
authors.affiliation: Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Obokata
authors.affiliation: Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan; Menzies Research Institute Tasmania, Hobart, Australia. Electronic address: kazz.negishi@nifty.com.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Negishi
authors.affiliation: Menzies Research Institute Tasmania, Hobart, Australia.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Marwick
authors.affiliation: Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Kurosawa
authors.affiliation: Hidaka Hospital, Takasaki, Gunma, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Ishida
authors.affiliation: Hidaka Hospital, Takasaki, Gunma, Japan; Department of Nephrology, Heisei-Hidaka Clinic, Takasaki, Gunma, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Ito
authors.affiliation: Hidaka Hospital, Takasaki, Gunma, Japan; Department of Medicine, Tokyo Women's Medical University Medical Center East, Tokyo, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ogawa
authors.affiliation: Hidaka Hospital, Takasaki, Gunma, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Ando
authors.affiliation: Department of Medicine and Biological Science, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kurabayashi
mesh_terms: D001794:Blood Pressure; D002318:Cardiovascular Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000503:physiopathology; D003430:Cross-Sectional Studies; D004452:Echocardiography; D005080:Exercise Test; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D007676:Kidney Failure, Chronic / Q000150:complications / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D006435:Renal Dialysis; D012307:Risk Factors; D013318:Stroke Volume; D016277:Ventricular Function, Left / Q000502:physiology*