title: The effect of a single dialysis session on spatial QRS-T angle in haemodialysis patients.
abstract: BACKGROUND
  Abnormal values of the spatial angle between the directions of ventricular depolarization and repolarization (QRS-T) reflect the action potential inhomogeneities and predict cardiac events and mortality in various patient groups. The study was designed to (i) compare QRS-T in haemodialysis (HD) patients and healthy subjects, (ii) assess the influence of HD on QRS-T and (iii) evaluate the possible associations between QRS-T and echocardiography, haemodynamic as well as biochemical parameters.
  
  
  METHODS
  The angular differences between the maximum spatial QRS and T vectors were measured in 73 HD patients and in 57 controls. QRS-T in patients was estimated pre- and post-dialysis together with the evaluation of blood chemistry and haemodynamic parameters.
  
  
  RESULTS
  Pre-dialysis QRS-T was higher compared with controls (30.18 ± 9.84 and 13.65 ± 7.23, respectively; P < 0.001). HD induced an increase of QRS-T (41.09 ± 11.74; P < 0.001). Pre-dialysis QRS-T adjusted for left ventricular mass index correlated with troponin T (r = 0.398, P = 0.001) and HDL (r = -0.270, P = 0.043). The differences between pre- and post-dialysis (Δ) QRS-T correlated with Δ potassium (r = 0.453, P < 0.001), Δ calcium (r = -0.309, P = 0.011) and Δ stroke index (SI; r = 0.311, P = 0.017). On multivariate analysis, troponin T was found to be an independent predictor of pre-dialysis QRS-T, whereas independent predictors of the HD-induced increase in QRS-T were potassium and cardiac index changes.
  
  
  CONCLUSIONS
  QRS-T is high in HD patients. HD enhances the inhomogeneities of action potential. Pre-dialysis QRS-T is mainly associated with troponin T elevation. HD-induced increase in QRS-T is mainly associated with potassium and SI changes. The possible clinical importance of the higher QRS-T in HD patients remains to be confirmed in further studies.
authors.affiliation: Department of Nephrology, Medical University of Lublin, Lublin, Poland. jaroszynskiaj@interia.pl
authors.forename: Andrzej
authors.initials: A
authors.lastname: Jaroszyński
authors.forename: Andrzej
authors.initials: A
authors.lastname: Wysokiński
authors.forename: Anna
authors.initials: A
authors.lastname: Bednarek-Skublewska
authors.forename: Andrzej
authors.initials: A
authors.lastname: Głowniak
authors.forename: Piotr
authors.initials: P
authors.lastname: Książek
authors.forename: Tomasz
authors.initials: T
authors.lastname: Sodolski
authors.forename: Jacek
authors.initials: J
authors.lastname: Furmaga
authors.forename: Andrzej
authors.initials: A
authors.lastname: Kutarski
authors.forename: Andrzej
authors.initials: A
authors.lastname: Książek
mesh_terms: D000328:Adult; D004562:Electrocardiography; D005260:Female; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000209:etiology; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D006435:Renal Dialysis; D020107:Troponin T / Q000097:blood
chemical_list: D020107:Troponin T