title: The effect of hemodialysis on left ventricular outflow tract gradient.
abstract: BACKGROUND
  The aim of the study was to assess the effect of hemodialysis (HD) on left ventricular outflow tract gradient (LVOTG) measured both in supine and upright position (provocative maneuver to unload LV cavity by rapid preload reduction). Supine/standing echocardiography was performed immediately before and immediately after HD. For additional verification of the hypothesis about preload-dependence of LVOTG, the echocardiograms after long (2-day delay HD due to weekend) versus short (usual 1-day) pause between HDs were compared.
  
  
  METHODS
  Forty-one patients on chronic HD (mean age 44 +/- 11 years) were examined using a portable hand-carried echocardiograph. In accordance with the prestudy assumption the ultrafiltration volume was significantly greater during HD after a long pause in comparison to HD after a short pause (3707 +/- 2826 mL vs. 2665 +/- 1152 mL P < 0.05).
  
  
  RESULTS
  After a long pause, the mean value of LVOTG at the pre-HD was mildly increased in the supine position and remained at a similar level in the upright position (13.1 +/- 6.1 vs. 13.6 +/- 9.1 mmHg). Mean LVOTG at the post-HD in the supine position was similar to pre-HD, however the orthostatic stress test induced a significant increase of LVOTG (13.9 +/- 15.2 vs. 18.2 +/- 19.9 mmHg P < 0.05). After a short pause at the pre-HD the LVOTG in the supine position and after the orthostatic provocation was very similar to measurements after long pause (13.3 +/- 9.1 vs. 13.3 +/- 10.8 mmHg). At the post-HD the mean value of LVOTG increased during upright posture but the differences were of borderline significance (13.2 +/- 6.6 vs. 17.9 +/- 18.6 mmHg P = 0.052).
  
  
  CONCLUSIONS
  HD predisposed to standing-provoked LVOTG especially when a long pause (2 days) between HDs induced a greater weight gain and subsequently a larger volume of ultrafiltration was needed to reduce hypervolemia.
authors.affiliation: Second Department of Cardiology CMUJ, Krakow, Poland. dimitrow@mp.pl
authors.forename: Pawel Petkow
authors.initials: PP
authors.lastname: Dimitrow
authors.forename: Joanna
authors.initials: J
authors.lastname: Michałowska
authors.forename: Danuta
authors.initials: D
authors.lastname: Sorysz
mesh_terms: D000328:Adult; D003326:Coronary Circulation; D004452:Echocardiography; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D006435:Renal Dialysis / Q000009:adverse effects*; D014694:Ventricular Outflow Obstruction / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology*