title: Color M-mode flow propagation velocity: is it really preload independent?
abstract: OBJECTIVE
  This study investigates the change in flow propagation velocity (FPV) in uremic patients who undergo regular hemodialysis (H/D).
  
  
  METHODS
  We studied 93 uremic patients (44 men and 49 women; 59 +/- 14-years-old) receiving regular hemodialysis. Patients were separated by baseline left ventricular ejection fraction (LVEF): 71 patients with LVEF > 50% (group 1), 13 patients with LVEF 35-50% (group 2), 7 patients with LVEF < 35% (group 3). All patients were in sinus rhythm before H/D. They received complete transthoracic echocardiographic examinations. Flow propagation velocity was measured by color M-mode echocardiography in apical four chambers view. All these parameters were obtained before and after H/D. Paired data were compared. According to different H/D amounts, we viewed the FPV response after H/D in variant baseline LVEF groups.
  
  
  RESULTS
  The baseline FPV became lower in patients with low LVEF. After H/D, obvious decrement of FPV occurred in group 1, but there were no obvious changes in groups 2 and 3. In fact, a slight increment of FPV was found in group 3. In patients with baseline LVEF > 50%, FPV after H/D was almost always lower, regardless of H/D amount. But there was different response in patients with baseline LVEF < 50%.
  
  
  CONCLUSIONS
  Flow propagation velocity is preload independent in patients with LVEF < 50%, but it is preload-dependent in patients with LVEF > 50%.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, Republic of China.
authors.forename: Shih-Kai
authors.initials: SK
authors.lastname: Lin
authors.forename: Shih-Hung
authors.initials: SH
authors.lastname: Hsiao
authors.forename: Tao-Yu
authors.initials: TY
authors.lastname: Lee
authors.forename: Wei-Chen
authors.initials: WC
authors.lastname: Huang
authors.forename: Tsui-Lieh
authors.initials: TL
authors.lastname: Hsu
authors.forename: Guang-Yuan
authors.initials: GY
authors.lastname: Mar
authors.forename: Chun-Peng
authors.initials: CP
authors.lastname: Liu
mesh_terms: D000368:Aged; D001783:Blood Flow Velocity; D018618:Echocardiography, Doppler, Color / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014511:Uremia / Q000150:complications / Q000000981:diagnostic imaging* / Q000628:therapy*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology