title: Left ventricular outflow tract mean systolic acceleration as a surrogate for the slope of the left ventricular end-systolic pressure-volume relationship.
abstract: OBJECTIVE
  The goal of this study was to analyze left ventricular outflow tract systolic acceleration (LVOT(Acc)) during alterations in left ventricular (LV) contractility and LV filling.
  
  
  BACKGROUND
  Most indexes described to quantify LV systolic function, such as LV ejection fraction and cardiac output, are dependent on loading conditions.
  
  
  METHODS
  In 18 sheep (4 normal, 6 with aortic regurgitation, and 8 with old myocardial infarction), blood flow velocities through the LVOT were recorded using conventional pulsed Doppler. The LVOT(Acc) was calculated as the aortic peak velocity divided by the time to peak flow; LVOT(Acc) was compared with LV maximal elastance (E(m)) acquired by conductance catheter under different loading conditions, including volume and pressure overload during an acute coronary occlusion (n = 10). In addition, a clinically validated lumped-parameter numerical model of the cardiovascular system was used to support our findings.
  
  
  RESULTS
  Left ventricular E(m) and LVOT(Acc) decreased during ischemia (1.67 +/- 0.67 mm Hg.ml(-1) before vs. 0.93 +/- 0.41 mm Hg.ml(-1) during acute coronary occlusion [p < 0.05] and 7.9 +/- 3.1 m.s(-2) before vs. 4.4 +/- 1.0 m.s(-2) during coronary occlusion [p < 0.05], respectively). Left ventricular outflow tract systolic acceleration showed a strong linear correlation with LV E(m) (y = 3.84x + 1.87, r = 0.85, p < 0.001). Similar findings were obtained with the numerical modeling, which demonstrated a strong correlation between predicted and actual LV E(m) (predicted = 0.98 [actual] -0.01, r = 0.86). By analysis of variance, there was no statistically significant difference in LVOT(Acc) under different loading conditions.
  
  
  CONCLUSIONS
  For a variety of hemodynamic conditions, LVOT(Acc) was linearly related to the LV contractility index LV E(m) and was independent of loading conditions. These findings were consistent with numerical modeling. Thus, this Doppler index may serve as a good noninvasive index of LV contractility.
authors.affiliation: Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Bauer
authors.forename: Michael
authors.initials: M
authors.lastname: Jones
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shiota
authors.forename: Michael S
authors.initials: MS
authors.lastname: Firstenberg
authors.forename: Jian Xin
authors.initials: JX
authors.lastname: Qin
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsujino
authors.forename: Yong Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Marta
authors.initials: M
authors.lastname: Sitges
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Cardon
authors.forename: Arthur D
authors.initials: AD
authors.lastname: Zetts
authors.forename: James D
authors.initials: JD
authors.lastname: Thomas
mesh_terms: D000054:Acceleration; D000704:Analysis of Variance; D000818:Animals; D001022:Aortic Valve Insufficiency / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002302:Cardiac Output; D004195:Disease Models, Animal; D015150:Echocardiography, Doppler / Q000592:standards; D006439:Hemodynamics; D016014:Linear Models; D008955:Models, Cardiovascular; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000503:physiopathology*; D009716:Numerical Analysis, Computer-Assisted; D015588:Observer Variation; D012756:Sheep; D013318:Stroke Volume / Q000502:physiology*; D013599:Systole / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*; D017725:Ventricular Pressure / Q000502:physiology*