How do I Calculate Echo Z-Scores?

For more information about the Echo Z-Score project, see: http://pediatricheartnetwork.com/Studies/CompletedStudies/EchoZScore.aspx

There are currently two options for calculating the Z-scores for common echo measurements using the PHN models: (1) with a table listing the exponential power to be used with body surface area (BSA), the mean value of the indexed measurement, and the standard deviation (SD) of the indexed measurement; or (2) with an online Z-score calculator.

  1. Calculating echo z-scores using the table of exponential power for BSA, mean, and SD:
    From the table below, one would take the values listed for the parameter of interest and use them along with the measurement value of the parameter and the BSA in the following formula to calculate the Z-score:


     Parameter  α Mean  SD 
      MVAP 0.50  2.31 0.24
      MVLAT 0.50 2.23 0.22
      MVA 1.00 4.06 0.68
      TVAP 0.50 2.36 0.28
      TVLAT 0.50 2.36 0.29
      TVA 1.00 4.39 0.83
      ANN 0.50 1.48 0.14
      ROOT 0.50 2.06 0.18
      STJ 0.50 1.69 0.16
      AAO 0.50 1.79 0.18
      ARCHPROX 0.50 1.53 0.23
      ARCHDIST 0.50 1.36 0.19
      ISTH  0.50  1.25 0.18
      LMCA 0.45 2.95 0.57
      LAD  0.45 1.90  0.34
      RCA 0.45 2.32 0.55
      PVSAX 0.50 1.91 0.24
      PVLAX 0.50 2.01 0.28
      MPA 0.50 1.82 0.24
      RPA  0.50 1.07 0.18
      LPA 0.50 1.10 0.18
      LVEDD 0.45 3.89 0.33
      LVPWT 0.40 0.57 0.09
      LVST 0.40 0.58 0.09
      LVEDL 0.45 6.31 0.46
      LVEDLEPI 0.45 6.87 0.45
      LVEDA 0.90 11.91 1.89
      LVEDAEPI 0.90 20.00 2.59
      LVEDV 1.30 62.02 11.94
      LVEDVEPI 1.30 113.14 17.85
      LVM 1.25 53.02 9.06
      LVMTV 0 0.88 0.16
      LVTTD 0 0.15 0.03
      LVSI 0 1.63 0.17

    Parameter Abbreviations: AAO=ascending aortic diameter; ANN=aortic annular diameter; ARCHDIST=distal transverse arch diameter; ARCHPROX=proximal transverse arch diameter; ISTH=aortic isthmus diameter; LAD=proximal left anterior descending coronary artery diameter; LMCA=left main coronary artery diameter; LPA=left pulmonary artery diameter; LVEDA=LV (LV) short-axis end-diastolic endocardial area; LVEDAEPI=LV short-axis end-diastolic epicardial area; LVEDD=LV short-axis end-diastolic endocardial diameter; LVEDL=LV long-axis end-diastolic endocardial length; LVEDLEPI=LV long-axis end-diastolic epicardial length; LVEDV=LV short-axis end-diastolic endocardial volume; LVEDVEPI=LV short-axis end-diastolic epicardial volume; LVM=LV mass; LVMTV=LV mass-to-volume ratio; LVPWT=LV short-axis end-diastolic posterior wall thickness; LVSI=LV sphericity index; LVST=LV short-axis end-diastolic septal thickness; LVTTD=LV thickness-to-dimension ratio; MPA=main pulmonary artery diameter; MVAP=mitral anteroposterior diameter; MVLAT=mitral lateral diameter; MVA=mitral area; PVLAX=pulmonary annular long-axis diameter; PVSAX=pulmonary annular short-axis diameter; RCA=proximal right coronary artery diameter; ROOT=aortic root diameter; RPA=right pulmonary artery diameter; STJ=sinotubular junction; TVAP=tricuspid anteroposterior diameter; TVLAT=tricuspid lateral diameter; TVA= tricuspid area.
  2. Calculating echo z-scores using an online calculator:
    The results from the PHN Echo Z-Score Project are available as a Z-score calculator on the ParameterZ website using the following link: http://www.parameterz.com/refs/lopez-circimaging-2017. In the future, the PHN website will have a Z-score calculator that can be easily accessed.