The technique cited by both articles is:
TAPSE was measured by two-dimensional echocardiograph-guided M-mode recordings from the apical four-chamber view with the cursor placed at the free wall of the tricuspid annulus ... align the sample volume as vertical as possible with respect to the cardiac apex ... Maximal TAPSE was determined by the total excursion of the tricuspid annulus from its highest position after atrial ascent to the lowest point of descent during ventricular systole.
Systolic Right Ventricular Function in Preterm and Term Neonates: Reference Values of the Tricuspid Annular Plane Systolic Excursion (TAPSE) in 258 Patients and Calculation of Z-Score Values. Neonatology. 2011 Jan 26;100(1):85-92
Right ventricular function in infants, children and adolescents: reference values of the tricuspid annular plane systolic excursion (TAPSE) in 640 healthy patients and calculation of z score values. J Am Soc Echocardiogr. 2009 Jun;22(6):715-9
This z-score calculator uses the table data published with the articles. The 1SD values are calculated by first determining if the measured value (score) is above or below the mean, then dividing by two the difference between the mean and the appropriate 2SD value, e.g.:
SD = [+2SD - mean] / 2
The z-score is then calculated in the conventional manner:
z = [score - mean] / SD
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