Reference intervals and percentile curve for left ventricular outflow tract (<scp>LVOT</scp>), velocity time integral (<scp>VTI</scp>), and <scp>LVOT</scp>‐<scp>VTI</scp>‐derived hemodynamic parameters in healthy children and adolescents: Analysis of echocardiographic methods association and agreement

<jats:sec><jats:title>Background</jats:title><jats:p>Echocardiographic reference intervals (<jats:styled-content style="fixed-case">RI</jats:styled-content>s) for left ventricular outflow tract (<jats:styled-content style="fixed-case">LVOT</jats:styled-content>) and velocity time integral (<jats:styled-content style="fixed-case">VTI</jats:styled-content>) are scarce in pediatrics.</jats:p></jats:sec><jats:sec><jats:title>Aims</jats:title><jats:p>(a) to generate <jats:styled-content style="fixed-case">RI</jats:styled-content>s and percentiles for <jats:styled-content style="fixed-case">LVOT</jats:styled-content>,<jats:styled-content style="fixed-case"> VTI</jats:styled-content>, and hemodynamic variables in healthy children and adolescents from Argentina; (b) to analyze the equivalence between stroke volume (<jats:styled-content style="fixed-case">SV</jats:styled-content>), cardiac output (<jats:styled-content style="fixed-case">CO</jats:styled-content>), and cardiac index (<jats:styled-content style="fixed-case">CI</jats:styled-content>) obtained from two‐dimensional echocardiography (2D) and <jats:styled-content style="fixed-case">LVOT</jats:styled-content>‐<jats:styled-content style="fixed-case">VTI</jats:styled-content> analysis with pulsed wave Doppler (<jats:styled-content style="fixed-case">PWD</jats:styled-content>); and (c) to analyze the association between subjects’ characteristics and <jats:styled-content style="fixed-case">VTI</jats:styled-content> and <jats:styled-content style="fixed-case">LVOT</jats:styled-content>‐<jats:styled-content style="fixed-case">VTI</jats:styled-content>‐derived parameters.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>Two‐dimensional and <jats:styled-content style="fixed-case">PWD</jats:styled-content> studies were done in 385 subjects (5–24 years). Mean and standard deviation age‐related and body surface area (<jats:styled-content style="fixed-case">BSA</jats:styled-content>)‐related equations were obtained for <jats:styled-content style="fixed-case">VTI</jats:styled-content> and <jats:styled-content style="fixed-case">LVOT</jats:styled-content>‐<jats:styled-content style="fixed-case">VTI</jats:styled-content>‐derived parameters (parametric regression methods based on fractional polynomials). <jats:styled-content style="fixed-case">BSA</jats:styled-content>‐ and age‐specific percentiles were determined.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Pulsed wave Doppler‐ and 2D‐derived parameters were positively correlated. However, <jats:styled-content style="fixed-case">PWD</jats:styled-content> values were always lower than those from 2D. Specific <jats:styled-content style="fixed-case">RI</jats:styled-content>s for <jats:styled-content style="fixed-case">PWD</jats:styled-content> and 2D data were necessary. Covariance analysis showed that sex‐specific <jats:styled-content style="fixed-case">RI</jats:styled-content>s were required for <jats:styled-content style="fixed-case">LVOT</jats:styled-content>, but not for <jats:styled-content style="fixed-case">VTI</jats:styled-content>,<jats:styled-content style="fixed-case"> VTI</jats:styled-content>‐derived <jats:styled-content style="fixed-case">CO</jats:styled-content> and <jats:styled-content style="fixed-case">CI</jats:styled-content>. Age‐related <jats:styled-content style="fixed-case">RI</jats:styled-content>s were obtained for <jats:styled-content style="fixed-case">LVOT</jats:styled-content>,<jats:styled-content style="fixed-case"> LVOT</jats:styled-content>‐<jats:styled-content style="fixed-case">VTI</jats:styled-content>, and <jats:styled-content style="fixed-case">VTI</jats:styled-content>‐derived <jats:styled-content style="fixed-case">CO</jats:styled-content> and <jats:styled-content style="fixed-case">CI</jats:styled-content>. <jats:styled-content style="fixed-case">BSA</jats:styled-content>‐related <jats:styled-content style="fixed-case">RI</jats:styled-content>s for <jats:styled-content style="fixed-case">VTI</jats:styled-content>‐derived <jats:styled-content style="fixed-case">CO</jats:styled-content> and <jats:styled-content style="fixed-case">CI</jats:styled-content> were obtained.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Stroke volume, <jats:styled-content style="fixed-case">CO</jats:styled-content>, and <jats:styled-content style="fixed-case">CI</jats:styled-content> data from 2D and <jats:styled-content style="fixed-case">PWD</jats:styled-content> are not equivalent. An accurate analysis of <jats:styled-content style="fixed-case">LVOT</jats:styled-content>‐<jats:styled-content style="fixed-case">VTI</jats:styled-content>‐derived parameters requires considering age and <jats:styled-content style="fixed-case">BSA</jats:styled-content>. In this study, age‐ and <jats:styled-content style="fixed-case">BSA</jats:styled-content>‐related <jats:styled-content style="fixed-case">RI</jats:styled-content>s and percentiles for <jats:styled-content style="fixed-case">LVOT</jats:styled-content>,<jats:styled-content style="fixed-case"> VTI</jats:styled-content>, and hemodynamic parameters in healthy children and adolescents were determined, discriminating data according to the methodological approach (2D or <jats:styled-content style="fixed-case">PWD</jats:styled-content>).</jats:p></jats:sec>