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

Abstract

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

Stroke volume and cardiac output non-invasive monitoring based on brachial oscillometry-derived pulse contour analysis: Explanatory variables and reference intervals throughout life (3–88 years)

“…To this end, parametric regression methods based on fractional polynomials (FPs) were implemented [18][19][20][21][24][25][26][27]. Briefly (as an example), mean and SD regression curves for age-specific SV(PCA), CO(PCA) and CI(PCA) were defined as fitting FPs.…”

“…Healthy subjects (n = 1449; 3-88 years) from the community were considered for enrolment (Table 1) [18][19][20][21][22]. Hypertension, diabetes or dyslipidemia were considered present if the subject reported being in treatment and/or a previous diagnosis of their condition.…”

“…Smoking at least one cigarette per week was defined as a current smoker. Family history of cardiovascular disease was defined by the presence of first-degree relatives with premature cardiovascular disease [18][19][20][21][22]. Body mass index (BMI) was calculated as the weight-to-squared height ratio converted into percentiles/z-scores (subjects < 18 years) [18][19][20][21][22].…”

“…[RIs]) of cardiovascular variables in several populations; with special emphasis which considers childhood, adolescence and/or adult life as a continuum [18][19][20][21][22][23].…”

Clinical Considerations When Introducing Sodium-Glucose Co-Transporter 2 Inhibition in Patients With Heart Failure

“…LVOT peak velocity and velocity time integral (VTI) measurements were obtained from the apical 5-chamber view with pulsed wave Doppler sample placed in the LVOT immediately below the hinge points of the aortic valve leaflets. Stroke volume (SV), cardiac output, and cardiac index were calculated as follows: SV=VTI× LVOT area, where LVOT area=π (LVOT diameter/2) 2 ; cardiac output=SV×heart rate; cardiac index=cardiac output/body surface area 17.…”