Background: Pediatric echocardiographic studies attempting to predict gold standard cardiac catheterization measures of left ventricular diastolic function (LVDFx) (pulmonary capillary wedge pressure (PCWP) or left ventricular end diastolic pressure (LVEDP)) are often retrospective, evaluated under variable hemodynamic and hydration conditions, and have demonstrated inconsistent results. We are unaware of any pediatric studies comparing echocardiographic measures of LVDFx with PCWP or LVEDP under the same loading conditions. We hypothesize, standard echocardiographic measurements of LVDFx can predict abnormal cardiac catheterization derived LVEDP or PCWP, when obtained under similar loading conditions and following …