Intraoperator, intraobserver and interoperator variability of echocardiographic measurements in healthy foals

Abstract

The repeatability of various echocardiographic measurements is unknown. To determine the intraoperator, intraobserver and interoperator variability of echocardiographic measures in healthy foals. Echocardiographic examinations were carried out on 6 healthy foals by 3 experienced echocardiographers. Intraoperator variability was determined by having a single echocardiographer obtain and measure images from 6 foals scanned on 3 consecutive days. Interoperator and intraobserver variability were determined by having 3 echocardiographers each obtain images from an additional 6 sedated foals. Within-day interoperator variability was determined by having each echocardiographer measure their own images. Intraobserver variability was determined by having a single echocardiographer measure images obtained by all 3 echocardiographers. The coefficient of variation (CV) and standard error were calculated for each measure. The variability for most measurements was either very low (CV < 5%) or low (CV = 5-15%). Measurements of right ventricular internal diameter (RVID) in systole and E-point to septal separation (EPSS) showed moderate (CV 15-25%) to high variability (CV > 25%) in all 3 categories. Measurements of the left ventricular ejection time (LVET) and velocity time integral from the right parasternal long axis view of right outflow tract in the fourth intercostal space showed moderate intraoperator variability. Measurements of the LVET, RVID in diastole and left atrial appendage (LAA) showed moderate interoperator variability and measurements of the RVID in diastole and acceleration time from the short axis view of the right outflow tract in the right third intercostal space showed moderate interobserver variability. The intraoperator, intraobserver and interoperatorvariabilities for most echocardiographic measurements in foals are low. Most standard transthoracic echocardiographic measurements in foals have a low enough variability to warrant their use in serial clinical evaluations or experimental studies. Repeated measurements of RVID, EPSS, LVET and LAA should be interpreted with caution.