Comparison of Left Ventricular Outflow Tract Diameter Measurements Using Echocardiography in Newborn Infants.

Objective: This study aimed to compare left ventricular outflow tract (LVOT) diameter measurements using two-dimensional (2D) echocardiography at the sino-tubular junction (STJ) and at the aortic valve (AV) hinges in newborn infants.

Study Design: This is a retrospective study in a tertiary neonatal unit where infants underwent echocardiography for evaluation of murmur or as part of cardiovascular assessment. Three consecutive cardiac cycles were chosen to measure the LVOT diameter in end systole at the STJ and at the AV hinges. Bias and levels of agreement were examined using Bland-Altman plot. Intraobserver variability was examined using intraclass correlation.

Results: A total of 366 measurements were obtained from 61 infants with a mean (standard deviation) gestation and birth weight of 33.4 (6.9) weeks and 2,181 (1369) g, respectively. There was good correlation between the LVOT diameter measurements using the STJ and AV hinges ( = 0.958,  < 0.001). The mean (standard deviation and 95% confidence interval) bias between LVOT diameter measurements using STJ and AV hinges were 0.93 (0.45 and 0.06-1.81) mm. There was good intraobserver variability between the measurements using both methods.

Conclusion: Using 2D echocardiography, LVOT measurements using the STJ tend to be higher when compared with LVOT measurements using the AV hinges.

Key Points: · Echocardiographic assessment of left ventricular output is undertaken frequently.. · Left ventricular outflow tract can be measured at the aortic valve hinges, sinus of valsalva, or sino-tubular junction.. · Left ventricular outflow tract measured at the sino-tubular junction tends to higher when compared with aortic valve.