Derivation of Transthoracic Echocardiographic Reference Ranges for Left Ventricular, Left Atrial and Aortic Root M-Mode Dimensions in Preterm Infants

Abstract

Background: M-mode measurement of left heart dimensions is routine in transthoracic echocardiography. Reference ranges are well defined in adults and paediatric patients. No such data have been published in preterm neonates. Methods: All echocardiographic studies performed in Monash Newborn between 3rd December 2007 and 2nd December 2010 were identified. Infants with congenital heart disease, a greater than small sized patent ductus arteriosus or technically inadequate M-mode images were excluded. M-mode left ventricular, left atrial and aortic root measurements were made retrospectively by an experienced cardiac sonographer. Analysis was limited to infants with a birth or current weight ≤3.5 kg and ≤45 completed weeks of corrected gestational age (cGA) at the time of echocardiography. Analysis was performed in SPSS. Regression curves were modelled with respect to weight and cGA and reference curves for ±1 and ±2 standard deviations calculated using the method of Altman (Statistics in Medicine, 1993). Results: 234 studies were identified, mean GA at birth 30 weeks, birth weight 1.5 ± 0.9 kg. All measured parameters increased with weight and cGA (all P < 0.001). Standard deviation increased, but did not reach statistical significance over the given weight and cGA range. Examples for Left ventricular end diastolic dimension (LVEDd), posterior wall and aortic root dimensions below. Conclusions: The derivation of reference ranges for left ventricular dimensions in preterm infants will permit better recognition of abnormalities and better description and documentation of change with the opportunity to calculate Z scores.