Left ventricular myocardial mass determined by cross-sectional echocardiography in normal newborns, infants, and children.

Changes in left ventricular muscle mass may be an important diagnostic or prognostic finding in children with congenital heart defects, but there are no data on normal mass as determined by cross-sectional echocardiography (CSE) in children. Fourteen newborns, 12 infants, and 69 children (1.5-17 years old) with a structurally normal heart were studied. End-diastolic and end-systolic volume and mass were calculated from biplane-paired echocardiographic imaging planes-apical two-chamber and apical four-chamber views-using both an area/length and a Simpson's rule geometric method. Data were compared with M-mode measurements. There was a good correlation between area/length and Simpson's rule method [r = 0.94, standard error (SE) 4 g/m2]. To validate the measurements, interobserver data were gathered and end-diastolic and end-systolic mass measurements were compared. Interobserver variability for the measurements on the echocardiographic recordings was low at 4.8%; for end-diastolic mass the correlation between two observers was r = 0.99 (SE 3.3 g/m2) and for end-systolic mass r = 0.97 (SE 7.6 g/m2). Correlation between end-systolic and end-diastolic mass was acceptable (r = 0.88, SE 5.9 g/m2) for the CSE mass determination, but poor for the M-mode measurements (r = 0.51, SE 20.2 g/m2). Similarly, correlation between M-mode mass and mass estimated by CSE was poor, at r = 0.58 for end-diastolic and r = 0.094 for end-systolic mass.(ABSTRACT TRUNCATED AT 250 WORDS)