CHANGES IN THE VOLUME AND PERFORMANCE OF THE LEFT-VENTRICLE IN THE EARLY NEONATAL-PERIOD

To evaluate the effect of changes in preload on left ventricular (LV) performance, we used echocardiography to measure end-diastolic dimensi on, end-systolic dimension, and stroke volume in newborns at 2, 12, 24 , and 120 h of age. The stroke volume was calculated by the pulsed Dop pler technique. The stroke volume showed the highest level at 2 h of a ge. The size of the ductus arteriosus correlated with the stroke volum e. These results indicated that the increase in stroke volume was rela ted to the increase in LV preload due to the shunt flow volume through the patent ductus arteriosus. M-mode echocardiographic indexes such a s end-diastolic dimension, LV end-diastolic volume, and LV ejection fr action did not show any significant changes from 2 to 120 h of age. We conclude that M-mode echocardiographic evaluation of LV performance i s unreliable in the early neonatal period. Our data also provide a use ful basis for the interpretation of abnormal left ventricular systolic function in the early neonatal period.