MATERIALS AND METHODSThe loading condition of the left ventricle changes markedly during the transition from fetal to neonatal circulation and continues to be unstable shortly after birth. During this period, pulmonary blood flow, which acts as preload to the left ventricle, increases because of left-to-right ductus arteriosus shunting (I, 2). Among the hemodynamic factors affecting left ventricular diastolic filling, preload appears to play an important role, as has been recently suggested (3,4). Interest has more recently been directed toward the possibility of using Doppler echocardiography to assess left ventricular diastolic hemodynamics in the early neonatal period (5-8). However, the impact of changes in preload on the transmitral flow pattern in neonates is as yet unclear. The purpose of our study was to evaluate by Doppler echocardiography the serial changes of left ventricular filling patterns in normal neonates during their transition to postnatal circulation.Study population. The study population consisted of20 normal term neonates. Their mothers had uncomplicated pregnancies with no evidence of toxemia, diabetes mellitus, or pregnancyinduced hypertension. None of the infants were acutely ill or showed any evidence of congenital malformations. The mean birth weight was 3068 ± 351 g (mean ± SD), and the mean gestational age was 39 ± I wk. Each mother received an explanation of the study and gave informed consent. Serial echocardiographic examinations were performed on each subject at 2, 12, and 24 h after birth.Examination technique. A complete two-dimensional echocardiographic examination was performed on the subjects with an Aloka SSD 870 ultrasonoscope with a 5.0-MHz transducer. The size of the Doppler sample volume was set at an axial length of 2 mm, with a wall filter setting of 400 Hz. All neonates were examined while they were lying quietly in the supine position breathing room air. To record the transmitral flow velocity profile, a standard apical two-chamber view was visualized, and the Doppler sample volume was placed in the inflow area of the left ventricle just below the level of the mitral annulus, adjusted to record the maximal flow velocities. The ascending aortic flow was measured from the suprasternal long axis view. The sample volume was placed in the AO immediately distal to the aortic valve. Care was taken to carry out these studies with the transducer beam as close to parallel to the presumed blood flow direction as possible. Because the angle between the estimated direction of blood flow and the Doppler beam was 20 degrees or less in the selected planes, no angle correction of the Doppler signal was made. All examinations were recorded at a paper speed of 100 mm/s, The electrocardiogram and respiration of each subject (with a pressure transducer placed against the abdominal wall) were simultaneously recorded. With the aid of a computer-interfaced digitizer pad (Cardio 500, Kontron Medical System), the various Doppler flow indices were measured from 506 Abbreviations AD, ascendin...
To evaluate the effects of altered preload on the Doppler flow pattern of right ventricular inflow in the first day of life, serial Doppler echocardiography of the pulmonary artery (PA) and tricuspid valve was performed in 16 normal neonates at 2, 12, and 24 hr. A computerinterfaced digitizer pad was utilized to measure the followings: PA flow velocitytime integral, total transtricuspid flow velocity-time integral, flow velocity-time integral of early diastolic filling (E area), and flow velocity-time integral of atrial contraction (A area). The PA flow velocity-time integral, total transtricuspid flow velocity-time integral, E area, A area, peak E, and peak A were increased significantly by 24 hr compared with the values at 2 hr of age. However, the peak E/A, E/A area and peak E/total transtricuspid flow velocity-time integral did not show significant changes from 2 to 24 hr. The ductus arteriosus size was inversely correlated with the peak E (r= -0.46, p <0.05), E area (r= -0.37, p <0.05), and A area (r= -0.34, p <0.05). Therefore, the increase in right ventricular preload at 24 hr is considered to be due to the cessation of the left-to-right shunt through the ductus arteriosus. These results suggest that the pattern of early and late diastolic filling of the right ventricle were dependent on the increase in preload. We can therefore conclude that the redistribution of transtricuspid flow induced by the preload condition should be taken into account to interprete the transtricuspid velocity pattern in terms of diastolic function. right ventricular diastolic function; neonate; ductus arteriosus Pulsed Doppler echocardiography has recently been used to assess right ventricular diastolic filling in a variety of diseases including valvular pulmonic stenosis, pulmonary hypertension, constrictive pericarditis and cardiac tamponade (Appleton et al. 1988;Hatle et al. 1989;Klein et al. 1990;Vermilion et al. 1990,
To examine the effects of ductal closure on left ventricular (LV) systolic and diastolic function during the early neonatal periods, 45 normal term neonates delivered after uncomplicated pregnancies (mean 39 weeks) were studied using two-dimensional and Doppler echocardiography. We measured ductus arteriosus size, arterial blood pressures, ascending aortic size, LV dimensions, and transmitral flow velocity patterns and calculated LV output and rate-corrected fiber shortening fraction (mVcfc) at 2, 12, 24, and 120 hours after birth. The inner diameter of the ductus arteriosus was 4.3 +/- 0.7mm at 2 hours, 2.1 +/- 0.6 mm at 12 hours, and had closed in 42 of 45 neonates at 24 hours. LV output and LV end-diastolic dimension showed the highest level at 2 hours of age. However, the mVcfc did not change from 2 to 120 hours of age. The peak velocity during early diastole (peak E) was significantly greater at 2 hours than at 12 hours. The peak velocity during atrial contraction (peak A) remained unchanged during this period. The normalized peak filling rate at isovolumic relaxation time did not change over 120 hours. The present study demonstrated changes in LV systolic function and LV diastolic filling during the early neonatal period. LV systolic and diastolic function was preserved under the hemodynamic changes associated with the early neonatal period.
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