| Fetal echocardiography is a well-established tool for the prenatal diagnosis of congenital structural heart diseases and arrhythmias. High-resolution imaging and Doppler interrogation, which has evolved over the past two decades, has permitted an accurate evaluation of fetal cardiac morphology and function and has resulted in a better understanding of the prenatal natural history and predictors of outcome for most fetal cardiovascular abnormalities. Fetal cardiac dysfunction is the leading factor for high perinatal mortality. Recently, a conceptually new Doppler-derived index ?Tei index for quantitative assessment of fetal overall ventricular function was proposed, and this study was therefore designed to define the value of this index in normal fetuses, and evaluate the influence of the gestational age and fetal heart rate on the index.Study population and Methods 一, Study populationFrom December 2002 to February 2003, fetal echocardiographicexaminations were performed in 143 consecutive pregnant women, among them 131 were included as our study group (age 27.3±3.6 years, range 21-43 years, gestational age 32.6±5.6 weeks, range 15-40 weeks). They fulfilled the following inclusion criteria: (1) no evidence of structural cardiovascular disease founded by fetal echocardiography, (2) no evidence of other organ system diseases detected prenatally by 2-dimensional or Doppler ultrasonography, (3) without clinical signs of cardiovascular diseases by follow-up after birth, (4) all fetuses included were singletons and appropriate for gestational age infants. Fetuses with either persistent arrhythmias or poor Doppler imaging quality were excluded. @二, Echocardiographic ExaminationComplete M-mode, two-dimensional and color Doppler echocardiograms were performed by using GE LOGIQ 700 and Philips ATL HDI 5000 color Doppler blood flowing scanners with 2.5-7.0 MHz transducers. Fetal echo or Fetal Heart setup was used.1. Fetal heart rate was measured and fetal gestational age was assessed by biparietal diameter and femur length.2. The ventricular inflow velocity pattern was recorded from the 4-chamber or long-axis views with the pulsed wave Doppler sample volume of 2 to 4 mm positioned at the tips of the atrioventricular valve leaflets during diastole. Subsequently, the ventricular outflow velocity pattern was recorded from the long-axis view with pulsed wave Doppler sample volume positioned just below the aortic or pulmonary annulus. Care was taken to direct the transducer beam as close as possible to the Doppler beam at <30 in selected planes. The Doppler examination was recorded at a paper speed of 50 or 100mm/s, and simultaneously printed for later analysis. All echocardiographic examinations were performed by oneexperienced echocardiographer.2.1 Tei index: is defined as the sum of isovolumic contraction and relaxation times divided by ventricular ejection time. The ejection time was measured from the onset to the end of corresponding ventricular outflow velocity pattern. The mitral or tricuspid closing-to-opening time was measured as the interval from the end to the onset of the corresponding atrioventricular inflow velocity pattern. Interval "a" is the time from the cessation to the onset of the next mitral inflow, which is equal to the sum of the isovolumic contraction time, ejection time and isovolumic relaxation time. The ejection time "b" is measured as duration of LV outflow. The sum of the isovolumic contraction time and isovolumic relaxation time was easily obtained by subtracting "6" from "a". The LV Tei index was calculated as {a-b)/b. The measurement of Doppler time intervals of RV is as same as that of LV.2.2 To account for slight variations in fetal heart rate, each interval was measured in 3 consecutive beats and the values averaged to obtain each interval duration. In fetuses with either premature atrial or ventricular beats, care was taken to exclude these ectopic beats when determining Tei index. Meanwhile, fetal heart rate was measured and... |
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