The Use Of Tissue Doppler Imaging (TDI) In The Evaluation Of Cardiac Function In Fetuses With Intrauterine Growth Retardation (IUGR)

Background:Intrauterine growth retardation (IUGR) caused by placental insufficiency is recognized among the main causes of perinatal morbidity and mortality. In intrauterine growth retardation fetuses with cerebroplacental flow redistribution (CPR) the scarcity of oxygen and nutrients has consistently been shown to negatively affect cardiac function, ranging from sub-clinical systolic dysfunction to overt heart failure and cardiovascular deterioration may directly account for the increased perinatal mortality seen in this high risk patient group. Whereas most studies in IUGR fetuses have focused on systolic performance, diastolic function may be more susceptible to hypoxemia and thus a more sensitive early marker for fetal compromise. Diastolic flows through the atrio-ventricular valves have previously been investigated in normal,and in pathological pregnancies. Tissue Doppler Imaging (TDI) represents a new development of the Doppler technique, allowing direct measurements of regional myocardial velocities. In adults, several studies have shown that the systolic myocardial velocity of the mitral valve annulus along the left ventricular long axis correlates closely with left ventricular (LV) pressure changes and LV ejection fraction (EF) validated by angiography. The ratio between flow velocity (E) and annular velocity (E’) in early diastole (E/E’ratio) has also been shown to correlate strongly with filling pressures, and E/(E’×S’) correlate strongly with systolic and diastolic function. Thus, it has been proposed that regional myocardial velocities reflect global cardiac function, and can be used to estimate systolic and diastolic function in both ventricles.Objective:Using the newly introduced ultrasound technique, Tissue Doppler Imaging (TDI), we investigated the correlation between diastolic tissue velocities and diastolic blood flow velocities and compared diastolic myocardial tissue velocities in IUGR fetuses with CPR and normal fetuses.Method:Inpatients and outpatients at the department of Obstetrics and Gynecology in2nd Xiangya Hospital were collected from October,2011to December,2012. Twenty-one singleton fetuses with IUGR-CPR were included, and mean pregnancy week is29.2±3.9(22to36weeks). Eighty normal singleton fetuses comprised the control group with a mean pregnancy week at28.6±3.4(18to36weeks). The IUGR group inclusion criteria are as follows:singleton, estimated body weight below the10th percentile of local reference curves, umbilical artery pulsatility index (PI) is2SD greater than the normal reference range, no other system malformations were found, postnatal weight is10th percentile lower than normal peer one’s birth weight. The inclusion criteria of control group include:healthy singleton with a normal body weight and normal UA-PI, the postnatal weight are also normal.The American GE Voluson730and E8which are dedicated for fetal examination were used. Conventional examination include Biparietal diameter, Cerebellar, Head Circumference, Abdominal Circumference and so on,body weight can be calculated by the machine automatically. Choosing the fetal heart progress,check the apical and parasternal four-chamber plane, and obvious fetal defections were exclued.Adjusting the PRF and WMF in order to make the image as clearly as possible, puting the1～2mm width sample volume at the tip of both mitral and tricuspid, and then measure the flow velocity. TDI assessment was performed with the sample volume placed at the basal segment of the left ventricular side wall (LV), and the right ventricular free wall (RV). Peak velocity in early (E) and late (A) diastole were measured by pulsed-wave Doppler, and the peak annular velocities in systole (S’) and early (E’) and late (A’) diastole were also measured by TDI. The ratios between flow velocity and annular velocity E/A、E’/A’、E/E’、E/(E’×S’) ratios were calculated for each location. Results:There was a tendency towards increased E、A、E’、A’、S’、E/A and E’/A’ with the increasing of pregnancy in both groups at LV and RV especially at RV (P<0.05), with consistantly E<A and E’<A’, the ratios E/E’、E/(E’×S’) increased in normal fetuses but decreased in IUGR ones.Values were lower except MPI when compared to normal fetuses (P <0.05), and no linear correlation was found between MPI and gestational ages (P>0.05)Conclusions:Fetal heart function enhanced in the processing of pregnancy in both groups, and atrial contraction make up a dominantly position in cardiac diastolic function. Global heart function especially the diastolic function were jeopardized by placental dysfunction in IUGR fetuses. TDI may be more sensitive than atrioventricular spectral Doppler for the detection of ventricular dysfunction in IUGR fetuses.