Influence Of Location Of Sample Volume On Fetal Pulmonary Flow Parameters

Objective:To investigate the influence of different locations of sampling volume(SV)on fetal pulmonary flow parameters of normal fetuses in second and late trimesters.To achieve this goal,blood flow spectrum information was detected by locating SV in three different spots of fetal pulmonary valve orifice noted as a,b and c,as following:a,putting SV at the inner side,closed to the aorta;b,putting SV at the center of PA;c,putting SV at the lateral side of PA,away from the aorta.Methods:Four hundred and twenty four normal fetuses in second and late trimesters were divided by gestational age(GA)into such 5 groups as 20?23+6 weeks,24?27+6 weeks,28?31+6 weeks,32?35+6 weeks,and 36?40+6 weeks.Then velocity waveform parameters were measured by locating SV in three different spots of fetal pulmonary valve orifice noted as a,b and c,as following:a,putting SV at the inner side,closed to the aorta;b,putting SV at the center of PA;c,putting SV at the lateral side of PA,away from the aorta.Wherein the velocity waveform parameters included velocity time integral(VTI),the maximum velocity(Vmax),the mean velocity(Vmean),the maximum pressure gradient(PGmax),the mean pressure gradient(PGmean),ejection time(ET),acceleration time(AT),and AT/ET ratio(AT/ET).Intergroup comparison for VTI,Vmax,Vmean,PGmax,PGmean,ET,AT and AT/ET of gestational weeks were performed by ANOVA.Paired t-test was used to make comparison between the parameters measured in the different SV locations(a,b and c)for all gestational weeks.The correlation between VTI,Vmax,Vmean,PGmax,PGmean,ET,AT,AT/ET and gestational age was analyzed by means of Pearson Correlation Analysis.Results:The differences shown in the intergroup comparison for VTI,Vmax,Vmean,PGmax,PGmean,AT,AT/ET of gestational weeks were all of statistical significance(P=0.000).There was linear correlation between VTI,Vmax,Vmean,PGmax,PGmean,AT,AT/ET and gestational weeks.AT,AT/ET,Vmax,Vmean comparison between group a and group b was of statistical significance(P=0.000),while the AT,AT/ET,Vmax,Vmean comparison between group a and group c was not(P>0.05),but the AT.AT/ET,Vmax,Vmean comparison between group b and group c was also of statistical significance(P=0.000).Conclusion:VTI,Vmax,Vmean,PGmax,PGmean,AT,and AT/ET all increased with gestational age growth,and the fetal pulmonary flow parameters were influenced by different SV locations.Therefore,the influence of SV location should be taken into account in the diagnosis of fetal congenital cardiovascular malformations.