الفهرس 
Fetal EchocardiographyOnly 14 pages are availabe for public view
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Abstract
Autoimmune associated complete heart block is irreversible. However, several cases reports have suggested that less severe forms of heart block might be reversible with maternal steroid therapy. To identify fetuses with prolonged AV time intervals, normal values first have to be obtained.
Aim: The aim of the present study was to establish an Egyptian normal reference values for human fetal mechanical PR interval using M-mode, PWD, and TDI as well as to compare ease of recording and reliability of ultrasonographic approaches used to measure fetal mechanical PR interval and detect the different factors affecting on the normal values.
Design: Prospective observational study.
Methods: from (August 2008 to August 2009) sixty normal pregnant Egyptian ladies with uncomplicated pregnancies were enrolled in the study with mean age of (27.8±5.3). Those ladies were between 14-26 weeks gestation. All of them had measured fetal mechanical PR interval by M-mode, PWD and TDI.
Results: Measurement of mechanical PR interval was done using 5 different methods, M-mode (Ao valve and post. wall of LA) method was performed on 6 of the pregnant female (10%), PWD (LV in/out) method was performed on the whole study group (100%), PWD (SVC/Ao) method was performed on 11 pregnant female (18.3%),while the application of TDI (Aa-IV) method was performed on 59 pregnant female (98.3%) and TDI (Aa-Sa) method could be performed in 59 pregnant female(98.3%).We excluded M-mode method and PWD (SVC/Ao) method from further analysis. According to gestational age the study population was divided into three groups: group (I) <18 weeks, group (II) 18-22 weeks and group (III)>22 weeks. The present study revealed that mechanical PR interval values using PWD (LV in/out) in the three groups were 115±7,120±17 and125±8 ms respectively with no statistical difference between those groups. Using TDI (Aa-IV) in all three groups normal values were 87±7, 90±7 and 93±7 ms respectively with statistical significant difference where (P- value 0.002). Mechanical PR interval values using TDI (Aa-Sa) in all three groups were125±7,126±7 and 135±10 ms respectively with statistical significance difference where (P- value 0.002). There was significant positive correlation between gestational age and different methods used to measure fetal mechanical PR interval. There was no significant correlation between fetal heart rate and different methods when measuring fetal mechanical PR interval.
Conclusion: As comparing the different methods we found that using PWD (LV in/out) is the most applicable method in the assessment of the mechanical PR interval and also both methods of TDI. There are differences in normal PR interval values measured by the 5 methods. The present study showed that there was correlation between mechanical PR interval and gestational age, there is increase in mechanical PR interval with increase the gestational age and there is no change of mechanical PR interval with increase of heart rate.