(Backgroud) Early detection of atrio-ventricular (AV) block caused by maternal anti-SSA antibody is important to start early treatment to the affected fetuses. To examine suitability to screen prolonged mechanical AV interval by fetal echocardiography, 3 different Doppler measurement method, 1) simultaneous recording of the superior vena cava and the ascending aorta (SVC-aAo), 2) simultaneous recording of mitral inflow and aortic outflow (mitral A-wave/aortic outflow), and 3) simple mitral inflow (mitral A-wave/mitral valve closure) are compeared.
(Methods) All 34 fetuses with normal cardiac structure with normal rhythm and without maternal anti-SSA antibody who underwent fetal echocardiography in our institution from March to November 2008 were included.
(Results) The mean value and the standard deviation of the measurement value in all cases: SVC-aAo : 111.5±13.96 msec, mitral A-wave/aortic outflow : 123±8.66 msec, mitral A-wave/mitral valve closure : 88±5.92 msec. There was no correlation to the gestational age. Measurement using mitral A-wave/mitral valve closure is the most easily obtained measurement and has smallest standard deviation.
(Conclusion) Although all three measurements of mechanical AV interval can be reliably obtained by fetal Doppler echocardiography, mitral A-wave/mitral valve closure seems to be the most suitable one to screen first degree AVB.