We performed measurement of mechanical atri oventricular conduction time intervals in human fetuses assessed by Doppler echocardiography and provided re ference values. We found that atrioventricular cond uction time interval was prolonged with gestational age and decreased with increasing fetal heart rate. No correlation between gestat ional age and heart rate was found. Using normal limits established by this study, mechanical atrioventricular interval >135 ms in the 20th week and/or >145 ms in the 26th week of gestation could be suspected of having the first-degree AV block. We compared reference values with fetuses of mothers with anti-SSA Ro/SSB La autoantibodies, being in risk of isolated congenital heart block development. One of 21 fetuses of mothers with positive autoantibodies was affected by prolonged atrioventricular interval according to the established limits, with sinus rhythm after the birth., V. Tomek ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy