Reliable diagnosis of congenital heart defects and arrhythmias in utero has been possible since the introduction of fetal echocardiography. The nation-wide prenatal ultrasound screening program in the Czech Republic enabled detection of cardiac abnormities in 1/3 of patients born with any congenital heart disease and up to 83 % of those with critical forms. Prenatal frequency of individual heart anomalies significantly differed from the postnatal frequency. Fetal isolated complete atrioventricular block and supraventricular tachycardia may lead to heart failure and are important causes of fetal mortality. The regression of heart failure was achieved by a conversion to the sinus rhythm in the supraventricular tachycardia and by increase of ventricular rate in the complete atrioventricular block., V. Tomek ... [et al.]., and Obsahuje seznam literatury