Abstract
Aim: Analysis of the spectrum of prenatally diagnosed supraventricular fetal tachydysrhythmias and evaluation of the effect of treatment during the intrauterine period. Method: Ultrasound assessment of the fetal heart for early diagnosis of paroxysmal supraventricular tachycardia and for assessment of signs of circulatory failure by its severity (failure and fetal hydrops).
In indicated cases, drug therapy using the protocol developed by the Fetal Cardiology Working Group (FCWG) set up by the Association of European Pediatric Cardiology (AEPC) followed by evaluation of the therapeutic effect. Results: Among 60 fetuses with supraventricular paroxysmal tachycardia (SVT), sustained SVT was present in 40 (60%) while intermittent SVT was seen in 20 (40%).
Reentry AV tachycardia (mean rate - 246/min) was involved in 41 (68%) cases whereas atrial flutter (mean atrial rate - 429/min) was demonstrated in 10 (17%); atrial ectopic activity (mean rate - 191/min) was observed in 9 (15%) fetuses. Circulatory failure occurred in a total of 34 (57%) fetuses, with hydrops documented in 20 of these (33%), failure (including hydrops) was not present in only 26 (43%).
Intrauterine management (with digoxin as the drug of first choice) was provided in 38 (63%) fetuses, while SVT management was not indicated or was rejected in the remaining 22 (37%) fetuses on grounds on natural course of the arrhythmia (heart rates not threatening the fetus blood circulation). Among the 38 fetuses receiving treatment, tachycardia conversion to sinus rhythm was successful in 26; in this group, 19 (73%) fetuses showed signs of circulatory failure.
In the remaining 12 (32%) fetuses in whom attempts at tachycardia reversal failed, signs of circulatory failure were demonstrated in 11 (92%) cases. Therapeutic success was dependent on the severity of fetal circulatory failure.
In the group of 18 treated fetuses with hydrops, tachycardia conversion was successful in only 9 (50%) fetuses; in the group of 11 treated fetuses with ultrasound-demonstrated signs of failure, conversion was obtained in 8 (73%) cases whereas, in the group of 9 fetuses without failure, conversion was achieved in all (100%) cases. Pulse rate (PR) was consistent with the severity of heart failure: in fetuses with hydrops, with and without failure, mean heart rates (HR) were 253/min, 230/min, and 222/min, respectively.
Of the 38 treated fetuses, a total of 31 (82%) healthy newborns were delivered. Five (13%) fetuses with advanced circulatory failure died in the intrauterine period, one child died after delivery, while one pregnancy was terminated for psychiatric reasons.
In the group of 22 untreated fetuses, there were 19 (86%) healthy newborns, intrauterine death occurred in two cases (with management rejected in one case), whilst pregnancy was terminated in one case because of the presence of a serious congenital heart defect. Conclusion: Prenatal echocardiography is a most reliable method allowing timely detection of serious tachydysrhythmias posing immediate threat to the life of the fetus during the intrauterine period.
Timely intrauterine management allows to save the lives of a high proportion of children not born yet; however, the effect of treatment decreased with advancing fetoplacental circulation failure. Digoxin is a suitable antiarrhythmic of first choice in the intrauterine management of fetal paroxysmal supraventricular tachycardia.
Timely detection and management of fetal paroxysmal supraventricular tachycardia makes it possible to modulate heart failure successfully in most cases, thereby improving the prognosis of the affected fetuses.