Background: This presentation describes the management of a patient at 27 weeks, admitted for fetal SVT and ascites. 

Case: Fetal tachycardia was evident at 17 weeks gestation, however the patient did not follow-up with medical recommendations. Fetal SVT was subsequently confirmed by ultrasound, with a FHR of 235-240 along with ascites.  She was admitted  to our OB High Risk Unit under the care of our Maternal Fetal Medicine physicians, with a plan for continuous fetal monitoring and digoxin therapy.

The patient had an arrhythmia herself upon admission, with no prior history.  Her EKG reflected a sinus arrhythmia.  The FHR was in the 240s 100% of the time, until antiiarrhythmic administration to the mother.  The patient was informed that there was a 20% risk of therapy failure, and a 25-30% risk of fetal mortality.

Daily EKGs, cardiology consult, pediatric cardiology consult and neonatology consult were ordered.  1:1 AV Block was confirmed by fetal echocardiogram.  Propranolol was added the digoxin plan.  In spite of this, the fetus only converted to sinus rhythm for 4-6 beats, 1-2 times per minute.  The fetus also developed pericardial effusions.  Flecainide was added, but consent was also obtained  for the possible administration of adenosine via a cordocentesis procedure. 

The addition of flecainide converted the fetus to normal sinus rhythm, and the ascites resolved.  The patient was discharged with a prescription for flecainide, and biweekly ultrasounds.

The only readmission for the patient was at 39 weeks, when she was scheduled for an induction of labor.  The patient was still taking flecainide, and continued this through labor.  The FHR was 110-120 on admission, and the patient's vital signs were normal.  The patient had a repeat Neonatology consult prior to delivery, so she was informed that the newborn would be going to the NICU following birth, for cardiac monitoring.

She had an uneventful birth with 9/9 apgars.  The newborn had a normal heart rate, but the EKG result was questionable AV block.  The newborn had persistent normal sinus rhythm subsequently, and was discharged on no medications, but did have follow-up appointments with a pediatric Cardiologist.

Conclusion: This was a successful multidisciplinary effort, that resulted in the delay of delivery until term for an infant who had refractory supraventricular tachycardia, hydrops, heart block and pericardial effusions.  The morbidity and mortality risks are high with such a combination, so the patient benefitted from a team with a wealth of experience.

Keywords:

  fetal supraventricular tachycardia, ascites, hydrops