Prospective Observational Cohort Study of Fetal Atrial Flutter & Supraventricular Tachycardia

Participation Requirements

• Sex:

  FEMALE

• Eligible Ages:

  16 to 50

Participation Criteria

Inclusion Criteria:

1. Mother has provided written informed consent to participate
2. Fetal AF or SVT with or without hydrops
3. Tachyarrhythmia that is significant enough to justify immediate transplacental pharmacological treatment:

* Tachycardia ≥ 180 bpm during at least 10% of observation time of 30 minutes or longer
* Tachycardia ≥ 170 bpm during +100% of time (≤ 30 0/7 weeks of gestation)
* Tachycardia ≥ 280 bpm (irrespective of SVA duration)
* SVT with fetal hydrops (irrespective of duration)
4. Gestational age \<36 0/7 weeks at time of enrollment
5. Singleton Pregnancy
6. Healthy mother with ± normal pre-treatment cardiovascular findings:

* ECG within normal range (sinus rhythm; QTc ≤ 0.47; PR ≤ 0.2 sec; QRS: ≤ 0.12 sec; insignificant anomalies; isolated premature beats; isolated complete right bundle
* Maternal resting heart rate ≥ 50 bpm
* Maternal systolic BP ≥ 85 mmHg

Exclusion Criteria:

1. Primary delivery for postnatal cardioversion
2. Antiarrhythmic fetal treatment for more than 2 days at time of enrollment
3. Any maternal-fetal conditions associated with high odds of premature delivery and/or death
4. History of significant maternal heart condition (open heart surgery; sick sinus syndrome; long QT, Brugada syndrome; ventricular tachycardia; WPW syndrome; high-degree heart block; cardiomyopathy)