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Oral Concurrent Session 8 - Fetus and Fetal Intervention

Oral Concurrent Sessions

Oral Concurrent Session 8 - Fetus and Fetal Intervention

(90) Chronotropic rescue prior to cord clamping in fetal complete AV Block and severe bradycardia

Saturday, February 1, 2025

9:00 AM – 9:15 AM

Location: Aurora Ballroom B, Lobby Level

Submitting Author and Presenting Author(s)

Samantha Holmes, MD

Pediatric Cardiology Advanced Imaging Fellow
University of Colorado, School of Medicine
Aurora, Colorado, United States

Coauthor(s)

EB

Emily Bucholz, MD, MPH, PhD

Assistant Professor, Pediatrics-Cardiology
University of Colorado, School of Medicine
Aurora, Colorado, United States
CL

Camila Londono-Obregon, MD

Assistant Professor, Pediatrics-Cardiology
University of Colorado, School of Medicine
Aurora, Colorado, United States
JG

Jason Gien, MD

Professor, Neonatology
University of Colorado, School of Medicine
Aurora, Colorado, United States
NB

Nicholas Behrendt, MD

Associate Professor-OBGYN Maternal Fetal Medicine
University of Colorado, School of Medicine
Aurora, Colorado, United States
Michael V. Zaretsky, MD (he/him/his)

Professor, Maternal Fetal Medicine
University of Colorado, School of Medicine
Aurora, Colorado, United States
Henry L. Galan, MD

Professor, Maternal Fetal Medicine
University of Colorado, School of Medicine, Children's Hospital of Colorado
Aurora, Colorado, United States
Bettina Cuneo, MD

Professor (Clinical Scholar Track), Surgery
University of Arizona
Tucson, Arizona, United States

Objective: Fetal complete AV block (CAVB) occurs in 2% of pregnancies with Anti-Ro antibodies or inherited arrhythmias. Only about 10% have a ventricular (V) rate of < 50 beats per minute (bpm) but case mortality rate is 42%. We hypothesized that survival of fetal CAVB with V ≤52 bpm prior to delivery would improve with chronotropic rescue using epinephrine (epi) or ventricular pacing at or after cesarean delivery and prior to cord clamping.

Study Design: Single center retrospective series of fetal CAVB divided into 2 groups based on V rate at time of delivery. Group 1 consists of V rates > 52bpm receiving standard delivery room (DR) resuscitation at delivery. Group 2 consists of V rates ≤52 bpm receiving either standard resuscitation or chronotropic rescue prior to cord clamping and delivery. Maternal, fetal and neonatal medical records and echocardiograms were reviewed for atrial/ventricular rates, cardiac function and survival or demise. We calculated median for both groups.

Results: From 2013-2024, 19 fetal CAVB subjects (10 in group 1, 9 in group 2), 18 with maternal Anti-Ro antibodies and one with an inherited arrhythmia, were delivered (Figure 1). Group two delivered and presented at an earlier gestational age (GA), had lower V rates at presentation and received more in utero terbutaline than in group one. All in group one survived after standard DR resuscitation. In group 2a, three died after standard DR resuscitation and pacing within 30 minutes of birth because of pulseless electrical activity: their V rates decreased 50 (39-51) bpm and cardiac function became severely depressed after cord clamping. In group 2b, 6/6 survived after receiving high dose epinephrine (n=5) or EXIT to pacing prior to cord clamping (n=1); their V rate increased 63 (57-70) bpm and cardiac function was normal after cord clamping (Figure 2). All with chronotropic rescue were successfully paced at < 6 hours.

Conclusion: Chronotropic rescue prior to cord clamping may improve survival by increasing V rate and maintaining cardiac function in CAVB with ventricular rates ≤52 bpm and a history of in utero terbutaline treatment.