Ex utero Intrapartum Treatment to Ventricular Pacing: A Novel Delivery Strategy for Complete Atrioventricular Block with Severe Bradycardia

Abstract

Fetuses with anti-SSA-mediated complete atrioventricular block (CAVB) are at high risk for perinatal death if they present at <20 weeks of gestation and develop ventricular rates of <55 beats per minute (bpm), cardiac dysfunction, or hydrops [Izmirly et al.: Circulation 2011;124:1927-1935; Jaeggi et al.: J Am Coll Cardiol 2002;39:130-137; Eliasson et al.: Circulation 2011;124:1919-1926]. After our experience with two such fetuses who died with pulseless electrical activity despite being paced within 30 min of birth, we performed an ex utero intrapartum treatment procedure to ventricular pacing on a 36-week CAVB fetus with cardiac dysfunction, mild hydrops, and a ventricular rate of 46 bpm. While still on placental bypass, temporary epicardial ventricular pacing leads were successfully placed; the infant was delivered and made a successful transition to postnatal life. This approach can improve the 11-fold increase in mortality for the preterm fetus with long-standing CAVB, severe bradycardia, and heart failure.

Prenatal diagnosis and management of congenital complete heart block

“…A temporary epicardial pacing wire was sutured into the RV through a subxyphoid approach. The umbilical cord was then clamped, and the patient was delivered immediately with a permanent pacemaker placed on the third day of life (Cuneo et al, ; Table ). Invasive surgical placement of fetal pacemakers comes with significant surgical and medical risks, but these studies encouragingly demonstrate that fetal pacing is possible.…”

Ex utero intrapartum treatment (EXIT) procedure: Indications and procedural considerations

“…Subramanian et al 12 found that regional anaesthesia has been used; however, this may lead to increased maternal anxiety, and due to the high risk of blood loss, general anaesthetic is more appropriate. Epidural was used in some cases as a form of post-operative pain relief 12,15 . General anaesthetic allows for the use of inhalation agents which cause tocolysis, described by Braden et al 2 as complete uterine relaxation.…”

“…In addition to inhalational agents such as desflurane 2, 12 sevoflurane 1 and isoflurane 15 , nitroglycerine was reported by multiple authors as being used to maintain tocolysis 2,8,11,12 . Tocolytic agents may cause maternal hypotension, which in turn may interfere with the maintenance of placental circulation and fetal oxygenation 8 .…”

“…Phenylephrine 2,8 and dopamine 1 were reported as being used to maintain maternal blood pressure. Cuneo et al 15 suggested that inhalational agents may cause bradycardia in the fetus, a potential complication particularly in fetuses with cardiac anomalies, and administered epinephrine and isoproterenol intravenously to counter this.…”

“…Although tocolysis is necessary for the success of the surgery, it increases the risk of severe bleeding 12 . The harmonic scalpel 12 and staplers 6,15 have been used to reduce this risk of haemorrhage. Subramanian et al 12 cites one case in which the procedure had to be abandoned due to haemorrhage despite the use of harmonic scalpel; however, this was not an outcome in any of the cases reviewed.…”