Prenatal Management Strategy for Immune-Associated Congenital Heart Block in Fetuses

Abstract

Fetal congenital heart block (CHB) is the most commonly observed type of fetal bradycardia, and is potentially life-threatening. More than 50% of cases of bradycardia are associated with maternal autoimmunity, and these are collectively termed immune-associated bradycardia. Several methods have been used to achieve reliable prenatal diagnoses of CHB. Emerging data and opinions on pathogenesis, prenatal diagnosis, fetal intervention, and the prognosis of fetal immune-associated CHB provide clues for generating a practical protocol for clinical management. The prognosis of fetal immune-associated bradycardia is based on the severity of heart blocks. Morbidity and mortality can occur in severe cases, thus hieratical management is essential in such cases. In this review, we mainly focus on optimal strategies pertaining to autoimmune antibodies related to CHB, although the approaches for managing autoimmune-mediated CHB are still controversial, particularly with regard to whether fetuses benefit from transplacental medication administration. To date there is still no accessible clinical strategy for autoimmune-mediated CHB. This review first discusses integrated prenatal management strategies for the condition. It then provides some advice for clinicians involved in management of fetal cardiovascular disorder.

Keywords: fetal immune-associated heart block; outcome; prenatal diagnosis; prenatal management; transplacental drug administration.

Figure 1

Prenatal management for immune-associated bradycardia. Note 1: Immune-associated: this figure refers specifically Anti-Ro/SSA (+) or Anti-La/SSB (+). Note 2: PR interval>150 ms. Note 3: Dexamethasone: 4–8 mg/qd, monitor the decrease of amniotic fluid, the length of fetal femur and the delay of fetal biparietal diameter by 2 weeks etc. Reduce and stop drugs in time. Note 4: Hydroxychloroquine: 200 mg po bid, continuous use during pregnancy. Outcome 1: I°AVB and sinus bradycardia do not require pacing therapy in childhood, and long-term follow-up is performed. Note 5: Intravenous immunoglobulin usage: (1) 1 g/Kg ivgtt, twice a week for 2 weeks, and then used according to the situation; (2) 1 g/kg ivgtt at 16–30 weeks of gestation, and 1 g/kg ivgtt once a month after 2 weeks of continuous use. Outcome 1: The sinus bradycardia and part of I°AVB patients do not need treatment during fetal stage, and continuous observation is required. Outcome 2: II°AVB: most patients do not need pacing therapy after birth. According to their growth and development and clinical symptoms, protective or therapeutic pacing therapy can be considered. Outcome 3: For II°AVB or III°AVB with symptomatic bradycardia, cardiac dysfunction or low cardiac output; Congenital III°AVB with wide QRS, ventricular ectopic or cardiac dysfunction; Congenital III°AVB with ventricular rate lower than 55 times/min; Asymptomatic congenital patients with III°AVB and not wide QRS and normal cardiac function, a protective pacemaker may be considered for treatment. Outcome 4: Death in utero; Or a referral to a general hospital that can provide rapid life support and intrapartum pacing therapy. AVB, atrioventricular block; FHR, fatal heart rate; AV interval, the time interval between the beginning of atrial systole and the beginning of ventricular systolic ejection; EFE, endocardial fibroelastosis; DCM, dilated cardiomyopathy.