Transient Recovery of Complete Atrioventricular Block Due to Maternal Anti-SS-A Antibody Through Antenatal Steroid Administration After 27 Weeks of Gestation

Abstract

Maternal anti-SS-A antibodies may cause complete atrioventricular block or myocardial damage in a fetus. Effective treatment for this has not been established. Although antenatal steroids may be a treatment option for anti-SS-A antibody-related myocarditis or atrioventricular block, a complete atrioventricular block is usually considered irreversible once established. Previous reports have indicated that, in cases where antenatal steroids were effective for atrioventricular block, they were administered earlier in the pregnancy. Here we present a case where maternal steroid administration initiated from 27 weeks, which is beyond the recommended optimal treatment period, was effective in altering a complete atrioventricular block to a grade I atrioventricular block.

Keywords: atrioventricular block; fetal; myocarditis; ss-a antibody; steroid.

Figure 1. Fetal echocardiogram and postnatal electrocardiogram.

(A) M-mode for an atrial and ventricular wall on fetal echocardiogram shows a complete atrioventricular block with 156 bpm of atrial rate and 101 bpm of ventricular rate. Arrows indicate atrial and ventricular contractions. (B) Electrocardiograms (lead II) just after birth. A complete atrioventricular block is displayed. Arrows indicate P wave. The paper speed is 25 mm/sec. (C) Electrocardiograms (lead II) one day after birth. The first-degree atrioventricular block is displayed. Arrows indicate P wave. The paper speed is 25 mm/sec. (D) Electrocardiograms (lead II) four months after birth. The recurrence of a complete atrioventricular block is shown. Arrows indicate P wave. The paper speed is 25 mm/sec.

Figure 2. Pre- and postnatal changes of the status of atrioventricular block and ventricular rates.

In parallel with dexamethasone administration, atrioventricular conduction improved to a second degree and the ventricular rate increased. Just after birth, it transiently changed to a complete atrioventricular block, but from one day of age, it changed to a first-degree atrioventricular block, and the ventricular rate was maintained. Red circles indicate a complete atrioventricular block. Black circles indicate first- or second-degree atrioventricular block. AVB: atrioventricular block.