Bradyarrhythmias
We identified 23/40 cases of bradyarrhythmia, comprising 16/23 cases of CHB, 4/23 cases of AV block, and 3/23 cases of sinus bradycardia. Of these, 17/23 fetuses exhibited normal cardiac and extracardiac anatomy, while 6/23 had associated anatomical abnormalities (5 cardiac and 1 cystic hygroma). The cardiac anomalies included pulmonary stenosis with cardiomegaly (n=1/5), right ventricle hypoplasia, atrioventricular septal defect (n=2/5), and heterotaxy (n=1/5). None had chromosomal abnormalities or congenital infections. Figure 3 illustrates few cases diagnosed employing M-mode and pulsed wave Doppler.
Among the CHB cases, 9/16 were associated with Maternal Systemic Lupus Erythematosus (SLE), with 1/9 case also linked to secondary antiphospholipid syndrome (APS) and maternal hypothyroidism, and another 1/9 associated with Sjögren’s syndrome. There were 2/16 cases of Type 2 diabetes mellitus (DM) noted in the mother. We offered antibody testing (anti-Ro, anti-La) to all mothers with fetuses exhibiting bradyarrhythmia. Anti-Ro alone tested positive in 5/16 cases, both antibodies were positive in 1/16 patient, 10/16 mothers had negative antibodies and remained negative throughout pregnancy.
Among the cases of CHB associated with SLE and positive maternal antibodies (n=9/16), a combined treatment of hydroxychloroquine (HCQ) and dexamethasone was administered until delivery. Weekly follow-ups were done to monitor fetal AV intervals, cardiac function, fetal development, and maternal side effects of dexamethasone and HCQ. There were 2/16 intrauterine fetal demises: one at 36 weeks among the SLE cases and another at 30 weeks with fetal heterotaxy. Additionally, 3/16 neonatal deaths occurred among the two fetuses with atrioventricular septal defects and one with right ventricle hypoplasia on postnatal days 10, 1 month, and 5th day, respectively. All these cases had exhibited persistent bradycardia with irregular rhythm. Termination of pregnancy (TOP) was chosen by 4/16 patients at an earlier gestation. There were 7/16 liveborn infants who have not been prescribed any medication and are currently under cardiology with expectant management.
Among the AV block cases, there were 3 second degree block and one first degree block case. Among the second-degree block cases, 1/4 case was complicated with fetal growth restriction (FGR) with absent end-diastolic flow (AEDF) and had later on progressed to CHB. An emergency lower segment caesarean section (LSCS) was performed at 32 weeks of gestation. The neonate-maintained heart rate between 50-55 beats per minute (bpm) and was started on beta adrenergic, postnatally. There were 2/3 cases of seronegative second-degree AV block. Among them, one case was associated with FGR and severe oligohydramnios and was delivered vaginally at 34 weeks due to preterm labor. The neonate, maintained a heart rate between 60-70 bpm and was on expectant management without the need for medical or surgical intervention. The other case had atrial septal defect (ASD) and total anomalous pulmonary venous connection (TAPVC) with hydrops fetalis, and the patient opted for termination at 21 weeks. The remaining 1/4 case had a first-degree AV block with SLE and positive anti-Ro antibody and hydrops fetalis. However, antenatal steroid therapy for six weeks resulted in the resolution of hydrops, and the fetal heart rhythm reverted to normal. Postnatally, the neonate-maintained sinus rhythm.
Among the 3/23 cases of sinus bradycardia, there were no associated cardiac abnormalities or positive maternal antibodies and 2/3 cases reverted to normal sinus rhythm. Postnatal ECG and echo for these cases were normal. In 1/3 fetus, the prenatal diagnosis of sinus bradycardia changed to CHB on postnatal evaluation with HR <40bpm with minimal response to beta sympathomimetics and required pacing which was done 24 hours after birth. However, severe pericardial effusion was noted on PND 3 and the baby expired.