Remission of congenital complete heart block without anti-Ro/La antibodies: A case report
A single-term, appropriate-for-date, girl baby, with birth weight 2478 g, born out of a non-consanguineous marriage to a 24-year-old primigravida mother, presented at birth with a heart rate of 45/minute. The baby was born by normal vaginal delivery and had APGAR scores of 7 and 8 at one and five minutes. The obstetric history revealed documented fetal bradycardia during labor, but normal heart rate on the ultrasound scans at 18 and 35 weeks of gestation. The mother had no history of gestational diabetes, hypertension, hypothyroidism, any fever with rash, or drug intake during pregnancy, nor did she have any symptoms suggestive of connective tissue disease. There was no history of cardiac disease in the family.\nAt birth, the baby was otherwise healthy with a heart rate of 45/minute, without any symptoms of congestive cardiac failure. Serum electrolytes were normal and echocardiography revealed no structural heart disease. The baby was put on continuous electrocardiographic monitoring. The electrocardiogram (EKG) on day one revealed complete AV dissociation with an atrial rate of 115/minute, ventricular rate of 45/minute, QRS duration of 0.08 seconds (occasionally > 0.08 seconds), corrected QT interval (QTc) of 0.48 seconds, and an left bundle branch block (LBBB) pattern []. EKG on day three revealed no AV dissociation with both atrial and ventricular rates of 93/minute and QRS duration of 0.08 seconds []. Although the EKG reverted to sinus rhythm, the PR interval (0.18 seconds) was prolonged, the QRS duration was at the upper limit of normal, and the EKG showed a right bundle branch block (RBBB) pattern. There was marked ST depression in V1 and marked right axis deviation, indicating normal right ventricle (RV) dominance in the newborn period. The EKG on day four showed a similar picture as on day three with a rate of 107/minute. On day six, however, the bradycardia again worsened. This time the ventricular rate varied between 45 and 60/minute, atrial rate was 150/minute, and QRS duration was 0.08-0.1 seconds. This pattern prevailed over the next seven days. From day 13 onward, there was spontaneous improvement, with disappearance of AV dissociation and atrial–ventricular rates improving to 100/minute. The baby remained asymptomatic during the hospital stay. Cardiac function was regularly monitored using functional echocardiography, and the fractional shortening (FS%) was found to range between 32 and 38% during this period, which was normal for term neonates. Hence, cardiac pacing was withheld. The baby was discharged on day 29 of life. During this period, the heart rate varied between 85 and 120/minute, but no further episodes of AV dissociation were noted. The mother was tested for serum anti-nuclear antibody using the indirect immunofluorescence technique. Subsequently the mother's serum was subjected to antigen-specific enzyme immunoassay, using microtiter plates coated with a combination of antigens SSA/Ro, SSB/La, Sm, U1-RNP, Jo-1, and Scl70. The test results were negative.\nThe baby was followed up weekly for two months, then every fortnight for the next 14 months []. The baby did not develop any such episodes further. Serial echocardiography during this one-year follow-up revealed no evidence of any cardiac dysfunction. EKGs were done in both the parents and were found to be normal.