Maternal Sjögren Syndrome and Isolated Complete Fetal AV Block: Prenatal Diagnosis and Therapy

Introduction

Isolated congenital complete AV block (AVB) is a rare condition that occurs in approximately 1 of every 20 000 pregnancies (Ramsey-Goldman R et al. Arthritis Rheum 1986; 29: 1269 – 1273). The mothers of the affected neonates are commonly diagnosed with systemic lupus erythematosus (SLE), Sjögren syndrome (SS), or other rheumatic diseases. Complete fetal AVB, which usually develops during gestational weeks 16 to 24, is characterized by a significant fetal mortality rate (15 – 30 %) and morbidity rate (Friedman DM et al. Circulation 2008; 117: 485 – 493; Buyon JP et al. J Am Col Cardiol 1998; 31: 1658 – 1666; Rein AJJT et al. Circulation 2009; 119: 1867 – 1872). Two-thirds of affected offspring will require permanent pacing (Friedman DM et al. Circulation 2008; 117: 485 – 493; Buyon JP et al. J Am Col Cardiol 1998; 31: 1658 – 1666; Rein AJJT et al. Circulation 2009; 119: 1867 – 1872).

After one child is affected, the risk of complete AVB in subsequent children increases from 18 % to 25 %. Maternal, fetal, and genetic factors may therefore also contribute to the development of this disorder (Buyon JP et al. J Am Col Cardiol 1998; 31: 1658 – 1666; Rein AJJT et al. Circulation 2009; 119: 1867 – 1872).

Fetal heart block is typically detected by ultrasound before 30 weeks of gestation (Buyon JP et al. J Am Col Cardiol 1998; 31: 1658 – 1666).

With the advancements in high-resolution ultrasound equipment, fetal echocardiography has become the method of choice for the diagnosis and analysis of fetal AV block and arrhythmias (Lopes LM et al. Circulation 2008; 118: 1268 – 1275). The performance of a fetal echocardiogram is essential to follow the course of disease and may suggest the presence of associated myocarditis by detecting decreased contractility and secondary changes, such as an increase in cardiac size, pericardial effusions, and tricuspid regurgitation. Serial fetal echocardiography at 16, 18, 22, and 24 weeks of gestation may be reasonable for all women at risk of giving birth to a child with congenital heart block. More frequent echocardiographic examinations may be advisable if abnormalities are detected (Waltuck J et al. Ann Intern Med. 1994; 120: 544 – 551).

Complete heart block has been shown to respond to transplacental glucocorticoid therapy with improved cardiac conduction. Because there may be concurrent myocarditis, treatment in utero may also improve cardiac contractility, leading to the rapid resolution of hydrops (Copel JA, et al. Am J Obstet Gynecol. 1995; 173: 1384 – 90).

Given the identification of an irreversible block within 1 to 2 weeks of normal sinus rhythm and its occurrence before 24 weeks of gestation, it would appear appropriate to perform intensive monitoring between 16 and 24 weeks of gestation. The goal of the described monitoring is to identify a biomarker of reversible injury such as PR interval prolongation > 150 msec, moderate/severe tricuspid regurgitation, and/or atrial echodensity (Friedman DM et al. Circulation 2008; 117: 485 – 493).