Evaluation of PR interval in anti-Ro/La positive mothers: fetal and neonatal outcame

Background: Isolated congenital heart block (CHB) occurs in 2–3% of fetuses whose mothers have anti-Ro/La antibodies. Mechanical PR interval (mPR) can now be measured in utero allowing for the detection of first degree heart block. Identification of prolonged PR interval may be the first sign of maternal connective disease and may rapidly progress to CHB. We report our experience in the management of pregnant patients with Ro/La antibodies.

Methods: Retrospective audit from 2000 to September 2007 of all Ro/La positive mothers were examined. Each patient was monitored by serial echocardiography weekly from 16 up to 34 and then every two weeks up to the end of pregnancy. mPR was measured by pulsed Doppler, from the onset of the mitral valve A wave to the onset of aortic ejection wave.

Results: We monitored 95 pts with autoimmune disease of which 32 pts had Ro/La antibodies. Four patients were referred to our unit for CHB. In these pts we started immediately dexamethasone which had no effect on the block. In two fetuses, one whose mother had a previous child affected by CHB, was observed first degree heart block at 24 weeks and in the other at 35 wks, treatment with dexamethasone made regression to normal PR in both pts. The four children with CHB had a pacemaker inserted: two had a permanent pacemaker inserted at few days of age, and two, due to prematurity, had an external pacemaker up to three months followed by permanent pacemaker.

Conclusions:

Mesaurement of mPR interval is valuable in the assessment high risk pregnancies and can provide an important tool to decide in whom to start treatment. Serial assessment is justified by the possibility to prevent CHB which is irreversible and affected children need permanent pacing.

Literatur: Clowse M., 2006 Yasmeen S, 2001 Witter FR, 2000 Gordon PA, 2007 Ross G, 2003

Fetal PR interval; Ro/La antibodies; congenital heart block; dexamethasone therapy