Perfusion of human foetal heart with anti-Ro/SSA antibodies induces transient heart block. Anti-Ro/SSA antibodies may cross-react with T- and L-type calcium channels, and anti-p200 antibodies may cause calcium to accumulate in rat heart cells. These actions may explain a direct electrophysiological effect of these antibodies. Congenital complete heart block is the more severe manifestation of so-called "Neonatal Lupus". In clinical practice, it is important to distinguish in utero complete versus incomplete atrioventricular (AV) block, as complete AV block to date is irreversible, while incomplete AV block has been shown to be potentially reversible after fluorinated steroid therapy. Another issue is the definition of congenital AV block, as cardiologists have considered congenital blocks detected months or years after birth. We propose as congenital blocks detected in utero or within the neonatal period (0-27 days after birth). The possible detection of first degree AV block in utero, with different techniques, might be a promising tool to assess the effects of these antibodies. Other arrhythmias have been described in NL or have been linked to anti-Ro/SSA antibodies: first degree AV block, in utero and after birth, second degree (i.e. incomplete block), sinus bradycardia and QT prolongation, both in infants and in adults, ventricular arrhythmias (in adults). Overall, these arrhythmias have not a clinical relevance, but are important for research purposes.
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