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Congenital atrioventricular block: clinical presentation, clinical evaluation, and management

Congenital atrioventricular block (CAVB) is a cardiac conduction disorder that is diagnosed in utero, at birth, or within the first month of life. When it is diagnosed between the first month and the 18th year of life, it is defined as childhood atrioventricular (AV) block. CAVB may occur in association with concomitant congenital heart disease, or be isolated, in a structurally normal heart (e.g. immune-mediated, inherited, or idiopathic CAVB). The majority of isolated CAVB is an immune-mediated AV block, due to transplacental passage of maternal autoantibodies, damaging the fetal cardiac conduction system. Only in a third of infants with immune-mediated CAVB is a well-defined autoimmune disease known in the mother. During fetal life, fetal echocardiography still represents the gold standard for the diagnosis of CAVB. Two major negative prognostic markers are low ventricular rate and the appearance of foetal hydrops. As regards prognosis, a risk for heart failure, syncope, and sudden death is present both during fetal and postnatal life. Dilated cardiomyopathy represents another complication in CAVB history, with different possible aetiologies (right ventricular permanent pacing, reactivation of autoimmune myocarditis). The indications for pacemaker implantation in patients with CAVB are similar to those for acquired heart disease, with some special technical considerations due to young age (epicardial versus endocardial systems, pacing site, etc.). As a future perspective, leadless cardiac stimulation in children with CAVB may represent a definitive solution and an answer to many questions.