Congenital and childhood atrioventricular blocks: pathophysiology and contemporary management

Abstract

Atrioventricular block is classified as congenital if diagnosed in utero, at birth, or within the first month of life. The pathophysiological process is believed to be due to immune-mediated injury of the conduction system, which occurs as a result of transplacental passage of maternal anti-SSA/Ro-SSB/La antibodies. Childhood atrioventricular block is therefore diagnosed between the first month and the 18th year of life. Genetic variants in multiple genes have been described to date in the pathogenesis of inherited progressive cardiac conduction disorders. Indications and techniques of cardiac pacing have also evolved to allow safe permanent cardiac pacing in almost all patients, including those with structural heart abnormalities.Conclusion: Early diagnosis and appropriate management are critical in many cases in order to prevent sudden death, and this review critically assesses our current understanding of the pathogenetic mechanisms, clinical course, and optimal management of congenital and childhood AV block. What is Known: • Prevalence of congenital heart block of 1 per 15,000 to 20,000 live births. AV block is defined as congenital if diagnosed in utero, at birth, or within the first month of life, whereas childhood AV block is diagnosed between the first month and the 18th year of life. As a result of several different etiologies, congenital and childhood atrioventricular block may occur in an entirely structurally normal heart or in association with concomitant congenital heart disease. Cardiac pacing is indicated in symptomatic patients and has several prophylactic indications in asymptomatic patients to prevent sudden death. • Autoimmune, congenital AV block is associated with a high neonatal mortality rate and development of dilated cardiomyopathy in 5 to 30 % cases. What is New: • Several genes including SCN5A have been implicated in autosomal dominant forms of familial progressive cardiac conduction disorders. • Leadless pacemaker technology and gene therapy for biological pacing are promising research fields. In utero percutaneous pacing appears to be at high risk and needs further development before it can be adopted into routine clinical practice. Cardiac resynchronization therapy is of proven value in case of pacing-induced cardiomyopathy.

Undifferentiated connective tissue diseases and adverse pregnancy outcomes. An undervalued association?

“…For this reason, among pregnant UCTD subjects with anti‐Ro/SSA antibodies, anti‐La/SSB antibodies with or without autoimmune hypothyroidism, antenatal hydroxychloroquine prophylaxis should be strongly considered . In CHB cases, steroids and other treatments should be administered according to current standards . Prophylactic anticoagulation with low molecular weight heparin and/or low‐dose aspirin throughout pregnancy and 6‐week postpartum is the accepted standard treatment to prevent fetal losses and complications of pregnancy among “high‐risk” carriers of aPL (positivity in all the three aPL assays, the presence of a past thrombotic event) .…”

Modern Technology for Prevention of Sudden Cardiac Death – a Clinical Update on Device Therapy in Children with Congenital Heart Diseases

“…Cardiac conduction disorders can occur in structurally normal hearts, in various types of CHD, or following the surgical correction of complex structural heart diseases. 24 Atrioventricular blocks in children can result in Adam-Stokes crisis or even SCD. It has been demonstrated that the implantation of cardiac pacemakers in atrioventricular block following surgical intervention in CHD was associated with a significant decrease in the risk of SCD and episodes of Adam-Stokes attacks.…”

Thoracoscopic Implantation of an Epicardial Pacemaker in a Child With Complete Atrioventricular Block

“…Наиболее часто ПАВБ проявляется синкопальными или предсинкопальными состояниями, реже -снижением толерантности к физическим нагрузкам, задержкой физического и психомоторного развития. Нередко ПАВБ протекает бессимптомно и становится случайной находкой на электрокардиограмме (ЭКГ) [9,10].…”

“…Проведение постоянной электрокардиостимуляции (ЭКС) является общепризнанным методом лечения больных ПАВБ независимо от этиологии заболевания. Было доказано, что имплантация ЭКС повышает качество и продолжительность жизни не только у пациентов с наличием клинических проявлений, но также и у бессимптомных больных [4, 9,11]. Согласно современным представлениям, у детей весом менее 15 кг предпочтительно эпикардиальное расположение электродов, что позволяет сохранить возможность венозного доступа для дальнейших имплантаций эндокардиальных систем стимуляции [9,[12][13][14][15].…”

“…Было доказано, что имплантация ЭКС повышает качество и продолжительность жизни не только у пациентов с наличием клинических проявлений, но также и у бессимптомных больных [4, 9,11]. Согласно современным представлениям, у детей весом менее 15 кг предпочтительно эпикардиальное расположение электродов, что позволяет сохранить возможность венозного доступа для дальнейших имплантаций эндокардиальных систем стимуляции [9,[12][13][14][15]. По данным разных исследователей частота осложнений при имплантации ЭКС у детей с эпикардиальным расположением электродов достигает 14% [16,17].…”