Cardiac dysfunction commonly occurs in congenital heart block associated with maternal anti-SSA antibodies, especially after pacemaker implantation. We report the case of a 4-year-old girl with antibody-associated congenital heart block and a large secundum atrial septal defect who presented with significant cardiac dysfunction 4 years after pacemaker implantation. Histological findings were useful for determining the course of treatment and perioperative risk of intracardiac repair.

Congenital heart block is a rare and lethal condition in paediatric population associated with maternal connective tissue disorders and rarely with structural cardiac disease like atrioventricular canal defects with or without left isomerism and congenitally corrected transposition of great arteries. Pacing in neonate if indicated is generally accomplished by epicardial pacing systems. However, in cases of significant bradycardia and haemodynamic instability, temporary pacemaker implantation via transvenous approach remains as a suitable option. Despite the advances in percutaneous catheter interventions, use of transvenous pacing in newborn is extremely challenging due to inadvertent risk of vessel injury, thrombus formation and mortality, and most of the time technical inability to place the lead within the right ventricular cavity. We report a case of congenital complete atrioventricular block in a premature male with birth weight of 1.51 kg who was managed with temporary pacemaker implantation through umbilical vein.

We report a baby girl with an antenatal diagnosis of biventricular non-compaction and complete heart block detected at 22 weeks’ gestation. Postnatal echocardiography confirmed severe biventricular non-compaction hypertrophic cardiomyopathy, multiple muscular ventricular septal defects, and mild–moderate pulmonary valve stenosis. Skeletal muscle biopsy confirmed complex 1 mitochondrial respiratory chain deficiency. An epicardial VVI pacemaker was implanted on day 3 of life and revised at 7 years of age. She remains stable at 8 years of age following pacing and medical treatment with carvedilol, aspirin, co-enzyme Q10, and carnitine. This represents the first report of biventricular non-compaction hypertrophic phenotype in association with congenital complete heart block and complex 1 mitochondrial respiratory chain deficiency in a child.

A child of a mother with maternal anti-Ro and anti-La antibodies presented antenatally with abnormal myocardial function, and was found to have a first degree heart block at birth. The extent of the abnormality in the conduction system progressed, with appearance of left bundle branch block in addition to further prolongation of PR interval. A pacemaker was implanted prophylactically, but patient has remained well, with no further deterioration in her atrioventricular conduction.

Second degree atrioventricular block is uncommon in children. In order to evaluate its outcome, and to find early prognostic factors, we reviewed the history and evolution of 21 children with this arrhythmia discovered on their surface electrocardiogram. Twenty-four-hour monitoring displayed variations in the conduction patterns in almost all children, from long PR interval to complete heart block alternating in the same patient. At follow-up (nine months to 19 years), 13 children (62%) had received implantation of a pacemaker because of progression either to complete atrioventricular block or to severe ventricular bradycardia. Atrioventricular conduction improved on exercise in 11 children, but this did not predict a favorable outcome since four of them required pacing. In contrast, deterioration during sinus acceleration in four patients predicted further aggravation. A supra-Hisian location of the block did not protect against the occurrence of syncope in the two patients who underwent His recordings. Finally, the outcome was not linked to age at diagnosis. Second degree atrioventricular block, therefore, should be considered a serious disease because of its trend to worsen towards complete block and/or severe complications. Close follow-up, including repeated 24-hour monitoring, is the most effective way to unmask such a progression and to avoid its clinical consequences.