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Congenital complete atrioventricular block: clinical and electrophysiologic predictors of need for pacemaker
Insights
Children with congenital complete atrioventricular (A-V) block and a resting heart rate of 50 beats/min or less are at high risk for fatal Adams-Stokes attacks. Pacemaker therapy effectively prevents these syncopal episodes.
Area of Science:
- Pediatric Cardiology
- Electrophysiology
- Congenital Heart Disease
Background:
- Congenital complete atrioventricular (A-V) block poses a risk of potentially fatal Adams-Stokes attacks.
- Identifying children at high risk for these syncopal events is crucial for timely intervention.
Purpose of the Study:
- To evaluate methods for predicting Adams-Stokes syncope risk in children with congenital complete A-V block.
- To assess the efficacy of pacemaker therapy for symptom relief in these patients.
Main Methods:
- Follow-up of 24 children with congenital complete A-V block for 1-19 years.
- Comparison of resting heart rate, ECG, intracardiac electrophysiology, and exercise testing in children with and without syncope.
- Analysis of pacemaker implantation outcomes.
Main Results:
- A persistent resting heart rate ≤50 beats/min significantly correlated with syncope incidence (p<0.01).
- Intracardiac electrophysiology and treadmill exercise testing showed limited predictive value for syncope.
- Exercise-induced ventricular ectopic beats may predict risk in older individuals.
- Ventricular pacemakers were implanted in 10 children, rendering them asymptomatic during 1-10 year follow-up.
Conclusions:
- Resting bradycardia is a key indicator for identifying children with congenital complete A-V block at risk of Adams-Stokes syncope.
- Pacemaker therapy is a safe and effective treatment for relieving symptoms in young patients with congenital complete A-V block.
Abstract:
Because of initial Adams-Stokes attack in the patient with congenital complete atrioventricular (A-V) block may sometimes prove fatal, there is a need to be able to identify the patient at great risk of having such attacks. Twenty-four children with congenital complete A-V block were followed up for 1 to 19 years to determine the efficacy of current methods of predicting risk for Adams-Stokes syncope and the usefulness of pacemaker therapy in relieving symptoms. The heart rate at rest, configuration of surface electrocardiographic complexes, data obtained during intracardiac electrophysiologic study and response to graded treadmill exercise testing were compared in children with and without syncope. One or more Adams-Stokes episodes were experienced by eight children, one of whom died. Only a persistent heart rate at rest of 50 beats/min or less demonstrated any significant (probability [p] less than 0.01) correlation with the incidence of syncope. Intracardiac electrophysiologic study was of little benefit because of site of block did not correlate with syncope. Although the increase in heart rate during treadmill exercise testing showed no correlation with prevalence of syncope or location of block, exercise-induced ventricular ectopic beats may have predictive value in older children and young adults. Ventricular pacemakers were implanted in 10 children. Each child was asymptomatic over a 1 to 10 year follow-up period. Because extreme bradycardia may contribute to the prevalence of Adams- Stokes attacks in children with congenital complete A-V block, careful evaluation of heart rate at rest may be an effective means of differentiating patients at risk of syncope. Pacemaker therapy is a feasible and effective method of treatment in young children and relieves symptoms