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Heart block in children. Evaluation of subsidiary ventricular pacemaker recovery times and ECG tape recordings
Insights
In children with complete heart block, prolonged recovery times after pacing may indicate a higher risk of symptoms. Further electrophysiologic studies are needed to confirm these findings in pediatric patients.
Area of Science:
- Pediatric Cardiology
- Electrophysiology
- Cardiac Pacing
Background:
- Complete heart block in children can result from congenital conditions or surgery.
- Assessing ventricular pacemaker function is crucial for managing these patients.
Purpose of the Study:
- To evaluate subsidiary ventricular pacemaker function in children with complete heart block.
- To determine the relationship between recovery times, pacing parameters, and symptoms.
Main Methods:
- Twenty children with complete heart block underwent overdrive ventricular pacing to measure recovery times.
- Long-term ECG monitoring was performed in a subset of patients.
- Electrophysiologic studies included His bundle recordings and His bundle pacing.
Main Results:
- Prolonged recovery times were observed in patients with block above the His bundle, particularly those with symptoms like syncope or dizziness, and those with a wide QRS complex.
- Some asymptomatic patients also exhibited prolonged recovery times.
- One symptomatic patient with congenital heart block and prolonged recovery experienced asymptomatic paroxysmal ventricular tachycardia.
Conclusions:
- Prolonged recovery times and paroxysmal tachycardia may predispose children with complete heart block to symptomatic events.
- Further electrophysiologic investigation is warranted to understand these risk factors in pediatric heart block.
Abstract:
To evaluate subsidiary ventricular pacemaker function in 20 children with congenital or surgically induced complete heart block, we measured recovery times following overdrive ventricular pacing. Long-term ECG tape recordings were performed in eight of these children. Ages ranged from 1 month to 17 years. The resting R-R intervals ranged from 595 to 1,740 msec. The ventricles were paced at various cycle lengths of 400 to 1,000 msec with either transvenous electrode catheters or surgically implanted epicardial electrodes. His bundle recordings showed that the site of block did not allow separation of patients with symptoms from those without symptoms. Prolonged recovery times were present in patients with block above the His bundle recording site who had symptoms of syncope or dizziness, as well as in patients who had a wide QRS. However, some asymptomatic patient with heart block above the His bundle recording site also had long recovery times. None of the asymptomatic patients who had ECG tape recordings had paroxysmal tachycardia in more than 300 hours of recordings. However, one symptomatic patient with congenital heart block and a prolonged recovery time had brief episodes of paroxysmal ventricular tachycardia that produced no symptoms at the time of recording. The results suggest that the coexistence of prolonged recovery times and paroxysmal tachycardia may be predisposing factors to the development of symptoms in patients with complete heart block. We believe that further electrophysiologic investigation of this possibility is warranted in patients with heart block.