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The incidence of retrograde conduction in children
Insights
Retrograde conduction is common in children with pacemakers, potentially causing tachycardia. This finding is crucial for implanting physiological pacemakers in pediatric patients.
Area of Science:
- Pediatric Cardiology
- Electrophysiology
Background:
- Physiological pacemakers are increasingly used in children.
- Retrograde conduction (ventriculo-atrial) is clinically significant in this population.
- Pacemakers sensing retrograde P waves can initiate reciprocating tachycardia.
Purpose of the Study:
- To evaluate the incidence and characteristics of retrograde conduction in pediatric patients.
- To assess the impact of prior cardiac surgery on retrograde conduction.
- To inform the implantation of physiological pacemakers.
Main Methods:
- Retrospective review of 127 pediatric patients.
- Antegrade and retrograde electrophysiologic studies.
- Analysis of ventriculo-atrial conduction and conduction times.
Main Results:
- Sixty percent of patients exhibited ventriculo-atrial conduction.
- Incidence was lower (33%) in post-tetralogy of Fallot repair patients.
- No retrograde conduction was observed in patients with third-degree A-V block.
- Mean retrograde conduction times varied significantly with pacing rate.
Conclusions:
- Retrograde conduction is frequent in pediatric patients undergoing electrophysiologic studies.
- Variability in conduction times and incidence in specific subgroups (e.g., post-ToF repair) are important considerations.
- These findings necessitate careful consideration during physiological pacemaker implantation in children.
Abstract:
With the increasing use of "physiological" pacemakers in the pediatric age group, retrograde conduction in children has become of clinical importance. Pacemakers which sense atrial depolarization may sense "retrograde" P waves. The pacemaker may then act as the antegrade limb of a reciprocating tachycardia circuit, while the patient's own conduction system acts as the retrograde limb. We reviewed the data of 127 patients who underwent antegrade and retrograde electrophysiologic study at Texas Children's Hospital, with regard to retrograde conduction. Sixty percent of the patients had ventriculo-atrial conduction through the A-V node; the incidence of retrograde conduction in patients after surgical correction of a tetralogy of Fallot was significantly lower (33%). None of the patients with third-degree A-V block had retrograde conduction. The mean retrograde conduction time was 162 ms (range 70-335 ms) at the slowest pacing rate and 257 ms (range 80-475 ms) at the fastest pacing rate. This high incidence of retrograde conduction and the variability of conduction times must be taken into account when "physiological" pacemakers are to be implanted.