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Follow-up evaluation of infant paroxysmal atrial tachycardia: transesophageal study
Insights
Follow-up studies in infants with accessory atrioventricular connections show that paroxysmal atrial tachycardia (PAT) can recur. Conduction properties of the accessory pathway change over time, impacting diagnosis and management of pediatric PAT.
Area of Science:
- Pediatric Cardiology
- Electrophysiology
- Congenital Heart Disease
Background:
- Paroxysmal atrial tachycardia (PAT) in infants often involves accessory atrioventricular (AV) connections.
- Previous transesophageal studies evaluated these connections in early infancy.
- Long-term electrophysiologic changes in these pathways are not well understood.
Purpose of the Study:
- To assess the inducibility and electrophysiologic characteristics of PAT in infants with accessory AV connections.
- To compare findings from initial evaluations with follow-up transesophageal studies.
- To evaluate changes in AV conduction and accessory pathway function over time.
Main Methods:
- Follow-up transesophageal electrophysiologic studies were performed in 35 infants (mean age, 12 months).
- Standard pacing protocols were used to induce PAT, with adjustments using isoproterenol and atropine.
- Antegrade and retrograde accessory pathway conduction properties were analyzed and compared to initial studies.
Main Results:
- PAT was reinitiated in 68% of infants at follow-up.
- AV nodal function remained unchanged between initial and follow-up studies.
- Significant changes in accessory pathway conduction were observed, with reduced pre-excitation and altered ventriculoatrial intervals during PAT.
Conclusions:
- Accessory AV connections in infants can exhibit dynamic electrophysiologic changes over time.
- These changes may influence the recurrence and inducibility of PAT.
- Regular electrophysiologic follow-up may be necessary for infants with accessory AV connections and a history of PAT.
Abstract:
We report results of follow-up transesophageal electrophysiologic studies in 35 infants seven to 27 months old (mean, 12 months) in whom paroxysmal atrial tachycardia (PAT) using an accessory atrioventricular (AV) connection had been previously evaluated by transesophageal study in the first 2 months (mean, 14 days) of life. No infants were receiving antiarrhythmic drug therapy at the time of follow-up study. To evaluate AV conduction and initiate PAT, a standard transesophageal pacing protocol was used: single extrastimuli in sinus rhythm, incremental pacing to second-degree AV block, and burst pacing at cycle lengths near those resulting in second-degree AV block. If PAT was not initiated during the baseline period, the protocol was repeated during the infusion of isoproterenol and after administration of atropine. At follow-up study, PAT was reinitiated in 24 of 35 (68%) infants, six of whom had exhibited recent spontaneous recurrence of PAT. AV nodal function did not differ in those with and those without inducible PAT. However, when initial and follow-up studies were compared, changes in antegrade conduction of the accessory AV connection were observed, since only five of 10 infants with preexcitation at initial study continued to exhibit preexcitation at follow-up study (1/5 infants only after isoproterenol). Additionally, changes in retrograde conduction of the accessory AV connection were observed; the ventriculoatrial interval in PAT induced at follow-up study increased by 20 to 40 msec in eight of 24 infants and by 50 to 80 msec in five of 24 infants compared with the interval at initial study.(ABSTRACT TRUNCATED AT 250 WORDS)