Persistent Junctional Reentrant Tachycardia
Persistent junctional reentrant tachycardia is a rare form of long RP tachycardia, accounting for approximately 1% of SVT in a study review of 21 patients.3 As with the patient in this case, PJRT usually presents in early childhood.3 In a recent review of 194 patients with PJRT, 57% were infants.4 The condition involves an accessory pathway most commonly located in the posterior-superior septal region; conduction involves a retrograde impulse through the decremental accessory pathway.5 On ECG, findings include a negative P wave in inferior leads, a long RP interval, and a 1:1 AV conduction.6
A long-term multicenter follow-up study of 32 patients showed that rates of tachycardia vary among patients, from 100 to 250 beats/minute.7 Tachycardia-induced cardiomyopathy (TIC), which is secondary to the incessant nature of tachycardia, may be present in up to 30% to 50% of patients.3,8 In a recent multicenter study, PJRT was responsible for 23% of cases of TIC.9 Although the exact mechanism of this property is unknown, decremental conduction and unidirectional block of the accessory pathway appear to be contributing factors.6
Treatment
Adenosine is the initial drug of choice for narrow complex tachycardia with stable hemodynamic status and an available intravascular access.10 In a study evaluating the effectiveness of adenosine for managing SVT in the pediatric ED setting, it was more than 70% effective in cardioverting patients presumed to have SVT.11 However, in PJRT, owing to the incessant pattern, adenosine may either terminate the tachycardia (causing asystole) or, as seen in this patient, convert tachycardia to sinus rhythm for only a few seconds.12 Reinitiation of tachycardia in sinus beat without the need for a premature complex contributes to its incessant nature.13
In a multicenter study looking at clinical profile and outcome for PJRT, Vaksmann et al8 found a greater than 80% success rate in controlling the dysrhythmia with amiodarone and verapamil. For long-term management of tachyarrhythmia, medical therapy has been recommended in early childhood compared to older children in whom catheter ablation is an effective approach.7 Spontaneous resolution of PJRT has been documented but is rare.14
Conclusion
Pediatric cardiac emergencies require very specific treatment. As such, it is important that the emergency physician distinguish the different the types of tachyarrhythmias—especially in cases that do not respond to treatment with adenosine. In the pediatric patient, PJRT is a potentially life-threatening arrhythmia that requires a high index of suspicion. Clues to diagnosis include negative P waves in inferior leads, long RP interval, and 1:1 atrioventricular conduction.
Dr Fichadia is a fellow, pediatric emergency medicine, Wayne State University, Children’s Hospital of Michigan. Dr Perez is a clinical instructor, pediatric emergency medicine, Wayne State University, Children’s Hospital of Michigan.