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J Am Coll Cardiol, 1999; 33:366-375 © 1999 by the American College of Cardiology Foundation |




a Division of Pediatric Cardiology, Department of Pediatrics, University of Michigan Health System, Ann Arbor, Michigan, USA
b Division of Cardiology, Department of Internal Medicine, University of Michigan Health System, Ann Arbor, Michigan, USA
University-Arrhythmia Service, Departments of Pediatrics and Internal Medicine, Oregon Health Sciences University, Portland, Oregon; USA
Manuscript received June 11, 1997; revised manuscript received September 7, 1998, accepted October 22, 1998.
Reprint requests and correspondence: Dr. Macdonald Dick II, F1310 Box 0204, C.S. Mott Childrens Hospital, University of Michigan, Ann Arbor, Michigan 48109-0204
mdick{at}umich.edu
| Abstract |
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The purpose of this study is to review the clinical course of persistent junctional reciprocating tachycardia (PJRT) in 21 patients spanning a wide age range to examine the electrophysiologic characteristics of the conduction system in these patients with PJRT, particularly in regards to its incessant nature and to evaluate the long-term response to radiofrequency ablation.
Background
Persistent junctional reciprocating tachycardia is uncommon, occurring in 1% of patients with supraventricular tachycardia. Its presentation, course and treatment are incompletely characterized.
Methods
The clinical, electrocardiographic, electrophysiologic and echocardiographic data of 21 patients with PJRT were reviewed.
Results
In 9 of these 21 patients, the mean tachycardia cycle length increased significantly (p < 0.0001) as the patients grew, from a mean tachycardia cycle length of 308 ± 64 ms in the patients less than 2 years, 414 ± 57 ms in the patients between 2 years and 5 years, to 445 ± 57 ms in the patients greater than 5 years, primarily due to slowing of retrograde conduction in the accessory pathway. Persistent junctional reciprocating tachycardia was associated with impaired ventricular function in 11, improving spontaneously in 4 and, after successful ablation of the accessory pathway, in 7. All patients except one were uncontrolled on one or more medications. Ablation of the accessory pathway was successful in 19 of 21 patients.
Conclusions
We conclude that PJRT is characterized by an onset in early childhood and by an age-related prolongation of the tachycardia cycle length mediated primarily through conduction delay in the concealed, retrogradely conducting accessory pathway. Ablation of the accessory pathway provides definitive treatment for PJRT.
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| Methods |
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Electrocardiograms (ECG) were reviewed and the R-R, P-R (defined as the onset of the P wave to the Q or R wave in the QRS complex), and R-P intervals (calculated as the difference between the R-R interval and the R-P interval) were measured. Serial ECGs were available from 9 patients presenting within the first 2 years of life. The intervals from these serial ECGs were then plotted as a function of the patients age. Serial echocardiograms were reviewed and the patients shortening fraction, ejection fraction, E-point sepal separation and associated valvar regurgitation were measured. Decreased ventricular function was defined by a shortening fraction of less than 0.30 and/or left ventricular ejection fraction of less than 0.50 and presence of E-point septal separation.
Informed consent for electrophysiologic (EP) study (n = 21) and radiofrequency ablation (n = 20) was obtained from all patients/parents who underwent electrophysiologic study (median age of 12.8 years; mean 17.1 years, range 3.7 to 83.6 years). The indications for EP study included determination of the mechanism of the arrhythmia (n = 21), drug testing (n = 3) and impaired ventricular function (n = 6, transient in 4 of these). With the advent of transcatheter treatment of arrhythmias, persistent tachycardia in all (except #14 when on amiodarone therapy) led to the recommendation of radiofrequency ablation. Medications were discontinued at least 5 half-lives prior to electrophysiologic study except in the one patient taking amiodarone (#14). Electrophysiologic study was performed as previously described (11,12). The retrograde effective and functional refractory periods were measured using extrastimulation coupled to either the ventricular depolarization during the tachycardia or the drive cycle length during ventricular pacing. In addition the ventricular pacing rate at which retrograde block occurred during rapid ventricular pacing was determined. Retrograde properties of the accessory pathway were distinguished from those of the His-Purkinje atrioventricular node system by recording and measuring at the mapped site of the pathway distant from the recordings in the His bundle region.
One 15-year-old boy was treated by intraoperative cryoablation prior to the advent of radiofrequency ablation. Radiofrequency energy was delivered to ablate the accessory pathway supporting the tachycardia in the other 20 patients.
Figures 13 suggested that the electrocardiographic intervals increased with age. Therefore, the electrocardiographic intervals (R-R, P-R, R-P in msec) from the 9 patients who presented before age 2 years were classified by patient age into 3 groups (
2 years, >2
5 years, and >5 years). The grouped data were then expressed as the mean and 1 standard deviation and compared by an analysis of variance with Bonferroni correction (Statview v4.57 Abacus Concepts, Inc. 19921996). To examine for possible differences in retrograde and antegrade conduction times among the 7 patients in whom data were available, the means and the standard deviations of these 2 parameters were computed and compared by an analysis of variance (Statview v4.57 Abacus Concepts, Inc. 19921996). Finally, to examine for possible differences in retrograde conduction between our patients with either incessant tachycardia (n = 19) and paroxysmal tachycardia (n = 3), the mean cycle length and retrograde conduction intervals along with their standard deviations were computed and compared by a nonparametric t-test (Microsoft Excel v7.0a, Microsoft Corp. 1995). A p value
0.05 was taken to denote statistical significance.
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| Results |
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Ventricular function.
Fifteen of the 21 patients were evaluated by echocardiography at presentation; 11 demonstrated a mean shortening fraction of 0.22 ± 0.05 (range = 0.15 to 0.30; normal
0.28) and E-point septal separation, consistent with decreased ventricular function. Four of 11 patients with decreased myocardial function had clinical symptoms of severe congestive heart failure as infants. The remaining 7 patients increased their mean shortening fraction from 0.20 to 0.32 after successful ablation of the accessory pathway. Interestingly, shortening fraction increased spontaneously in 3 of the 11 patients (from a mean 0.23 to a mean of 0.36) with increasing age and slower heart rates (2 patients PJRT heart rate decreased from 183 to 119 and 128 to 104 respectively, and one patients rhythm converted to sinus rhythm on amiodarone therapy). Echocardiographic data could not be interpreted in one patient because of an implanted pacemaker. The clinical impression and follow-up of the infants suggested that tachycardia-related decreased ventricular function was prominent in this group (who had faster PJRT heart rates) and that an improvement in ventricular function was associated with decreasing heart rates; however, due to the limited number of infants studied, this association was not statistically significant.
Drug therapy. Pharmacological management in these patients was unsuccessful in all but patient #14; he had received ineffectual trials of several medications but was eventually successfully treated with amiodarone; however, hyperthyroidism and noncompliance complicated this approach and ablation was recommended and successfully performed.
Radiofrequency ablation. The median age at ablation was 12.8 years. One patient underwent successful surgical cryoablation of the accessory pathway at age 15 years prior to the advent of radiofrequency ablation. The remaining 20 underwent radiofrequency ablation. The shortest ventriculoatrial conduction time was used to identify the site of energy application. Seventeen of 21 accessory pathways (81%) were located at the coronary sinus ostium or in the right posterior septal region; the pathways of the remaining 4 patients were in the free wall (Table 1). Two to 35 radiofrequency energy applications were performed in the 19 patients; ablation of the pathway was successful in 16 of the 21 patients during the initial session. One patient was thought to have multiple pathways and the accessory pathway supporting PJRT was not successfully ablated. This patient declined a second trial of radiofrequency energy application. Transient ablation occurred in 5 patients; recurrence of the tachycardia was noted at less than one hour, and at 1, 3 and 7 days after ablation. Radiofrequency ablation for recurrence was successful in all but one. Patient #5, a 5-year-old boy with diminished ventricular function, developed complete heart block at his third session. The location of the pathway in this patient was posterior, near the coronary sinus os. During radiofrequency application, the catheter tip abruptly recoiled from its mapped site near the coronary sinus os to the apex of triangle of Koch; an immediate 3 second run of rapid junctional tachycardia ensued. The energy was discontinued at the end of the 3 seconds, but complete permanent heart block was present. The escape rhythm was a His bundle rhythm at 55 beats per minute with a narrow (normal) QRS complex; a pacemaker was implanted. During the procedure another patient with a left-sided pathway demonstrated persistent tachycardia after transient successful (15 min) radiofrequency ablation, but at follow-up electrophysiologic study 6 months later, he was in normal sinus rhythm, had no inducible tachycardia and no electrophysiologic evidence for a persistent pathway (20). Following radiofrequency ablation, retrograde conduction was absent in two patients of the seven patients studied (Table 4). In addition, the ventricular pacing rate at which retrograde block occurred, presumably through the His-Purkinje atrioventricular node, as indicated by the shortest V-A interval recorded in the His bundle region, was slower in the four other patients studied after ablation than that observed prior to ablation. Follow-up after definitive treatment (i.e., following all RFA sessions) ranges from 2.9 to 8 years without reoccurrence, except in the patient who has declined a second ablation attempt. The one patient with the pacemaker is doing well.
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| Discussion |
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18 years) and 50% presented during the first year of life. However, clinically asymptomatic patients presenting later are not uncommon, due to perhaps, as suggested by the clinical course of several of our patients, unrecognized paroxysmal relatively "slow" tachycardia for many years. PJRT makes its appearance most often in early childhood. To examine for a trend in the data with age, the curvilinear lines in Figures 2, 3 and 4 were created by subjecting the data to a nonparametric smoothing technique (Systat, Inc, Aurora, Colorado). The patients were on no medications for the initial electrocardiogram; within the first 2 years as well as later in their course digoxin, flecainide and propranolol were used predominantly, with no effect on the tachycardia. No measurements were made in the two patients during amiodarone therapy. Although drug effect cannot be fully excluded from the serial observations depicted in these figures, it is unlikely that marked effects occurred given the persistence of the arrhythmia and the uneven use of and inconsistent compliance with the antiarrhythmic agents. Thus, during the first several years of life, the rate tends to slow as a function of delay in conduction not only in the normal atrioventricular His-Purkinje axis but also, and most importantly, in the concealed accessory pathway. At about two years of age, the PJRT rate and conduction in both directions tend to stabilize (Fig. 3 and 4). Some patients, as illustrated by three patients in this cohort in whom "persistence" of the tachycardia was dependent upon isoproterenol, and, perhaps, by our older patients as well, may revert to a more paroxysmal form (14).
In contrast to our experience, Yagi et al. have reported that, despite the concordance in the mean PJRT cycle length between their paroxysmal and incessant groups, retrograde conduction through the accessory pathway was significantly shorter in the paroxysmal form compared to the incessant form (14). Conversely, anterograde conduction via the atrioventricular node was significantly shorter in the incessant form than in the paroxysmal form of tachycardia. Our patients differed from their group. Their patient group was, on the average, considerably older than our patient group. In addition, our younger patients (<10 years) had a significantly shorter mean PJRT cycle length and faster tachycardia then either of their 2 groups. Our three patients with the paroxysmal form, in contrast to the patients of Yagi et al., were converted to the incessant form with isoproterenol. Among our cohort the incessant tachycardia was associated not only with shorter PJRT cycle lengths and retrograde conduction intervals but also with slightly younger ages. Thus, our experience, in conjunction with the study of Yagi et al. and others (14,15), suggests that patients with PJRT comprise a wide clinical spectrum.
These data suggest that the cycle length of PJRT increases with age (Fig. 2, 3 and 4). Average tachycardia rates are much faster in infants and younger patients than in older patients. Although slowing of conduction both anterograde through the normal atrioventricular nodeHis-Purkinje axis and retrograde through the accessory pathway contributes to the increase in the tachycardia cycle length and occurs at similar rates (similar shaped curves in Fig. 3 and 4), this age-related change in the tachycardia rate is primarily dependent upon prolongation of retrograde conduction through the accessory pathway. Furthermore, as indicated by the data from these patients, the conduction properties of the retrograde accessory pathway are slower compared to those of the anterograde atrioventricular node and compared to those of the usual "fast" accessory pathway found in patients with atrioventricular reentrant tachycardia. However, a recent study indicating that the ventricular insertion of the accessory pathway inserts at the atrioventricular groove and not deep within the right ventricular rejects the notion that an increased length of the accessory pathway accounts for the "slow" retrograde conduction (13). On the other hand, because the conduction properties as well as the anatomic location of the retrograde accessory pathway in these patients are similar (but clearly anatomically independent) to those of the atrioventricular node anterograde, one may postulate that factors that are influential in atrioventricular conduction, such as abundant autonomic innervation, membrane-channel function, adenosine and beta1 receptor densities and decremental conduction may also be similar between the two pathways. In addition, because the PJRT cycle length, as expected, tracks much more with the functional refractory period of the retrograde accessory pathway as the patient ages (Tables 1, 3 and 4) than with properties of the anterograde atrioventricular node, it is apparent that changes in the retrograde pathway are the major factors in the difference in clinical courses observed in different patients.
Patients with PJRT may present with clinical or laboratory findings of impaired ventricular function compatible with tachycardia related cardiomyopathy. The tachycardia has infrequent spontaneous, but intermittent periods of remission. In older patients the tachycardia appears to be less incessant, perhaps due to variable autonomic tone. Because the PJRT heart rates are faster at younger age and since congestive heart failure is more common at younger ages, the two may be related. Even though a general trend seemed to support this hypothesis, a statistical significance, due to limited sample size, could not be demonstrated. This observation may also be, in part, due to limitations to accurately assess ventricular function by available noninvasive means. Three patients with cardiomyopathy in this study improved spontaneously, perhaps associated with the progressively slower rate of the tachycardia as the patient grew older; however, one of these three patients improved with only a slight decrease in the tachycardia rate. Because reversibility of tachycardia induced cardiomyopathy is well known (1619), intractable tachycardia-related decreased function in the older patient may be best managed with radiofrequency ablation of the retrograde accessory pathway. Furthermore, there are no ideal or even satisfactory antiarrhythmic medications for this arrhythmia. Because of uniform, full recovery of ventricular function occurring either postablation or spontaneously, intervention with either amiodarone or radiofrequency ablation should be considered only when cardiac function is severely impaired for a minimum of 12 yr or when the patient is of adequate size for a safe ablation attempt.
Several investigators have demonstrated that radiofrequency ablation can be used effectively for the treatment of PJRT (7,8,10,15). Our study confirms that radiofrequency ablation can be extended effectively for the treatment of PJRT to most patients. Five patients (24%) experienced recurrence and required repeat sessions for successful ablation; these patients received ablation during the first four years of our radiofrequency programs, perhaps accounting, in part, for the recurrence rate. Although one of our patients experienced complete heart block as a result of an abrupt spontaneous shift in the position of the catheter tip, this complication (20), given the usual anatomy of the pathway distant from the atrioventricular node and His bundle, should be a very rare event. Furthermore, the observation of spontaneous resolution of ventricular dysfunction and the increased complications at smaller than 15 kg along with the experimental evidence that links an expansion of radiofrequency lesion size (in the canine ventricle, but, interestingly, not the porcine ventricle) with subject growth and age (2123) suggest deferment of ablation in small children until they are of sufficient size or until significant symptoms develop. However, radiofrequency should be considered as treatment for patients with intractable tachycardia, and especially for those with decreased ventricular function, or with symptoms attributable to the persistent tachycardia. Patients with recurrent or persistent tachycardia after the initial attempt of radiofrequency can be considered for repeat radiofrequency ablation of their accessory pathway.
Clinical implications.
PJRT is an arrhythmia that usually presents in infancy or childhood, but may not be recognized until adulthood. Symptoms of congestive heart failure are more common in younger patients. Some patients may be unaware of the underlying persistent tachycardia and may present with decreased ventricular function, exercise intolerance or syncope much later in life. Age-related changes in both the rate and the "persistence" of this tachycardia may mask its diagnosis. The heart rate relative to different ages may not be sufficiently fast to result in symptoms or to provoke further examination by the patients physician; thus, the diagnosis may be delayed until tachycardia related symptoms or paroxysms of palpitations and tachycardia become apparent to the patient or patients family. Since the heart rate associated with PJRT will most likely slow with age, radiofrequency ablation may be deferred in small children with this tachycardia. However, because the tachycardia has both an infrequent spontaneous (and intermittent) resolution (1/21 in our series) and a variable expression of impaired ventricular function, and since it may be effectively and safely treated with radiofrequency ablation, we recommend that electrophysiologic study and radiofrequency ablation should be considered at suitable patient size (
15 kg) and upon the appearance of symptoms related to the tachycardia and/or impaired ventricular function.
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