Junctional ectopic tachycardia after congenital heart surgery

PURPOSE

In this literature review, we try to give anesthesiologists a better understanding about Junctional Ectopic Tachycardia (JET), a narrow complex tachycardia that frequently occurs during and after surgery for congenital heart disease.

SOURCE

Information was found in the databases of Pubmed, Science Direct, Medline and the Cochrane Library, by using the mesh terms "Tachycardia, Ectopic Junctional", combined with "Diagnosis", "Etiology", "Physiopathology", "Complications" and "Therapy". The publication date of the articles ranged from 1990 to 2012.

PRINCIPAL FINDINGS

Risk factors for the development JET are surgery near the AV node, a duration of cardiopulmonary bypass longer than 90 minutes, young age, the use of inotropic drugs and hypomagnesaemia. The diagnosis of Junctional Ectopic Tachycardia can be made on a 12-lead ECG, demonstrating a narrow-complex tachycardia with inverted P-waves and VA dissociation. Adenosine administration and an atrial electrocardiogram can help to confirm the diagnosis. If JET has a minimal impact on the hemodynamic status of the patient, risk factors should be avoided and the adrenergic tonus should be reduced. Hemodynamic unstable JET can be treated by amiodarone, hypothermia and pacing. Extracorporeal membrane oxygenation (ECMO) and radiofrequency or cryoablation are treatment options for life-threatening and resistant JET.

CONCLUSION

JET is the most frequent arrhythmia during and after congenital cardiac surgery. The ECG is the only available method to diagnose JET, demonstrating inverted P-waves and VA-dissociation. Amiodarone seems to be the most effective treatment option, because it can restore sinus rhythm and reduces the JET rate.

Case report: an infant with congenital junctional ectopic tachycardia requiring extracorporeal mechanical oxygenation

PURPOSE OF REVIEW

A case report of an infant with hemodynamic compromise and impending collapse due to congenital junctional ectopic tachycardia. Medical therapy was maximized and he required the rapid initiation of extracorporeal life support, in order to achieve hemodynamic stability.

RECENT FINDINGS

This case report briefly reviews the presentation and treatment options for congenital junctional ectopic tachycardia, as well as the indications for initiation of mechanical support for this potentially lethal condition.

SUMMARY

Congenital junctional ectopic tachycardia is a rare though often fatal arrhythmia of the newborn or infant. Medical treatment options may be limited, or may require time to attain efficacy. Despite aggressive escalation of antiarrhythmic therapy, mechanical support in the form of extracorporeal mechanical oxygenation is a viable option, until the arrhythmia is well controlled and the myocardium recovers function.

Documenting junctional ectopic tachycardia following pediatric open heart surgery

OBJECTIVE

To determine appropriated documentations for diagnosis junctional ectopic tachycardia (JET) before treatment in post-operative open heart surgery and identify risk factors for post-operative cardiac arrhythmias in children.

MATERIAL AND METHOD

The authors performed a retrospective chart review in 277 patients who underwent surgical corrections at British Columbia's Children Hospital from January 1st, 2000 to December 31st, 2001. History, clinical symptoms, complication of surgery and post-operative cardiac arrhythmias were reviewed from medical records. The authors investigated whether JET was being diagnosed accurately and whether it was being adequately documented prior to the initiation of therapy. The authors also identified risk factors that were associated with JET. All documentations before treatment were reviewed by Pediatric cardiologists to confirm diagnosis.

RESULTS

Although the diagnostic accuracy (84%), sensitivity (87%), and specificity (84%) are high, a significant number of patients with post-operative arrhythmias were treated without adequate documentation of the arrhythmia. The documentation of arrhythmias in the Intensive Care Unit was largely limited to rhythm strips, with very few 12-lead ECGs and wire studies performed to assist with the diagnosis.

CONCLUSION

The presented data indicates that, in this critically-ill population, there was an unacceptable number of patients with post-operative arrhythmias who may have been treated inappropriately. It is very important to emphasize the interpretation of wire studies, an investigation normally done in a critical care setting and whose interpretation is very important to the accurate diagnosis of pediatric arrhythmias.

Postoperative junctional ectopic tachycardia (JET)

Postoperative junctional ectopic tachycardia (JET) is a potential life-threatening tachycardia that mainly occurs after surgical correction of congenital heart defects. The arrhythmia itself or the related treatment has significant clinical impact on the postoperative course and intensive care stay. In general, JET is a self-limiting disorder that usually resolves within one week. However, JET occurs usually within the first 24 to 48 hours after corrective surgery, when systolic and diastolic function of the heart is impaired. Thus, the rapid heart rate leads to an acute further deterioration of cardiac output that requires adequate treatment. The diagnosis of JET is made by the typical ECG-appearance with narrow QRS-configuration at a rate of 170 to 260 bpm and AV-dissociation. A variety of different therapeutic strategies have been tested in postoperative and congenital/spontaneous JET. Treatment success is usually defined as a stable decrease in the ventricular rate below 140-150/min, the possibility of atrial pacing and thereby the improvement of cardiac output. Optimal success is the reinstitution of sinus rhythm. Many of the treatment strategies reported are based on specific institutional treatment protocols. These include conventional supportive treatment, specific medical antiarrhythmic therapy, specific forms of pacing and surface cooling. Today, the administration of high doses of amiodarone usually leads to adequate control of the rate and enables pacing. Surgical intervention or catheter ablation of the HIS-bundle is rarely necessary. This article reviews the literature about JET over the past years and offers a specific treatment protocol.

[Management by hypothermia of junctional ectopic tachycardia appearing after pediatric heart surgery]

Junctional ectopic tachycardia (JET) is a complication of the repair of congenital cardiac malformations that responds poorly to conventional treatment. We report our experience with the use of moderate hypothermia in its management. Twelve infants with postoperative JET treated with hypothermia were reviewed. The mean interval between the diagnosis of JET and initiation of hypothermia was 1.5 0.5 hours. In the first 24 hours of hypothermia, central temperature and heart rate decreased significantly. Arterial pressure and diuresis tended to increase and central venous pressure tended to decrease. No direct adverse events occurred. All the patients but one survived and are alive and free of neurological deficits after 15 12 months.

[Ectopic junctional tachycardia of the neonate]

Congenital ectopic junctional tachycardia (EJT) is a rare arrhythmia presenting in the first 6 months of life. It is often resistant to antiarrhythmic drugs and its poor prognosis (35% mortality) explains its often complex management. The authors report two cases which illustrate its unpredictability with a potential to degenerate to serious ventricular arrhythmias. The possibility of progression to atrioventricular block, increased by antiarrhythmic therapy, may lead to implantation of a cardiac pacemaker. The poor outcome of the two babies underlines the severity of these arrhythmias.

Use of a modified, commercially available temporary pacemaker for R wave synchronized atrial pacing in postoperative junctional ectopic tachycardia

Junctional ectopic tachycardia (JET) is a life-threatening arrhythmia frequently seen after surgical correction of congenital heart defects. This study evaluates the use of a modified, commercially available temporary dual chamber pacemaker used to reestablish AV synchrony by R wave synchronized atrial pacing, a technique not routinely applied because of a lack of appropriate equipment. Ten consecutive children with postoperative JET (median maximum heart rate 185, range 130-240 beats/min) age 0.3-45 (median 5.2) months were studied. R wave synchronized atrial pacing was performed using the VAT mode with inverse connection of the pacing wires (effectively AVT mode), short postventricular atrial refractory period (100 ms), and long AV (effectively VA) delay. AV delay was adjusted to achieve maximum increase in arterial pressure by optimal AV resynchronization. Pacing was successfully applied in all patients for a median period of 29 (range 10-96) hours until tachycardia cessation and led to an immediate increase in systolic, mean, and pulse pressure by 8.9 +/- 3.2 (P < 0.001), 8.1 +/- 4.0 (P < 0.001), and 11.9 +/- 7.8% (P < 0.005), respectively. Two patients developed pacemaker-mediated tachycardia, which could be easily stopped by AV (effectively VA) delay prolongation. Atrial flutter was induced in one patient by asynchronous atrial pacing during the VAT (effectively AVT) mode and managed by overdrive pacing. In conclusion, R wave synchronized atrial pacing could be easily performed using a modified, commercially available temporary dual chamber pacemaker. Significant hemodynamic benefit was achieved due to optimal AV resynchronization at intrinsic heart rate and spontaneous ventricular activation sequence. R wave synchronized atrial pacing should be included in the standard management protocol of postoperative JET.

Role of invasive electrophysiologic testing in the evaluation and management of adult patients with focal junctional tachycardia

Focal junctional tachycardia (FJT) is characterized by a rapid often irregular narrow complex tachycardia with episodes of atrioventricular (AV) dissociation. This uncommon arrhythmia is most likely due to abnormal automaticity or triggered activity. The patients are often quite symptomatic and if left untreated may develop heart failure particularly if their tachycardia is incessant. In patients refractory to medical management, the role of radiofrequency ablation involves either (1) selective ablation of the tachycardia focus while preserving AV conduction or as a last resort (2) AV junction ablation followed by pacemaker implantation. The clinician should first assess whether ventriculoatrial (VA) conduction is present or absent during tachycardia. If present, radiofrequency ablation should be applied at the site of earliest retrograde atrial activation. In the absence of VA conduction and hence an atrial target site, sequential lesions should be applied in the posterior septum (slow pathway region) followed by lesions applied in midseptum and anteroseptum respectively if tachycardia persists. To further minimize the risk of AV nodal block, some authors delivered radiofrequency energy during atrial overdrive pacing to assess AV conduction during ablation. Others recommended mapping the perinodal region and applying radiofrequency ablation at the site where catheter manipulation resulted in tachycardia termination. Using this ablative approach, the risk of AV block is around 5-10%.

Postoperative junctional ectopic tachycardia in children: incidence, risk factors, and treatment

BACKGROUND

Junctional ectopic tachycardia (JET) occurs commonly after pediatric cardiac operation. The cause of JET is thought to be the result of an injury to the conduction system during the procedure and may be perpetuated by hemodynamic disturbances or postoperative electrolyte disturbances, namely hypomagnesemia. The purpose of this study was to determine perioperative risk factors for the development of JET.

METHODS

Telemetry for each patient admitted to the cardiac intensive care unit from December 1997 through November 1998 for postoperative cardiac surgical care was examined daily for postoperative JET. A nested case-cohort analysis of 33 patients who experienced JET from 594 consecutively monitored patients who underwent cardiac operation was performed. Univariate and multivariate analyses were conducted to determine factors associated with the occurrence of JET.

RESULTS

The age range of patients with JET was 1 day to 10.5 years (median, 1.8 months). Univariate analysis revealed that dopamine or milrinone use postoperatively, longer cardiopulmonary bypass times, and younger age were associated with JET. Multivariate modeling elicited that dopamine use postoperatively (odds ratio, 6.2; p = 0.01) and age less than 6 months (odds ratio, 4.0; p = 0.02) were associated with JET. Only 13 (39%) of the patients with JET received therapeutic interventions.

CONCLUSIONS

Junctional ectopic tachycardia occurred in 33 (5.6%) of 594 patients who underwent cardiac operation during the study period. Postoperative dopamine use and younger age were associated with JET. It may be speculated that dopamine should be discontinued in the presence of postoperative JET.

[The treatment of postoperative junctional ectopic tachycardia]

OBJECTIVE

To evaluate treatment of junctional ectopic tachycardia after cardiac surgery.

MATERIAL AND METHODS

Twenty-seven patients (5.5 % of 488 patients who underwent surgery) were treated for junctional ectopic tachycardia between 1994 and 1998. There were 14 boys and 13 girls with a mean age of 11 11 months. Seven suffered from tetralogy of Fallot, seven from ventricular septal defect, six from atrioventricular septal defect, three from transposition of the great vessels and the remaining four had other complex heart diseases. The mean initial frequency was 186 27 beats/min. Crystalloid cardioplegia was applied in 274 patients (1994-1996) and 20 patients (7.4 %) showed junctional ectopic tachycardia. Hematic cardioplegia was performed in 214 patients (1997-1998) and seven patients (3.2 %) developed junctional ectopic tachycardia. Of the 33 patients who were treated during the surgical procedure with high mean doses of sympathomimetic catecholamine agents, 27 (81 %) developed tachycardia. Tachycardia developed 8.24 7 hours after surgery (range: 1-24 hours) in 25 patients and after 4 and 5 days in the remaining two patients. The mean duration of tachycardia was 4 days.

RESULTS

In all patients rectal temperature was reduced to 32-34 C. Nineteen patients (70 %) showed a quick response (1-2 hours), although the technique was effective as an isolated procedure in only one patient. Sympathomimetic catecholamine level was reduced to 2-5 g/kg/min in 20 patients but this was effective in 14 (70 %). In 15 patients intravenous amiodarone was also administered and was effective in 11 patients (73 %). Finally, intravenous propafenone was administered to 5 patients. The most effective treatments were hypothermia with reduction of sympathomimetic catecholamine levels in 7 patients (100 %) or intravenous amiodarone in 4 (80 %). Tachycardia led to low cardiac output in 10 patients and only four recovered normal sinus rhythm. Eight patients died. Of these, hemorrhage in the junction area was confirmed in six patients.

CONCLUSIONS

Junctional ectopic tachycardia is favored by high levels of sympathomimetic catecholamines after surgery. On the other hand, myocardial protection with hematic cardioplegia reduces tachycardia. Moderate hypothermia with reduction of sympathomimetic agents or intravenous amiodarone reverses ectopic tachycardia.

Impact of junctional ectopic tachycardia on postoperative morbidity following repair of congenital heart defects

OBJECTIVE

To determine the incidence of postoperative junctional ectopic tachycardia (JET), we reviewed 343 consecutive patients undergoing surgery between 1997 and 1999. The impact of this arrhythmia on in-hospital morbidity and our protocol for treatment were assessed.

METHODS

We reviewed the postoperative course of patients undergoing surgery for ventricular septal defect (VSD; n=161), tetralogy of Fallot (TOF; n=114), atrioventricular septal defect (AVSD; n=58) and common arterial trunk (n=10). All patients with JET received treatment, in a stepwise manner, beginning with surface cooling, continuous intravenous amiodarone, and/or atrial pacing if the haemodynamics proved unstable. A linear regression model assessed the effect of these treatments upon hours of mechanical ventilation, and stay on the cardiac intensive care unit (CICU).

RESULTS

Overall mortality was 2.9% (n=10), with three of these patients having JET and TOF. JET occurred in 37 patients (10.8%), most frequently after TOF repair (21.9%), followed by AVSD (10.3%), VSD (3.7%), and with no occurrence after repair of common arterial trunk. Mean ventilation time increased from 83 to 187 h amongst patients without and with JET patients (P<0.0001). Accordingly, CICU stay increased from 107 to 210 h when JET occurred (P<0.0001). Surface cooling was associated with a prolongation of ventilation and CICU stay, by 74 and 81 h, respectively (P<0.02; P<0.02). Amiodarone prolonged ventilation and CICU stay, respectively, by 274 and 275 h (P<0.05; P<0.06).

CONCLUSIONS

Postoperative JET adds considerably to morbidity after congenital cardiac surgery, and is particularly frequent after TOF repair. Aggressive treatment with cooling and/or amiodarone is mandatory, but correlates with increased mechanical ventilation time and CICU stay. Better understanding of the mechanism underlying JET is required to achieve prevention, faster arrhythmic conversion, and reduction of associated in-hospital morbidity.

Catheter ablation of atrioventricular junction via retrograde route in a patient with single ventricle

Radiofrequency catheter ablation of the atrioventricular junction (AVJ) was performed by the retrograde route in a 19-year-old woman with atrial fibrillation and single ventricle following the bidirectional Glenn procedure. Two energy applications resulted in complete atrioventricular block and dependence on an epicardial ventricular pacemaker.

Congestive heart failure treated by the upgrade from VVI to DDD pacing

The case is presented of an elderly woman with normal left ventricular (LV) systolic function and VVI pacing complicated by severe congestive heart failure. The symptoms and findings of congestive heart failure became refractory to medical treatment and resolved with the upgrade of the VVI to a DDD system. Right heart catheterization during VVI pacing showed increased mean pulmonary capillary wedge and right atrial pressures both being normalized under DDD pacing. This case report illustrates the need to consider permanent physiological pacing in elderly patients, even in presence of normal LV systolic function, to ensure AV synchrony when the atrium can be paced, since diastolic LV dysfunction is quite common in these subjects.

Successful radiofrequency ablation in an infant with drug-resistant permanent junctional reciprocating tachycardia

Over the past decade, the technique of radiofrequency ablation has evolved substantially. Currently, most forms of cardiac arrhythmias seen in children can be treated with good long-term results and low risk of adverse outcome. Curative arrhythmia treatment with this technique, however, is still uncommon in neonates and infants. Reported here is our experience in the management of an 8-week-old with drug-resistant permanent junctional reciprocating tachycardia.

Radiofrequency catheter ablation of junctional ectopic tachycardia in adults

Junctional ectopic tachycardia is an arrhythmia seen principally in infants and children, in adults it is even more rare and is difficult to treat with antiarrhythmic drugs and is associated with a poor prognosis. To our knowledge, there is not information about treatment with nonpharmacological methods in adults. We report two adult patients with junctional ectopic tachycardia who underwent successful radiofrequency catheter ablation of the automatic focus located in the His bundle region. The tachycardia was eliminated in both patients with AV block in one and the AV conduction was preserved in the other. After six and 48 months of follow-up both patients are asymptomatic and free of recurrences.

Paired ventricular pacing: an alternative therapy for postoperative junctional ectopic tachycardia in congenital heart disease

Junctional ectopic tachycardia (JET) is one of the most life-threatening postoperative arrhythmias in children with congenital heart disease, and medical management is difficult. Paired ventricular pacing (PVP) may provide a safe alternative mode of management. We evaluated the safety and efficacy of PVP for the management of postoperative JET in patients with congenital heart disease. A retrospective collection of data was done from 1981-1995. PVP was successfully tried in five postoperative patients (age range: 37 days to 22 years, median: 10 months). Onset of JET was 3-60 hours (mean +/- SD, 19 +/- 23 hours) postoperatively. The maximal JET rate was 261 +/- 39 beats/min. PVP was used as the first line of management in three patients and was successful in all patients. It resulted in an instantaneous increase in blood pressure from 66 +/- 9 to 94 +/- 15 mmHg (42% increase) and was required for 12 +/- 14 hours (range 2-36 hours). No complications were noted. Therefore, in our experience, this is a safe alternative modality for the control of postoperative JET.

Junctional ectopic tachycardia evolving into complete heart block

Transition from congenital junctional ectopic tachycardia to complete AV block was observed in an 8 month old girl, over a 36 hour period, during initial hospital admission. Two years later she had evidence of a rapidly increasing left ventricular end diastolic diameter, associated with lowest heart rates during sleep of < 30 beats/min. A transvenous permanent pacemaker was therefore implanted. This finding supports the idea that a pathological process in the area of the AV junction, initially presenting as junctional ectopic tachycardia may later extend to sudden complete atrioventricular block.

Postoperative junctional ectopic tachycardia

PURPOSE

To report the management of junctional ectopic tachycardia after cardiac surgery in an infant. Postoperatively, the patient suffered profound cardiac decompensation secondary to the accelerated rhythm and required extracorporeal membrane oxygenation (ECMO) for haemodynamic support.

CLINICAL FEATURES

A 14-day-old, 3.5 kg boy exhibited junctional ectopic tachycardia after cardiopulmonary bypass. Left atrial pressure was 25-28 mmHg. No impact on the tachycardia was seen after rapid overdrive atrial pacing or after 20 micrograms fentanyl i.v., 45 micrograms digitalis, 100 mg magnesium or procainamide (loading dose 15 mg, then 30 mg.kg-1.min-1). Active cooling decreased the nasopharyngeal temperature to 35.2 degrees C, when the heart rate decreased below 180 bpm with a left atrial pressure of 8-10 mmHg. Dopamine (2 micrograms.kg-1.min-1) and dobutamine (5 micrograms.kg-1.min-1) were added to improve the cardiac output. Sodium nitroprusside (0.25 to 1 microgram.kg-1.min) maintained the systolic pressure < 100 mmHg. On arrival in ICU, heart rate increased to 200 bpm. The patient received cardiac massage for severe hypotension 75 min after surgery. Emergency ECMO was instituted for circulatory support. Procainamide, digoxin, dopamine, dobutamine, sodium nitroprusside and hypothermia were continued. Sinus rhythm resumed on the first postoperative day, but procainamide and induced hypothermia at 34 degrees C were maintained for 36 hr after normalization of the rhythm to prevent recurrence of the tachycardia. Total duration of ECMO was three and a half days. Recovery was uneventful.

CONCLUSION

The use of ECMO, as a first line of defence, is suitable for the emergency support of patients with JET because of the ease of support of circulation and precise control of hypothermia.

Permanent junctional re-entry tachycardia. A multicentre long-term follow-up study in infants, children and young adults

AIMS

Permanent junctional re-entry tachycardia is a relatively uncommon form of re-entry tachycardia with antegrade conduction occurring through the atrioventricular node and retrograde conduction over an accessory pathway usually located in the postero-septal region. It was the aim of the study to investigate the course of permanent junctional re-entry tachycardia with particular regard to the effectiveness of pharmacological treatment and ablation procedures; evaluation was performed with respect to the patient's symptoms, tachycardia rate, frequency of the tachycardia and left ventricular function.

METHODS AND RESULTS

The long-term follow-up of 32 patients with permanent junctional re-entry tachycardia was evaluated. The first presentation with supraventricular tachycardia occurred between the 27th week of gestation and 27 years. The tachycardia rate ranged from 100 to 250 beats.min-1. During Holter-ECG, permanent junctional re-entry tachycardia was documented as present for over 50% of the time in 24 h in 22 patients (69%). Left ventricular performance was impaired in nine patients (28%) due to a tachycardia-related cardiomyopathy. Symptoms or signs of heart failure were mild to moderate in eight and severe in four patients; 20 patients showed no clinical impairment. Follow-up time was 1 to 31 (mean 10) years; current age of the patients ranged from 1.5 months to 35 (mean = 15 x 3) years. Four patients needed no therapy because of the infrequency of permanent junctional re-entry tachycardia episodes. Twenty-five patients initially received antiarrhythmic drugs, which were effective or partially effective in 14 (56%). Eight of them are still on medical therapy; in five treatment was discontinued because of absence of symptoms. Eleven patients had ablation of the accessory pathway during follow-up, three underwent ablation as a primary procedure.

CONCLUSION

Permanent junctional re-entry tachycardia in our experience is an arrhythmia with a large variety of clinical symptoms. Patients with a slow tachycardia rate and infrequent episodes of tachycardia may never develop symptoms and therefore do not need any therapy. Patients with frequent permanent junctional re-entry tachycardia, a fast tachycardia rate and impaired left ventricular function need effective therapy. In infancy and early childhood medical therapy is recommended as a first option, whereas in older and symptomatic patients catheter ablation is an effective and safe procedure.

Incessant tachycardias

Incessant tachycardias are some of the rarer forms of normal QRS tachycardias. They are usually diagnosed in infancy or childhood and often present with heart failure secondary to left ventricular dysfunction. Permanent junctional reciprocating tachycardia is a rare type of orthodromic atrioventricular re-entry. Control with drugs is possible but best long-term results are achieved with radio-frequency ablation. Congenital His bundle tachycardia is an automatic arrhythmia characterized by ventriculo-atrial dissociation on the electrocardiogram. The risk of atrio-ventricular block with radiofrequency ablation is high and long-term drug treatment is often effective. Atrial ectopic tachycardia is also automatic and may originate in the left or right atrium. Drug suppression is possible but radiofrequency ablation offers the prospect of cure. All three arrhythmias are likely to persist long term. Drug treatment with class IC or class III drugs is most likely to be effective. Rate control or arrhythmia suppression are likely to lead to improvement or normalization of left ventricular function.

Evaluation of a staged treatment protocol for rapid automatic junctional tachycardia after operation for congenital heart disease

OBJECTIVES

This study sought to 1) develop an efficient treatment protocol for postoperative automatic junctional tachycardia (JT) using conventional drugs and techniques, and 2) identify clinical features associated with this disorder by analyzing a large study group.

BACKGROUND

Postoperative JT is a transient arrhythmia that may be fatal after operation for congenital cardiac defects. Its precise cause is unknown. A variety of palliative treatments have evolved, but because of a low incidence of JT, large studies of the most efficient therapeutic sequence are lacking.

METHODS

A protocol for rapid JT (>170 beats/min) was adopted in 1986, and was tested in 71 children between 1986 and 1994. Staged therapy involved 1) a reduction of catecholamines; 2) correction of fever; 3) atrial pacing to restore synchrony; 4) digoxin; 5) phenytoin or propranolol or verapamil; 6) procainamide or hypothermia; and 7) combined procainamide and hypothermia. Effective therapy was defined as a sustained reduction of JT rate <170 beats/min within 2 h. Clinical profiles of the study group were contrasted with all patients without JT from this same era to identify features associated with JT.

RESULTS

Of the multiple treatment stages, only correction of fever and combined procainamide and hypothermia appeared to be efficacious. By refining the protocol to eliminate nonproductive stages, the time to JT control was significantly shortened for the last 30 patients. Treatment was ultimately successful in 70 of 71 children. Postoperative JT was strongly associated with young age, transient atrioventricular block and operations involving ventricular septal defect closure.

CONCLUSIONS

A staged approach to therapy, with emphasis on combined hypothermia and procainamide in difficult cases, appears to be an effective management strategy for postoperative JT. These results may also serve as comparison data for evaluation of newer and promising JT options, such as intravenous amiodarone. Trauma to conduction tissue may play a central role in the etiology of this disorder.

Successful management of junctional tachycardia by hypothermia after a Fontan operation

We report herein the findings of a 2-year-old boy in whom junctional tachycardia developed 2 days after he underwent a modified Fontan operation and thereafter was successfully treated by hypothermia without paralyzing and artificially ventilating the patient. Chlorpromazine was useful in achieving moderate hypothermia by surface cooling without producing any unfavorable effects associated with topical cooling.

[The esophageal approach in rhythmology]

The possibility of detecting the electrical activity of the heart from the oesophageus has been recognised for nearly a century. On the other hand, transesophageal pacing has only been really developped in the last fifteen years, which explains the recent interest for this technique in clinical practice. Easily put into practice, but not always well tolerated, the oesophageal approach has many uses in rhythmology. The principal diagnostic applications are in unlabelled tachycardias whether with narrow or wide QRS complexes, the evaluation of the Wolff-Parkinson-White syndrome, the study of sinus node function or nodal conduction. The therapeutic applications are dominated by the reduction of supraventricular tachycardias especially atrial flutter, with a success rate similar to that of endocavitary stimulation. The facility of realisation, especially at the patient's bedside, without need for fluoroscopie control, makes it a useful tool in emergencies, especially if the endocavitary approach cannot be used. The only reserve is the painful character of pacing in some patients.

Mechanisms and therapy of complex arrhythmias in pediatric patients

In recent years, the distinction between the diagnostic and therapeutic techniques used in the assessment and management of pediatric and adult patients with arrhythmias has gradually blurred. Nonetheless, arrhythmias in the pediatric patient are still often different from the adult patient in one of two important ways. First, a variety of arrhythmia mechanisms remain relatively unique to the pediatric population, some because of developmental issues and others because of early presentation of an incessant tachycardia. Second, the presentation and management of certain arrhythmias is sometimes markedly affected by patient age or the presence of structural congenital heart disease. A sampling from each of the above categories is reviewed and discussed.

Successful management of junctional tachycardia by hypothermia after cardiac operations in infants

BACKGROUND

Junctional ectopic tachycardia is an early postoperative complication after intracardiac repair of congenital heart disease, especially in infants. Because of the high ventricular rate and the usually poor response to antiarrhythmic drugs, this condition is associated with a high morbidity and mortality. The purpose of this study was to assess the safety and efficacy of moderate body surface hypothermia in the treatment of postoperative junctional ectopic tachycardia in infants.

METHODS

Six consecutive infants with postoperative junctional ectopic tachycardia (mean age at operation, 14 weeks) were treated with surface cooling. The decision to start treatment was based on the definition of a critical heart rate (180 to 200 beats/min) in the presence of junctional ectopic tachycardia diagnosed according to established criteria. Moderate hypothermia (rectal temperature between 32 degrees and 34 degrees C) was achieved by placing ice bags on the child's body surface. The patients were sedated, mechanically ventilated, and paralyzed.

RESULTS

Mean interval between diagnosis of tachycardia and initiation of hypothermia was 4 hours. Rectal temperature was rapidly (within 1 hour) lowered to 32 degrees to 34 degrees C in all 6 patients. This significantly lowered the tachycardia rate from 219 +/- 27 beats/min to 165 +/- 25 beats/min (mean +/- standard deviation; p < 0.001). Three patients with signs of low cardiac output had restoration of stable hemodynamics once the tachycardia rate had been decreased by hypothermia. Cooling was maintained for a period of 24 to 88 hours (mean, 59 hours). No serious side effects were observed.

CONCLUSIONS

Early institution of moderate hypothermia by body surface cooling was a safe and efficient measure to control ventricular rate in infants with postoperative junctional ectopic tachycardia.

[Endocavitary percutaneous ablation of tachyarrhythmias]

The indication and result of catheter ablation for supraventricular and ventricular arrhythmias are reviewed, with special emphasis on the need to inform the patient undergoing this type of procedure, the possible complications and our center's results.

Amiodarone management of junctional ectopic tachycardia after cardiac surgery in children

OBJECTIVE

To assess the effectiveness and safety of amiodarone in the treatment of junctional ectopic tachycardia (JET) after open heart surgery in children.

PATIENTS

Between January 1990 and December 1991, 16 consecutive patients aged 6 days to 14 years with JET associated with significant haemodynamic impairment after cardiopulmonary bypass were treated with amiodarone as the principal antiarrhythmic drug.

INTERVENTIONS

Amiodarone 5 mg/kg was administered intravenously over one hour and the same dose was subsequently infused over 12 hours. This was reviewed every 12 hours and repeated as necessary until a satisfactory heart rate and stable haemodynamics were achieved. Atrial pacing was used whenever possible to provide atrioventricular synchrony.

RESULTS

Except for one patient with a JET rate of 160/min, the maximum JET rate ranged from 180/min to 245/min with a mean(SD) of 200 (20)/min. After amiodarone, the heart rates reduced to a mean(SD) of 170 (20), 164 (27), 158 (27), 157 (24), and 153 (19)/min at two, four, eight, 12, and 24 hours respectively. A reduction in tachycardia rate allowing atrial pacing was achieved in 10 patients by two hours. Haemodynamic variables improved in most patients with an increase in mean systolic blood pressure by an average of 15 mm Hg and a decrease in atrial filling pressures by an average of 3.5 mm Hg at four hours after amiodarone administration. There were three deaths: one was a moribund patient who died soon after the onset of JET and the other two deaths were not directly related to JET.

COMPLICATIONS

Late bradycardia with hypotension was recorded in one patient. Asymptomatic late sinus bradycardia was seen in several others.

CONCLUSIONS

Amiodarone can be used safely and effectively to control JET with haemodynamic improvement in most patients. The addition of atrial pacing confers the advantage of atrioventricular synchrony.

[Ablative methods, therapeutic alternative to medical treatment for junctional tachycardia]

The clinical syndrome corresponding to junctional tachycardia is generally known as Bouveret's disease, but actually corresponds to two quite separate entities: 1) tachycardia related to a secondary atrioventricular pathway or Kent bundle; 2) intranodal tachycardia arising in the atrio-ventricular node. Until recently, anti-arrhythmics were used to treat most of the cases of accessory pathways. If this was unsuccessful or if the anti-arrhythmics induced adverse effects and in life-threatening cases affecting Kent bundles, surgical section was sometimes proposed, carrying a non-negligible risk of morbidity and mortality. Intranodal arrhythmia is not a serious, but may call for prophylactic antiarrhythmic treatment if it becomes too frequent and disabling. Before the advent of ablative treatment, there was no satisfactory alternative to antiarrhythmic treatment. Ablation of the accessory pathways or selection ablation of the slow pathway of the atrio-ventricular node (sometimes of the rapid pathway) is not achieved by applying a high-frequency current (radiofrequency), which has virtually replaced fulguration (destruction using a modified electrical current). In both types of tachycardia, a cure is obtained in 90% of cases with a low incidence of complications and virtually no risk of mortality, which contrasts favorably with long-term antiarrhythmic treatment (or surgical section of Kent bundles), which justifies the large-scale development of radiofrequency ablation.

Automatic atrial and junctional tachycardias in the pediatric patient: strategies for diagnosis and management

Unlike supraventricular arrhythmias secondary to reentry, automatic rhythm disturbances in children are rare and more resistant to standard pharmacological therapy. This article reviews strategies for the diagnosis and management of two of the more common pediatric automatic rhythm disturbances, that is, atrial ectopic tachycardia, and junctional ectopic tachycardia. The place of newer nonpharmacological therapy, such as catheter ablation, in the treatment of these entities is beginning to be explored, yet has not been fully delineated. Despite these limitations, there is enough experience with these difficult tachycardias in the pediatric age group to formulate some strategies for optimal diagnosis and management.

[Therapy of postoperative ectopic junctional tachycardia by surface hypothermia]

Postoperative junctional ectopic tachycardia is associated with a poor prognosis in patients after open-heart surgery. This dysrhythmia has been shown to be resistant to medical treatment as well as to epicardial pacing and external cardioversion. Successful therapy with surface hypothermia in an infant with junctional ectopic tachycardia (ventricular rate 210-230 bpm) after repair of tetralogy of Fallot is presented. Hypothermia (rectal temperature 32-34 degrees C) was effective in decreasing the ventricular rate of the dysrhythmia (< 170 bpm). After spontaneous cessation of the tachycardia, sinus rhythm resumed, resulting in stable hemodynamics.

[Radiofrequency treatment of junctional tachycardia]

Atrioventricular nodal tachycardias due to intranodal reentry or to an accessory pathway are accessible to radical cure with radiofrequency currents applied either at the site of recording of characteristic slow potentials or at the tricuspid or mitral atrioventricular rings. One hundred and six patients with atrioventricular nodal reentry were treated by modification of the slow anterograde reentrant pathway with a 100% success rate and without any serious complications (especially atrioventricular block). One hundred and eighty six patients had one or more overt or latent accessory pathways and were treated by the same method. The ablation site was decided on indirect criteria and not by the recording of the specific activity of the accessory pathway. The success rate was 97%, also with no significant complications. The duration of the treatment was 41 +/- 22 min for the accessory pathways. The exposure time to ionising radiation was 14 +/- 14 min and 31 +/- 34 min respectively. These results suggest that the indications of radiofrequency current ablation could be extended.

[Long-term outcome of a hospital series of patients with atrio-ventricular accessory pathway]

Ninety five patients with a mean age of 39 +/- 19 years, 82 of whom were symptomatic, having an accessory atrioventricular bidirectional conduction pathway (WPW syndrome: 77; "concealed": 18) were followed up for an average of 7.3 +/- 2.6 years. The objectives were to analyse: the incidence and causes of death and the possible predictive factors of death due to the WPW syndrome--the influence of medical treatment and type of medication on survival and symptoms. Of the 8 cardiac deaths, 6 seemed to be related to the WPW syndrome, a prevalence of 7.8% and an annual incidence of 1.1/1000. The main risk factors which were identified were: age 62 +/- 8 years versus 37 +/- 15 years in survivors; p < 0.02--associated organic heart disease, especially ischaemic heart disease (5/6)--the description of severe symptoms, in particular recurrent syncope--documented malignant spontaneous or induced arrhythmias (5/6)--anterograde AV conduction with an effective refractory period < or = 230 msec in 4, though it was only 270 msec in the other 2 patients, indicating that this parameter is not specific--amiodarone (6/6) did not prevent the fatal outcome in this particular group of patients. In the "benign" forms, only betablocker drugs could significantly reduce the frequency and severity of symptoms, especially when compared with Class I or IC antiarrhythmics. These results suggest that the indications of radical treatment should be widened in high risk patients, especially when elderly and with associated coronary artery disease. They also suggest that the role of betablocker drugs should be reevaluated in the so-called "benign" symptomatic forms.

[Focal junctional tachycardia in adults. Anatomo-electrophysiological aspects apropos of a case]

The authors report the case of a 65 year old patient with focal junctional tachycardia complicating infectious myocarditis which had a fatal outcome. The ECG recordings showed episodes of tachycardia alternating with junctional rhythm at 90/min. There were signs of retrograde conduction. The anatomopathological findings were typical of acquired myocarditic lesions in the lower part of the atrioventricular node with congenital abnormalities, in particular a bifid node and His bundle with an accessory paraseptal atrioventricular bundle. This is the first description, to the best of the authors's knowledge, of junctional tachycardia associated with a latent pre-excitation.

Moderate hypothermia in the management of resistant automatic tachycardias in children

BACKGROUND

Automatic focus tachycardias are often resistant to electrical and pharmacological treatment. Moderate systemic hypothermia (32-34 degrees C) may reduce the tachycardia rate in children with His bundle tachycardia after cardiac surgery.

METHODS

The case notes of seven children with automatic focus tachycardias treated with hypothermia were reviewed. Six had His bundle tachycardia after cardiac surgery and one had ectopic atrial tachycardia; all had signs of low cardiac output.

RESULTS

Hypothermia led to a reduction in heart rate in all patients (from 211 (28) (mean (SD] to 146 (5) beats/minute, p less than 0.001), with rises in systolic blood pressure (from 74 (14) mm Hg to 97 (10) mm Hg, p less than 0.01) and hourly urine output (from 0.5 (0.4) ml/kg to 4.6 (2.8) ml/kg, p less than 0.02). No direct adverse effects were noted. The arrhythmia did not resolve in three children, who died (two with His bundle tachycardia after Fontan procedures and one with ectopic atrial tachycardia); the other four regained sinus rhythm which was maintained at follow up of 3-13 (mean 9) months.

CONCLUSIONS

Moderate systemic hypothermia led to slowing of the arrhythmia rate and an improvement in cardiac output in patients with resistant automatic focus tachycardias. It can be used to improve the haemodynamic condition while other measures of arrhythmia control are being pursued or until spontaneous recovery of normal rhythm.

Atrial pacing as an adjunct to the management of post-surgical His bundle tachycardia

OBJECTIVE

To examine the benefits of restoring atrioventricular synchrony to children with His bundle tachycardia after operation for congenital heart disease.

DESIGN

Review of clinical outcome of adopting the technique of R wave synchronised atrial pacing as an adjunct to the management of His bundle tachycardia from September of 1987 till June of 1990.

PATIENTS

Eleven consecutive children (aged between 3 days and 13 years) with haemodynamically significant His bundle tachycardia after cardiopulmonary bypass surgery.

INTERVENTIONS

Atrial pacing synchronised either manually or automatically to the R wave of the His bundle tachycardia was implemented so that atrial depolarisation preceded the following R wave by an appropriate PR interval.

RESULTS

An immediate and sustained increase in mean systemic blood pressure (average 15 mm Hg, range 6-30 mm Hg) was seen with the onset of atrial pacing in 10 of the 11 children. One child, who had undergone a Fontan procedure, developed atrial flutter shortly after the onset of atrial pacing and required direct current cardioversion. Four children died. Of the seven survivors, six have sustained sinus rhythm which returned between two and 10 days after the onset of tachycardia. One of the survivors has severe neurological impairment attributed to a period of low cardiac output during tachycardia; the others are alive and well. In those children who did badly the mean time between arrhythmia occurrence and the start of atrial pacing or cooling or both was nine hours; in those who did well it was one hour.

CONCLUSIONS

Atrial pacing synchronous with the His bundle is a useful adjunct in the management of children with His bundle tachycardia after surgery for congenital cardiac disease.

The pulmonary artery lasso: epicardial pacing lead causing right ventricular outflow obstruction

Permanent pacing in small children may require placement of an epicardial pacing system. This report describes a young child who underwent pacemaker implantation with epicardial ventricular lead placement in infancy as an adjunct to antiarrhythmic therapy for congenital junctional ectopic tachycardia. At 5 years of age, a harsh systolic murmur was detected for the first time. Evaluation by catheterization and transluminal echocardiography showed right ventricular outflow obstruction (pressure gradient 40 mmHg) secondary to extrinsic compression by the epicardial lead. Surgical removal of the lead relieved the obstruction.

Evolving concepts in the management of congenital junctional ectopic tachycardia. A multicenter study

We reviewed the records of 26 infants with congenital junctional ectopic tachycardia (JET) from seven institutions to examine the evolution in the management of this tachycardia that is difficult to treat. JET was defined electrocardiographically as an incessant tachycardia with normal QRS morphology and atrioventricular (AV) dissociation. The ventricular rate ranged from 140 to 370 beats/min (mean, 230 beats/min); 16 of 26 patients had cardiac failure. Treatment success was defined as a stable decrease in the rate of JET, below 150 beats/min; partial success was a significant decrease of JET rate with alleviation of symptoms. All patients received digoxin with no significant effect. Propranolol was given to 16 patients, with two successes and one partial success. Combinations of other conventional agents were used in 11 patients with two successes; 14 patients were treated with amiodarone, which resulted in eight successes and three partial successes; three patients died suddenly on medical treatment (amiodarone, one patient; propranolol, one patient; or amiodarone plus propranolol, one patient); sudden AV block was a possible cause and consequently, two later patients had pacemaker implantation as well as medical treatment. His catheter ablation was successfully performed twice but contributed to death in a newborn; three surgical His ablations were performed for intractable JET with two successes and one death. The overall mortality was 35%. Among survivors, treatment has been stopped without any complications in five patients ranging in age from 10 months to 8 years (mean, 3.5 years). It seems that amiodarone alone is the best drug for treatment of congenital JET; necessity for permanent pacing remains unsettled. His ablation should be reserved only for intractable JET.

Ventricular paired pacing to control intractable junctional tachycardia following open heart surgery in a child

A 5-month-old girl presented postoperatively with an atrioventricular (A-V) junctional tachycardia at a rate of 245/min following surgical repair of tetralogy of Fallot. The systolic blood pressure dropped to 60 mmHg with this rapid heart rate, and the infant became shocked. Drugs and overdrive pacing were ineffective in suppressing the A-V junctional tachycardia and in improving cardiac output. Ventricular paired pacing was used successfully to halve the mechanically effective ventricular rate and to restore cardiac output. When ventricular paired pacing was stopped after 12 h, the spontaneous rhythm was an atrial rhythm with 1-1 A-V conduction. The patient was discharged in sinus rhythm on the 5th postoperative day.

Relative efficacy of various physical manoeuvres in the termination of junctional tachycardia

The ability of four vagotonic physical manoeuvres to terminate paroxysmal junctional tachycardias was tested in 35 patients with inducible and sustained arrhythmia. Each manoeuvre was used up to three times in an attempt to terminate an induced tachycardia and was judged to be effective if it terminated two out of the three induced episodes. The Valsalva manoeuvre in the supine position was effective in 19 (54%), right carotid sinus massage in 6 (17%), left carotid sinus massage in 2 (5%), and the diving reflex in 6 (17%) cases. 4 of the 6 patients who responded to right carotid sinus massage and all patients who responded to the diving reflex also responded to the Valsalva manoeuvre. The Valsalva manoeuvre while standing was effective in 9 (20%) patients only. Patients in whom the manoeuvres terminated the tachycardias were significantly younger than those who did not respond (median age: 30 vs 45 years, p less than 0.01). Physical manoeuvres were much more successful in terminating atrioventricular re-entry tachycardias (19/24) than atrioventricular nodal re-entry tachycardias (3/11, p less than 0.01). Efficacy of the manoeuvres was related to their bradycardic effect in sinus rhythm.

Hypothermia for the treatment of postsurgical greatly accelerated junctional ectopic tachycardia

Three infants developed greatly accelerated junctional ectopic tachycardia with a heart rate greater than 200 beats/min after open heart surgery. When the heart rate exceeded 200 beats/min for 5 hours, all the infants had congestive heart failure and clinical signs of low cardiac output. Conventional therapy (cardioversion, lidocaine, verapamil, digoxin and ice to face) has been shown in the past to be unsuccessful in controlling the heart rate. Because hypothermia is known to decrease automaticity of the heart, these patients were treated with induced hypothermia. The goal was to arbitrarily decrease the junctional ectopic rate to less than 180 beats/min to increase cardiac filling time. The duration of the junctional ectopic tachycardia greater than 180 beats/min ranged from 0.5 to 17 hours after cooling began. The duration of the hypothermia ranged from 4 to 24 hours. Spontaneous reversion to sinus rhythm occurred either during the hypothermia or shortly thereafter in all three patients. The blood pressure and urinary output remained stable during hypothermia. Hypothermia is an effective means of controlling the rate of greatly accelerated junctional ectopic tachycardia after open heart surgery in infants. Although hypothermia does not convert junctional ectopic tachycardia to sinus rhythm, it slows the rate to a more acceptable level, allowing the infants' survival and eventual recovery of sinus rhythm.