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Junctional Ectopic Tachycardia

  • Author: M Silvana Horenstein, MD; Chief Editor: Stuart Berger, MD  more...
 
Updated: Feb 11, 2014
 

Background

Junctional ectopic tachycardia (JET) is characterized by rapid heart rate for a person's age that is driven by a focus with abnormal automaticity within or immediately adjacent to the atrioventricular (AV) junction of the cardiac conduction system (ie, AV node–His bundle complex). It does not have the electrophysiologic features associated with reentrant tachycardia (eg, AV node reentry) because this form of tachycardia does not respond to a single extrastimulus, does not convert with programmed stimulation or cardioversion, and may or may not have ventriculoatrial (VA) dissociation; also, administration of adenosine results in VA dissociation without termination. The QRS is usually normal, and retrograde P waves may be seen in the terminal portion of the QRS.

JET primarily occurs in 2 forms: idiopathic chronic junctional ectopic tachycardia, which is observed in the setting of a structurally normal heart, and transient postoperative junctional ectopic tachycardia occurs following repair of congenital heart disease.

In addition, nonparoxysmal junctional tachycardia is a related but rare pattern of arrhythmia that can be observed in the setting of digoxin toxicity.

For patient education resources, see Heart Health Center, as well as Supraventricular Tachycardia.

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Pathophysiology

The pathophysiology of JET is unclear. Postoperative JET is associated with manipulation within the crux of the heart. It is believed to be secondary to trauma, infiltrative hemorrhage, or inflammation of the conduction tissue.[1] The incidence of JET after cardiac surgery is approximately 14%. Specifically, tetralogy of Fallot repair and longer aortic cross clamp times increase the risk of developing postoperative JET.[2] Congenital JET is rare and difficult to control. It is most often incessant, and many patients require multiple antiarrhythmic medications, ablation, and even pacemaker insertion due to resultant complete AV node block.

As implied by the synonym junctional automatic tachycardia, the mechanism may be automaticity. Others have suggested that triggered activity is responsible for this disorder.[3]

The location of the responsible tissue is probably truly ectopic to the primary conduction pathway of the AV junction because JET has been successfully treated by the application of radiofrequency catheter lesions without the production of AV block. Intracardiac mapping shows a normal heart volume interval and VA dissociation, or VA association if VA conduction is present.

Junctional acceleration, albeit at a lesser rate than typical JET, is a recognized phenomenon during and following radiofrequency energy delivery for modification of slow pathway conduction in the therapy of AV node reentry.

Histamine, eosinophil cation protein, or other products of mast cell, eosinophil, or basophil degranulation that are liberated in response to cardiopulmonary bypass have been implicated in the genesis of transient postoperative JET. The relative levels of various cytokines may also play a role. Low magnesium levels have been noted in children who develop JET following cardiopulmonary bypass surgery.

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Prognosis

Spontaneous resolution of congenital junctional ectopic tachycardia (JET) has been observed in as many as one third of patients who reach age 1 year. Patients who continue to experience JET may do so at slower rates.

Curative attempts with radiofrequency catheter ablation therapy are probably warranted in patients with uncontrolled JET or if their size and age is sufficient to minimize procedural risks. Nevertheless, permanent AV block is a significant potential risk in the ablation of congenital JET.

Postoperative JET usually subsides after 36 hours without recurrence.

Morbidity/mortality

Although not a frequent type of arrhythmia, JET is one of the most serious and difficult-to-treat supraventricular tachycardias. Rare case reports have suggested that JET may be associated with progression to complete AV block. This does not appear to be the case in postoperative JET and has not been the author's experience in the rare cases of idiopathic JET.

Postoperative JET is usually transient and begins upon rewarming the patient. Its morbidity and mortality relates to the fact that it occurs at an extremely vulnerable period following cardiac surgery, when nodal inflammation and ischemia may be present and ventricular function is often diminished. The additional insults of poor ventricular filling because of tachycardia and the loss of AV sequential contraction are considered to significantly contribute to morbidity and mortality. However, if the JET rate is not too fast or is somewhat faster than the sinus node rate, it can be well tolerated until JET spontaneously subsides.

In a large series of patients with postoperative JET, dopamine use and an age less than 6 months were associated with the development of this tachycardia.[4] However, only 39% of patients required intervention.

Congenital JET occurs in neonates and infants as an incessant tachycardia that usually results in tachycardia-induced cardiomyopathy. Mortality in these patients has been reported to be as high as 34% and may occur secondary to congestive heart failure, sudden onset of ventricular fibrillation, and sudden evolution to paroxysmal complete AV block and as result of proarrhythmic effect of drug therapy and medical interventions.

In fetuses with JET (as well as those with ventricular tachycardia) third-degree AV block should be ruled out.[6]

Age

JET is one of the rarest forms of supraventricular tachycardia in infants. Congenital JET is presumed to be present from birth but may not be identified until months or years later.

Postoperative JET most commonly occurs in younger patients (it was found to occur more frequently in patients younger than 6 mo) but is also known to occur in teenagers and adults after cardiopulmonary bypass surgery.

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Epidemiology

Frequency

United States

Postoperative JET occurred in 5.6% of 594 patients who underwent cardiac surgery.[4] JET was seen more frequently with postoperative use of dopamine and in younger patients.

International

In one series, postoperative JET was identified in 7.5% of young patients undergoing Fontan procedures. Another recent series described JET in 10.2% of 874 pediatric patients undergoing cardiopulmonary bypass.[5]

Postoperative JET that required intervention was identified in 1.5% of infants undergoing the arterial switch procedure. It was also seen in 21.9% of patients who had undergone cardiac surgery for tetralogy of Fallot.[1]

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Contributor Information and Disclosures
Author

M Silvana Horenstein, MD Assistant Professor, Department of Pediatrics, University of Texas Medical School at Houston; Medical Doctor Consultant, Legacy Department, Best Doctors, Inc

M Silvana Horenstein, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Medical Association

Disclosure: Nothing to disclose.

Coauthor(s)

Robert Murray Hamilton, MD, MSc, FRCPC Electrophysiologist, Senior Associate Scientist, Physiology and Experimental Medicine, Labatt Family Heart Centre; Professor, Department of Pediatrics, University of Toronto Faculty of Medicine

Robert Murray Hamilton, MD, MSc, FRCPC is a member of the following medical societies: American Heart Association, Canadian Medical Association, Ontario Medical Association, Royal College of Physicians and Surgeons of Canada, Canadian Medical Protective Association, Heart Rhythm Society, Canadian Cardiovascular Society, Cardiac Electrophysiology Society, Pediatric and Congenital Electrophysiology Society, Society for Pediatric Research

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Hugh D Allen, MD Professor, Department of Pediatrics, Division of Pediatric Cardiology and Department of Internal Medicine, Ohio State University College of Medicine

Hugh D Allen, MD is a member of the following medical societies: American Academy of Pediatrics, American Society of Echocardiography, Society for Pediatric Research, Society of Pediatric Echocardiography, Western Society for Pediatric Research, American College of Cardiology, American Heart Association, American Pediatric Society

Disclosure: Nothing to disclose.

Chief Editor

Stuart Berger, MD Medical Director of The Heart Center, Children's Hospital of Wisconsin; Associate Professor, Department of Pediatrics, Section of Pediatric Cardiology, Medical College of Wisconsin

Stuart Berger, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American College of Chest Physicians, American Heart Association, Society for Cardiovascular Angiography and Interventions

Disclosure: Nothing to disclose.

Additional Contributors

Charles I Berul, MD Professor of Pediatrics and Integrative Systems Biology, George Washington University School of Medicine; Chief, Division of Cardiology, Children's National Medical Center

Charles I Berul, MD is a member of the following medical societies: American Academy of Pediatrics, Heart Rhythm Society, Cardiac Electrophysiology Society, Pediatric and Congenital Electrophysiology Society, American College of Cardiology, American Heart Association, Society for Pediatric Research

Disclosure: Received grant/research funds from Medtronic for consulting.

References
  1. Dodge-Khatami A, Miller OI, Anderson RH, et al. Surgical substrates of postoperative junctional ectopic tachycardia in congenital heart defects. J Thorac Cardiovasc Surg. 2002 Apr. 123(4):624-30. [Medline].

  2. Zampi JD, Hirsch JC, Gurney JG, Donohue JE, Yu S, LaPage MJ, et al. Junctional ectopic tachycardia after infant heart surgery: incidence and outcomes. Pediatr Cardiol. 2012 Dec. 33(8):1362-9. [Medline].

  3. Liu CF, Ip JE, Lin AC, Lerman BB. Mechanistic Heterogeneity of Junctional Ectopic Tachycardia in Adults. Pacing Clin Electrophysiol. 2011 Sep 28. [Medline].

  4. Hoffman TM, Bush DM, Wernovsky G, et al. Postoperative junctional ectopic tachycardia in children: incidence, risk factors, and treatment. Ann Thorac Surg. 2002 Nov. 74(5):1607-11. [Medline].

  5. Andreasen JB, Johnsen SP, Ravn HB. Junctional ectopic tachycardia after surgery for congenital heart disease in children. Intensive Care Med. 2008 May. 34(5):895-902. [Medline].

  6. Zhao H, Cuneo BF, Strasburger JF, Huhta JC, Gotteiner NL, Wakai RT. Electrophysiological characteristics of fetal atrioventricular block. J Am Coll Cardiol. 2008 Jan 1. 51(1):77-84. [Medline].

  7. Borgman KY, Smith AH, Owen JP, Fish FA, Kannankeril PJ. A genetic contribution to risk for postoperative junctional ectopic tachycardia in children undergoing surgery for congenital heart disease. Heart Rhythm. 2011 Dec. 8(12):1900-4. [Medline]. [Full Text].

  8. Imamura M, Dossey AM, Garcia X, Shinkawa T, Jaquiss RD. Prophylactic amiodarone reduces junctional ectopic tachycardia after tetralogy of Fallot repair. J Thorac Cardiovasc Surg. 2011 Oct 27. [Medline].

  9. Saul JP, Scott WA, Brown S, et al. Intravenous amiodarone for incessant tachyarrhythmias in children: a randomized, double-blind, antiarrhythmic drug trial. Circulation. 2005 Nov 29. 112(22):3470-7. [Medline].

  10. Imamura M, Dossey AM, Garcia X, Shinkawa T, Jaquiss RD. Prophylactic amiodarone reduces junctional ectopic tachycardia after tetralogy of Fallot repair. J Thorac Cardiovasc Surg. 2012 Jan. 143(1):152-6. [Medline].

  11. Guccione P, Di Carlo D, Papa M, et al. [Hypothermia treatment of junctional ectopic tachycardia after surgical repair of congenital heart defects]. G Ital Cardiol. 1990 May. 20(5):415-8. [Medline].

  12. Pfammatter JP, Paul T, Ziemer G, Kallfelz HC. Successful management of junctional tachycardia by hypothermia after cardiac operations in infants. Ann Thorac Surg. 1995 Sep. 60(3):556-60. [Medline].

  13. Walsh EP, Saul JP, Sholler GF, et al. Evaluation of a staged treatment protocol for rapid automatic junctional tachycardia after operation for congenital heart disease. J Am Coll Cardiol. 1997 Apr. 29(5):1046-53. [Medline].

  14. Wu MH, Lin JL, Chang YC. Catheter ablation of junctional ectopic tachycardia by guarded low dose radiofrequency energy application. Pacing Clin Electrophysiol. 1996 Nov. 19(11 Pt 1):1655-8. [Medline].

  15. Manrique AM, Arroyo M, Lin Y, El Khoudary SR, Colvin E, Lichtenstein S, et al. Magnesium supplementation during cardiopulmonary bypass to prevent junctional ectopic tachycardia after pediatric cardiac surgery: a randomized controlled study. J Thorac Cardiovasc Surg. 2010 Jan. 139(1):162-169.e2. [Medline].

  16. Emmel M, Sreeram N, Brockmeier K. Catheter ablation of junctional ectopic tachycardia in children, with preservation of atrioventricular conduction. Z Kardiol. 2005 Apr. 94(4):280-6. [Medline].

 
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Lead II rhythm strip of a surface ECG from a patient with postoperative JET. Atrial activity (P) is marked with blue lines and ventricular depolarization (QRS) is marked in red. Note the narrow QRS complexes due to their origin at the AV junction. Also note the dissociation between atrial and ventricular depolarizations where some of the QRS complexes seem to "follow" the P waves. However, this is not possible because the PR intervals are exceedingly short to allow conduction. In addition, some of the P waves fall after the QRS.
 
 
 
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