Junctional Ectopic Tachycardia in Children: Electrocardiography, Electrophysiology and Pharmacologic Response ARTHUR GARSON, Jr., MD PAUL C. GILLETTE, MD, FACC
Junctional tachycardia due to an automatic ectopic focus occurs in children in one of two clinical settings: (1) in the immediate postoperative period after surgery, near the atrioventricular (A-V) junction, and (2) spontaneously, causing chronic supraventricular tachycardia. In the surface electrocardiogram, junctional ectopic tachycardia appears as a narrow QRS tachycardia with A-V dissociation. This study evaluated four children, including two sisters, with junctional ectopic tachycardia; intracardiac electrophysiologic recordings were performed in three of them. In each child, ventricular depolarization was preceded by a His bundle potential and a normal H-V interval. Neither overdrive pacing nor programmed premature stlmulation of the atria or the ventricles influenced the tachycardia. Digoxin failed to alter the tachycardia, but alleviated congestive heart failure in all four patients. Propranolol slowed the rate of tachycardia in two patients, as did reserpine and phenytoin in one patient each. Chlorpromazine resulted in sinus rhythm in one patient. Duinidine and lidocalne were ineffective. Two patients died, one from low cardiac output associated with uncontrolled tachycardia, the other suddenly and unexpectedly while receiving digoxin and propranolol. The third patient’s tachycardia regressed after repair of a ventricular septal defect. She has had sinus rhythm for 9 months without medication. The tachy cardia of the fourth patient Is uncontrolled despite treatment with digoxin, propranolol and phenytoin. On the basis of this study, acute treatment of junctional ectopic tachycardia is recommended in the immediate postoperative period with intravenous propranolol (with a ventricular pacemaker available to treat bradycardia) and long-term treatment with oral digoxin plus either propranolol, phenytoin or chlorpromazine.
From the Lillie Frank Abercrombie Section of Cardiology, Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas. This study was supported in part by &ant RR-00 188 from the General Clinic Research Branch and Grant HL07190 from the National InstiMes of Health, U.S. Public Health Service, Bethesda, Maryland, and by a grant from Mr. Alexander Adams, Houston Texas. Manuscript received January 2, 1979; revised manuscript received March 20, 1979, accepted April 2, 1979. Address for reprints: Arthur Carson, Jr., MD, Baylor College of Medicine, Texas Children’s Hospital, 8821 Fannin, Houston Texas 77030.
Supraventricular tachycardia is the most common sustained tachyarrhythmia observed in chi1dren.l It occurs most often in infancy, and is generally seen as a regular tachycardia without discernible P waves in the surface electrocardiognnn2 The mechanism in most cases is reentry, and treatment with digoxin is usually effective.2*3 Keane et al4 described a less common form of supraventricular tachycardia in children4 in which P waves precede each QRS complex. The rhythm is more difficult to control and has been attributed to an atrial ectopic focus5 Least common is supraventricular tachycardia with atrioventricular (A-V) dissociation.l This is the most difficult to control and occurs in one of two clinical settings: (1) in the immediate postoperative period after surgery near the A-V junction, and (2) spontaneously, causing chronic supraventricular tachycardia.6s We thoroughly studied three such children and one of their sisters who had the same type of tachycardia. We believe that this type of supra-
Journal of CARDIDLDGY
TABLE I Four Patients Wlth Junctional Ectopic Tachycardia Case no.
Age at Diagnosis (days)
Rate of Tachycardia (beats/min)
160 220 260
P Wave Descriotion Followed each QRS complex, inverted in leads I, II, Ill and aVF A-V dissociation (normal P axis) A-V dissociation A-V dissociation
VSD, PDA, coarctation
VSD, Qp:Qs = 2:1 Cardiomyopathy No defects on clinical examination
Alive Alive Dead
AV = atrioventricular; PDA = patent ductus arteriosus; Qp:Qs = pulmonary to systemic flow ratio: VSD = ventricular septal defect.
tachycardia occurs as a result of an automatic ectopic focusg-I1 in the A-V junction. In this paper we define the electrocardiographic, electrophysiologic and pharmacologic characteristics of junctional ectopic tachycardia in children and suggest a plan for acute management in the postoperative period and long-term management of chronic tachycardia based on the knowledge of the mechanism. ventricular
Methods Patients (Table I): Four infants presented with junctional ectopic tachycardia. Three of these patients, aged 7 days to 2 months at the time of diagnosis, had a complete intracardiac electrophysiologic examination. The fourth patient (Case 4) had an electrocardiographic pattern similar to her sister’s (Case 3) but died at age 3 weeks without undergoing electrophysiologic study. Two of the four patients (Cases 1 and 2) had structural congenital heart defects (Table I). Patient evaluation: Each infant was first evaluated on the basis of history and physical examination, 15 lead electrocardiogram and chest roentgenogram. In Patients 2 and 3, all medications were discontinued 24 hours before the intracardiac electrophysiologic study (Patient 1 was receiving digoxin). All except Patient 1 were sedated with meperidine, 2 mg/kg, chlorpromazine, 0.5 mg/kg and promethazine, 0.5 mg/kg, 30 minutes before the study. One or two electrode catheters were inserted percutaneously into the femoral veins and positioned in the right side of the heart under fluoroscopic and electrocardiographic control for recording intracardiac electrograms. Atria1 and ventricular pacing and introduction of premature stimuli were performed as previously reported.3J2
developed during cardiac catheterization. In this patient, a 2 week old infant with severe congestive heart failure, it is possible that catheter manipulation induced the tachycardia. Surface electrocardiography revealed repetitive tachycardia in Patient 2 and persistent tachycardia in the other three patients, according to the definition of Keane et a1.4 Distinct P waves could be seen in the tracings of all four patients. In three patients, A-V dissociation was apparent with independent atria1 and ventricular rates (Fig. 1). Patient 1 manifested 1:l retrograde capture of the atria, and inverted P waves followed the QRS complex in the inferior limb leads. In each patient, the rate of the tachycardia varied from minute to minute. Intracardiac electrography: This study revealed that the tachycardia originated in the atrioventricular (A-V) junction in all patients. The ventricular depolarization was preceded by a His bundle potential with a normal H-V interval. In Patients 2 and 3, atria1 depolarizations were unrelated to the His and ventricular depolarizations (Fig. 2). In Patient 1, high right atria1 depolarization occurred after each His and low right atria1 depolarization, indicating retrograde atria1 activation with 1:l capture from the junctional tachycardia. The mechanism of the tachycardia was determined in each case to be an automatic focus based on previ-
Drug therapy: Drug therapy, other than premeditation, was given to only one patient (Case 1) in the catheterization laboratory. He received phenytoin, 5 mg/kg, and lidocaine, 1 mg/kg, each as an intravenous bolus injection. In all four cases, digoxin was selected as the initial drug for long-term treatment of tachycardia. If digoxin proved ineffective, a second drug was added. Before any drug was declared ineffective, the dose was increased until clinical signs of mild toxicity developed or the serum concentration was in the upper part of the range of effectiveness. Frequently, various drug combinations were used. The drug doses used and effective serum concentrations are given in Table II. The results of treatment were observed clinically by electrocardiogram in follow-up periods ranging from 1 day (in the patient who died in the hospital) to 6 years.
Results Clinical features: In three patients the tachycardia occurred spontaneously (Table I), and in Patient 1 it
TABLE II Drugs Used to Treat Junctional Ectopic Tachycardla
Oral Dosage (range) (mg/kg)
Digoxin Quinidine sulfate Propranolol Phenytoin Reserpine Chlorpromazine
0.005- 0.01 every 12 hours 7.5-10.0 every 6 hours 0.5-2.0 every 6 hours 1.5-3.0 every 6 hours 0.01-0.02 every 12 hours 0.5-l .O every 6 hours
Therapeutic Serum Concentration+ &g/ml) 0.5-2.5 2.3-5.0 5.0-50.0 ng/ml 10.0-20~0 t
Loading doses are required for digoxin and phenytoin. These doses are given as many times per day as indicated. For the total daily dose, multi ly digoxin X2, quinidine X4, etc. +8 oncentrations may vary between laboratories. These concentrations are from our laboratory. r Serum concentrations were not routinely available for chlorpromazine and reserpine.
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JUNCTIONAL ECTOPIC TACHYCARDIA
FIGURE 1. Case 3. Surface electrocardiogram (limb leads) at age 18 months showing junctional tachycardii with atrioventricular dissociation. The QRS rate is 215 and the atrial rate 95 beats/min. There is no evidence of an atrial depolarization conducting to the ventricles nor of a ventricular depolarization conducting retrograde to ths atria. The P wave axis is normal, indicating an origin of the atrial depolarization near the sinus node.
FIGURE 2. Case 3. Surface electrocardiographic leads (L) I, II and Ill recorded simultaneously with His bundle electrograms (HBE) during junctional ecotopic tachycardia. Each ventricular depolarization (at a cycle length [CL]) of 294 msec is preceded by a His bundle depolarization (H) with a normal H-V interval of 31 msec. Low right atrial (LBA) depolarizations occur independently every 480 msec. The vertical lines are 1,000 msec time lines. PW = patient’s initials.
In all patients the atria ously proposed criteria. 5~11~13 could be paced at a rate faster than the existing rate of tachycardia. This resulted in 1:l conduction to the ventricles. Similarly, rapid ventricular pacing resulted in capture of the ventricles. Despite the ability to capture and overdrive the atria and ventricles it was not possible to suppress the rate of the ectopic focus in any patient. It was also impossible to start or stop the tachycardia either with overdrive atria1 (Fig. 3) or
ventricular (Fig. 4) pacing or with single premature depolarizations. Direct current cardioversion failed in the one patient in whom it was tried. Drug therapy: In all patients, digoxin aided in controlling the symptoms of congestive heart failure, but when used alone it did not affect the rate of the tachycardia. The various effects of different drugs are listed in Table III. Follow-up: Patient 1 died 12 hours after onset of the tachycardia. He became severely hypotensive with the rapid heart rate. Drug therapy was ineffective. He was returned to the catheterization laboratory where rapid
FIGURE 3. Case 3. Right atrial pacing. Surface electrocardiographic leads(L) I, II and Ill and the high right atrial (m(A) stimulus are recorded. In the first four cycles each atrial stimulus is conducted to the ventricles (V), thus suppressing the tachycardia. After termination of atrial pacing (last Pi) the junctional tachycardia immediately resumes. The vertical lines are 1,000 msec time lines.
FIGURE 4. Case 3. Right ventricular pacing (Pi, first four cycles). Surface electrocardiographic leads I, II and Ill, and the right ventricular apex (RVA) electrogram are recorded. Immediately after ventricular pacing, tachycardia resumes. The vertical lines are 1,000 msec time lines.
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overdrive atria1 pacing captured the atria and resulted in intermittent 21 A-V block. The child was in extremis at the time and died shortly thereafter. Patient 2 is almost 4 years old. She underwent uneventful closure of a large ventricular septal defect at age 2 years. She had had sinus rhythm both before and after operation while receiving digoxin and chlorpromazine. One year after operation, the drug dosages were decreased and she maintained sinus rhythm. She has had no medication for 9 months and continues to have sinus rhythm. Patient 3 continues to have junctional ectopic tachycardia, but the rate is 110 to 130 beats/min. She is currently taking digoxin, phenytoin and propranolol. The left ventricular shortening fraction, assessed from the echocardiogram, remains abnormal but has improved since therapy was begun. Patient 4, the sister of Patient 3, died at age 3 weeks. The day before her death, while under treatment with digoxin and propranolol, she had a heart rate of 120 beats/min on physical examination. During her terminal episode, the heart rate reportedly slowed and she became cyanotic, with a respiratory rate of 90/min. The exact cause of death was not determined. An autopsy was not performed. Discussion Features of junctional ectopic tachycardia: All four patients were young (less than 8 weeks at the time of diagnosis) and three of the four had a greatly accelerated junctional heart rate (in excess of 200 beats/min). In patients whose junctional ectopic tachycardia occurs in the immediate postoperative period, the heart rate is generally slower (130 to 160 beats/min) and the arrhythmia is better tolerated. The surface electrocardiogram of three of the four children showed A-V dissociation. Although it is theoretically possible to have atria1 tachycardia with A-V dissociation,14J5 we believe that tachycardia with a narrow QRS complex with A-V dissociation originates in the A-V junction. It is not possible to define the mechanism of the tachycardia from the surface electrocardiogram. If the tachycardia does not respond to direct current cardioversion, it is more likely to be due to an ectopic focus.5J1 The diagnosis of an ectopic focus is confirmed by intracardiac stimulation studies.“~l’J” Recently, the distinction between ectopic focus and reentry has become less clear,*6 but we believe the clinical electrophysiologic distinction is useful because it separates patients into two groups that respond differently to management. Management of junctional ectopic tachycardia: Drug therapy: Our findings and those of others5-8 in-
dicate that junctional ectopic tachycardia is exceedingly difficult to control with medication. In the acute situation, intravenous lidocaine or phenytoin or intramuscular reserpine may be effective. Intravenous propranolol(O.01 mg/kg) can be used, but we suggest prior placement of a temporary ventricular pacemaker (to act as a safeguard should the heart rate decrease to an unacceptable level). Propranolol should be used cautiously in any patient with congestive heart failure.
TABLE III Response
to Drug Therapy Case 1
Digoxin Lidocaine Digoxin -I quinidine Digoxin -Ipropranolol Digoxin + Yeserpine Digoxin -Ichlorpromazine Digoxin + phenytoin Current
in Four Cases Case 3
Digoxin, propran0101, pnenytorn
E = effective; (E’) = effective but use discontinued because of lethargy and drowsiness; (Et) = effective but use discontinued because of ataxia; I = ineffective in treating tachycardia (digoxin effective in treating congestive heart failure); = drug not used.
In the chronic situation, we would begin with digoxin to treat the myocardial dysfunction that coexists in most patients with long-standing tachycardias.5 We would next add propranolol except in patients with severe congestive heart failure. Other drugs to be tried include chlorpromazine, reserpine and phenytoin. A combination of two drugs in addition to digoxin may be needed. Coumel et al.8 found amiodarone effective in decreasing the rate of tachycardia, but this drug is not available for general use in the United States. Temporary pacing: Waldo et a1.6described a case of junctional ectopic tachycardia in which paired ventricular pacing was used to halve the mechanically effective ventricular rate. We agree that this is the treatment of choice in patients with acute symptoms due to junctional ectopic tachycardia. Unfortunately, the method requires the use of a technique of paired pacing that is not available at all hospitals. If the ventricular rate can be controlled in this manner, drug therapy may then be carried on in a less hurried manner. Surgery: A theoretic and rather extreme therapy for chronic junctional ectopic tachycardia is surgical ablation of the bundle of His and installation of a permanent ventricular pacemaker. This has not been required in our experience to date. Differentiation
from atria1 ectopic tachycardia:
In atria1 ectopic tachycardia, P waves were generally clearly visible and precede each QRS complex with a P-R interval that is either normal or at the upper limit of normal for age.‘) Because both types of tachycardia are ectopic, the responses to cardioversion, overdrive pacing and premature stimulation are the same. Response to drug therapy differs. Although the same drugs are generally used, drug treatment results in a greater degree of control of atria1 ectopic tachycardia than of junctional ectopic tachycardia. Finally, it is of interest that none of our seven patients with atria1 ectopic tachycardia previously reported on5 had an associated congenital heart defect, whereas two
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JUNCTIONAL ECTOPIC TACHYCARDIA
of the four with junctional ectopic tachycardia had structural congenital heart defects. None of the patients with atria1 ectopic tachycardia died. Etiology of junctional ectopic tachycardia: At least two distinct causes of junctional ectopic tachycardia have been postulated. The first is trauma. Patient 1 most likely had trauma to the bundle of His region at cardiac catheterization, and the patient described by Waldo et a1.6had sutures placed near the bundle of His at the time of a Mustard operation. A second cause of junctional ectopic tachycardia is a hereditary factor. Two of our patients were sisters and their electrocardiograms were indistinguishable. Brechenmacher et a1.7recently described a patient with supraventricular tachycardia (which we would interpret as junctional ectopic tachycardia) who had a degenerated bundle of His at postmortem examination. This
patient had a first cousin with the identical form of tachycardia. Thus, degeneration of the conduction system can be manifested by tachycardia as well as by A-V block. Our data demonstrate that junctional ectopic tachycardia is a life-threatening arrhythmia in children. Its association with congenital heart disease may be related to injury to cells in the region of the bundle of His caused by procedures such as cardiac catheterization and surgery. These injured cells may display increased automaticity. It is tempting to associate degeneration of the His bundle with familial junctional ectopic tachycardia, but this conclusion needs further pathologic support. Unfortunately, in our Case 4 the heart is not available for detailed pathologic examination. It is indeed possible that this patient died from complete A-V block.
References 1. Fink B, Mandel WJ: Supraventricular arrhythmias. In, Cardiac Arrhythmias in the Neonate, Infant and Child (Roberts NK, Gelband ii, ed). New York, Appleton-Century-Crofts, 1977, p 184-186 Nadas AS, Fyler DC: Pediatric Cardiology, third edition. Philadelphia, WE! Saunders, 1972, p 66 Gliiette PC: The mechanisms of supraventricular tachycardia in children. Circulation 54:133-139, 1976 Keane JF, Piauth WH, Nadas AS: Chronic ectopic tachycardia in infancy and childhood. Am Heart J 84~748-757, 1972 Gillette PC, Garson A: Electrophysiologic and pharmacologic characteristics of automatic ectopic atrial tachycardia. Circulation 56:571-575, 1977 6. Waldo AL, Krongrad E, Kupersmith J, Levine OR, Bowman FO, Hoffman BF: Ventricular paired pacing to control rapid ventricular heart rate following open heart surgery. Circulation 53: 176- 180, 1976 7. Brechenmacher C, Coumel P, James TN: Intractable tachycardia in infancy. Circulation 53:377-381, 1976 8. Coumel P, Fidelie JE, Aitwel P, Brechenmacher C, Batisse A, Brelagne J, Cfementy J, Gerard R, Groiieau R, Huatt G, Mouy A, Nouallie J, Kachaner J, Rlbiere Y, Toumieux MD: Tachycardies focales Hissienes congenitales. Arch Mal Coeur 69:899-909,
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1975 9. Bigger JT Jr, Goidreyer BN: The mechanism of supraventricular tachycardia. Circulation 42:673-688, 1970 IO. Goidreyer BN, Bigger JT Jr: Site of reentry in paroxysmal supraventricular tachycardia in man. Circulation 43: 15-26, 197 1 11. Goldreyer BN, Galiaher JJ, Damato AN: The electrophysiologic demonstration of atrial ectopic tachycardia in man. Am Heart J 85:205-215, 1973 12. Gillette PC, Reltman MJ, Gutgesell HP, Vargo TA, Mulilns CE, McNamara DGr Intracardiac electrograohy in children and young adults. Am Heart J 89:36-44, 1975 13. Scheinman MM, Basu D, Hoiienberg M: Electrophysiologic studies In patients with persistent atrial tachycardia. Circulation 50: 266-273, 1974 14. Zlpes DP, Gaunt WE, Genetos BC, Giaesman RD. Noble RJ. Fisch C: Atrial tachycardia without P waves masquerading as an A-V junctional tachycardia. Circulation 55253-260, 1977 15. Josephson ME, Kaator JA: Paroxysmal supraventricular tachycardia. Is the atrium a necessary link? Circulation 54:430-435, 1976 16. Wit AL, Cranefleid PF: Triggered activity in cardiac muscle fibers of the simian mitral valve. Circ Res 38:85-98, 1976