Ivabradine is an effective antiarrhythmic therapy for congenital junctional ectopic tachycardia-induced cardiomyopathy during infancy: Case studies.

Junctional ectopic tachycardia (JET) is a rare form of arrhythmia that is most commonly seen during infancy. JET is continuous and incessant, characterized by persistently high heart rates that may result in impaired cardiac function and tachycardia-induced cardiomyopathy. Despite the availability of multiple antiarrhythmic treatments, including flecainide and amiodarone, management of JET is generally very difficult. Catheter ablation has a high risk of atrioventricular block and it may require the placement of a pacemaker. Ivabradine, also known as a cardiac pacemaker cell inhibitor, is a new-generation antiarrhythmic used to treat sinus tachycardia and angina pectoris in adult patients. In this article, we present three cases of subjects with infantile congenital JET who were admitted to our clinic with a tachycardia-induced cardiomyopathy. The age of the subjects ranged from 52 days to 10 months. Although the cases of tachycardia could not be controlled by multiple antiarrhythmics, including a combination of amiodarone and flecainide combined with either propranolol or digoxin, they were rapidly converted into sinus rhythm with an ivabradine treatment of 0.1-0.2 mg/kg/day. No cardiac or other side effects were observed during ivabradine treatment, and left ventricular functions and rhythms improved within 24 hours. These three cases therefore provide hope that ivabradine may be a suitable standard initial treatment for congenital JET. However, additional research is needed to confirm the validity of these results in other circumstances.

[Permanent junctional reciprocating tachycardia causing cardiomyopathy in an adult woman]. / Permanente junktionale Reentrytachykardie als Kardiomyopathie-Ursache bei einer erwachsenen Frau.

A 35-year-old female was referred with progressive dyspnoea and elevated heart rate. Surface electrocardiography (ECG) showed supraventricular tachycardia (SVT) with long RP interval and inverse P waves. ECG revealed left ventricular dilation and severe systolic dysfunction. An electrophysiological (EP) examination was performed due to incessant SVT despite betablocker medication. Permanent junctional reciprocating tachycardia (PJRT) was diagnosed and successfully ablated. During follow-up, the patient's symptoms abated and ECG parameters normalized. PJRT is usually found in infants and children, but should also be considered as a rare cause of incessant SVT and tachycardiomyopathy in adults.

Effect of dexmeditomidine on postoperative junctional ectopic tachycardia after complete surgical repair of tetralogy of Fallot: A prospective randomized controlled study.

INTRODUCTION: Incidence of junctional ectopic tachycardia (JET) after repair of tetralogy of Fallot (TOF) is 5.6-14%. Dexmeditomidine is a a-2 adrenoceptor agonist modulates the release of catecholamine, resulting in bradycardia and hypotension. These effects are being explored as a therapeutic option for the prevention of perioperative tachyarrhythmia. We undertook this study to examine possible preventive effects of dexmedetomidine on postoperative JET and its impact on the duration of ventilation time and length of Intensive Care Unit stay. METHODS: After obtaining approval from the hospitals ethics committee and written informed consent from parents, this quasi-randomized trial was initiated. Of 94 patients, 47 patients received dexmedetomidine (dexmedetomidine group) and 47 patients did not receive the drug (control group). RESULTS: Dexmedetomidine group had more number of complex variants like TOF with an absent pulmonary valve or pulmonary atresia (P = 0.041). Hematocrit on cardiopulmonary bypass (CPB), heart rate while coming off from CPB and inotrope score was significantly low in the dexmedetomidine group compared to control group. The incidence of JET was significantly low in dexmedetomidine group (P = 0.040) compared to control group. CONCLUSIONS: Dexmedetomidine may have a potential benefit of preventing perioperative JET.

A genetic contribution to risk for postoperative junctional ectopic tachycardia in children undergoing surgery for congenital heart disease.

BACKGROUND: Junctional ectopic tachycardia (JET) is a common arrhythmia complicating pediatric cardiac surgery, with many identifiable clinical risk factors but no genetic risk factors to date. OBJECTIVE: To test the hypothesis that the angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphism associates with postoperative JET. METHODS: DNA samples were collected from children undergoing the Norwood procedure; arterial switch operation; and repairs of Tetralogy of Fallot, balanced atrioventricular septal defect, and ventricular septal defect at a single center. The incidence of postoperative JET was associated with previously identified clinical risk factors and ACE I/D genotype. RESULTS: Of the 174 children who underwent the above-mentioned surgeries, 21% developed JET. Postoperative JET developed in 31% of children with the D/D genotype but only in 16% of those with the I/I genotype or the I/D genotype (P = .02). Clinical predictors of JET were selected a priori and included age, inotrope score, cardiopulmonary bypass time, and cross-clamp time. Multivariable logistic regression identified a significant correlation between the D/D genotype and postoperative JET independent of these predictors (odds ratio = 2.4; 95% confidence interval, 1.04-5.34; P = .04). A gene-dose effect was apparent in the homogeneous subset of subjects with atrioventricular septal defect (58% JET in D/D subjects, 12% JET in I/D subjects, and 0% JET in I/I subjects; P <.01). CONCLUSION: The common ACE deletion polymorphism is associated with a greater than 2-fold increase in the odds of developing JET in children undergoing surgical repair of atrioventricular septal defect, Tetralogy of Fallot, ventricular septal defect or the Norwood and arterial switch procedures. These findings may support the potential role of the renin-angiotensin-aldosterone system in the etiology of JET.

Cryoablation of junctional tachycardia at high risk of atrio-ventricular block.

INTRODUCTION: Transcatheter cryoablation is an alternative option for the treatment of supraventricular tachycardia, due to its very low risk of permanent atrio-ventricular block. However, the overcost of cryocatheter and the high recurrence rate of this emerging technology braked its large use. This study reports the results of an approach using cryoablation for the treatment of junctional tachycardia (JT) in selected patients at high risk of atrio-ventricular (AV) block. PATIENTS AND METHODS: Out of a series of 199 patients with JT treated by catheter ablation, 26 benefited from cryoablation (mean age 32.8+/-15 years, 15 males). The indications were the presence of an accessory pathway with a high risk of atrio-ventricular block (n=7), a slow pathway difficult to ablate, with a risk of atrio-ventricular block (n=7), a recurrence after a RF procedure, during which a transient atrio-ventricular block has occurred (n=4), and finally patients at young age (n=8). RESULTS: The primary success rate was 92%. No permanent AV block has been reported, neither with RF nor with cryoablation. The recurrence rate at 9+/-10 months was at 29% after cryoablation and 8.6% after RF. In case of AV nodal reentrant tachycardia, the additional cost of cryotherapy catheter has been avoided in 76.85% of cases. The use of a cryotherapy catheter and RF catheter has been necessary for the remaining cases. CONCLUSION: This study demonstrates that an approach, reserving cryoablation in selected patients at high risk of AV block is an alternative strategy to "the systematic use" of cryotherapy in the ablation of JT with a high efficacy, an excellent safety and a reduced cost.

Intrahisian conduction disease and junctional ectopic tachycardia.

Junctional ectopic tachycardia (JET) is an uncommon arrhythmia that mainly affects pediatric patients. However, its clinical presentation may rarely occur in adulthood. Owing to its incessant nature, limited responsiveness to antiarrhythmic agents and poor prognosis, catheter ablation of the junctional focus is often required, even though this may be accompanied by the occurrence of complete atrioventricular block. We report the case of a 68-year-old man with episodes of sustained ventricular tachycardia and repetitive JET whose initiation was often anticipated by a sudden intrahisian conduction delay in the immediately preceding sinus beats.

[Permanent junctional reciprocating tachycardia (PJRT) and dilated cardiomyopathy]. / Trajna spojna kruzna tahikardija (PJRT) i dilatacijska kardiomiopatija.

We present 14-year-old girl with permanent junctional reciprocating tachycardia which was refractory to medicamentous therapy, who also had dilated cardiomyopathy. She underwent successful radiofrequent catheter ablation of accessory pathway after wich the histologic changes in the myocardium were observed in the form of compensatory hypertrophy of cardiac muscle (cardiac remodelling). The question of cause and consequence appeared: whether the arrhythmia is a consequence of dilated cardiomyopathy, or it is tachycardia- induced cardiomyopathy. This particular issue is discussed in this article. Based on the diagnostic procedure and complete recovery of myocardium after catheter ablation of accessory pathway, it is obvious that the tachycardia was due to tachicardiomyopathy, i.e. cardiomyopathy caused by permanent reciprocating junctional tachycardia.

Intravenous amiodarone for incessant tachyarrhythmias in children: a randomized, double-blind, antiarrhythmic drug trial.

BACKGROUND: Intravenous (IV) amiodarone has proven efficacy in adults. However, its use in children is based on limited retrospective data. METHODS AND RESULTS: A double-blind, randomized, multicenter, dose-response study of the safety and efficacy of IV amiodarone was conducted in 61 children (30 days to 14.9 years; median, 1.6 years). Children with incessant tachyarrhythmias (supraventricular arrhythmias [n=26], junctional ectopic tachycardia [JET, n=31], or ventricular arrhythmias [n=4]) were randomized to 1 of 3 dosing regimens (low, medium, or high: load plus 47-hour maintenance) with up to 5 open-label rescue doses. The primary efficacy end point was time to success. Of 229 patients screened, 61 were enrolled during 13 months by 27 of 48 centers in 7 countries. Median time to success was significantly related to dose (28.2, 2.6, and 2.1 hours for the low-, medium-, and high-dose groups, respectively; P=0.028). There was no significant association with dose for any arrhythmia subgroup, including JET, but the subgroups were too small for an accurate assessment. Adverse events (AEs) were common (87%), leading to withdrawal of 10 patients. There were 5 deaths in the 30-day follow-up period (2 possibly related to the study drug). Dose-related AEs included hypotension (36%), vomiting (20%), bradycardia (20%), atrioventricular block (15%) and nausea (10%). CONCLUSIONS: In children, the overall efficacy of IV amiodarone, as measured by time to success, was dose related but not significantly for any arrhythmia subgroup. AEs were common and appeared to be dose related. Although efficacious for critically ill patients, the dose-related risks of IV amiodarone should be taken into account when treating children with incessant arrhythmias. Prospective, placebo-controlled trials would be helpful in assessing antiarrhythmic drug efficacy in children, because their results may differ from retrospective series and adult studies.

Late occurrence of adenosine-sensitive focal junctional tachycardia in complex congenital heart disease.

BACKGROUND: Although supraventricular tachycardia in complex congenital heart disease (CHD) has been reported after surgical repair, its exact electrophysiologic identification has been limited to intraatrial reentrant tachycardia (IART). Moreover, junctional tachycardia (JT) has not previously been described as a cause of late postoperative arrhythmia. METHODS AND RESULTS: Since 1993, a total of 12 patients with congenital heart disease presented with paroxysmal focal JT. The patients with only typical immediate postoperative junctional ectopic tachycardia were excluded. Medical records, standard electrocardiography and Holter monitoring were reviewed. An intracardiac electrophysiologic (EP) study was performed in 11 patients. Ten patients were in post-Fontan status (5.7% of total Fontan survivors). Focal JT occurred more frequently in heterotaxy syndrome among the Fontan survivors (7/52 vs. 3/124; P < 0.05). The commonest anatomy of the atrioventricular (AV) junction was complete AV canal in 8 patients. EP characteristics of focal JT were as follows: (1) various tachycardia mechanisms were identified (increased automaticity or a triggered mechanism in 6/11, and focal reentry in 5/11, including one concealed nodofascicular pathway) (2) ventriculoatrial conduction during tachycardia was either dissociation (7/12) or variable (5/12) (3) All JTs were terminated by adenosine. Class III antiarrhythmic agent was effective in 5/6. His bundle ablation was performed in one Fontan patient, who already had pacemaker because of accompanying intractable IART and sinus node dysfunction. CONCLUSION: Focal JT may be a source of late term supraventricular tachycardia in patients with complex CHD. The tachycardia mechanism was either automatic/triggered or reentrant. In all patients, JT was effectively terminated by adenosine.

[A new cause of increased troponin levels: junctional tachycardia]. / Une nouvelle cause d'élévation de la troponine: la tachycardie jonctionnelle.

The authors report 4 cases of acute coronary syndromes with increased troponine levels during junctional tachycardia in patients with angiographically normal coronary arteries. ST segment changes during junctional tachycardia have no predictive value for the detection of coronary artery disease. Increased troponine, a marker of myocardial cellular necrosis, is not a sign of coronary lesions. A disequilibrium between the increased metabolic and energetic requirements of the myocardium and decreased perfusion due to the tachycardia could explain this observation. The recommended management of these patients is not to perform coronary angiography initially in the absence of cerebrovascular risk factors, but rather to document myocardial ischaemia by a non-invasive method such as echocardiography or scintigraphy.

Left ventricular dysfunction resulting from frequent unifocal ventricular ectopics with resolution following radiofrequency ablation.

A case is presented, in which asymptomatic but persistent right ventricular outflow tract (RVOT) ectopics resulted in left ventricular (LV) dilatation and systolic dysfunction. The patient underwent extensive investigation with no other cause for the cardiomyopathy being found. Successful ablation of the RVOT ectopic focus resulted in normalization of LV size and function. This case suggests that frequent ventricular ectopy should be considered as a potentially remediable cause of LV dysfunction.

A permanent junctional reciprocating tachycardia with atypical location, treated with radiofrequency catheter ablation.

Permanent junctional reciprocating tachycardia (PJRT) is an incessant or almost incessant supraventricular tachycardia with a long RP interval, usually occurring in children and young adults. The differential diagnosis of PJRT includes an atrial tachycardia and atypical atrioventricular nodal reentrant tachycardia (AVNRT). The accessory pathways in PJRT are typically located in the posteroseptal region. We report a case of successful radiofrequency catheter ablation in a 28-year-old male patient with PJRT due to a left posterolateral accessory pathway.

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.