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

Timely Use of Venous-Arterial ECMO to Treat Congenital Pediatric Junctional Ectopic Tachycardia: A Case Report

Supraventricular tachycardia is the most common tachyarrhythmia in pediatrics. Although postoperative junctional ectopic tachycardia (JET) is a known complication of congenital heart surgery that is typically transient, congenital JET is rare and requires aggressive treatment to maintain hemodynamic stability. We describe the case of a 3-month-old, previously healthy female who presented with heart failure and cardiogenic shock secondary to congenital JET for whom extracorporeal membrane oxygenation (ECMO) provided time for selection of effective therapy. Adenosine, cardioversion, and transesophageal pacing were unsuccessful, and her echocardiogram demonstrated bilateral atrial dilation and severe left ventricular systolic dysfunction. Approximately 8 hours after presentation, venous-arterial ECMO was commenced allowing for successful treatment with amiodarone. Her electrocardiogram demonstrated atrioventricular dissociation consistent with JET. She was successfully decannulated from ECMO after 6 days. Her discharge echocardiogram showed normal ventricular function, and she had no significant ECMO sequelae. This case demonstrates the value of early ECMO initiation for cardiovascular support in pediatric patients with a life-threatening arrhythmia and in cardiogenic shock. ECMO support can allow for full diagnostic and therapeutic decisions to effectively reverse the consequences of uncontrolled arrhythmias unrelated to surgical complications.

Radiofrequency ablation on veno-arterial extracorporeal life support in treatment of very sick infants with incessant tachymyopathy

AIMS

To evaluate the use of extracorporeal membrane oxygenation (ECMO) in supporting infants who require radiofrequency ablation (RFA) for incessant tachyarrhythmias, with particular emphasis on modifications required to standard ablation techniques.

METHODS AND RESULTS

Three cases of RFA carried out in infancy on ECMO support were reviewed retrospectively. Two infants with permanent junctional reciprocating tachycardia (PJRT) and one with ventricular tachycardia (VT) presented in a low cardiac output state, owing to cardiomyopathy caused by incessant tachycardia. In each case antiarrhythmic drug therapy caused haemodynamic collapse, requiring emergency ECMO support. Drug therapy on ECMO was not successful. In one patient, the tachycardia was controlled on ECMO with antiarrhythmic drugs, but recurred following ECMO decannulation. Each patient had a successful RFA on ECMO support. Power delivery was low during ablation lesions. In the PJRT cases power as low as 3-5 Watts was effective. In the VT ablation, an irrigated tip RFA catheter was required when cooling remained poor even after temporarily stopping ECMO flow.

CONCLUSION

Extracorporeal membrane oxygenation provides a haemodynamically stable and safe platform for antiarrhythmic drug therapy and RFA in infants with incessant tachyarrhythmias. Once ECMO has been commenced, if the tachyarrhythmia remains difficult to control with antiarrhythmic drugs, RFA should be strongly considered, to avoid the risk of tachycardia recurrence following ECMO decannulation. Power delivery during ablation lesions may be low because of inadequate cooling of the catheter tip. Reducing or stopping flow in the ECMO circuit may not provide adequate cooling and an irrigated tip catheter may be required.

Management of pediatric tachyarrhythmias on mechanical support

BACKGROUND

Pediatric patients with persistent arrhythmias may require mechanical cardiopulmonary support. We sought to classify the population, spectrum, and success of current treatment strategies.

METHODS AND RESULTS

A multicenter retrospective chart review was undertaken at 11 sites. Inclusion criteria were (1) patients <21 years, (2) initiation of mechanical support for a primary diagnosis of arrhythmias, and (3) actively treated on mechanical support. A total of 39 patients were identified with a median age of 5.5 months and median weight of 6 kg. A total of 69% of patients were cannulated for supraventricular tachycardia with a median rate of 230 beats per minute. A total of 90% of patients were supported with extracorporeal membrane oxygenation for an average of 5 days. The remaining 10% were supported with ventricular assist devices for an average of 38 (20-60) days. A total of 95% of patients were treated with antiarrhythmics, with 43% requiring >1 antiarrhythmic. Amiodarone was the most frequently used medication alone or in combination. A total of 33% patients underwent electrophysiology study/transcatheter ablation. Radiofrequency ablation was successful in 9 patients on full flow extracorporeal membrane oxygenation with 3 radiofrequency-failures/conversion to cryoablation. One patient underwent primary cryoablation. A total of 15% of complications were related to electrophysiology study/ablation. At follow-up, 23 patients were alive, 8 expired, and 8 transplanted.

CONCLUSIONS

Younger patients were more likely to require support in the presented population. Most patients were treated with antiarrhythmics and one third required electrophysiology study/ablation. Radiofrequency ablation is feasible without altering extracorporeal membrane oxygenation flows. There was a low frequency of acute adverse events in patients undergoing electrophysiology study/ablation, while on extracorporeal membrane oxygenation.

Newly created animal model of human postoperative junctional ectopic tachycardia

OBJECTIVE

Junctional ectopic tachycardia complicates the postoperative recovery from open heart surgery in children. The reported risk factors include younger age, prolonged cardiopulmonary bypass times, and administration of inotropic agents. Junctional ectopic tachycardia occurs early after open heart surgery, in the setting of relative postoperative sinus node dysfunction, and exhibits QRS morphology consistent with an origin from the atrioventricular node or proximal conduction system. Our goal was to develop a reproducible animal model for postoperative junctional ectopic tachycardia.

METHODS

Eleven pigs, aged 2 to 4 months, underwent open heart surgery after induction of general anesthesia. Electrodes were sewn to the left atrium and right ventricle.

RESULTS

Sinus node dysfunction was created using clamp crushing without or with radiofrequency ablation (successful in 1 of 5 pigs) or sinus node removal (successful in 4 of 4). After prolonged cardiopulmonary bypass (>120 minutes) alone and with isoproterenol infusion, no spontaneous junctional ectopic tachycardia developed. Junctional ectopic tachycardia or fascicular tachycardia could be initiated after either slow atrioventricular nodal pathway ablation and/or digoxin administration. Junctional ectopic tachycardia occurred in 8 of 9 pigs (mean ventricular rate, 171 ± 32 bpm), and fascicular tachycardia occurred in 9 of 9 pigs (mean ventricular rate, 187 ± 39 bpm). His and right bundle recordings confirmed the conduction system origin.

CONCLUSIONS

Experimental junctional ectopic tachycardia or fascicular tachycardia can occur in the intraoperative setting of sinus node dysfunction, prolonged cardiopulmonary bypass, and enhanced conduction system automaticity. Conduction system automaticity occurred after either physical injury (ablation or tricuspid valve stretch) or measures to augment the transient inward current of the conduction system (isoproterenol and digoxin). This animal model can serve as the basis to assess new treatments of postoperative junctional ectopic tachycardia.

Extracorporeal membrane oxygenation support for intractable primary arrhythmias and complete congenital heart block in newborns and infants: short-term and medium-term outcomes

OBJECTIVES

To describe the experience with extracorporeal membrane oxygenation support for intractable primary arrhythmias in newborns and infants.

DESIGN

Retrospective study.

SETTING

A tertiary care pediatric hospital.

PATIENTS

Patients younger than 1 yr supported with extracorporeal membrane oxygenation for primary cardiac arrhythmias were identified from the institutional extracorporeal membrane oxygenation registry.

INTERVENTIONS

Extracorporeal membrane oxygenation support.

MEASUREMENTS AND MAIN RESULTS

Clinical characteristics and outcomes were investigated for patients with primary cardiac arrhythmia supported with extracorporeal membrane oxygenation. Outcomes investigated were time from initiation of extracorporeal membrane oxygenation support to arrhythmia control, duration of extracorporeal membrane oxygenation support, and results of interventions performed while supported with extracorporeal membrane oxygenation. We summarized the independent categorical and continuous variables using frequencies, percentages, and medians and ranges, respectively. Extracorporeal membrane oxygenation support was used in nine patients for rescue therapy for primary tachyarrhythmia and bradycardia. The primary arrhythmias were: focal atrial tachycardia (n = 2); reentrant supraventricular tachycardia (n = 3); junctional ectopic tachycardia (n = 2); and congenital complete atrioventricular block (n = 2) patients. Seven patients presented with severe hemodynamic compromise, with six patients requiring extracorporeal cardiopulmonary resuscitation. All patients required extracorporeal membrane oxygenation within 24 hrs of initial presentation. Balloon atrial septostomy was performed in three patients and ablation was performed in two patients. Sinus rhythm was achieved in all reentrant supraventricular tachycardia and rate control was established in both patients with focal atrial tachycardia and in one patient with junctional ectopic tachycardia while using extracorporeal membrane oxygenation support. All patients survived to hospital discharge, and median follow-up for the cohort was 5 yrs. There was one late death; all survivors had good overall and neurologic outcomes.

CONCLUSIONS

The requirement of extracorporeal membrane oxygenation support in newborns and infants with intractable arrhythmia is rare. Extracorporeal membrane oxygenation support does potentially carry morbidity; however, to prevent arrhythmia-related mortality, extracorporeal membrane oxygenation support and/or extracorporeal cardiopulmonary resuscitation should be considered in the management of hemodynamically unstable primary arrhythmias as an emergent lifesaving procedure.

Predictors of ECMO support in infants with tachycardia-induced cardiomyopathy

The development of tachycardia-induced cardiomyopathy (TIC) is related to the rate and duration of supraventricular tachycardia (SVT). Infants may be more susceptible to TIC because early symptoms might be unrecognized. Extracorporeal membrane oxygenation (ECMO) may improve outcome in patients with SVT and TIC; however, clinical predictors of infants who require ECMO support have not been determined. The purpose of this study was to identify predictors of the need for ECMO in infants with SVT and TIC. Sixteen infants <6 months of age who experienced resolution of TIC following control of arrhythmia were identified. Three patients (19%) required ECMO support. Comparisons were made between patients who required ECMO and those who did not. The groups were similar with respect to age at presentation, type of SVT, rate of SVT, and degree of ventricular dysfunction. However, patients requiring ECMO had increased median M-mode-derived left ventricular end diastolic dimension (LVED) z-score when compared to the medically managed patents (+2.8 vs. 0.0, P = 0.009). No patient in the medically managed group had an LVED z-score >2.3. Infants presenting with SVT and TIC with LVED z-score >2 are at increased risk for requiring ECMO support and early use of ECMO should be considered.

Mechanical circulatory support to control medically intractable arrhythmias in pediatric patients after cardiac surgery

Postoperative intractable arrhythmia can result in high morbidity and mortality. This report describes our experiences using mechanical circulatory support (MCS) to control medically intractable arrhythmias in three pediatric patients with congenital heart disease (CHD), after palliative or total corrective open-heart surgery.