Background: Junctional ectopic tachycardia (JET) is one troublesome supraventricular arrhythmia in postoperative pediatric cardiac surgical patients. Unless treated timely and effectively it may lead to morbidity and even mortality. Aim: To understand the role of Ivabradine in the treatment of JET in postoperative pediatric cardiac surgical patients. Case: We present a postoperative case of complete repair of Tetralogy of Fallot who was in normal sinus rhythm in the preoperative period and developed JET 4 hours later in postoperative period which was persistent despite measures to optimize the internal milieu of the body and conventional antiarrhythmics, that was successfully treated with Ivabradine at a dose of 0.05 mg/kg/12 hourly. Conclusion: Ivabradine can be used to successfully treat postoperative JET in cases of refractory to other antiarrhythmic drugs like Digoxin and Amiodarone.
Junctional ectopic tachycardia (JET) is the commonest rhythm disturbance following surgery for congenital heart disease [
Ivabradine is a new rate-controlling drug used as a selective antagonist of the If current and produces substantial reduction in the rate of spontaneous action potential firing in sinoatrial node cells [
We sought to assess if ivabradine could successfully control heart rate in a child with refractory JET. The successful treatment of our patient with oral ivabradine provides a new therapeutic option, having its action on AV node along with SA node, its uncommon use in postoperative pediatric cardiac surgical patients without any side effects.
A14 year old girl weighing 38 kg diagnosed with Tetralogy of Fallot (TOF) with Normal Sinus Rhythm (NSR) (
slow iv bolus was given over 20 minutes. But JET continued at a rate of 150 - 170/min. Intravenous digoxin was given at 5 mcg/kg slow iv bolus and repeated twice at two hourly intervals as per our ICU protocol. When digoxin after 3 doses was unable to control the heart rate, amiodarone was administered as 5 mg/kg as slow iv bolus followed by infusion at a rate of 10 mcg/kg/min. Amiodarone infusion for 24 hours did not able to settle either rhythm or tachycardia. Hence ivabradine was given enterally through nasogastric tube at a dose of 0.05 mg/kg/12 hourly. About three hours after the 1st dose, heart rate dropped to 80 beats/min and the rhythm of JET reverted back to normal sinus rhythm (NSR) (
JET is a common postoperative rhythm disturbance in patients of TOF repair [
incessant tachycardia and a fatal outcome [
Our patient underwent intracardiac repair for TOF. She developed JET in the ICU, which could be attributable to a major infundibular resection and postoperative moderate RV dysfunction as demonstrated by echocardiography. This JET was persistent despite the routine measures to normalize the internal biochemical milieu and treatment with regular antiarrhythmics like digoxin and amiodarone as per our ICU protocol. And also we stepped up the dobutamine infusion to support the RV, but when all these measures failed to control JET, we started Ivabradine enterally and dramatically the rate and rhythm came under control after the 1st dose and then RV function improved by next TTE.
There are several mechanisms by which a low or reduced heart rate could be of benefit. Myocardial ischemia occurs when coronary perfusion is insufficient to satisfy myocardial oxygen demand and heart rate is an important determinant of myocardial oxygen demand. A reduction in heart rate will increase the duration of diastole relative to cardiac cycle length, thus allowing more time for effective left ventricular perfusion. In this way, a reduction in heart rate should improve both aspects of myocardial oxygen balance.
Therefore, drugs that reduce heart rate should be of benefit in the postoperative tachyarrhythmia situations. However, current heart rate-reducing drugs like amiodarone, digoxin, etc. are non-specific and have actions on the cardiovascular and other systems, which both complicate the interpretation of the effects of heart rate lowering, and may be harmful. More specific heart rate lowering agents without having many side effects and drug interactions could, therefore, be of interest.
Ivabradine is a new, pure rate-lowering drug that acts by inhibiting the cardiac pacemaker If (funny) current channels underlying the normal pacemaker function of the sinus node [
Ivabradine was approved by the European Medicines Agency in 2005. Ivabradine has been used in adult patients to reduce the heart rate alone in sinus tachycardia in the treatment of stable angina and heart failure [
In a randomized controlled trial by Nguyen LS et al. on 19 postoperative coronary artery bypass graft surgery patients with LCO with dobutamine induced sinus tachycardia, intravenous ivabradine administered as loading dose of 10mg over 10 min, followed by 10 mg over 24 hours lead to effective control of heart rate, stroke volume and cardiac index [
In an uncontrolled study in 14 patients needing cardiac electrophysiological investigation or catheter radiofrequency ablation for supraventricular arrhythmia, but with normal electrophysiology at study baseline, a single intravenous administration of ivabradine (0.2 mg/kg corresponding to approximately 10 mg twice daily orally) reduced resting heart rate by approximately 14 bpm, but did not induce any change in major electrophysiological parameters other than those related to heart rate [
In a randomized, placebo-controlled study in 44 patients with left ventricular dysfunction, a single intravenous infusion of ivabradine 0.2 - 0.3 mg/kg reduced resting heart rate by over 17%, but did not alter left ventricular ejection fraction, fractional shortening or stroke volume as determined by echocardiography [
According to the electrophysiologic properties of ivabradine, the purpose of reporting this case review was to assess the efficacy and safety of ivabradine as an adjunctive agent in treating postoperative JET in children. Because pharmacologic treatment with various antiarrhythmic medications often fail to treat JET effectively, timely and catheter ablation carries a high risk of AV block, we used ivabradine as a novel adjunctive therapy to treat junctional tachyarrhythmias in post cardiac surgery children. Adding ivabradine to a combination of antiarrhythmic agents in our patient resulted in conversion to sinus rhythm.
Our protocol for treating JET in postoperative pediatric cardiac surgery is:
1) Controlling the core temperature to normal in case of fever (due to post CPB inflammation, LCO or infection).
2) Correcting serum electrolytes, particularly potassium and supplementing magnesium (to prevent subclinical hypomagnesemia).
3) Treating myocardial dysfunction/heart failure/LCO with the use of inotropes and inodilators at judicious doses while maintaining the mean arterial pressures appropriate for the age.
4) Maintaining euvolemic status (preload) of the patient.
5) Then digoxin for rate control, at a dose of 5 mcg/kg/min as slow infusion over 30 min followed by 2 more doses at 2 hourly intervals.
6) If the rate is not controlled by digoxin, we use amiodarone at a dose of 5 mcg/kg/slow iv bolus over 20 minutes and followed by 10 mcg/kg/min infusion for 24 hours postoperatively.
7) Recently we started using ivabradine in those children who become refractory to the other drugs and measures, with good success and quicker control of heart rate and rhythm.
Safety of Ivabradine:
As per SHIFT trial, both oral and intravenous ivabradine administration are associated with the incidence of supraventricular arrhythmias and also bradyarrhythmias that respond to standard antiarrhythmic measures and stopping ivabradine [
Ivabradine was a new addition to the antiarrhythmic drugs armamentarium in treating junctional tachyarrhythmias postoperatively in children undergoing intracardiac repair. Because ivabradine is a selective If inhibitor, one may infer that it is a more targeted therapy than the multichannel blocker amiodarone. However, there is no scientific evidence for this assumption, so a randomized trial is necessary to quantify and compare the efficacy of these drugs for the treatment of this specific arrhythmia. It would be worthwhile to determine whether ivabradine could potentially be the preferred first-line therapy in children with postoperative JET. RCT needs to be done in a large study population.
An informed consent was obtained from the child’s parents for publication of this case report.
We the authors declare that there is no conflict of interest among the authors in writing this manuscript.
Sahu, M.K., Niraghatam, H.V., Bansal, N., Singh, S.P., Rajashekar, P. and Choudhary, S.K. (2019) Ivabradine—The Final Crusader for Postoperative Junctional Ectopic Tachycardia, a Case Report with Literature Review. World Journal of Cardiovascular Surgery, 9, 73-82. https://doi.org/10.4236/wjcs.2019.98009