Ivabradine in a 15-day-old male neonate with refractory focal atrial tachycardia.

Ivabradine is used to reduce heart rate in children with chronic heart failure and dilated cardiomyopathy, it has recently been used off-label to treat tachyarrhythmias such as ectopic atrial tachycardia and junctional ectopic tachycardia (JET) in children. We report a successful ivabradine experience in a male neonate with refractory focal atrial tachycardia (FAT).

Successful treatment of the focal ectopic atrial tachycardia in an infant with a single dose of ivabradin.

We report on a 12-month-old boy with an ectopic atrial tachycardia successfully treated with the ivabradine that acts on cardiac pacemaker cells by selectively inhibiting the If channel. The patient was diagnosed with supraventricular tachycardia in another centre, and multi-drug therapy was unsuccessful to restore sinus ryhthm, so he was sent to our hospital for catheter ablation. We stopped the medications the patient was taking and started using ivabradine. Sinus rhythm was restored 2 hours after ivabradine treatment was started.

Ivabradine as a stabilising anti-arrhythmic agent for multifocal atrial tachycardia.

Multifocal atrial tachycardia has certain electrocardiographic similarities to atrial fibrillation. The mechanism of atrial fibrillation is heterogenous but in some cases may arise from a single ectopic driver with fibrillatory conduction to the rest of the atria. This has led to the speculation that multifocal atrial tachycardia may have a similar mechanistic unifocal site that disperses through the atrium in a fibrillatory pattern. Ivabradine has been reported to be efficacious in an adult with paroxysmal atrial fibrillation as well as in children with junctional or ectopic atrial tachycardias. This is the first report of successfully using ivabradine, a novel anti-arrhythmic If blocking agent, to convert multifocal atrial tachycardia in a 5-month-old critically ill infant to a pattern indicating a single ectopic atrial focus. This allowed the patient's single atrial focus to be ablated with return to sinus rhythm and decannulation from ventriculoarterial extracorporeal membrane oxygenation. This case suggests that multifocal atrial tachycardia may arise from a single automatic focus with downstream fibrillatory conduction to the atria.

Nonreentrant atrial tachycardia occurs independently of hypertrophic cardiomyopathy in RASopathy patients.

Multifocal atrial tachycardia (MAT) has a well-known association with Costello syndrome, but is rarely described with related RAS/MAPK pathway disorders (RASopathies). We report 11 patients with RASopathies (Costello, Noonan, and Noonan syndrome with multiple lentigines [formerly LEOPARD syndrome]) and nonreentrant atrial tachycardias (MAT and ectopic atrial tachycardia) demonstrating overlap in cardiac arrhythmia phenotype. Similar overlap is seen in RASopathies with respect to skeletal, musculoskeletal and cutaneous abnormalities, dysmorphic facial features, and neurodevelopmental deficits. Nonreentrant atrial tachycardias may cause cardiac compromise if sinus rhythm is not restored expeditiously. Typical first-line supraventricular tachycardia anti-arrhythmics (propranolol and digoxin) were generally not effective in restoring or maintaining sinus rhythm in this cohort, while flecainide or amiodarone alone or in concert with propranolol were effective anti-arrhythmic agents for acute and chronic use. Atrial tachycardia resolved in all patients. However, a 4-month-old boy from the cohort was found asystolic (with concurrent cellulitis) and a second patient underwent cardiac transplant for heart failure complicated by recalcitrant atrial arrhythmia. While propranolol alone frequently failed to convert or maintain sinus rhythm, fleccainide or amiodarone, occasionally in combination with propranolol, was effective for RASopathy patient treatment for nonreentrant atrial arrhythmia. Our analysis shows that RASopathy patients may have nonreentrant atrial tachycardia with and without associated cardiac hypertrophy. While nonreentrant arrhythmia has been traditionally associated with Costello syndrome, this work provides an expanded view of RASopathy cardiac arrhythmia phenotype as we demonstrate mutant proteins throughout this signaling pathway can also give rise to ectopic and/or MAT.

Successful use of sirolimus for refractory atrial ectopic tachycardia in a child with cardiac rhabdomyoma.

Cardiac rhabdomyomas are common in tuberous sclerosis. We report a child who developed rhabdomyoma related arrhythmia refractory to antiarrhythmic drug therapy. Reversion of the atrial ectopic tachycardia was achieved with mammalian target of rapamycin pathway (mTOR) inhibitor sirolimus. As per our knowledge, this is the first time that sirolimus has been successfully used in this setting.

Predictors of Pharmacological Therapy of Ectopic Atrial Tachycardia in Children.

Ectopic atrial tachycardia (EAT) is a relatively common type of supraventricular tachycardia in the pediatric population, and it can be resistant to antiarrhythmic drugs and lead to tachycardia-induced cardiomyopathy (TIC) if not properly managed. The purpose of this study was to determine the predictors of the response to pharmacological therapy in children with EAT. From January 2009 to April 2014, 115 children were admitted to our hospital with a diagnosis of EAT and placed on antiarrhythmic drugs. We examined the clinical history, response to therapy, and follow-up of the children. The incidence of TIC secondary to EAT was 22.6% (n = 26) in children. Incessant EAT accounted for 44.3% of all patients. Control of EAT with antiarrhythmic therapy was achieved in 73.9% (n = 85) of the children. The combination of sotalol and propafenone performed well in controlling EAT in children [complete control in 35 (49.3%) of 71]. The mean time of conversion to sinus rhythm was 24 days, and the mean duration of therapy was 11 months in children with resolution. Multivariate predictors of the control of EAT were age at presentation (OR 0.289, P = 0.038) and tachycardia type (OR 0.276, P = 0.006). TIC occurs in 22.6% of children with EAT. Incessant EAT is more frequently complicated by TIC. Independent factors associated with a good response to pharmacological therapy include a younger age at presentation and non-incessant tachycardia in children with EAT.

[Perinatal Presentation and Complicated Course of a Multifocal Atrial Tachycardia]. / Polymorphes und komplexes klinisches Bild einer multifokal-ektopen Vorhoftachykardie mit perinataler Manifestation.

We report a male newborn who became symptomatic with supraventricular tachycardia on the first day of life. Neither adenosine nor electric cardioversion could terminate the tachycardia, therefore intravenous esmolol (ß-receptor blocker) was initiated. Inspite of subsequent administration of various antiarrhythmic medications in increasingly higher doses, repeated supraventricular tachycardic episodes occurred. The electrocardiogram showed typical findings of a multifocal atrial tachycardia as the underlying cause. When tachycardic episodes occurred, they also presented as atrial flutter at 460 bpm and a 2:1 block. Finally, high dosage of amiodarone (10 mg/kgbw/d) led to continuous control of the heart rate without tachycardic episodes. To date our patient is mostly in sinus rhythm but without tachycardic episodes and doing well.

A case of atrial tachycardia treated with ivabradine as bridge to ablation.

Ivabradine is indicated in cardiac failure and ischemia to reduce sinus rate by inhibition of the pacemaker I(f) current in sinoatrial node. We report a case of an 18-year-old woman with left atrial tachyarrhythmia resistant to several antiarrhythmic drugs and to electric cardioversion who responded only to ivabradine, which significantly reduced heart rate without abolishing the arrhythmia itself. An ectopic focus in the ostium of left pulmonary veins was found and the patient was successfully ablated. We suggest that ivabradine might be therefore useful in the treatment of supraventricular tachyarrhythmias due to an enhanced automaticity.

Magnesium adjunctive therapy in atrial arrhythmias.

Magnesium (Mg) is an important intracellular ion with cardiac metabolism and electrophysiologic properties. A large percentage of patients with arrhythmias have an intracellular Mg deficiency, which is out of line with serum Mg concentrations, and this may explain the rationale for Mg's benefits as an atrial antiarrhythmic agent. A current limitation of antiarrhythmic therapy is that the potential for cardiac risk offsets some of the benefits of therapy. Mg enhances the balance of benefits to harms by enhancing atrial antiarrhythmic efficacy and reducing antiarrhythmic proarrhythmia potential as well as providing direct antiarrhythmic efficacy when used as monotherapy in patients undergoing cardiothoracic surgery.

Oral flecainide is effective in management of refractory tachycardia in infants.

BACKGROUND: Propranolol and digoxin have been used as first line drugs for treatment of supraventricular tachycardia (SVT) in infants. Flecainide and other drugs have been effective as a second line treatment for controlling refractory SVT. MATERIAL AND METHODS: This is a prospective study without randomization and control. The inclusion criteria were: infants (≤12 months) with tachyarrhythmia who failed to respond to first line drugs. Patients having post-surgical arrhythmias were excluded from the study. RESULTS: A total of 8 infants were treated with flecainide for refractory tachyarrhythmia's. Diagnosis on electrocardiogram (ECG) was atrioventricular reentry tachycardia (AVRT) in 5, atrial ectopic tachycardia (AET) in 2, a combination of AVRT and atrioventricular nodal reentry tachycardia (AVNRT) in 1. All patients had failed trial of antiarrhythmic drugs prior to presentation: digoxin and propranolol in 7, amiodarone in 3, cardioversion in 1. Flecainide (80-130 mg/m(2) orally) resulted in termination of the tachycardia in all 8 patients. Acute pharmacological termination of arrhythmia occurred with oral flecainide loading in 1 and temporarily with intravenous esmolol loading in 1 patient. Adjuvant therapy in form of propranolol was used in 5 and digoxin in 2. There were no side effects noted. Four episodes of recurrence were noted in 3 patients over 2 years, all of which responded to dose increase. Mean follow up time is 24.75 months. CONCLUSION: This small case series indicates that flecainide is an effective antiarrhythmic agent, free of side effects and when used orally is capable of terminating and controlling relatively resistant supraventricular tachycardia in children.

Nitric oxide delays atrial tachycardia-induced electrical remodelling in a sheep model.

AIMS: Rapid atrial pacing for 1 week leads to decreased expression of endocardial nitric oxide (NO)-synthase and decreased NO concentrations. We hypothesized that increasing NO bioavailability may reduce electrical remodelling induced by atrial tachycardia. METHODS AND RESULTS: We examined the effect of molsidomine, a NO donor, and N(ω)-nitro-l-arginine methylester (l-NAME), a NO-synthase inhibitor, on electrical remodelling occurring during 4 h of rapid atrial pacing in sheep. Haemodynamic and electrophysiological parameters were measured at baseline, 1 h after the start of the infusion and before the start of pacing, and 2 and 4 h after pacing. We measured the effect of molsidomine on atrial monophasic action potentials (MAPs) in non-instrumented sheep and on l-type Ca(2+) currents and intracellular Ca(2+) concentration ([Ca(2+)](i)) transients in right atrial cells, isolated from control sheep. In control sheep, rapid atrial pacing shortened the atrial effective refractory period (AERP) by 12 ± 0.18% after 4 h, an effect that was unaffected by l-NAME. Infusion of molsidomine increased AERP at baseline (+13.4 ± 1.04%) and transiently attenuated pacing-induced AERP shortening (13.6 ± 0.1% at 2 h). Molsidomine tended to increase MAP duration by 20.7 ± 13.4 ms. Incubation of isolated atrial myocytes with NO donor 3-morpholino-sydnonimine (SIN-1) increased significantly l-type Ca(2+) current and [Ca(2+)](i) transients. CONCLUSION: Infusion of molsidomine, a NO donor, delayed shortening of the action potential during short-term rapid atrial pacing, by increasing [Ca(2+)](i). Whereas the former could be protective against repetitive short episodes of atrial fibrillation, the latter might be detrimental in the long term.

Ectopic atrial tachycardia in an infant with transient erythroblastopenia of childhood.

Transient erythroblastopenia of childhood is a self-limited anemia occurring in previously healthy children, secondary to temporary cessation of erythrocyte production. Although the precise etiology is unclear, most cases are associated with a viral illness. The anemia may be severe, with associated pallor, tachypnea, and tachycardia; treatment is supportive. We present an unusual case of a child with viral-induced transient erythroblastopenia of childhood and associated ectopic atrial tachycardia, requiring therapy with antiarrhythmics.

Focal atrial tachycardia refractory to radiofrequency catheter ablation originating from right atrial appendage.

A 44-year-old female presented with incessant, drug-refractory atrial tachycardia (AT). An electrophysiological study suggested focal abnormal automaticity, and localized the AT origin to the apex of the right atrial appendage (RAA). Repeated radiofrequency catheter ablation to the site of the earliest endocardial activation during AT failed. At surgery, right atrial appendectomy terminated the AT. On macroscopic findings, the cavity of the RAA became a dead-end before the apex. In patients with drug and radiofrequency catheter ablation, refractory focal AT arising from the RAA, especially the apex of the RAA, in our opinion surgical treatment could be considered in the lack of efficacy of ablation.

Successful use of intravenous amiodarone in a child with combined postoperative junctional and ectopic tachycardias.

Early postoperative arrhythmias are a known complication of cardiac surgery. It is unusual, however, to encounter postoperative junctional and ectopic atrial tachycardias in the same patient. We describe our experience with a 2-year-old girl who suffered both these tachycardias after repair of a ventricular septal defect, the abnormal rhythms being controlled solely with intravenous administration of amiodarone.

An unusual cause of atrial tachycardia in a young patient with lymphoma.

An 8-year-old girl who was recently diagnosed as having anaplastic large-cell lymphoma presented with atrial tachycardia and dilated cardiomyopathy, which is a contraindication for further treatment with cardio-toxic chemotherapy. After starting digoxin therapy, the dilated cardiomyopathy resolved. Repeated episodes of atrial tachycardia in this case were not caused by any common disorder but were due to mechanical stimulation by a central venous catheter. Central venous catheters are known to cause mainly ventricular arrhythmias. However, atrial tachycardia is a rare manifestation of arrhythmia due to mechanical stimulation of the heart by a central venous catheter, with potentially important cardiovascular consequences.

Severe congenital RYR1-associated myopathy complicated with atrial tachycardia and sinus node dysfunction: a case report.

BACKGROUND: Cardiac arrhythmias are sometimes encountered in patients with hereditary myopathies and muscular dystrophies. Description of arrhythmias in myopathies and muscular dystrophies is very important, because arrhythmias have a strong impact on the outcomes for these patients and are potentially treatable. CASE PRESENTATION: A girl with severe congenital RYR1-related myopathy exhibited atrial tachycardia and sinus node dysfunction during infancy. She was born after uncomplicated caesarian delivery. She showed no breathing, complete ophthalmoplegia, complete bulbar paralysis, complete facial muscle paralysis, and extreme floppiness. At 5 months old, she developed persistent tachycardia around 200-210 beats per minutes. Holter monitoring revealed ectopic atrial tachycardia during tachyarrhythmia and occasional sinus pauses with junctional escape beats. Propranolol effectively alleviated tachyarrhythmia but was discontinued due to increased frequency and duration of the sinus pauses that led to bradyarrhythmia. There was no evidence of structural heart diseases or heart failure. The arrhythmia gradually resolved spontaneously and at 11 months old, she showed complete sinus rhythm. CONCLUSIONS: Although supraventricular arrhythmia is sometimes encountered in congenital myopathies, this is the first report of cardiac arrhythmia requiring drug intervention in RYR1-associated myopathy.