Safety of oral propafenone in the treatment of arrhythmias in infants and children (European retrospective multicenter study). Working Group on Pediatric Arrhythmias and Electrophysiology of the Association of European Pediatric Cardiologists

Adverse Drug Reactions in Children with Congenital Heart Disease: A Scoping Review

BACKGROUND

Congenital heart disease (CHD) is one of the leading causes of death. Safe and timely medical interventions, especially in children, can prolong their survival. The drugs prescribed for children with CHD are mainly based on the outcomes of drug therapy in adults with cardiovascular diseases, and their adverse drug reactions (ADRs) might be different. Therefore, the aim of this study was to investigate ADRs in children with CHD.

METHODS

This was a scoping review conducted in 2023. PubMed, Web of Science, Scopus, the Cochrane Library, Ovid, ProQuest, and Google Scholar databases were searched. All studies that reported ADRs for children with CHD and were published in English by 1 November 2023 were included in this study. Finally, the results were reported using a content analysis method.

RESULTS

A total of 87 articles were included in the study. The results showed that symptoms/signs/clinical findings, and cardiovascular disorders were the most common ADRs reported in children with CHD. The results also showed that most of the ADRs were reported for prostaglandin E1, amiodarone, prostaglandin E2, dexmedetomidine, and captopril, respectively.

CONCLUSION

The review underscores the wide array of ADRs in children with CHD, particularly in antiarrhythmics, diuretics, beta-blockers, anticoagulants, and vasodilators, which affected cardiovascular, respiratory, endocrine, metabolic, genitourinary, gastrointestinal, and musculoskeletal systems. Tailored treatment is imperative, considering individual patient characteristics, especially in the vulnerable groups. Further research is essential for optimizing dosing, pharmacogenetics, and alternative therapies to enhance patient outcomes in CHD management.

Formulation and stability of an extemporaneously compounded propafenone hydrochloride oral suspension for children with arrhythmia

OBJECTIVES

In children, supraventricular tachycardia is the most common form of arrhythmia, and propafenone is an effective class Ic antiarrhythmic agent used in this population. No suitable paediatric-specific, dosing-flexible preparation is available in Taiwan. The objective of this study was to develop a formulation of propafenone oral suspension prepared from commercially available propafenone tablets and commercially available oral syrup vehicles for related patients.

METHODS

An oral suspension of propafenone hydrochloride at a concentration of 10 mg/mL was prepared by mixing finely grounded propafenone hydrochloride tablets and a 1:1 mixture of Ora-Plus and Ora-Sweet. The beyond-use date was determined by analysing the samples stored at room temperature or 2-8℃ at time 0 and on days 7, 14, 21, 28, 35, 42, 56, and 90. Parameters to be inspected included appearance, pH measurement, high-performance liquid chromatography analysis, and microbial limit tests.

RESULTS

On the basis of the physicochemical and microbial stability results, the 10 mg/mL oral suspension of propafenone hydrochloride was stable at 2-8℃ and room temperature for at least 90 days. The suspension did not exhibit significant changes in drug concentration or pH level at any time point. Moreover, no apparent changes or microbial contaminations were observed for at least 90 days.

CONCLUSIONS

Propafenone hydrochloride in a 10 mg/mL oral suspension prepared by diluting fine powder with a 1:1 mixture of Ora-Plus and Ora-Sweet and stored in high-density polyethylene bottles and has a beyond-use date of 90 days when stored at 2-8℃ or room temperature. This finding enables us to improve the accuracy of dosage administration and reduce the risk of medication errors affecting the paediatric population.

Influence of CYP2D6 Genetic Variation on Adverse Events with Propafenone in the Pediatric and Young Adult Population

Propafenone is an antiarrhythmic drug metabolized primarily by cytochrome P450 2D6 (CYP2D6). In adults, propafenone adverse events (AEs) are associated with CYP2D6 poor metabolizer status; however, pediatric data are lacking. Subjects were tested for 10 CYP2D6 allelic variants and copy number status, and activity scores assigned to each genotype. Seventy‐six individuals (median 0.3 [range 0–26] years old) were included. Propafenone AEs occurred in 29 (38%); 14 (18%) required drug discontinuation due to AE. The most common AEs were QRS (n = 10) and QTc (n = 6) prolongation. Those with AEs were older at the time of propafenone initiation (1.58 [0.13–9.92] vs. 0.20 [0.08–2.01] years old; p = 0.042). CYP2D6 activity scores were not associated with presence of an AE (odds ratio [OR] 0.48 [0.22–1.03]; p = 0.055) but with the total number of AE (β₁ = −0.31 [−0.60, −0.03]; p = 0.029), systemic AEs (OR 0.33 [0.13–0.88]; p = 0.022), and drug discontinuation for systemic AEs (OR 0.28 [0.09–0.83]; p = 0.017). Awareness of CYP2D6 activity score and patient age may aid in determining an individual's risk for an AE with propafenone administration.

Electrophysiological effects and clinical utility of propafenone in children

AIM

This retrospective case series study sought to describe the safety and clinical effectiveness of propafenone for the control of arrhythmias in children with and without CHD or cardiomyopathy.

METHODS

We reviewed baseline characteristics and subsequent outcomes in a group of 63 children treated with propafenone at 2 sites over a 15-year period Therapy was considered effective if no clinically apparent breakthrough episodes of arrhythmias were noted on the medication.

RESULTS

Sixty-three patients (29 males) were initiated on propafenone at a median age of 2.3 years. CHD or cardiomyopathy was noted in 21/63 (33%). There were no significant differences between demographics, clinical backgrounds, antiarrhythmic details, side effect profiles, and outcomes between children with normal hearts and children with CHD or cardiomyopathy. Cardiac depression at the initiation of propafenone was more common amongst children with CHD or cardiomyopathy compared to children with normal hearts. Systemic ventricular function was diminished in 15/63 patients (24%) prior to starting propafenone and improved in 8/15 (53%) of patients once better rhythm control was achieved. Other than one child in whom medication was stopped due to gastroesophageal reflux, no other child experienced significant systemic or cardiac side effects during treatment with propafenone. Propafenone achieved nearly equal success in controlling arrhythmias in both children with normal hearts and children with congenital heart disease or cardiomyopathy (90% versus 86%, p = 0.88).

CONCLUSION

Propafenone is a safe and effective antiarrhythmic medication in children.

Evaluation of Clinical Course and Maintenance Drug Treatment of Supraventricular Tachycardia in Children During the First Years of Life. A Cohort Study from Eastern Germany

Supraventricular tachycardia (SVT) is considered the most common cause of arrhythmia in children and infants. Regarding the likelihood of a spontaneous resolution of SVTs during the first years of life, drug treatment aims to bridge the time until children 'grow out' out of the arrhythmia. The choice of antiarrhythmic agents and the planning of maintenance therapy are mainly based on clinical experience and retrospective single- and multi-institutional analyses and databases from all over the world approaching differently to this topic. The current study aimed to evaluate the clinical course, pharmacological treatment strategies, and constellations of risk for recurrences in the management of SVTs in children aged 3 < years. The database of the Heart Center Leipzig, Department of Pediatric cardiology, was searched for pediatric patients aged < 3 years with a clinically documented SVT between 2000 and 2019 that received pharmacologic treatment. Patients with complex congenital heart disease or arrhythmias following cardiac surgery were excluded. 69 patients were included. Pharmacologic treatment, follow-up schedule, recurrences, outcomes, and risk factors for complicated courses are reported. Drug therapy of SVTs in young children remains a controversial topic with heterogeneous treatment and follow-up strategies applied. Risk factors for recurrences and/or stubborn clinical courses are difficult rhythm control with 3 or more antiarrhythmic drugs, ectopic atrial tachycardias, and a first occurrence of the SVT in the fetal period. Prospective studies are needed to sufficiently evaluate optimal treatment strategies.

Antiarrhythmic Medication in Neonates and Infants with Supraventricular Tachycardia

Supraventricular tachycardia (SVT) is the most common arrhythmia in neonates and infants, and pharmacological therapy is recommended to prevent recurrent episodes. This retrospective study aims to describe and analyze the practice patterns, effectiveness, and outcome of drug therapy for SVT in patients within the first year of life. Among the 67 patients analyzed, 48 presented with atrioventricular re-entrant tachycardia, 18 with focal atrial, and one with atrioventricular nodal re-entrant. Fetal tachycardia was reported in 27%. Antiarrhythmic treatment consisted of beta-receptor blocking agents in 42 patients, propafenone in 20, amiodarone in 20, and digoxin in 5. Arrhythmia control was achieved with single drug therapy in 70% of the patients, 21% needed dual therapy, and 6% triple. Propafenone was discontinued in 7 infants due to widening of the QRS complex. After 12 months (6-60), 75% of surviving patients were tachycardia-free and discontinued prophylactic treatment. Patients with fetal tachycardia had a significantly higher risk of persistent tachycardia (p: 0.007). Prophylactic antiarrhythmic medication for SVT in infancy is safe and well tolerated. Arrhythmia control is often achieved with single medication, and after cessation, most patients are free of arrhythmias. Infants with SVT and a history of fetal tachycardia are more prone to suffer from persistent SVT and relapses after cessation of prophylactic antiarrhythmic medication than infants with the first episode of SVT after birth.

Old stuff still trending: use of propafenone as a safety net until catheter ablation in a patient with documented pre-excited atrial fibrillation and Wolff-Parkinson-White syndrome - a classic case report

BACKGROUND

Atrial fibrillation in Wolff-Parkinson-White syndrome may result in life-threateningly rapid antegrade conduction over a bypass tract, manifested by an irregular broad-complex (pre-excited) tachycardia that can degenerate to ventricular fibrillation. The shortest pre-excited RR interval below 250 ms during atrial fibrillation (AF) predicts increased risk of sudden cardiac death.

CASE SUMMARY

We report a case of a 43-year-old man with unremarkable cardiac history who presented due to sudden-onset feeling of palpitations and pre-syncope after strenuous lifting. Electrocardiography depicted fast pre-excited AF. The shortest pre-excited RR interval was estimated at 160 ms, indicating an accessory pathway (AP) with short antegrade refractory period at risk for mediating sudden cardiac death. Direct current cardioversion restored sinus rhythm unravelling delta waves. The patient was put on propafenone 450 mg/day having an uneventful clinical course. On Day 10 post-admission, electrophysiological study induced rapid AF but the shortest pre-excited RR interval was substantially increased to 264 ms. A left anterolateral AP was ablated. The patient remained symptom free until his latest follow-up in the 3rd-month post-ablation without manifest pre-excitation on the surface electrocardiogram.

DISCUSSION

Treatment options of pre-excited AF include anti-arrhythmic agents but mainly electrical cardioversion. Cardioversion can safely restore sinus rhythm, while use of anti-arrhythmics often requires intensive care unit monitoring due to the risk of QT prolongation. Catheter ablation is the mainstay of therapy for symptomatic patients. Our rare report highlights the direct impact of propafenone on prolonging the refractoriness of the AP, effectively and safely, and reappraises propafenone's worthiness as a protective measure following pre-excited AF episode until ablation.

Drug-Induced Arrhythmias: A Scientific Statement From the American Heart Association

Many widely used medications may cause or exacerbate a variety of arrhythmias. Numerous antiarrhythmic agents, antimicrobial drugs, psychotropic medications, and methadone, as well as a growing list of drugs from other therapeutic classes (neurological drugs, anticancer agents, and many others), can prolong the QT interval and provoke torsades de pointes. Perhaps less familiar to clinicians is the fact that drugs can also trigger other arrhythmias, including bradyarrhythmias, atrial fibrillation/atrial flutter, atrial tachycardia, atrioventricular nodal reentrant tachycardia, monomorphic ventricular tachycardia, and Brugada syndrome. Some drug-induced arrhythmias (bradyarrhythmias, atrial tachycardia, atrioventricular node reentrant tachycardia) are significant predominantly because of their symptoms; others (monomorphic ventricular tachycardia, Brugada syndrome, torsades de pointes) may result in serious consequences, including sudden cardiac death. Mechanisms of arrhythmias are well known for some medications but, in other instances, remain poorly understood. For some drug-induced arrhythmias, particularly torsades de pointes, risk factors are well defined. Modification of risk factors, when possible, is important for prevention and risk reduction. In patients with nonmodifiable risk factors who require a potentially arrhythmia-inducing drug, enhanced electrocardiographic and other monitoring strategies may be beneficial for early detection and treatment. Management of drug-induced arrhythmias includes discontinuation of the offending medication and following treatment guidelines for the specific arrhythmia. In overdose situations, targeted detoxification strategies may be needed. Awareness of drugs that may cause arrhythmias and knowledge of distinct arrhythmias that may be drug-induced are essential for clinicians. Consideration of the possibility that a patient's arrythmia could be drug-induced is important.

Supraventricular tachyarrhythmias during the intrauterine, neonatal, and infant period: A 10-year population-based study

BACKGROUND

We aimed to evaluate the incidence, type, and management of supraventricular tachyarrhythmias (SVT) during the first year of life in a retrospective, population-based, single-center study during a 10-year period.

METHODS

The analyzed patient cohort is based on data from the only specialized center managing all cases of neonatal and infant SVTs between 2009 and 2018 in the Slovak Republic (5.5 million population). A total of 116 consecutive patients <366 days old were included in the study.

RESULTS

Calculated SVT incidence ratio was 1:4500 in the first year of life. AV reentry tachycardia was the leading arrhythmia (49%). SVT in this specific population was frequently a transient problem with spontaneous resolution in 87% of patients during a median 3-year follow up. Congenital heart disease was common (16%). Intrauterine treatment by drugs administered to mother was safe and effective in preventing unnecessary cesarean deliveries. In arrhythmia termination, amiodarone and propafenone were equally safe and effective, with possible more favorable pharmacodynamics of the former. For prophylactic treatment, sotalol and propafenone were equally safe and effective and became the preferred basis of long-term drug therapy in our center. However, this therapy requires intensive monitoring during its initiation.

CONCLUSION

The prognosis of SVT in the first year of life is good: with optimized pharmacological treatment, the need for early catheter ablation and mortality rate are low (<1%) and there is a high rate of spontaneous arrhythmia resolution. Heart failure is a possible predictor of arrhythmia persistence with need for ablation in later life.

Surface functionalized quantum dots as biosensor for highly selective and sensitive detection of ppb level of propafenone

Monodispersed CdTe quantum dots (QDs) were prepared by using thioglycolic acid as surfactants in aqueous solution. The thioglycolic acid was chemically adsorbed on the surface of CdTe QDs that enables the QDs positively charged. In week acidic media, propafenone is positively charged, which can combine with the CdTe QDs to form larger ion-association complex via electrostatic attraction and hydrogen bond. Moreover, the formed ion-association complex could increase the intensity of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling-scattering (FDS) of CdTe QDs, and quench the CdTe QDs fluorescence. Importantly, under optimal experimental conditions, the increased RRS, SOS and FDS intensity, and quenched fluorescence intensity of CdTe QDs were in direct proportion to the propafenone concentration in a certain range, respectively. Among them, the RRS method exhibited the highest sensitivity. In a wide concentration range of propafenone from 0.003 to 7.0 μg mL^-1, the detection limit could reach 0.96 ng mL^-1, which was much lower than previously reported methods. To simulate practical applications, the possible foreign interfering substances were also investigated, such as common ions, amino acid, and glucide. The proposed method here is rapid, sensitive and shows promising application for detection of ppb level of propafenone in human serum.

Management of Supraventricular Tachycardia in Infants

Supraventricular tachycardia is the most common tachyarrhythmia encountered in infants. In older children and adults, definitive treatment of the supraventricular tachycardia substrate with catheter ablation is a common approach to management. However, in infants, the risks of catheter ablation are significantly higher, and the patients often outgrow the potential to experience episodes. Therefore, antiarrhythmic medications are often utilized to minimize the likelihood of experiencing episodes. This article reviews the common arrhythmia mechanisms encountered in infants and the medications used to treat these patients.

Management of postoperative junctional ectopic tachycardia in pediatric patients: a survey of 30 centers in Germany, Austria, and Switzerland

Postoperative junctional ectopic tachycardia (JET) is a frequent complication after pediatric cardiac surgery. Current recommendations on how and when to treat JET are inconsistent. We evaluated the management strategies of postoperative JET in German-speaking countries. We sent an online survey to 30 centers of pediatric cardiology that perform surgery for congenital heart defects in Germany (24), Austria (4), and Switzerland (2). The survey asked 18 questions about how and in what treatment sequence postoperative JET was managed. All 30 centers completed the survey (100% return rate). There was general agreement that the management of JET is based on administration of antiarrhythmic drugs, body surface cooling, and temporary pacing. Many centers presented treatment algorithms based on published literature, all centers named amiodarone as the first drug of choice. Significant disagreement was found concerning the timing and sequential order of additional therapeutic measures and particularly about the dosing of amiodarone and the role of R-wave synchronized atrial pacing.

CONCLUSION

This survey reveals that from center to center, the treatment of postoperative JET may vary substantially. Future work should focus on those treatment modalities where a high rate of variation is found. Such studies may be of value to achieve commonly adopted treatment recommendations. What is known: • Treatment of postoperative junctional ectopic tachycardia is predominantly based on administration of antiarrhythmic drugs, therapeutic cooling, and temporary pacing. • Amiodarone is the antiarrhythmic drug of choice in this context. What is new: • Dosing and duration of administration of amiodarone differ relevantly from center to center. • The sequential order of drug administration, therapeutic cooling, and pacing is not consistent.

Pharmacologic cardiac resynchronization of a 1-year-old boy with severe left ventricular dysfunction

Postero-septal accessory pathways (AP) are a rare cause of intraventricular dyssynchrony and severe LV dysfunction in children. Beside the common treatment with radiofrequency ablation of septal substrates we present the case of a successful pharmacologic resynchronization in a 13/12 years old male toddler with Wolff-Parkinson-White syndrome (WPW) and severe LV dysfunction (left ventricular biplane EF of 31 %) due to intraventricular dyssynchrony with septal to posterior wall motion delay (SPWMD) of 350 ms. Interventricular mechanical delay (IVMD) was 65 ms. Using propafenone, pharmacologic cardiac resynchronization could be achieved. Pharmacologic resynchronization should be considered as safe and effective alternative to catheter ablation in very young children.

Profuse oral secretions after propafenone administration in neonates

Propafenone, an antiarrhythmic drug that is effective for treating supraventricular tachycardias, can induce well-known proarrhythmic and systemic adverse effects. We describe a previously unreported adverse effect in 3 newborns: oral propafenone-induced profuse oral secretions and respiratory distress of sufficient severity to necessitate discontinuation of propafenone.

Dofetilide for atrial arrhythmias in congenital heart disease: a multicenter study

BACKGROUND

Very little is known about use of the class III antiarrhythmic dofetilide in patients with congenital heart disease (CHD).

METHODS

A multicenter retrospective review of experience with dofetilide in CHD patients was undertaken.

RESULTS

Twenty adults with CHD and refractory atrial arrhythmias were treated with dofetilide at four institutions over a 7-year period. Three (15%) experienced adverse effects during in-hospital initiation of dofetilide (two with torsade de pointes, one with excessive QTc prolongation) and were not continued on this therapy. The remaining 17 were discharged taking dofetilide, with either resolved or improved arrhythmia. One was lost to follow-up. Five subsequently discontinued dofetilide due to waning effectiveness, manifest by recurrence of their arrhythmias. Eleven (55%) remained on dofetilide at most recent visit, with a median follow-up of nearly 1 year. Seven of these 11, or 35% of the CHD patients originally started on dofetilide, experienced a complete resolution of their arrhythmia. The remaining four had breakthrough episodes of atrial arrhythmia, but remained on dofetilide. No patient experienced torsade de pointes after the in-hospital initiation period.

CONCLUSIONS

Used appropriately, dofetilide appears to be a viable adjunct to catheter-based ablation and alternative pharmacological approaches for the treatment of atrial arrhythmias in adult patients with congenital heart disease.

Extemporaneous suspension of propafenone: attending lack of pediatric formulations in Mexico

BACKGROUND

Physicians have frequently encountered difficulties when prescribing drugs not available in doses suitable for pediatric age groups. Furthermore, children have difficulty swallowing tablets. This study aimed to determine the stability of an oral propafenone suspension made from commercial tablets with a syrup vehicle and to establish its reliable use with children.

METHODS

An extemporaneous suspension of propafenone 1.5 mg/ml was prepared with commercial tablets. Its physicochemical and microbiologic stability was established by constant monitoring during 90 days at room temperature (15 +/- 5 degrees C) and at refrigeration (3-5 degrees C). Plasma levels of propafenona were measured in two children with supraventricular tachycardia at steady state.

RESULTS

The suspension was stable, maintaining its original physicochemical and microbiologic properties. Moreover, no apparent changes in color or odor were observed. Plasma levels of propafenone in patients demonstrated therapeutic concentrations after they had taken the suspension, with no unwanted outcome.

CONCLUSIONS

The conservation of both physicochemical and microbiologic stability of the suspension represents an option for the administration of propafenone to children.

Management of infants with idiopathic dilatation of the right atrium and atrial tachycardia

Idiopathic dilatation of the right atrium (IDRA) is a rare anomaly defined as isolated enlargement of the right atrium in the absence of other cardiac lesions known to cause right atrial dilatation. IDRA is a congenital anomaly with unknown pathogenesis and highly variable clinical presentation. Optimal management of severe IDRA is controversial and individualized. Literature reports of long-term follow-up have been limited. We describe a child with IDRA with rapid atrial tachycardia (AT) refractory to both medical and surgical management, and we provide long-term follow-up on our two previously reported cases, both of whom had documented AT. For infants with AT, the clinical course is unpredictable, and medical therapy is the first line of treatment. The decision to proceed with surgical resection of a giant right atrium should be made on an individual basis. Atrial resection along with a modified right atrial MAZE procedure could be considered in infants with life-threatening atrial tachyarrhythmia refractory to medical treatment. Surgical scarring of the right atrium may produce substrate for atrial arrhythmia, which may also be refractory to medical therapy. Histological examination of excised atrial tissue remains inconsistent and not contributory to the determination of the etiology of IDRA. Our three infants with IDRA illustrate unique features of their variable clinical courses, as well as continued difficulties with establishing clear guidelines with regard to surgical management of this unusual disorder.

Bioavailability of an extemporaneous suspension of propafenone made from tablets

Propafenone is an effective antiarrhythmic agent used in children, while in Mexico no specific formulation for children is available, which causes errors in adequate dosage. The aim of this study was to determine the bioavailability of a suspension prepared extemporaneously using commercial tablets of propafenone. The bioavailability was determined in two groups of rabbits (n = 8): the first group received a single intravenous dose of 2 mg/kg of propafenone; the second was orally administered an extemporaneous suspension of propafenone prepared from commercial tablets. Blood samples were drawn at several times during the next 24 h and analysed by HPLC to determine drug levels. The extemporaneous suspension was tested previously with satisfactory results regarding physicochemical and microbiologic stability. The area under the curve (AUC) for the i.v. route was 5600.6 ng/ml.h and for oral administration the AUC was 3327.6 ng/ml.h. The bioavailability was calculated at 59.41%. These results are consistent with previous reports for solid dosage forms. The propafenone suspension prepared extemporaneously using commercial tablets is bioavailable using an animal model; nevertheless, it is necessary to carry out human studies either in volunteers or in patients to confirm these results.

Impact of curative ablation on pharmacologic management in children with reentrant supraventricular tachycardias

BACKGROUND

The introduction of radiofrequency catheter ablation as a curative treatment option has led to a much better outlook for children with recurrent supraventricular reentrant tachycardias (SVT). This study sought to evaluate the impact of ablation on pharmacologic treatment of SVT.

METHODS

Two time periods were retrospectively compared with regard to number of episodes of SVT in different age groups, number of acute drug conversions of SVT, chronic antiarrhythmic drug treatments prescribed: in the first period (1989-1994) management of SVT was exclusively pharmacological whereas during the second period (1995-2000) ablation was an option for patients aged 5 years or older.

RESULTS

The study included 88 pediatric patients with recurrent SVT, 40 in the first period, 48 in the latter. Of these, 16 children (all >5 years of age) had an ablation procedure during the second time period. In patients aged >5 years, the number of documented SVT fell from a mean of 3.7/patient to two episodes. The number of acute drug conversions of SVT decreased from a mean of 1.1/patient to 0.2 (p<0.05) during the second period. In the group of children aged >5 years chronic antiarrhythmic treatment was given during a mean of 15 months/patient in period one compared to 4.6 months (p<0.05) in the second period.

CONCLUSION

In the current era with increasing use of ablation as first-line treatment in older children with recurrent SVT, acute as well as chronic pharmacologic intervention for SVT has become significantly less frequent.

Intravenous flecainide for the treatment of junctional ectopic tachycardia after surgery for congenital heart disease

BACKGROUND

Junctional ectopic tachycardia (JET) is a life-threatening arrhythmia producing severe hemodynamic dysfunction, which may complicate the postoperative course of surgery for congenital heart disease. Strict care and a fast and effective antiarrhythmic strategy are essential, because mortality largely depends on the duration of the arrhythmia.

METHODS

Seven consecutive neonates with postoperative JET without any evidence of myocardial ischemia received intravenous flecainide after conventional therapies proved ineffective. Atrial pacing at the minimal rate for atrioventricular synchrony was followed by a 10-min intravenous infusion of 1.6 mg/kg flecainide, then continuous infusion of 0.4 mg/kg flecainide per hour. Treatment was considered effective based on restoration of sinus rhythm or a JET rate no higher than 170 bpm within 4 hours of flecainide loading. Overall mean flecainide infusion lasted 31.2 hours (range 25 to 53 hours). Side effects were assessed by monitoring plasma flecainide levels, electrocardiogram, arterial pressure, and central venous pressure.

RESULTS

Flecainide was effective in all 7 patients after an infusion duration of 3.6 +/- 1.5 hours. Sinus rhythm was restored after 7.2 +/- 9.7 hours. After 4 hours of loading, heart rate fell from 219 +/- 14 to 136 +/- 7 bpm (p < 0.0001), arterial pressure increased from 69 +/- 8 to 93 +/- 10 mm Hg (p < 0.0001), while central venous pressure decreased from 8.0 +/- 1.6 to 5.2 +/- 1.9 mm Hg (p = 0.0007). No side effect or recurrence was noted.

CONCLUSIONS

Flecainide can exert a fast antiarrhythmic effect on postoperative JET, and its infusion can be modulated to maintain the concentration within the therapeutic range, thus avoiding toxicity. We propose further consideration of flecainide for treatment of JET in neonates without myocardial ischemia.

Postoperative junctional ectopic tachycardia in children: incidence, risk factors, and treatment

BACKGROUND

Junctional ectopic tachycardia (JET) occurs commonly after pediatric cardiac operation. The cause of JET is thought to be the result of an injury to the conduction system during the procedure and may be perpetuated by hemodynamic disturbances or postoperative electrolyte disturbances, namely hypomagnesemia. The purpose of this study was to determine perioperative risk factors for the development of JET.

METHODS

Telemetry for each patient admitted to the cardiac intensive care unit from December 1997 through November 1998 for postoperative cardiac surgical care was examined daily for postoperative JET. A nested case-cohort analysis of 33 patients who experienced JET from 594 consecutively monitored patients who underwent cardiac operation was performed. Univariate and multivariate analyses were conducted to determine factors associated with the occurrence of JET.

RESULTS

The age range of patients with JET was 1 day to 10.5 years (median, 1.8 months). Univariate analysis revealed that dopamine or milrinone use postoperatively, longer cardiopulmonary bypass times, and younger age were associated with JET. Multivariate modeling elicited that dopamine use postoperatively (odds ratio, 6.2; p = 0.01) and age less than 6 months (odds ratio, 4.0; p = 0.02) were associated with JET. Only 13 (39%) of the patients with JET received therapeutic interventions.

CONCLUSIONS

Junctional ectopic tachycardia occurred in 33 (5.6%) of 594 patients who underwent cardiac operation during the study period. Postoperative dopamine use and younger age were associated with JET. It may be speculated that dopamine should be discontinued in the presence of postoperative JET.

Electrophysiologic effects and efficacy of intravenous propafenone in terminating atrioventricular reentrant tachycardia in children

In pediatric patients with atrioventricular reentrant tachycardia, intravenous propafenone exhibits its electrophysiologic effects in a dose-dependent manner by slowing or blocking retrograde conduction at the accessory connection. The high drug efficacy (81%) in terminating tachycardia is not dependent on patient age or retrograde conduction properties of the accessory connection.

Pharmacologic management of arrhythmias in patients with congenital heart disease

The management of cardiac arrhythmias has evolved rapidly over the past decade. This includes the development of more effective antiarrhythmic medications as well as catheter- and device-based therapies. Antiarrhythmic medications remain the primary treatment modality for most acute arrhythmias; however, the long term use of these medications may be accompanied by severe adverse effects. For this reason, antiarrhythmic medications are increasingly used in conjunction with other forms of therapy, such as catheter ablation or pacemaker implantation. Patients with congenital heart disease often have an increased propensity for cardiac arrhythmias due to both inherent conduction system abnormalities and impaired ventricular function. The purpose of this review is to examine the currently available antiarrhythmic drugs and assess their role in the treatment of arrhythmias in patients with congenital heart disease. It is important to emphasize that patients with congenital heart disease often have hemodynamic limitations and may be at an increased risk for developing adverse effects with antiarrhythmic agents. An awareness of the arrhythmias associated with congenital heart disease, the natural history of these arrhythmias, and the potential benefit of treatment with antiarrhythmic medications versus other forms of therapy provides a rational basis for therapy in this challenging population of patients.

Supraventricular tachycardia in the neonate and infant

Supraventricular tachycardia (SVT) is the most common sustained arrhythmia to present in the neonatal and infancy age group. Predisposing factors (congenital heart disease, drug administration, illness and fever) occur only in 15% of infants. The presentation of SVT in the neonate is frequently subtle, and may include pallor, cyanosis, restlessness, irritability, feeding difficulty, tachypnea, diaphoresis and grunting. Congestive heart failure is more common in infants under 4 months of age (35% incidence). Age-related differences in the distribution of SVT mechanisms occur in different age groups. In infants under 1 year of age, the mechanisms underlying SVT are atrial tachycardia (15%), AV nodal re-entry tachycardia (5%), and AV reciprocating tachycardia (80%). Options for acute management include: use of the diving reflex, intravenous adenosine, transesophageal pacing, and cardioversion. Intravenous administration of verapamil should be avoided. Data regarding freedom from recurrence of untreated SVT in the first year of life are limited, and may be in the range of 25-60%. Chronic therapy with digoxin, beta-blockers, flecainide, sotalol and amiodarone has proved effective in controlling recurrent episodes of SVT. Radiofrequency ablation can be employed successfully in medically refractory cases, but should be avoided in this age group (increased complication rate).

Supraventricular tachycardia in infants, children and adolescents: diagnosis, and pharmacological and interventional therapy

Supraventricular tachycardia is the most frequent form of symptomatic tachydysrhythmia in children. Neonates and infants with paroxysmal supraventricular tachycardias generally present with signs of acute congestive heart failure. In school-aged children and adolescents, palpitations are the leading symptom. Chronic-permanent tachycardia results in a secondary form of dilated cardiomyopathy. Therapy for episodes of tachycardia depends on the individual situation. In severe haemodynamic compromise, or if ventricular tachycardia is suspected, tachycardia should immediately be terminated by external cardioversion during deep sedation. Vagal manoeuvres are effective in patients with atrioventricular reentrant tachycardias. Adenosine is the drug of first choice in any age group for tachycardias involving the atrioventricular node; its advantages include short half-life and minimal or absent negative inotropic effects. Adenosine may also be used in patients with wide QRS complex tachycardia. Intravenous verapamil is contraindicated in neonates and infants because of the high risk of electromechanical dissociation. In older children (>5 years) and adolescents, verapamil may be administered with the same restrictions as in adult patients (wide QRS complex tachycardia, significant haemodynamic compromise). Spontaneous cessation of tachycardia can be expected in most neonates and infants during the first year of life. Prophylactic pharmacological treatment in this age group is advisable because recognition of tachycardia is often delayed until the occurrence of symptoms. Withdrawal of drug treatment should be attempted around the end of the first year. However, in older children, spontaneous cessation of tachycardia is rare. Prophylactic drug therapy is performed on an empirical basis. Digoxin may be administered in all forms of supraventricular tachycardia in which the atrioventricular node is involved, except in patients with pre-excitation syndrome aged >1 year. In patients with atrioventricular reentrant tachycardia, class IC drugs such as flecainide and propafenone are effective. Sotalol is also effective in atrioventricular reentrant tachycardia, as well as in primary atrial tachycardia. Although amiodarone has the highest antiarrhythmic potential, it should be used with caution because of its high rate of adverse effects. In school-aged children and adolescents, radiofrequency catheter ablation of the anatomical substrate is an attractive alternative to drug therapy, with a rate of permanent cessation of the tachycardia of up to 90%. Despite the clear advantages of this procedure, it should be performed only with unquestionable indication; the long term morphological and electrophysiological sequelae on the growing atrial and ventricular myocardium are still unknown.

Antiarrhythmic drug therapy in the neonate

The neonate presents a challenge for the practitioner considering antiarrhythmic therapy: pharmacokinetics are different than in older children or adults; and the arrhythmia substrate may also differ, with respect to issues of ion channel and autonomic nervous system development. This paper reviews the need for antiarrhythmic drug therapy in the neonate, developmental aspects of pharmacokinetics, autonomic regulation and cellular electrophysiology and the antiarrhythmics available today with an emphasis on newer drug therapy.