Radiofrequency catheter ablation of accessory pathways in infants

Optimizing outcomes of catheter ablation in infants and toddlers

Since the introduction of transcatheter ablation in the late 1980s, there has been significant technical development. With a very high success rate and low complication rate, ablation has now become the standard of care in children and adults. However, long-term data remain insufficient and the application of ablation therapy in small children is debatable. In this review, current treatment strategies and results in toddlers and infants will be discussed. There has been improvement in success rate and complication rate for ablation in small children. Technological advancements in non-fluoroscopic electroanatomical mapping systems (3D systems) have led to the reduction of radiation and have facilitated ablations in complex cases. However, long-term effects of ablation lesions in small children remain a potential concern.

Anatomic Challenges In Pediatric Catheter Ablation

Pediatric patients present unique anatomic challenges for catheter ablation. Small patient size requires special adaptation and understanding to perform safe procedures when clinically indicated. The anatomic variations of congenital heart disease also create problems that require pre-procedural preparation for each case in addition to a specialized understanding of a vast anatomic variation and surgical repairs. This understanding coupled with the knowledge of the pathophysiology of arrhythmia disorders and the biophysics of catheter ablation technology are required to perform successful and safe ablation procedures in this special population.

Multiple cardiac perforations following radiofrequency catheter ablation: case report and literature reviews

INTRODUCTION

Multiple cardiac ruptures after radiofrequency catheter ablation that requires surgical repair are uncommon.

METHODS AND RESULTS

We describe a 64-year old male patient with paroxysmal atrial fibrillation who had a cardiac tamponade following radiofrequency ablation. Surgical exploration demonstrated two ruptures in the left atrium, one in the right atrium, and one hematoma in the right atrium. MEDLINE, the Cochrane Library, and related databases were searched up to June 2011 without language restrictions, and related literature was reviewed and discussed. The patient has survived from prompt cardiac repair of cardiac ruptures and recovered from surgery without complications.

CONCLUSIONS

Urgent exploratory surgery with cardiopulmonary bypass is the key to salvage the patient.

Acute coronary artery stenosis during slow pathway ablation for atrioventricular nodal reentrant tachycardia in a child

Coronary injury during radiofrequency ablation is a rare but n. potentially life-threatening complication that has been reported for attempted elimination of accessory pathways. This is the first report of coronary artery injury during slow pathway ablation for AV nodal reentrant tachycardia. Manifest signs of injury may be transient or nonexistent and easily missed. Controlled studies are needed to determine the true risk of coronary artery injury during radiofrequency ablation for supraventricular tachycardia, particularly in small children.

Registro español sobre organización, recursos y actividades en Cardiología Pediátrica

INTRODUCTION

We present the findings of the registry of activities and resources of the Spanish Society of Pediatric Cardiology in 2002, with the objective of providing a national reference for professionals and entities involved in the study and treatment of congenital heart defects.

METHODS

Data were retrospectively collected through questionnaires sent from the Spanish Society of Pediatric Cardiology to the heads of pediatric cardiology units with medical and surgical activities, as well as to all the members of the Society and those of the Pediatric Cardiology Section of the Spanish Society of Cardiology.

RESULTS

Thirty-eight centers, including 17 national centers with medical and surgical activities, completed the questionnaire. Human resources consisted of 110 cardiologists, 43 surgeons and 12 residents in training. All the centers had the elementary tools for diagnosis and all except one had Echo-2D-Doppler. There were eight catheterization laboratories exclusively used for pediatric activities and nine further laboratories that combined adult and pediatric activities. A total of 83,061 patients were attended in outpatient clinics and there were 6,938 hospital admissions in 22 centres. A total of 279 ablation procedures were performed in 12 electrophysiology laboratories. The seventeen centres with surgical activities performed 2,498 cardiac catheterisms (968 interventional) and 2,292 cardiac surgical interventions.

CONCLUSIONS

Given the large number of participating centers, the present report provides exhaustive information on the organization, resources and activities of pediatric cardiology in Spain. Pediatric cardiology should be granted official recognition of its work so that teaching hospitals, organization, resources and activities can be regulated.

Radiofrequency catheter ablation of arrhythmias in infants and small children

The issue of the proper use of radiofrequency catheter ablation in infants and small children is controversial. Rarely, catheter ablation techniques are indicated to cure malignant arrhythmias in the pediatric population. Indications, techniques, complications and success rates are reviewed.

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).

[Catheter ablation of accessory pathways in infants and children weighing less than 10 kg]

INTRODUCTION

Low weight is considered an independent risk factor for the appearance of complications in radiofrequency catheter ablation of accessory pathways in children.

OBJECTIVES

The purpose of this study was to evaluate the results and long term follow-up of radiofrequency catheter ablation in eight infants and small children of accessory pathways of less than 10 kg in weight.

METHODS AND RESULTS

There were 3 boys and 5 girls with a mean age of 6.3 +/- 5 months (range, 2.5 to 17) and an average weight of 6.2 +/- 1.9 kg (range, 3.5 to 9). The eight patients underwent a single successful ablation procedure. Five left free wall pathways were ablated by transseptal approach, two right posteroseptal pathways were ablated from the inferior vena cava and a left posteroseptal was approached from the inferior vena cava into the coronary sinus. A deflectable 5F bipolar electrode catheter with a 3 mm tip was used in the first five patients and a deflectable 5F tetrapolar catheter with a 4 mm tip and temperature monitoring using closed loop control in the 3 remaining patients. An abrupt increment in impedance due to the development of a coagulum was observed in 2 procedures. One patient developed an acute ischemic complication during ablation of a left lateral accessory pathway by transseptal approach. This patient had mild pericardial effusion after the procedure. Moderate pericardial effusion was also noted in another patient after radiofrequency ablation that resolved itself spontaneously. In the remainder of the procedures there were not complications. After a mean follow-up of 32.3 +/- 22.1 months (median 42) all patients are asymptomatic without antiarrhythmic treatment.

CONCLUSIONS

a) radiofrequency catheter ablation can be performed successfully in infants and small children weighing less than 10 kg, and b) echocardiography must be performed inmediately after the procedure in infants to investigate pericardial effusion.

Radiofrequency current application on immature porcine atrial myocardium: no evidence of areas of slow conduction after 12-month follow-up

INTRODUCTION

Radiofrequency current (RFC) application is a widely used procedure for treatment of supraventricular arrhythmias. The purpose of this study was to investigate late electrophysiologic sequelae of RFC lesions at immature atrial myocardium in pigs, as they have not yet been systematically investigated in vitro.

METHODS AND RESULTS

RFC application (temperature guided) was performed in seven piglets (mean age 6 weeks) by a steerable 6-French electrode catheter positioned at the lateral aspect of the tricuspid valve annulus. After 12 months, hearts were removed, and lesions with surrounding tissue were isolated. The viable tissue at the border of the specimen was paced with a cycle length of 500 and 600 msec. One hundred fifty impalements were performed on each specimen using capillary microelectrodes to record action potential characteristics from the lesion's surface and the surrounding tissue. In all seven specimens, no transmembrane action potentials from the fibrotic surface of each of the lesions could be recorded. The surrounding viable tissue was sharply demarcated electrically. No areas of slow conduction were detected. Action potential characteristics as mean maximum diastolic transmembrane potential, mean action potential duration at 90% repolarization, and upstroke velocity of phase 0 of the action potential were all normal.

CONCLUSION

No evidence of areas of slow conduction 12 months after RFC application at immature atrial myocardium suggests that this technique is safe regarding occurrence of late atrial tachyarrhythmias after the procedure.