Complications associated with radiofrequency catheter ablation of cardiac arrhythmias

Ablation of accessory pathways in different anatomic locations using focal pulsed field ablation

BACKGROUND

Ablation of accessory pathways (APs) is the cornerstone for treatment of patients with Wolff-Parkinson-White syndrome and manifestation of atrioventricular reentrant tachycardia. Pulsed field ablation (PFA) is a new type of nonthermal energy source delivered to the underlying tissue via the ablation catheter and used for ablation of arrhythmic substrates.

OBJECTIVE

The purpose of this study was to determine the efficiency and long-term outcome of ablation of APs of different localizations using a focal pulsed electrical field.

METHODS

Electrophysiological study was performed in patients with indication for AP ablation. An ablation catheter was used to map the position of AP insertion. Pulsed electric field was delivered through a standard ablation catheter. In left-sided APs, the first ablation attempt was within the coronary sinus (CS). Patient follow-up was scheduled 1-3 months after the ablation. Additional check-up was performed after 6 and 12 months.

RESULTS

Fourteen 14 patients (3 pediatric) were treated. Termination of AP conduction was achieved in all procedures. The cohort consisted of 3 right free wall, 3 posteroseptal, and 8 left-sided APs. Ablation through CS was successfully used in 7 of 8 patients with left-sided APs. No complications were reported. Median follow-up was 5.5 months. Conduction recurrence through AP was documented in 1 patient.

CONCLUSION

Focal PFA for AP shows promising results in terms of efficacy and safety. A high rate of successful termination of left-sided APs by ablation within CS may represent a new standard approach. The safety and efficacy profile of PFA seems to be transferable to the pediatric population.

Capsule endoscopy in examination of esophagus for lesions after radiofrequency catheter ablation: a potential tool to select patients with increased risk of complications

BACKGROUND

Esophageal injury can result from left atrial radiofrequency ablation (RFA) therapy, with added concern because of its possible relationship to the development of atrial-esophageal (A-E) fistulas.

OBJECTIVE

Evaluate utility of esophageal capsule endoscopy to detect esophageal lesions as a complication of RFA therapy in the treatment of atrial fibrillation (AF).

METHODS

Consecutive patients with AF who underwent left atrial RFA therapy and received capsule endoscopy within 48 hours postablation. Video was reviewed by a single gastroenterologist. The medical records were also reviewed for symptoms immediately postablation and at the 3-month follow-up.

RESULTS

A total of 93 consecutive patients were included and 88 completed the study and were analyzed. The prevalence of esophageal lesions was 17% (15/88 patients). Nine percent (8/88) of these patients had lesions anatomically consistent with the location of the ablation catheter. Six patients with positive capsule findings had symptoms of chest pain (3/6, 50%), throat pain (2/6, 33%), nausea (1/6, 17%), and abdominal pain (1/6, 17%). An additional 24 patients were symptomatic postablation, but with normal capsule findings. All patients with identified lesions by capsule endoscopy received oral proton pump inhibitor therapy, and were instructed to contact the Cleveland Clinic in the event of worsening symptoms. No delayed complications were reported at the 3-month follow-up.

CONCLUSION

This study supports the use of capsule endoscopy as a tool for the detection of esophageal injury post-RFA therapy. PillCam ESO is well tolerated and provides satisfactory images of the areas of interest in the esophagus without potential risk related to insufflation with regular esophagogastroduodenoscopy.

Lengthier cryoablation and a bonus cryoapplication is associated with improved efficacy for cryothermal catheter ablation of supraventricular tachycardias in children

INTRODUCTION

Cryoablation is an effective treatment for children with supraventricular tachycardias (SVT). The present study documents the effect of two different cryoablation protocols on acute and chronic success rates.

METHODS AND RESULTS

Fifty-three consecutive patients (age range, 5-20 years) were treated; patients 1 to 17 were treated by a standard ablation protocol and patients 18 to 53 were treated by a modified ablation protocol that required lengthier cryoablations plus delivery of a bonus cryoapplication to consolidate the acutely successful irreversible lesion created at intervention. Electrophysiological study (EPS) was performed with diagnostic catheters and cryoablations were performed with a 7FR 4 mm tip catheter (CryoCath Technologies). Acute endpoints for non-inducibility of atrioventricular nodal re-entrant tachycardia (AVNRT) by programmed atrial stimulation at baseline or during isoproterenol performed 30 min post procedure, as well as non-inducibility and conduction block over the accessory pathway (AP). The chronic endpoint was arrhythmia recurrence post intervention. No permanent cryo-related complications or adverse outcomes were reported. Acute success rates for patients 1 to 17 and 18 to 53 were 88 and 100%, respectively. The cumulative percentage of patients without arrhythmia recurrence at 12 month follow-up was significantly different at 73 and 90%, respectively.

CONCLUSIONS

Lengthier cryoablation delivery, approximating 7 min per cryoablation, increases the acute success rate at intervention. Moreover, these lengthier cryoablation deliveries plus a bonus cryoapplication to consolidate the acutely successful irreversible lesion created at intervention may also significantly improve the chronic success rate, while also maintaining an excellent safety profile for cryoablation treatment of children with SVT such as AVNRT and AP located near the AV junction.

Change in Size of Lesions Over 3 Weeks After Radiofrequency Ablation of Left Ventricle

INTRODUCTION

The initial success or failure of radiofrequency ablation (RFA) does not always reflect the long-term outcome that can lead to complications such as late atrioventricular block or recurrence of accessory pathways. We hypothesize that these occurrences may be due to a change in lesion size over time.

METHODS AND RESULTS

Intramural RFAs were performed on five greyhounds at thoracotomy using an epicardial approach into the left ventricular (LV) wall. Twenty-one gauge needle electrode ablations were created in the anterior aspect of the left ventricle. Radiofrequency energy was delivered at 600 Hz for 60 seconds and at an electrode temperature of 90 degrees C. Eight ablations were created in each greyhound and the chest was closed. After 3 weeks, a further eight ablations were created under the same conditions in the lateral aspect of the LV, ensuring they were well away from the chronic lesions, and the dogs were sacrificed an hour later. All lesions were removed, stained with Gomori Trichrome and measured. There was no significant difference in lesion size detected in the 1-hour-old lesions compared with 3-week-old lesions. Acute lesions were well demarcated by an area of fibrous scar and a central necrotic region. Chronic lesions showed chronic inflammatory cells and strands of collagen.

CONCLUSIONS

This study shows no change in lesion dimension over time and hence a change in size may not contribute to a change in RFA outcome over time.

Innovations in cardiovascular pathology: anatomic and electrophysiologic determinants associated with ablation of atrial arrhythmias

The pathologist is required to evaluate hearts and surgical specimens following innovative therapies to ablate arrhythmias. For the treatment or cure of atrial fibrillation, ablation of the pulmonary vein sleeves and left atrium is increasingly encountered. The recognized contribution of the right atrium, Bachmann's bundle and other sites such as the vein of Marshall and epicardial ganglia has given rise to specific procedures to target these areas. Improved and safe power sources are needed to achieve these goals. Catheters and devices have been developed using different energy types to create therapeutic lesions. The pathologist will encounter different sources of energy and catheter and probe device modifications for surgical and catheter-based endocardial and epicardial therapy. This article reviews the pathology of ablation and the recent innovations in the treatment of atrial arrhythmias.

Endocardial flap of left atrial dissection following radiofrequency ablation

This report describes an unusual mobile strand found by transesophageal echocardiography prior to a patient's second radiofrequency ablation for paroxysmal atrial fibrillation. This structure arose from the limbus of the left upper pulmonary vein, a location where radiofrequency energy bursts were delivered during the first ablation procedure. After seven months of therapeutic anticoagulation, there was no evidence of change in the size of the mass or of thromboembolism and the patient underwent radiofrequency ablation without complication. We believe this structure most likely represents an endocardial flap of left atrial dissection temporally related to radiofrequency ablation.