Administration of Isoproterenol and Adenosine to Guide Supplemental Ablation After Pulmonary Vein Antrum Isolation

Radiofrequency and Cryo-Ablation Effect on Transvenous Pacing and Defibrillatory Lead Integrity: An In Vitro Study

INTORDUCTION

Medical societies and cardiac implantable electronic device (CIED) manufacturers recommend avoiding close or direct contact between the body of transvenous leads and ablation catheters used to treat cardiac arrhythmias. These recommendations are made despite the lack of clinical studies. However, the target myocardium for successful ablation can be contiguous to CIED leads.

METHODS AND RESULTS

We examine in vitro the effects of direct application of radiofrequency (RF) and cryo-ablation energy on the integrity and functionality of CIED leads (excluding the pacing electrodes and defibrillation coils). A saline bath was created to mimic the body milieu. CIED leads, including all commercially available lead insulation materials, were connected to a CIED pulse generator and placed in direct contact with an ablation catheter in the tissue bath. RF and cryo-ablation energy were delivered under various conditions, including maximal ablation power, temperature, and impedance via the RF generator. CIED lead functionality, reflective of conductor integrity, was evaluated through lead impedance monitoring during ablation. CIED leads were then visually inspected, and examined with optic and electron microscopy as per protocol. A total of 42 leads were studied. All leads showed the absence of insulation damage at the site of ablation visually and with microscopy. Lead functionality was also preserved in all leads.

CONCLUSION

Catheter ablation in contact with CIED leads using radiofrequency or cryo-ablation in vitro did not affect lead body integrity and function despite aggressive ablation settings. It may be reasonable to perform ablation in contact with the body of CIED leads when clinically necessary.

Pharmacological Tests in Atrial Fibrillation Ablation

The invasive management of atrial fibrillation (AF) has been considerably changed by the identification of major sites of AF initiation and/or maintenance within the pulmonary vein antra. Percutaneous catheter ablation of these targets has become the standard of care for sustained maintenance of sinus rhythm. Long-term failure of ablation is related to an inability to create a durable transmural lesion or to identify all of the non-pulmonary vein arrhythmia triggers. Pharmacological challenges during catheter ablation have been suggested to improve outcomes in both paroxysmal and persistent AF. Herein we review the mechanism and evidence for the use of pharmacological adjuncts during the catheter ablation of AF.

A case of paroxysmal atrial fibrillation with a non-pulmonary vein trigger identified by intravenous adenosine triphosphate infusion

A 54-year-old woman was referred to our institution with frequent chest discomfort and was diagnosed with drug-refractory paroxysmal atrial fibrillation. Radiofrequency catheter ablation (RFCA) was performed using a three-dimensional electroanatomic mapping system. After completion of left and right circumferential pulmonary vein isolation (CPVI), an intravenous bolus of adenosine triphosphate (ATP, 20 mg) was administered to evaluate the electric reconduction between the pulmonary vein (PV) and left atrium (LA). Although no PV-LA reconduction was observed, atrial fibrillation (AF) was reproducibly induced. As the duration of AF was very short (<20 s), no further RFCA to the LA was performed. One month later, the patient presented with frequent atrial tachyarrhythmias (ATs), and RFCA was repeated. Although no electric reconduction was observed in the left- or right-sided PVs, incessant ATs and AF were induced after an intravenous bolus administration of ATP. The earliest atrial activation site initiating ATs was consistently identified from electrodes positioned in the superior vena cava (SVC), and both ATs and AF were no longer inducible after electric isolation of the SVC. ATP-induced PV/non-PV ectopy may be a marker of increased susceptibility to autonomic triggers of AF and could potentially predict recurrent AF after CPVI.

Right-to-left frequency gradient during atrial fibrillation initiated by right atrial ectopies and its augmentation by adenosine triphosphate: Implications of right atrial fibrillation

BACKGROUND

A left-to-right dominant frequency (DF) gradient commonly exists in paroxysmal atrial fibrillation (AF). AF initiated by right atrial (RA) ectopy (AF-RAE) is rare.

OBJECTIVE

This study aimed to investigate characteristics of AF-RAE using pharmacological maneuvers and spectral analysis.

METHODS

Seventy-nine consecutive patients referred for catheter ablation of paroxysmal AF were enrolled. Infusions of isoproterenol and adenosine triphosphate (ATP) were used to induce AF. Patients with AF-RAE and patients with AF initiated only by pulmonary vein (PV) ectopies were classified into the RA-ectopy group (n = 7[9%]) and PV-ectopy group (n = 32[41%]), respectively. ATP was also injected during ongoing AF to unmask the driver of AF. High RA, coronary sinus, and PV-left atrial junction electrograms and electrocardiogram lead V1 underwent spectral analyses.

RESULTS

Patients in the RA-ectopy group were younger (51 ± 13 years vs 63 ± 7 years; P = .01) and more commonly had a family history of AF (71% vs 9%; P < .001) than patients in the PV-ectopy group. There was a baseline right-to-left DF gradient in the RA-ectopy group (PV-left atrial junction: 6.0 ± 0.4 Hz; coronary sinus: 5.7 ± 0.6 Hz; RA: 7.3 ± 0.8 Hz; P < .05) in contrast to a left-to-right DF gradient in the PV-ectopy group (5.9 ± 0.8, 5.3 ± 0.7, 5.2 ± 0.8 Hz; P < .01). ATP injection predominantly increased the DF of the high RA in the RA-ectopy group and augmented a right-to-left DF gradient (7.9 ± 1.8, 7.6 ± 1.0, 10.7 ± 0.7 Hz; P < .001), whereas it augmented a left-to-right DF gradient in the PV-ectopy group (7.9 ± 1.0, 6.4 ± 0.5, 6.6 ± 1.2 Hz; P < .05).

CONCLUSION

A rare type of paroxysmal AF initiated by RA ectopy may be maintained by a reentrant driver localized in the RA (so-called RA fibrillation).

Arrhythmia Termination Versus Elimination of Dormant Pulmonary Vein Conduction as a Procedural End Point of Catheter Ablation for Paroxysmal Atrial Fibrillation: A Prospective Randomized Trial

Background—

Pulmonary vein isolation (PVI) is still associated with a substantial number of arrhythmia recurrences in paroxysmal atrial fibrillation (AF). This prospective, randomized study aimed to compare 2 different procedural strategies.

Methods and Results—

A total of 152 patients undergoing de novo ablation for paroxysmal AF were randomized to 2 different treatment arms. The procedure in group A consisted of PVI exclusively. In this group, all isolated PVs were challenged with adenosine to reveal and ablate dormant conduction. In group B, PVI was performed with the patient either in spontaneous or in induced AF. If AF did not terminate with PVI, ablation was continued by targeting extra-PV AF sources with the desired procedural end point of termination to sinus rhythm. Primary study end point was freedom from arrhythmia during 1-year follow-up. In group A, adenosine provoked dormant conduction in 31 (41%) patients with a mean of 1.6±0.8 transiently recovered PVs per patient. Termination of AF during PVI was observed in 31 (65%) patients, whereas AF persisted afterward in 17 (35%) patients. AF termination occurred in 13 (76%) patients by AF source ablation. After 1-year follow-up, significantly more group B patients were free of arrhythmia recurrences (87 versus 68%; P=0.006). During redo ablation, the rate of PV reconduction did not differ between both groups (group A: 55% versus group B: 61%; P=0.25).

Conclusions—

Elimination of extra-PV AF sources after PVI is superior to sole PV isolation with the adjunct of abolishing potential dormant conduction.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02238392.

How To Achieve Durable Pulmonary Vein Antral Isolation?

The inability to achieve durable pulmonary vein isolation(PVI) remains a major limitation to a catheter ablation for thew treatment of atrial fibrillation(AF), potentially resulting in AF recurrence.In this review,we discuss the research performed investigating methods to improve lesion permanence for the goal of durable PVI.Investigations evaluted procedural techniques,various catheres utilized, adjunctive pharamacologic therapy and novel energy sources designed to improve ablation lesion permanence are discussed.