[Show abstract][Hide abstract] ABSTRACT: Purpose:
Data on epicardial contact force efficacy in dual epicardial-endocardial atrial fibrillation ablation procedures are lacking. We present an in vitro study on the importance of epicardial and endocardial contact forces during this procedure.
The in vitro setup consists of two separate chambers, mimicking the endocardial and epicardial sides of the heart. A circuit, including a pump and a heat exchanger, circulates porcine blood through the endocardial chamber. A septum, with a cut out, allows the placement of a magnetically fixed tissue holder, securing porcine atrial tissue, in the middle of both chambers. Two trocars provide access to the epicardium and endocardium. Force transducers mounted on both catheter holders allow real-time contact force monitoring, while a railing system allows controlled contact force adjustment. We histologically assessed different combinations of epi-endocardial radiofrequency ablation contact forces using porcine atria, evaluating the ablation's diameters, area, and volume.
An epicardial ablation with forces of 100 or 300 g, followed by an endocardial ablation with a force of 20 g did not achieve transmurality. Increasing endocardial forces to 30 and 40 g combined with an epicardial force ranging from 100 to 300 and 500 g led to transmurality with significant increases in lesion's diameters, area, and volumes.
Increased endocardial contact forces led to larger ablation lesions regardless of standard epicardial pressure forces. In order to gain transmurality in a model of a combined epicardial-endocardial procedure, a minimal endocardial force of 30 g combined with an epicardial force of 100 g is necessary.
Full-text · Article · Jan 2016 · Journal of Interventional Cardiac Electrophysiology
[Show abstract][Hide abstract] ABSTRACT: The aim of this survey was to provide insight into current practice regarding ablation of persistent atrial fibrillation (AF) among members of the European Heart Rhythm Association electrophysiology research network. Thirty centres responded to the survey. The main ablationtechnique for first-time ablation was stand-alone pulmonary vein isolation (PVI): in 67% of the centres for persistent but not long-standing AF and in 37% of the centres for long-standing persistent AF as well. Other applied techniques were ablation of fractionated electrograms, placement of linear lesions, stepwise approach until AF termination, and substrate mapping and isolation of low-voltage areas. However, the percentage of centres applying these techniques during first ablation did not exceed 25% for any technique. When stand-alone PVI wasperformed in patients with persistent but not long-standing AF, the majority (80%) of the centres used an irrigated radiofrequency ablation catheter whereas 20% of the respondents used the cryoballoon. Similar results were reported for ablation of long-standing persistent AF (radiofrequency 90%, cryoballoon 10%). Neither rotor mapping nor one-shot ablation tools were used as the main first-time ablation methods. Systematic search for non-pulmonary vein triggers was performed only in 10% of the centres. Most common 1-year success rate offantiarrhythmic drugs was 50-60%. Only 27% of the centres knew their 5-year results. In conclusion, patients with persistent AF represent a significant proportion of AF patients undergoing ablation. There is a shift towards stand-alone PVI being the primary choice in many centresfor first-time ablation in these patients. The wide variation in the use of additional techniques and in the choice of endpoints reflects the uncertainties and lack of guidance regarding the most optimal approach. Procedural success rates are modest and long-term outcomes areunknown in most centres.
[Show abstract][Hide abstract] ABSTRACT: To the Editor: Verma et al. (May 7 issue)(1) report that the performance of neither linear ablation nor ablation of complex fractionated electrograms provided an incremental benefit when added to pulmonary-vein isolation to decrease the rate of recurrent atrial fibrillation. Di Biase et al.(2) note that the left atrial appendage acts as a potential trigger for atrial fibrillation or atrial tachycardia in approximately 27% of patients with atrial fibrillation who require repeat catheter ablation. They found that recurrent atrial fibrillation was significantly reduced in patients undergoing isolation of the left atrial appendage (segmental or circumferential ablation), with a recurrence rate . . .
Preview · Article · Aug 2015 · New England Journal of Medicine
[Show abstract][Hide abstract] ABSTRACT: Atrial fibrillation (AF) is the most common chronic arrhythmia in the adult population. Ablation lines have largely replaced the historical and challenging cut and sew techniques. Surgical ablation of AF is commonly performed in cases with other indications for cardiac surgery and less commonly as a stand-alone therapy. Pulmonary vein isolation is the cornerstone of this procedure. Extended left atrial ablation lines may increase efficacy in cases with longstanding persistent or permanent AF. Additional efficacy by adding right atrial ablation is controversial but is often performed in cases undergoing right atrial or atrial septal surgery. Left atrial volume reduction is recommended in cases with large left atria and AF undergoing another cardiac surgery. Arrhythmia recurrence is not uncommon after surgical ablation of AF and varies among studies due to heterogeneity in patient population, lesion set and endpoints. Freedom from AF recurrence was 65-87% at 12 months and 58-70% at 2 years follow-up. Long-term monitoring is recommended due to an increased prevalence of asymptomatic recurrences. The strongest predictors of AF recurrence are longstanding or persistent AF and a large left atrium. The most common mechanisms of recurrence are pulmonary vein reconnection, non-pulmonary vein triggers, and gaps in the ablation lines. About 20% of atrial tachyarrhythmia recurrences are atrial flutter or atrial tachycardia. There are not enough data in the surgical literature to support withdrawal of anticoagulation after surgical AF ablation. Patients selected for stand-alone surgical ablation usually have low risk profiles and low postoperative mortality rates (0.2%). This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
Full-text · Article · Jun 2015 · Journal of Cardiovascular Electrophysiology
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Since its introduction in 1953, lone atrial fibrillation (LAF) has not been defined with any consistency, resulting in an enormous variation in the way the term is used. Inherent to this, results from studies vary considerably. Many predisposing factors and pathogenic influences have been discovered over the past years, which raise the question if the term LAF should still be used and if the treatment should be different from non-lone atrial fibrillation (non-LAF). Therefore this systematic review on LAF provides an overview of risk factors and triggers, the second part focuses on the application of catheter and surgical ablation techniques.
METHODS: A systematic literature search was performed in the PubMed database. All identified articles were screened and checked for eligibility by the two authors. Additional literature was sought by screening the references of eligible articles.
RESULTS: The term LAF is used very variably and inconsistently, and results concerning etiology in different studies are often contradictory. Overall finding is that LAF has many risk factors (e.g. subclinical atherosclerosis, enlarged left atrial volume, left ventricular dysfunction, occult hypertension, arterial stiffness, systemic inflammation and genetic factors) and can be induced by many different triggers (e.g. use of substances, endurance sports, mental stress and sleeping). However, compared to non-LAF there are no unique mechanisms related to LAF. Concerning the therapy, catheter ablation is first or second choice after antiarrhythmic drugs, however surgical and hybrid approaches may be indicated in complex cases.
CONCLUSIONS: Insufficient evidence exists to consider LAF as a real, isolated and useful entity. A re-definition or even avoiding the use of the term LAF might be appropriate.
Full-text · Article · Jun 2015 · Journal of Atrial Fibrillation