Thursday, August 20, 2009

Epicardially Based Pulmonary Vein Isolation for the Treatment of Atrial Fibrillation Utilizing Laser Energy in the Pig Model

Citation : Li Poa, M.D, Jane Olin, DVM, Lester Wong, M.D, Philip Poa, CP, Pablo Zubiate, M.D, C.C.P, Christina Poa, CP.Epicardially Based Pulmonary Vein Isolation for the Treatment of Atrial Fibrillation Utilizing Laser Energy in the Pig Model.JAFIB.2009 August;Volume 1 Issue(8): 505-509.

Purpose - Atrial fibrillation is a common disease that increases the incidence of cerebrovascular embolic events and cardiac dysfunction. Foci for atrial fibrillation have been mapped and found to be for the most part located within the ostia of the pulmonary veins. Since 2002 microwave and radiofrequency energy sources have been used to create pulmonary vein isolation lesions. This abstract summarizes the safety and efficacy of performing vein isolation lesions with laser as the energy source.
Description - The large pig model was utilized for creation of isolation lesions around the pulmonary veins. The Optimaze E360 Surgical Ablation Handpiece from Edwards Lifesciences was utilized, it contains a 4 centimeter diffusing diode laser (980nm). All six of the pig models tolerated the procedure with a 40-day normal post procedure growth pattern.
Evaluation - Upon reoperation one pig developed ventricular fibrillation with resection of adhesions. All five remaining pigs were fully tested and demonstrated complete electrical isolation. Gross pathology revealed intact well defined ablation lesions with an otherwise completely normal cardiac structure. All lesions were fully transmural at each histological sectioned point.
Conclusions - Laser technology in the form of the Optimaze E360 Surgical Ablation Handpiece from Edwards Lifesciences, is able to reliably and consistently produce well defined electrical isolation scars around the pulmonary veins. This device is also amenable to performing the isolation procedure using a minimally invasive approach.

Key Words: atrial fibrillation, pulmonary vein, laser

Dronedarone For Atrial Fibrillation: Unbridled Enthusiasm Or Just Another Small Step Forward?

Citation : James A. Reiffel, M.D.Dronedarone For Atrial Fibrillation: Unbridled Enthusiasm Or Just Another Small Step Forward? .JAFIB.2009 August;Volume 1 Issue(8): 500-504.

The Federal Food and Drug Administration (FDA) approved the marketing of dronedarone (Multaq, sanofi-aventis) for use in patients with atrial fibrillation (AF) or flutter (AFL) [with a requirement for a recent episode] that is paroxysmal or persistent – the latter having been converted to sinus rhythm or with conversion planned – who have, in addition to AF, certain “high-risk” markers for adverse outcomes that were derived from the enrollment criteria for the landmark ATHENA trial (1). These markers include one or more of: age >70 yrs, hypertension, diabetes mellitus, prior cerebrovascular accident, left atrial size of 50 mm or larger, or LVEF <40%. Contraindications include class IV heart failure or symptomatic heart failure with a recent decompensation; second or third degree AV block without a functioning pacemaker; bradycardia < 50 bpm; concomitant use of a strong CYP3A inhibitor or a QT prolonging agent that may induce torsades de pointes; QTc Bazett interval of 500 ms or longer; or severe hepatic impairment.

Paroxysmal Lone Atrial Fibrillation is Associated with an Abnormal Atrial Substrate: Characterizing the “Second Factor”

Citation : Charles R. Mitchell, MD and Mithilesh K. Das, MD.Paroxysmal Lone Atrial Fibrillation Is Associated With An Abnormal Atrial Substrate: Characterizing The “Second Factor” .JAFIB.2009 August;Volume 1 Issue(8): 496-499.

Stiles et al, recently published a study titled “Paroxysmal Lone Atrial fibrillation is associated with an abnormal atrial substrate: Characterizing the Second Factor” in The Journal of The American College of Cardiology.” Authors demonstrated structural and electrophysiological abnormalities in the atria of patients with paroxysmal lone atrial fibrillation (AF). The authors postulate that these factors are likely contributors to the “second factor” that predisposes to the development and progression of AF.

Atrial Fibrillation Ablation: First-Line Therapy?

Citation : Atul Verma MD.Atrial Fibrillation Ablation: First-Line Therapy? .JAFIB.2009 August;Volume 1 Issue(8): 487-495.

Background: Ablation for atrial fibrillation (AF) is a widely-accepted treatment for this arrhythmia. Ablation is traditionally reserved for second-line therapy in patients who have failed drug therapy, but it may be ready for first-line treatment.
Objective: This article outlines the rationale for using ablation as first-line therapy for AF.
Findings: AF increases both morbidity and mortality. Unfortunately, drug-based therapy for AF is very ineffective and may contribute adversely to both patient morbidity and mortality. Ablation addresses the root causes of AF and thus may be curative. The technique for ablation has become quite consistent and the outcomes better than those with drug therapy. The complication risk is also acceptably low. There is even preliminary evidence to suggest that AF ablation is superior as first-line treatment compared to drugs.
Conclusion: AF ablation is rapidly evolving towards becoming first-line therapy for some patients with this debilitating arrhythmia.

The Autonomic Nervous System and Atrial Fibrillation: The Roles of Pulmonary Vein Isolation and Ganglionated Plexi Ablation

Citation : Benjamin J. Scherlag, PhD, Hiroshi Nakagawa, M.D, Ph.D, Eugene Patterson, PhD, Warren M. Jackman, MD, Ralph Lazzara, MD, Sunny S. Po, MD, PhD.The Autonomic Nervous System and Atrial Fibrillation: The Roles of Pulmonary Vein Isolation and Ganglionated Plexi Ablation .JAFIB.2009 August;Volume 1 Issue(8): 471-486.

After the sequential successes of catheter ablation for the treatment of preexcitation syndromes (WPW), junctional reentry (AVNRT) atrial flutter (AFL) and ventricular arrhythmias, clinical electrophysiologists have focused on the myocardial basis of atrial fibrillation (AF). Thus, the strategy for ablation of drug and cardioversion refractory AF was to isolate the myocardial connections from the focal firing pulmonary veins (PVs) in addition to altering the atrial substrate maintaining AF. However, the overall success rates have not achieved the success rates of the other types of ablation procedures. In this review we have summarized the favorable aspects and drawbacks of pulmonary vein isolation (PVI). As for the role of the Intrinsic Cardiac Autonomic Nervous System (ICANS), both basic and clinical evidence has shown that ganglionated plexi (GP) stimulation promotes initiation and maintenance of AF, and that GP ablation reduces recurrence of AF following catheter or surgical ablation of these structures. Based on these findings, the GP Hyperactivity Hypothesis has been proposed to explain, at least in part, the mechanistic basis for the focal form of AF. For example, PV isolation may not always be necessary for elimination of AF, as in paroxysmal AF. GP ablation alone, in these cases, may suffice for focal AF termination. In the persistent and chronic forms the substrate for AF may be more extensive and therefore require GP ablation plus PV isolation and/or CFAE ablations. Clinical reports, both catheter based as well as minimally invasive surgical procedures, which include PVI plus GP ablation have shown relatively long-term success rates much closer to or equal to those achieved by myocardial ablation procedures in patients with WPW, AVNRT and AFL.

Cost-effectiveness of Catheter Ablation Treatment for Patients with Symptomatic Atrial Fibrillation

Citation :Nathalie Eckard , Thomas Davidson1 , Hakan Walfridsson , Lars-Ake Levin.Cost-effectiveness of Catheter Ablation Treatment for Patients with Symptomatic Atrial Fibrillation .JAFIB.2009 August;Volume 1 Issue(8): 461-470.

Background: Atrial Fibrillation is the most common cardiac arrhythmia. It increases the risk of thromboembolic events and many atrial fibrillation patients suffer quality of life impairment due to disturbed heart rhythm. Pulmonary vein isolation using radiofrequency catheter ablation treatment is aimed at maintaining sinus rhythm ultimately improving quality of life. Randomized clinical trial have shown that catheter ablation is more effective than antiarrhythmic drugs for the treatment of atrial fibrillation, but its impact on quality of life and cost-effectiveness has not been widely studied.
Aims: To assess the cost-effectiveness of radiofrequency ablation (RFA) vs. antiarrhythmic drug (AAD) treatment, among symptomatic atrial fibrillation patients not previously responding to AAD.
Methods: A decision-analytic Markov model was developed to assess costs and health outcomes in terms of quality adjusted life years (QALYs) of RFA and AAD over a lifetime time horizon. We conducted a literature search and used data from several sources as input variables of the model. One-year rates of atrial fibrillation with RFA and AAD, respectively, were available from published randomized clinical trials. Other data sources were published papers and register data.
Results: The RFA treatment strategy was associated with reduced costs and an incremental gain in QALYs compared to the AAD treatment strategy. The results were sensitive to whether long-term quality of life improvement is maintained for the RFA treatment strategy and the risk of stroke in the different atrial fibrillation health states.
Conclusion: This study shows that the short-term improvement in atrial fibrillation associated with RFA is likely to lead to long-term quality of life improvement and lower costs indicating that RFA is cost-effective compared to AAD.

Laser Ablation Of Atrial Fibrillation: Mid-Term Clinical Experience

Citation : Li Poa, MD, Miguel Puig, MD, Pablo Zubiate, MD, Edward Ranzenbach, PAC, Shari-Knutson Miller, PAC, Christina Poa, PC.Laser Ablation Of Atrial Fibrillation: Mid-Term Clinical Experience .JAFIB.2009 August;Volume 1 Issue(8): 454-460.

Background: Atrial Fibrillation is known to account for one third of all the strokes caused in the US in the population above the age of 70. Patients treated with the surgical Cox MAZE operation have been shown to have a 150 fold decrease in the incidence of stroke over an 18 year period. However, the original Cox MAZE although extremely successful in treating atrial fibrillation and decreasing the incidence of strokes was not performed widely because of complexity and invasiveness of the procedure. A variety of alternative energy based curative ablation strategies are now available for more minimally invasive therapeutic management of atrial fibrillation (AF). In this communication, we report our clinical experience in AF therapy utilizing laser energy ablation technology.

Methods: Fifty two consecutive AF patients underwent concomitant or isolated ablation prior to any coexisting cardiac procedures that included CABG (coronary artery bypass surgery, MV (mitral valve) or AV (aortic valve) repairs. All patients had an epicardially based ablation pattern with basic lesions being en bloc box type pulmonary vein isolation which included the antral surface of the left atrium, directed ganglionectomies of the the right anterior and inferior ganglions, posteriomedial ablation of the IVC ( inferior vena cava), and a right isthmus ablation. Twenty seven patients had ligation of their left atrial appendage, 14 patients had resection of the ligament of Marshall, and three patients had endocardial placed lesions of a mitral annular connecting type lesion. In order to maintain the patients in normal sinus rhythm (NSR), electrical cardioversion and anti-arrhythmic drugs were employed as required.

Results: At a median follow-up of 250 days, 44 of the total 52 patients (84.6%) exhibited NSR.. No complications or mortality were reported due to the laser procedure.

Conclusion: Laser ablation was successfully and safely used for endocardial and epicardial AF ablation concomitant to other cardiovascular procedures and in the lone atrial fibrillation treatment utilizing a two port thoracoscopic approach.