Catheter-based Radiofrequency Ablation Research Articles

M1942 Comparison of Catheter-Based Radiofrequency Ablation and Photodynamic Therapy for Barrett's Esophagus

M1942 Comparison of Catheter-Based Radiofrequency Ablation and Photodynamic Therapy for Barrett's Esophagus

Endovenous Radiofrequency Ablation for the Treatment of Varicose Veins

Chronic venous insufficiency (CVI) is the most common vascular disease and represents a significant health care problem in the United States. Reflux of the great saphenous vein is the most common cause of this condition, whose symptoms include varicose veins, leg swelling, skin discoloration, and ulceration. The traditional treatment of this condition is saphenofemoral ligation with stripping of the saphenous vein followed by varicose vein removal, if necessary. Recent advances in minimally invasive endovenous therapy have led to the development of catheter-based radiofrequency ablation (RFA) of the saphenous vein, which has gained an increasing acceptance in clinical practice. Endovenous RFA was introduced into clinical practice in Europe in 1998 and in the United States in 1999. Since then, over 250,000 procedures have been performed worldwide. Procedure safety and efficacy are well understood, with over 60 publications on the subject in the peer review literature, including four randomized trials comparing this technology with traditional vein stripping surgery. With the advent of tumescent anesthesia, the majority of RFA procedures are now performed in an office setting. This article examines the current technology using RFA in saphenous vein ablation with the Closure catheter system. Procedural techniques and clinical outcome using RFA in saphenous vein ablation are discussed. Clinical data comparing RFA versus saphenous vein stripping are also examined. Lastly, the clinical utility of a new RFA catheter, ClosureFAST, is discussed. ClosureFAST is a new generation of RFA catheter and has exhibited significant improvement in the ease of use and the procedure speed over the previous generation catheters while maintaining the favorable patient recovery profile seen with the RFA technology.

Percutaneous Epicardial Catheter Ablation Opens Another Chapter in the Catheter‐Based Ablation for Atrial Fibrillation

Over the past two decades, no other story in cardiology has received as much attention as the nonpharmacological treatment of cardiac arrhythmias, catheter-based ablation. The story began to unfold with the development of the catheterbased radiofrequency (RF) ablation of accessory pathways, proven to be the first nonsurgical curative treatment in cardiology.1,2 Shortly thereafter, electrophysiologists realized they could perform ablations to cure a variety of supraventricular tachycardia (SVT) easily and effectively, yielding spectacular outcomes that had rarely been witnessed with other treatment modalities. What followed is quite remarkable. Professionals from several disciplines (i.e., basic and clinical scientists, engineers, and health care providers)—from various industries to academia—formed the vanguard of interventional electrophysiology. The ensemble of new talents and intellects helped create new catheters, mapping systems, and a variety of tools and technologies that facilitated ablation procedures. These advances dramatically transformed the field of clinical electrophysiology—from the sedate specialty that merely carried out diagnostic electrophysiologic studies or antiarrhythmic drug testing—to an exciting and dynamic discipline that provided effective treatment for SVT via its interventional approach. Fortunately, the story did not end with SVT ablation, but continued for all types of cardiac arrhythmias. At present, most tachyarrhythmias can be reproducibly ablated with great success. For example, patients with typical cavotricuspid isthmus-dependent atrial flutter can now be ablated in 1 hour or less with a success rate of over 95% and a very low likelihood of complications. One by one, many arrhythmias joined the long list of tachycardias that use catheter ablation as the first-line treatment. However, finding the best way to ablate atrial fibrillation (AF), “the mother of all arrhythmias,” remains a major challenge—the Holy Grail for the electrophysiologist! Just as the Knight Templar faced daunting tasks when searching for the grail, so has the electrophysiologist dealt with many obstacles when ablating AF. First, the electrophysiologic mechanisms underlying human AF remain unclear and are likely to be somewhat different from patient to patient (i.e., paroxysmal to persistent). The seminal work by Haissaguerre et al.3 clearly establishes the important role of pulmonary veins (PVs) as triggering and perpetuating AF. As

This Month in Anesthesiology

This Month in Anesthesiology

Utility of Intracardiac Echocardiography in Left Heart Ablation for Tachyarrhythmias

Catheter-based radiofrequency ablation in the left heart can provide effective therapy for tachyarrhythmias. The recent development of the real time intracardiac echocardiography (ICE) with 2D and Doppler color flow imaging can facilitate left heart ablation procedures. This report reviews the use of ICE during radiofrequency catheter ablation procedures for atrial fibrillation (AF) and ventricular tachycardia and is based on our own experience in 955 patients. ICE has a critical role for guiding transseptal catheterization, assisting placement of mapping/ablation catheters and monitoring lesion morphologic changes, especially in the pulmonary vein ostia, Marshall ligament region, thickened interatrial septum, left atrial posterior wall contiguous to esophagus, aortic valve cusps, and the epicardial regions. One of the more powerful utilities of ICE lies in its ability to identify and potentially reduce procedural complications including damage to intracardiac structures, residual atrial septal defect, left atrial thrombus formation, pulmonary vein stenosis, esophageal injury, myocardial air-embolization and pericardial effusion during left heart ablation.

Cell Therapy for Rate Control in Atrial Fibrillation

Physicians and patients alike have long sought ways by which to tame the rapid and irregular heartbeats that typically accompany atrial fibrillation (AF). In addition to offering symptomatic relief from palpitations, this goal has gained further importance since the recognition that sustained rapid, and perhaps also irregular, ventricular rates can lead to adverse structural cardiac remodeling and the development of a tachycardia-induced cardiomyopathy.1 In many instances, maintenance of sinus rhythm is either impractical or unachievable, and in addition to therapeutic anticoagulation, most patients will require some strategy to control their ventricular rate during AF. Article p 2485 The mainstays of pharmacological rate control for AF have remained unchanged for decades and consist of digoxin, β-blockers, and the nondihydropyridine calcium channel antagonists verapamil and diltiazem alone or in combination.2,3 However, medical treatment often is limited by a lack of efficacy or intolerance of side effects. Research involving novel agents such as selective A1 adenosine agonists4,5 remains in early stages and is unlikely to overcome the drawbacks of currently available drugs. A nearly 100% efficacious approach to ventricular rate control in AF is catheter-based radiofrequency ablation of the AV junction (AVJ).6,7 Experimentally, the same result is achievable with cryoablation,8 laser energy,9 or ethanol infusion into the AV nodal artery.10 Although appropriate in selected patients,6,11–13 radiofrequency AVJ ablation has the distinct disadvantage of rendering them permanently pacemaker dependent. An increased risk of tachyarrhythmic sudden death after AVJ ablation may be countered by pacing at higher rates early after the procedure; however, concerns exist over the potential long-term hemodynamic consequences of obligate right ventricular pacing, particularly in the presence of preexisting heart failure.14–17 A notionally more appealing procedure is catheter-based radiofrequency AVJ modification18; however, a high rate of unintended AV implantation …

Echocardiographically guided left atrial ablation: Characterization of a new technique

Several techniques for percutaneous catheter-based radiofrequency ablation of left atrial myocardium have been described. Each is potentially limited by anatomic inaccuracy, radiation requirement, cardiac/extracardiac collateral damage, proarrhythmia, lesion impermanence, or unclear procedural endpoint. The purpose of this study was to describe a new technique that may address some of these limitations. In 200 consecutive patients with atrial fibrillation (AF), complete ablative encircling of right and left pulmonary venous vestibules was performed using radiofrequency energy applied via a standard ablation electrode. Lesions were guided by a collaborative nonfluoroscopic imaging strategy involving intra-left atrial echocardiography and CARTO. A discrete procedural endpoint was sought: complete electrical isolation of all myocardium subtended by the encircling lesions. After a procedure in which the total fluoroscopy time averaged 6 minutes, isolation was achieved on the left and right sides in 198 and 199 patients, respectively. In addition to the vestibule-encircling lesions, isolation required one or more additional focal lesions within the subtended myocardial territory in the majority of left vestibules and in a minority of right vestibules. Significant procedural morbidity was observed, including cerebroembolism resulting in death and mesenteric embolism resulting in hemicolectomy. Procedural success, defined at 2 years after the initial procedure and requiring no interim procedure, antiarrhythmic drug therapy, or apparent arrhythmia burden, was observed in a significantly greater proportion of patients with a paroxysmal (87%) than persistent AF (60%) syndrome. Only a small proportion of patients with recurrent AF had recurrence of conduction in previously isolated zones. This technique may have advantages over those previously reported, including improved anatomic accuracy, improved lesion safety and efficacy, and diminished radiation exposure.

Outcomes After Cardiac Perforation During Radiofrequency Ablation of the Atrium

Perforation during catheter procedures in either the atrium or ventricle is relatively uncommon, but potentially fatal if tamponade ensues. This study analyzes the occurrence and outcomes of cardiac perforation during catheter-based radiofrequency ablation procedures in the left atrium. All patients with a periprocedure perforation who have undergone radiofrequency ablation for atrial fibrillation (AF) or tachycardia were included. Of 632 procedures performed from January 1999 to October 2004, 15 (2.4%) were complicated by perforation requiring pericardiocentesis. The perforation site was left atrium in 9 (60.0%), right atrium in 1 (6.7%), and right ventricle in 5 (33.3%). Intracardiac echocardiography was used in 13 (86.7%) and revealed an effusion before overt instability in 11 (73.3%). Thirteen (86.7%) patients developed a blood pressure <60 mmHg. The pressure stabilized in all patients after pericardiocentesis (hypotension to intervention: 10.1 +/- 5.1 minutes). The total blood volume removed was 848 +/- 880 mL (left atrium/right atrium: 1,074 +/- 1,002 vs right ventricle: 396 +/- 266, P = 0.168). Two patients required surgery to close left atrium dome perforations. The ablation was completed in 7 (46.7%) patients. Ten (66.7%) later developed early reoccurrence of AF. All patients were neurologically intact at hospital discharge. During a 1.5 +/- 1.1 year follow-up, AF was eliminated (n = 4) or controlled (n = 1) in 5 (71.4%) patients with complete procedures, and 2 (20.0%) patients underwent successful repeat ablation. The incidence of perforation during ablation of the left atrium is low. Most perforations occur in the left atrium; however, few require surgical closure. Although less than with uncomplicated procedures, the majority of patients with complete ablations achieve long-term elimination of AF.

Stroke prevention in atrial fibrillation: Warfarin faces its challengers

Warfarin is exceedingly effective and underutilized in treating atrial fibrillation. Recently completed studies of alternative therapies include trials of ximelagatran versus warfarin, antiplatelet therapy plus lower-intensity warfarin versus usual warfarin, and strategies of rhythm versus rate control. Results of these studies suggest new options for treatment, and caveats regarding those who appear to have durable sinus rhythm. Ongoing trials include studies of combined antiplatelet therapy and other antithrombins. Nonpharmacologic approaches include the Maze III procedure and similar operations, left atrial appendage obliteration, and catheter-based radiofrequency ablation procedures. The place of these latter therapies will only be defined through subsequent clinical trials.

Role of intracardiac ultrasound in interventional electrophysiology.

Interventional procedures in the electrophysiology and catheterization laboratory are rapidly advancing. Critical to the advancement of these procedures is accurate identification of critical anatomic landmarks and catheter position. Fluoroscopy remains the mainstay for general identification of anatomic landmarks but is inadequate for the precise imaging needed for complex procedures. Precise imaging of anatomic landmarks and catheter position is now possible during the procedure with the use of intracardiac echocardiography (ICE). This paper reviews the rapid development and utilization of ICE in interventional electrophysiology. Several recent studies show ICE as a major contribution to providing a safer, more reliable, and more cost-effective means of accomplishing the tasks performed by existing techniques. In the electrophysiology laboratory, the dependence on this new technology has been due to the rapid development of catheter-based radiofrequency ablation of the pulmonary veins for treatment of atrial fibrillation. Since the initial use of ICE in facilitating ablation of atrial fibrillation, other uses for ICE are continuously being identified. A comprehensive look is provided at the history and development of this new technology along with the most recent applications of ICE in interventional electrophysiology.

RADIOFREQUENCY CATHETER ABLATION FOR ATRIAL FIBRILLATION

Until recently, catheter-based radiofrequency ablation for atrial fibrillation was limited to palliative approaches of either atrioventricular node ablation or modification. It is now recognized that at least a proportion of patients with paroxysmal atrial fibrillation may be suitable for curative ablation of an underlying single arrhythmogenic focus. With the intense interest in this area, a catheter-based cure involving endocardial linear lesion creation for patients with chronic or paroxysmal atrial fibrillation may not be far in the future.

Radiofrequency catheter modification of sinus pacemaker function guided by intracardiac echocardiography.

The sinus P wave arises from a pacemaker complex distributed along the crista terminalis. We investigated the feasibility of modification of sinus pacemaker function using graded applications of radiofrequency energy along the crista terminalis in dogs to achieve sinus rate control. Modification of sinus pacemaker function (30 +/- 5% reduction in intrinsic heart rate with retention of a normal P-wave axis) was performed in 11 dogs (group 1). Total sinus pacemaker ablation (> 50% reduction in intrinsic heart rate with development of a low ectopic atrial or a junctional rhythm) was performed in 4 dogs (group 2). Intracardiac echocardiography was used to identify the crista terminalis as an anatomic marker of sinus node location. Sinus pacemaker modification caused a significant decrease in intrinsic heart rate (31% reduction, P < .001), heart rate responsiveness to isoproterenol (30% reduction, P < .0001), and average (20% reduction, P = .0002) and maximal (22% reduction, P = .0007) heart rates during 24-hour Holter monitoring. In 6 of the 11 animals, the targeted rate reduction of 30 +/- 5% was accurately achieved (mean, 31.6 +/- 4.3%; P < .001), and in the other 5, significant reduction of intrinsic heart rate was achieved but with greater variation (28.0 +/- 17.3%, P < .005). Corrected sinus node recovery time was not prolonged. After modification, earliest activation was mapped to the crista terminalis inferior to the lesion in all animals. In long-term follow-up (3.7 +/- 1.0 months), effects were maintained. After total sinus pacemaker ablation, junctional and low atrial escape pacemakers were unstable. This study demonstrates the feasibility of modification of sinus pacemaker function for sinus rate control using catheter-based radiofrequency ablation guided by intracardiac echocardiography. This can be done while pacemaker stability and attenuated responsiveness to autonomic influences are preserved. Intracardiac echocardiography accurately defined the crista terminalis and provided a reliable means to anatomically localize catheter position in relation to the sinus node.