Ablation Of Chronic Atrial Fibrillation Research Articles

Feature subset selection and classification of intracardiac electrograms during atrial fibrillation

Abstract Several approaches have been adopted for the identification of arrhythmogenic sources maintaining atrial fibrillation (AF). In this paper, we propose a classifier that discriminates between four classes of atrial electrogram (EGM). We delved into the relation between levels of fractionation in EGM signals and the fibrillation substrates in simulated episodes of chronic AF. Several feature extraction methods were used to calculate 92 features from 429 real EGM records acquired during radiofrequency ablation of chronic AF. We selected the optimal subset of features by using a genetic algorithm, followed by K -nearest neighbors (K-NN) classification into four levels of fractionation. Sensitivity of 0.90 and specificity of 0.97 were achieved. Subsequently, the results of the classification were extrapolated to signals of a 3D human atria model and a 2D model of atrial tissue. The 3D model simulated an episode of AF maintained by a rotor in the posterior wall of the left atrium and the 2D model simulated an AF episode with one stable rotor. We used the K-NN classifier trained on a given set of real EGM signals to detect a specific class of signals presenting the highest level of fractionation located near the rotor's vortex. This method needs to be tested on real clinical data to provide evidence that it can support ablation therapy procedures.

Chronic Atrial Fibrillation Ablation with Harmonic Scalpel during Mitral Valve Surgery.

ObjectiveTo evaluate surgical treatment of chronic atrial fibrillation with ultrasound in patients with mitral valve disease, considering preoperative clinical characteristics of patients undergoing surgical procedure and follow-up in the immediate postoperative period, in hospital and up to 60 months after discharge.MethodsWe studied 100 patients with chronic atrial fibrillation and mitral valve disease who underwent surgical treatment using ultrasound ablation. Patient data were reviewed by consulting the control reports, including signs and symptoms, underlying disease, functional class, hospital stay, surgical procedure time, ablation time, immediate complications, and complications at discharged and up to 60 months later. Actuarial curve (Kaplan-Meier) was used for the study of permanence without recurrence after 12, 24, 36, 48 and 60 months.Results86% of the patients had rheumatic mitral valve disease, 14% had degeneration of the mitral valve, 40% had mitral regurgitation, and 36% had mitral stenosis. Main symptoms included palpitations related to tachycardia by chronic atrial fibrillation (70%), congestive heart failure (70%), and previous episodes of acute pulmonary edema (27%). Early results showed that 94% of the patients undergoing ultrasound ablation reversed the rate of chronic atrial fibrillation, 86% being in sinus rhythm and 8% in atrioventricular block. At hospital discharge, maintenance of sinus rhythm was observed in 86% of patients and there was recurrence of chronic atrial fibrillation in 8% of patients. At follow-up after 60 months, 83.8% of patients maintained the sinus rhythm.ConclusionSurgical treatment of chronic atrial fibrillation with ultrasound concomitant with mitral valve surgery is feasible and satisfactory, with maintenance of sinus rhythm in most patients (83.8%) after 60 months of follow-up.

慢性心房細動アブレーションに向けたオンラインリアルタイム位相マッピングの意義：ExTRa Mapping研究

慢性心房細動アブレーションに向けたオンラインリアルタイム位相マッピングの意義：ExTRa Mapping研究

Electrophysiologic Results After Thoracoscopic Ablation for Chronic Atrial Fibrillation

Thoracoscopic ablation for lone atrial fibrillation (AF) has evolved rapidly in the past decade. We investigated the electrophysiologic results and midterm durability of totally thoracoscopic ablation in patients with lone persistent AF. Seventy-nine consecutive patients with paroxysmal AF (8 patients, 10.1%), persistent AF (17 patients, 21.5%), and long-standing persistent AF (54 patients, 68.3%) were prospectively enrolled. Thoracoscopic ablation consisted of a bilateral closed-chest approach to performing pulmonary isolation (a box lesion), ganglionated plexus ablation, division of the Marshall ligament, and left atrial auricle resection. An electrophysiologic study was performed 5 days after the surgical procedure in 61 patients (77%). Freedom from AF was assessed with electrocardiograms or Holter monitoring every 3 months, with a mean follow-up of 12.1 (maximum, 28) months. No deaths or conversion to cardiopulmonary bypass occurred. During electrophysiologic study, 28 residual pulmonary vein potentials were observed in 15 patients (19%). Out of a total of 28 gaps, 20 (71%) were located in the superior and inferior ridges of pulmonary veins. Six gaps (21%) were detected in the carina of pulmonary veins. The mitral isthmus was ablated in 2 patients (7%). Freedom from AF at 2 years was 92.6 ± 3.3%. Freedom from cardiac-related events at 2 years was 74.7 ± 6.0%. Cox regression analysis demonstrated that the predictors of atrial arrhythmias were old age, hypertension, and left atrial volume index. Thoracoscopic ablation followed by electrophysiologic confirmation was safe and provided excellent midterm durability in patients with AF. However, the incidence of residual potentials around the pulmonary veins was not negligible.

Doppler flow signals in small amount pericardial effusion after radiofrequency ablation

A 59-year-old man underwent radiofrequency ablation for chronic atrial fibrillation. The angiogram was normal. The left and right atriums is significantly dilated, no thrombi was detected in the atriums and atrial appendage by transesophageal echocardiography. Post-ablation, sinus rhythm was return. He was started on amiodarone.

Impact of Left Anterior Line on Left Atrial Appendage Contractility in Patients Who Underwent Catheter Ablation for Chronic Atrial Fibrillation

Left anterior line (LAL) has been used as a substitute for mitral isthmus line for catheter ablation of chronic atrial fibrillation (AF). However, it results in left anterolateral conduction delay and might affect left atrial (LA) contractility. We aimed to investigate whether LAL decreases LA appendage function. This study included 46 patients (30 men, mean age 58 ± 9 years, group 1) with persistent AF who underwent catheter ablation including LAL. Thirty patients with paroxysmal AF who received no additional LA ablation were compared as control group (21 males, mean age 56 ± 8 years, group 2). Transthoracic and transesophageal echocardiography with Doppler tissue imaging was performed in sinus rhythm before and after the ablation. We compared the following variables: (1) E/A ratio of the mitral flow velocity, (2) ratio of early mitral inflow and mitral septal annulus velocity (E/Em), (3) peak velocity of appendage outflow (ApVmax), and (4) time delay from QRS onset to appendage outflow (TDqa). LA diameter was significantly reduced after ablation in both groups. In group 1, parameters for diastolic function (E/A ratio, 1.7 ± 0.5 vs 2.0 ± 0.6, P = 0.197; E/Em, 11.7 ± 4.8 vs 11.6 ± 5.1, P = 0.883) and appendage flow (ApVmax, 55.2 ± 19.9 cm/s vs 50.3 ± 19.3 cm/s, P = 0.203; TDqa, -77.3 ± 30.1 ms vs -66.1 ± 60.8 ms, P = 0.265) did not change significantly after ablation. Changes of ApVmax and TDqa after ablation were not significantly different between two groups (P = 0.409 and P = 0.195, respectively). LAL ablation did not aggravate mitral flow pattern or change appendage outflow. LAL could be used without concern over worsening LA diastolic and appendage function.

Cardiac Remodeling After Atrial Fibrillation Ablation.

Radiofrequency catheter ablation procedures are considered a reasonable option for patients with symptomatic, drug refractory atrial fibrillation (AF). Ablation procedures have been reported to effectively restore sinus rhythm and provide long-term relief of symptoms. Both electrical and structural remodeling occurs with AF. A reversal of the electrical remodeling develops within 1 week after restoration to sinus rhythm following the catheter ablation. The recovery rate is faster in the right atrium than the left atrium. Reverse structural remodeling takes longer and is still present 2 to 4 months after restoration of sinus rhythm. The left atrial transport function also improves after successful catheter ablation of AF. Left atrial strain surveys from echocardiography are able to identify patients who respond to catheter ablation with significant reverse remodeling after ablation. Pre-procedural delayed enhancement magnetic resonance imaging is also able to determine the degree of atrial fibrosis and is another tool to predict the reverse remodeling after ablation. The remodeling process is complex if recurrence develops after ablation. Recent evidence shows that a combined reverse electrical and structural remodeling occurs after ablation of chronic AF when recurrence is paroxysmal AF. Progressive electrical remodeling without any structural remodeling develops in those with recurrence involving chronic AF. Whether progressive atrial remodeling is the cause or consequence during the recurrence of AF remains obscure and requires further study.

Cardiac resynchronization therapy in acute pulmonary edema: A case report

We are reporting a case of 71-year old lady with a dual chamber demand pacemaker, who developed acute pulmonary edema due to an acute left ventricular (LV) dysfunction and worsening in mitral valve regurgitation after atrioventricular nodal ablation for uncontrolled atrial fibrillation. This was attributed to right ventricular apical pacing leading to LV dyssynchronization. Patient dramatically improved within 12-24 h after upgrading her single chamber pacemaker to biventricular pacing. Our case demonstrates that biventricular pacing can be an effective modality of treatment of acute congestive heart failure. In particular, it can be used when it is secondary to LV dysfunction and severe mitral regurgitation attributed to significant dyssynchrony created by right ventricular pacing in patients with atrioventricular nodal ablation for chronic atrial fibrillation.

Cardiopulmonary Hemodynamic Clues for Pulmonary Vein Stenosis Diagnosis

Pulmonary vein stenosis (PVS) post radiofrequency ablation for chronic atrial fibrillation poses a diagnostic challenge for the clinician. PVS presents with nonspecific symptoms, signs and radiographic features, and may be associated with significant pulmonary vascular involvement. Interestingly, others have described variation of the pulmonary artery wedge pressure between sites of the lung as a clue to pulmonary veno-occlusive disorders. We report, to the best of our knowledge, the first case that describes the regional loss of V waves while recording the mean pulmonary artery wedge pressure (mPawp) as well as the difference in pulmonary artery wedge pressure gradients as the main diagnostic clues for PVS.

Prediction of Underling Sinus Node Dysfunction during Chronic Atrial Fibrillation before Catheter Ablation Using Apnea/Hypopnea Index

Background: Indication of ablation has been expanded to include chronic atrial fibrillation (CAF) for enabling high degree of sinus rhythm maintenance. We have encountered patients undergoing pacemaker implantation, in whom sick sinus syndrome became clinically evident after ablation. The study aims to investigate whether underling sinus node dysfunction (SND) during CAF can be predicted before deciding the indication for ablation. Methods and Results: Sixty consecutive patients with CAF who underwent ablation between January to December 2010 were enrolled in the study. Nocturnal polysomnography as well as echocardiography was performed for all patients before ablation. We used the double Lasso catheter and electro anatomical mapping guided extensive encircling pulmonary vein isolation (EEPVI). We performed electrophysiological studies after EEPVI, and SND was defined as corrected SN recovery time of ≥550 ms. SND was detected in 26 (43%) patients (SND group); the other patients showed normal sinus node function (NSN group). The apnea/hypopnea index (AHI) was significantly greater in the SND group than in the NSN group (25.7±13 vs 15.8±10, P=0.0022). On multivariate analysis, sleep apnea syndrome (SAS) was an independent predictor of SND after ablation for CAF. Conclusion: This study suggested that underlying SND in CAF patients can be predicted by evaluating SAS before ablation.

New Insight of Chronic Atrial Fibrillation: Lessons from CHADS2 and CHADS-Vas Score and Long-Term Catheter Ablation Outcome

The optimal treatment of chronic atrial fibrillation includes the effort to restore sinus rhythm and maintenance of sinus rhythm. Catheter ablation has been considered as one of the choice for treatment of chronic atrial fibrillation. The short and intermediate-term (one year) outcome after one single ablation procedure is not as good as the ablation of paroxysmal atrial fibrillation. This presentation will show the long-term outcome of catheter ablation for chronic atrial fibrillation, also present the new insight of chronic atrial fibrillation based on the analysis of stroke risk score, including the CHADS2 and CHADS2-Vas score, and the correlation with the atrial substrate properties. Based on this investigation, the optimal patient population selected for the catheter ablation of chronic atrial fibrillation will be more acceptable.

Visualization of lesion transmurality and depth of necrosis using an ablation catheter that incorporates ultrasound imaging: A small step or a major leap forward on the road to a more durable catheter ablation procedure for treatment of atrial fibrillation?

Percutaneous catheter ablation has revolutionized the care of patients with atrial fibrillation. Pulmonary vein isolation has become the cornerstone of most ablation procedures for the treatment of atrial fibrillation following the observation by Haissaguerre et al 1 Haissaguerre M. Jais P. Shah D.C. et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins. N Engl J Med. 1998; 339: 659-666 Google Scholar that pulmonary veins were a frequent source of ectopic beats initiating atrial fibrillation. Pulmonary vein isolation may be combined with linear ablation or ablation of other targets for treatment of persistent or longstanding persistent atrial fibrillation. Pulmonary vein electrical reconnection to the left atrium is not uncommon and may be the primary reason for procedure failure among patients with paroxysmal atrial fibrillation. 2 Callans D.J. Gerstenfeld E.P. Dixit S. et al. Efficacy of repeat pulmonary vein isolation procedures in patients with recurrent atrial fibrillation. J Cardiovasc Electrophysiol. 2004; 15: 1050-1055 Google Scholar , 3 Shah A.N. Mittal S. Sichrovsky T.C. et al. Long-term outcome following successful pulmonary vein isolation: pattern and prediction of very late recurrence. J Cardiovasc Electrophysiol. 2008; 19: 661-667 Google Scholar , 4 Cheema A. Dong J. Dalal D. et al. Incidence and time course of early recovery of pulmonary vein conduction after catheter ablation of atrial fibrillation. J Cardiovasc Electrophysiol. 2007; 18: 387-391 Google Scholar Pulmonary vein reconnections also have been demonstrated to be important triggers in patients with persistent atrial fibrillation undergoing repeat ablation. 5 Haissaguerre M. Jais P. Shah D.C. et al. Catheter ablation of chronic atrial fibrillation targeting the reinitiating triggers. J Cardiovasc Electrophysiol. 2000; 11: 2-10 Google Scholar Recovery of conduction across linear ablation lesions is also likely to play a role in procedure failure among patients with persistent atrial fibrillation. 6 Rostock T. O'Neill M.D. Sanders P. et al. Characterization of conduction recovery across left atrial linear lesions in patients with paroxysmal and persistent atrial fibrillation. J Cardiovasc Electrophysiol. 2006; 17: 1106-1111 Google Scholar With current technology, some tissue that is ablated recovers electrical activity. Any technology that could safely increase the probability that ablated tissue would remain ablated would be an important contribution. Real-time lesion assessment using a novel combined ultrasound and radiofrequency ablation catheterHeart RhythmVol. 8Issue 2PreviewAssessment of lesion size and transmurality is currently via indirect measures. Real-time image assessment may allow ablation parameters to be titrated to achieve transmurality and reduce recurrences due to incomplete lesions. Full-Text PDF

Different Patterns of Atrial Remodeling After Catheter Ablation of Chronic Atrial Fibrillation

Multiple remodeling patterns have been observed after catheter ablation of atrial fibrillation (AF). We aimed to clarify the electrical/structural properties associated with recurrences after ablation of chronic AF. After a stepwise ablation procedure in 120 consecutive patients with persistent/long-lasting persistent AF, 36 had a recurrence of AF (Group 1/Group 2: recurrence with paroxysmal/persistent AF, n = 16/20). During the first procedure, the left atrial (LA) bipolar voltage did not differ between the 2 groups, and the LA volume was smaller in Group 1 than in Group 2 and it was the only factor predicting the recurrent types (P = 0.009, OR = 1.04). In the second procedure, the bipolar voltage of the global left atrium increased (1.33 ± 0.11 mV vs 1.76 ± 0.16 mV, P = 0.001) in Group 1 and decreased (1.31 ± 0.14 mV vs 0.90 ± 0.12 mV, P = 0.01) in Group 2, when compared with that of the first procedure. The LA low-voltage area (<0.5 mV) decreased in Group 1, and increased in Group 2. The LA volume (90 ± 8 cm(3) vs 72 ± 8 cm(3), P = 0.002) decreased in the second procedure in Group 1. It remained the same in Group 2. The right atrial substrates did not change between the procedures. After a follow-up of 27 ± 3 months, all patients in Group 1 and 14 patients in Group 2 remained in sinus rhythm (P = 0.02). A better outcome with reverse electrical and structural remodeling occurred after the ablation of chronic AF when the recurrence was paroxysmal AF. Progressive electrical remodeling without any structural remodeling developed in those with a recurrence involving persistent AF.

Avaliação inicial da ablação operatória biatrial por radiofrequência de fibrilação atrial

To evaluate the results of intraoperative radiofrequency ablation with biatrial procedure in the treatment of chronic atrial fibrillation in patients with associated cardiac disease. Between February 2008 and May 2009, 15 consecutive patients were underwent mitral valve procedure plus modified radiofrequency biatrial ablation of chronic atrial fibrillation. The mean age was 47.73 +/- 9.85 years and 60% were male. The mean left atrial diameter was 55.06 +/- 7.56 mm. There were no hospital mortality or complications related to radiofrequency ablation. The mean follow-up period was 7 +/- 4 months. At the time of hospital discharge nine (60%) patients were in sinus rhythm. After a mean follow-up period 11 (73.3%) were in sinus rhythm. Intraoperative biatrial radiofrequency ablation is a safe and effective technique for the treatment of chronic atrial fibrillation, with satisfactory midterms outcomes in terms of conversion to sinus rhythm.

Apparent pacemaker malfunction following atrioventricular node ablation

61-year-old woman received backup ventricular pacing and atrioventricular (AV) node ablation for chronic atrial fibrillation with poor ventricular rate control. Following uneventful single-chamber pacemaker implantation (Sensia; Medtronic Inc, USA), AV node ablation was performed, which resulted in complete AV block with ventricular escape rates of 35 beats/min to 40 beats/min. A lower pacemaker rate was then programmed in VVI mode (95 beats/min lower heart rate) to prevent bradycardia, a potential trigger for torsades de pointes (1). During postprocedure monitoring, telemetry recordings showed multiple episodes of long pauses with no pacing output (Figure 1). The pacemaker pacing and sensing parameters, and lead and impedance, even with pacemaker pocket manipulation, were normal. Analysis of the tracing showed that the pauses between the intrinsic R wave and the paced beat were exactly 1200 ms. Also, the pauses between any two intrinsic R waves remained less than 1200 ms. There were no pauses following paced beats. These findings suggested that the hysteresis feature had been left on at a rate of 50 beats/min, which was confirmed. The patient had regained some degree of AV nodal conduction and her intrinsic R waves appeared intermittently at shorter cycle lengths than the lower rate interval, which triggered the hysteresis feature and caused the pauses. This feature was switched off and no pauses were documented subsequently. Hysteresis programmed on would not be a problem in a pacemakerdependent patient with complete AV block and low ventricular escape rates. However, if AV nodal conduction recovers, as in the present patient, hysteresis could be the cause of cardiac pauses, a potential trigger for life-threatening torsades de pointes. imAges in cArdiology

The Impact of Left Atrial Size on Long‐Term Outcome of Catheter Ablation of Chronic Atrial Fibrillation

The left atrial (LA) size is an important predictor of atrial fibrillation (AF) procedural termination and the long-term outcome. We sought to evaluate the long-term outcome in regard to the LA size and procedural termination. Eighty-seven consecutive chronic AF patients (72 males, 53 +/- 10 years) underwent 3D mapping (NavX) and ablation. A stepwise approach including circumferential pulmonary vein (PV) isolation, linear ablation, and continuous complex-fractionated electrogram (CFE) ablation (targeting fractionation intervals of < 50 ms). Electrical cardioversion was applied to those without any procedural termination. The freedom from AF was defined as the maintenance of sinus rhythm without the use of any class I or III antiarrhythmic drugs after the blanking period. Among the 87 patients, all received a circumferential PV isolation, 93% a linear ablation, and 59% a continuous CFE ablation. Those with AF procedural termination (n = 30) had a better long-term outcome when compared with those without termination during a follow-up of 21 +/- 12 months. Moreover, a Kaplan-Meier analysis showed that in those with an LA diameter of less than 45 mm (n = 49), the freedom from AF rate was higher when procedural termination was achieved (P = 0.004). On the contrary, the outcome was comparable in those with an LA diameter of >or= 45 mm (n = 38), whether AF procedural termination occurred or not (P = 0.658). AF procedural termination was related to the long-term success during chronic AF ablation, especially in those with an LA diameter of less than 45 mm. The favorable effect of termination decreased when the LA diameter was >or= 45 mm.

Ablation Therapy of Atrial Fibrillation in Heart Failure

Congestive heart failure and atrial fibrillation (AF) often coexist, and each adversely affects the other with respect to management and prognosis. Evidence from the AFFIRM investigators highlights the potential benefit of maintaining sinus rhythm if it could be achieved without the adverse effects of antiarrhythmic drugs. Catheter ablation for AF has been established as an effective therapeutic option for AF that is resistant to pharmacologic rhythm or rate control, with successful long-term maintenance of sinus rhythm in the absence of treatment with antiarrhythmic drugs reported in the majority of patients. Though the results of catheter ablation have been improving, with the success rate reported as more than 80% for paroxysmal AF, ablation of chronic AF has been more difficult and has required more extensive ablation. The results can be expected to improve with a better understanding of the substrate maintaining AF and with the development of more effective techniques. Curative ablation of AF offers the unique opportunity to maintain sinus rhythm without antiarrhythmic drugs, which can have deleterious effects. Several studies have demonstrated that restoration and maintenance of sinus rhythm by catheter ablation without the use of drugs in patients with heart failure and AF improve cardiac function, symptoms, exercise capacity, and quality of life.

Ectopic Focus in an Accessory Left Atrial Appendage

A 65-year-old man with symptomatic atrial fibrillation refractory to medical therapy was referred for repeat pulmonary vein (PV) isolation. Clinical symptoms included paroxysmal palpitations once to twice per week with associated light-headedness and chest pain. Initial PV isolation had been performed 6 months earlier without cessation of atrial fibrillation despite combined medical therapy with oral flecainide and bisoprolol. His past medical history was significant for hypertension, and in his family history, 1 brother had experienced a stroke at the age of 57 years. Physical examination, ECG, chest radiography, and coronary angiography were normal. Holter 24-hour ECG recordings revealed occasional atrial premature beats and paroxysmal atrial tachycardia. A magnetic resonance imaging study of the patient’s PVs and left atrium (LA) was performed before the repeat radiofrequency ablation. Images were acquired with a 1.5-T whole-body magnetic resonance system (Siemens Avanti, Siemens Medical Solutions, Forcheim, Germany) with an 8-element cardiac synergy coil for radiofrequency signal reception. First-pass breath-hold 3-dimensional contrast-enhanced magnetic resonance angiography of the PV was obtained after pump injection (3 mL/s) of 15 mmol of …

Rhythm-'a-line-ment' during catheter ablation of chronic atrial fibrillation: the role of left atrial linear lesions

Although recommended by the current guidelines for the treatment of atrial fibrillation (AF),1,2 catheter ablation of long-standing persistent AF (herein referred to as chronic AF) still remains a challenge for the interventional electrophysiologist. Initial attempts at a successful treatment of chronic AF have concentrated on different lesion sets. In the past, we have learned that pulmonary vein (PV) isolation alone, irrespective of its extension in terms of isolated atrial tissue around the PVs, is not sufficient to achieve a considerable success rate and, therefore, is restricted to a very selected cohort of chronic AF patients.3,4 Thus, additional arrhythmogenic processes beyond the PVs have become evident in the pathophysiology of chronic AF. Based on the concept of the ‘multiple wavelet’ hypothesis and in an effort to replicate the results of the surgical treatment of AF, linear lesions were applied to the left atrium, alone or in addition to PV isolation. However, with bidirectionally blocked lines at the left atrial roof and the mitral isthmus,4 or even with complete electrical isolation of the posterior left atrium including the PVs,5 the success rates range between 60 and 70%. Since a significant number of patients did not benefit from a standardized lesion set, the new concept rather to tailor the ablation approach to the patients' individual chronic AF processes has been implemented by Haissaguerre and co-workers.6 This concept was based on the observation that chronic AF could occasionally be terminated by ablation. Thus, using the combination of different strategies, … *Corresponding author. Tel: +49 40 428034120, Fax: +49 40 428034125, Email: willems{at}uke.uni-hamburg.de

Dual Independent Atrial Tachycardias After Ablation of Chronic Atrial Fibrillation

We report the case of a 71-year-old man with two atrial tachycardias evolving simultaneously and independently in two dissociated regions after extensive ablation for chronic atrial fibrillation. One tachycardia was a focal tachycardia originating from the right inferior pulmonary vein and activating the posterior left atrium with a 2:1 conduction block, while the other tachycardia was an atrial flutter circulating around the tricuspid annulus, activating the right atrium and the anterior wall of the left atrium. These two atrial tachycardias were successfully ablated prior to restoration of sinus rhythm.