Focal Atrial Tachycardia Originating from the Left Atrial Appendage: Electrocardiographic and Electrophysiologic Characterization and Long-Term Outcomes of Radiofrequency Ablation

Combination of electrophysiological mapping, radiofrequency catheter ablation, and atrial appendectomy in a 5-year-old girl with tachycardia-induced cardiomyopathy: a case report

BACKGROUND

Atrial tachycardia (AT) originating from the left atrial appendage (LAA) is uncommon and the most difficult arrhythmia to eliminate. Therefore, we present the case of a 5-year-old girl with tachycardia-induced cardiomyopathy (TIC) caused by AT originating from the LAA and successfully treated with RFCA associated to left atrial appendectomy. With resolution of AT, we observed a progressive improvement of LV function. The effectiveness and safety of this combination therapy were evaluated over a one-month follow-up period.

CASE PRESENTATION

A 5 -year-old female was evaluated for three days of incessant cough and a syncopal episode. Surface echocardiography and 24-hour monitoring showed that the infant had persistent atrial tachycardia. Echocardiography revealed an enlarged tele diastolic diameter (46.1 mm) and malfunctioning (EF 28.53%) left ventricle. The location of the lesion at the apex of the LAA was further confirmed by electrophysiological study and RFCA. After RFCA, the infant's ECG monitor showed that sinus rhythm was maintained for up to 22 h. Subsequently, atrial tachycardia recurred and sinus rhythm disappeared. Finally, atrial appendectomy was performed and sinus rhythm returned to normal.

CONCLUSIONS

The heart function of the infant improved and sinus rhythm was maintained, further demonstrating the safety and effectiveness of combined treatment with RFCA and atrial appendectomy after electrophysiological localization of AT from LAA to TIC.

Case report: Widely split P' waves in a patient with focal atrial tachycardia

Background

Widely split P waves in sinus rhythm have been reported previously. However, widely split P' waves in focal atrial tachycardia (AT) on a surface electrocardiogram (ECG) have rarely been reported. The electrophysiological mechanism is relatively difficult to clarify, requiring a electrophysiological study.

Case summary

A 67-year-old patient, who had undergone two radiofrequency ablations for atrial fibrillation, presented with recurrent palpitation. During the palpitation episode, the 12-lead ECG showed AT with a 3:1 atrioventricular conduction rate. P' waves were markedly prolonged in duration and widely split in morphology. An electrophysiological study showed that the tachycardia arose from the left atrial appendage (LAA) and was conducted through two distinct pathways. The impulse of one pathway was transmitted solely via the superior part of the atrium, including the Bachmann bundle. The second pathway was conducted via the coronary sinus and transmitted the impulse from the LAA to the ventricle. After the site showed that the earliest activation was ablated, repeated intravenous infusion of isoprenaline and programmed atrial stimulation did not induce tachycardia.

Conclusion

Widely split P' waves in AT indicate intra- and interatrial conduction blocks, which can be easily overlooked due to the presence of low-voltage areas. Therefore, an electrophysiological study is crucial for identifying the origin of the tachycardia and elucidating the mechanistic details.

Detailed analysis of tachycardia cycle length aids diagnosis of the mechanism and location of atrial tachycardias

AIMS

Although the mechanism of an atrial tachycardia (AT) can usually be elucidated using modern high-resolution mapping systems, it would be helpful if the AT mechanism and circuit could be predicted before initiating mapping.

OBJECTIVE

We examined if the information gathered from the cycle length (CL) of the tachycardia can help predict the AT-mechanism and its localization.

METHODS

One hundred and thirty-eight activation maps of ATs including eight focal-ATs, 94 macroreentrant-ATs, and 36 localized-ATs in 95 patients were retrospectively reviewed. Maximal CL (MCL) and minimal CL (mCL) over a minute period were measured via a decapolar catheter in the coronary sinus. CL-variation and beat-by-beat CL-alternation were examined. Additionally, the CL-respiration correlation was analysed by the RhythmiaTM system. : Both MCL and mCL were significantly shorter in macroreentrant-ATs [MCL = 288 (253-348) ms, P = 0.0001; mCL = 283 (243-341) ms, P = 0.0012], and also shorter in localized-ATs [MCL = 314 (261-349) ms, P = 0.0016; mCL = 295 (248-340) ms, P = 0.0047] compared to focal-ATs [MCL = 506 (421-555) ms, mCL = 427 (347-508) ms]. An absolute CL-variation (MCL-mCL) < 24 ms significantly differentiated re-entrant ATs from focal-ATs with a sensitivity = 96.9%, specificity = 100%, positive predictive value (PPV) = 100%, and negative predictive value (NPV) = 66.7%. The beat-by-beat CL-alternation was observed in 10/138 (7.2%), all of which showed the re-entrant mechanism, meaning that beat-by-beat CL-alternation was the strong sign of re-entrant mechanism (PPV = 100%). Although the CL-respiration correlation was observed in 28/138 (20.3%) of ATs, this was predominantly in right-atrium (RA)-ATs (24/41, 85.7%), rather than left atrium (LA)-ATs (4/97, 4.1%). A positive CL-respiration correlation highly predicted RA-ATs (PPV = 85.7%), and negative CL-respiration correlation probably suggested LA-ATs (NPV = 84.5%).

CONCLUSION

Detailed analysis of the tachycardia CL helps predict the AT-mechanism and the active AT chamber before an initial mapping.

Treatment Strategy in Atrial Tachycardia Originating From the Atrial Appendage

Background: Atrial appendage tachycardia (AAT) originating from the atrial appendage (AA) is extremely difficult to eliminate using radiofrequency catheter ablation (RFCA). The optimal management strategy for AAT refractory to RFCA remains unclear.

Objective: This study aims to investigate the long-term result of ablative therapy and the optimal alternative management for AAT refractory to RFCA.

Methods: A total of 51 patients with AAT originating from the AA undergoing RFCA were recruited. Video-assisted atrial appendectomy and oral ivabradine were performed on those with AATs refractory to RFCA, and this study aimed to evaluate their safety and long-term efficacy.

Results: We included 51 patients (51/586, 8.7%) with AATs confirmed by activation mapping and contrast venography. Among them, there were 28 (54.9%) AATs originating from the distal AA. In total, 14 (27.4%) AATs were refractory to RFCA, including 13 originating from the distal AA and one arising from the proximal AA. Ten of 11 (90.9%) AATs originating from the distal AA were eliminated after an atrial appendectomy, and the other three AATs were suppressed using oral ivabradine. Origins from the distal AA refractory to RFCA and early age of AAT onset ≤26.5 years indicated the need for atrial appendectomy. No major complications occurred, and nine patients with tachycardia-induced cardiomyopathy fully recovered. Long-term success was achieved in 98.0% of patients with multiple treatment managements.

Conclusion: AATs originating from the distal AA were more refractory to RFCA. RFCA was the cornerstone of AAT catheter ablation. Video-assisted thoracoscopic atrial appendectomy was an effective strategy for those origins at the distal AA and the age of AAT onset ≤26.5 years. Ivabradine represents a promising treatment for AAT temporarily in pediatric and young adult patients.

Incessant Atrial Tachycardia: Problem Solving With Minimally Invasive Surgery

A 35-year-old female with sarcoidosis sought medical attention due to palpitations. The ECG showed an atrial tachycardia (AT), apparently originating in the left atrium. A 24-hour Holter monitoring revealed AT to be present during the entire day. Cardiac magnetic resonance exhibited no cardiac involvement by sarcoidosis but registered a mildly depressed left ventricular ejection fraction (LVEF). Atrial electroanatomical mapping showed the earliest activation zone on the distal portion of the left atrial appendage (LAA). Considering the high risk for perforation with catheter ablation in this region, she was sent to thoracoscopic surgical LAA exclusion with a clip device; it was possible to witness the termination of the arrhythmia during the procedure. She was safely discharged two days after surgery and has completed a one-year follow-up without recurrence of AT or symptoms, and with normalization of LVEF.

Epicardial Termination of Left Atrial Appendage Atrial Tachycardia

This case report describes a third successful attempt to ablate a focal atrial tachycardia originating from the left atrial appendage in a highly symptomatic 49-year-old woman using a combined endocardial–epicardial approach, which could be taken into consideration as a safe and effective alternative method for treating similar arrhythmias originating from complex sites.

Role of the Left Atrial Appendage in Systemic Homeostasis, Arrhythmogenesis, and Beyond

The left atrial appendage (LAA) affects body homeostasis via atrial natriuretic peptide and the renin-angiotensin-aldosterone system and plays an important role in atrial compliance. Approximately 90% of clots in nonvalvular atrial fibrillation (AF) are formed in the LAA. AF is the most common sustained cardiac arrhythmia and is frequently associated with stroke. Because anticoagulation for stroke prophylaxis carries a higher bleeding risk, LAA closure via epicardial and endocardial approaches has gained popularity and is being increasingly pursued for arrhythmogenic, homeostatic, and stroke-reduction benefits. This review discusses the homeostatic role of the LAA and its involvement in arrhythmogenesis and thrombus formation.

The Left Atrial Appendage Ostium: Hotspots for Localized Re-Entry

OBJECTIVES

The goal of this study was to characterize the location and electrophysiological properties of left atrial appendage (LAA) atrial tachycardia (AT).

BACKGROUND

The LAA has been reported to be a source of AT and atrial fibrillation (AF) triggers.

METHODS

This study retrospectively reviewed ATs mapped to the LAA. Activation and entrainment mapping were used to determine the mechanism and localize each AT circuit/origin.

RESULTS

From 2014 to 2018, a total of 45 patients (mean age 65 ± 10 years; 69% male) had 51 LAA ATs: 43 (84%) after AF ablation and 8 de novo (no prior AF). Overall, 50 (98%) were due to localized re-entry/micro-re-entry, whereas only 1 was a focal triggered AT. All 50 micro-re-entrant LAA ATs were mapped to the anterior base (70%) or LAA ridge (30%), and all were successfully treated with focal ablation; no case required LAA isolation. After successful ablation of the initial AT at the LAA base, 23 (62%) of 37 patients with AF also had inducible macro-re-entrant peri-mitral flutter, but none had AF triggers from inside the LAA.

CONCLUSIONS

LAA ATs are almost always micro-re-entrant in mechanism and originate from either the anterior base or LAA ridge. AT originating from inside the LAA body is very rare. The anterior and ridge aspects of the LAA-left atrium junction seem to be arrhythmogenic hotspots prone to localized re-entry. These ATs are treatable with focal ablation without LAA isolation but are frequently associated with macro-re-entrant peri-mitral flutter.

Thoracoscopic stand-alone appendectomy for atrial tachycardia originating from the left atrial appendage in a patient with severe left ventricular dysfunction

Focal atrial tachycardia (AT) originating from the left atrial appendage (LAA) is one of the rare supraventricular tachycardias and is likely to cause arrhythmia-induced heart failure. Surgical treatment could be an alternative therapy because antiarrhythmic drugs and catheter ablation therapy to focal AT originating from the distal portion of the LAA is still challenging. We report a case of successful operation of minimally invasive thoracoscopic appendectomy in a patient with poor left ventricular (LV) function due to drug-resistant AT originating from the LAA for the first time. A 51-year-old female who had AT with a poor LV function suffered from congestive heart failure. We diagnosed the ongoing AT as focal AT that originated from the distal portion of LAA by electrophysiological examination. Total thoracoscopic stand-alone appendectomy was performed safely. AT was terminated and restored to sinus rhythm immediately after appendectomy. <Learning objective: Although catheter ablation has become a first-line treatment for almost all cardiac arrhythmias, it is difficult to achieve complete cure of atrial tachycardia (AT) originating from the distal portion of left atrial appendage (LAA) because there is AT recurrence and risk of cardiac perforation and ischemic stroke. Minimally invasive thoracoscopic appendectomy is curative and can be applied safely even in patients who have poor left ventricular function due to focal AT originating from the LAA.>.

Epicardial Ablation of Supraventricular Tachycardias

Supraventricular arrhythmias are the most common cardiac arrhythmias encountered; however, it is uncommon that supraventricular tachycardias require percutaneous epicardial access for successful mapping and ablation. There are particular scenarios where epicardial access and ablation should be considered. Certain accessory pathways particularly in the posteroseptal region may require epicardial access for successful ablation. These pathways may also be approached from within the coronary sinus system. In addition, tachycardias near the phrenic nerve in the right atrium or left atrium may require epicardial access for successful ablation or to allow displacement of the phrenic nerve facilitating safe catheter ablation.

Atrial tachycardia from an unusual site-Left atrial appendage tachycardia: Challenges in ablation

Left atrial appendage (LAA) tachycardia are rarely encountered in clinical practice (2.1% of focal atrial tachycardia). Out of these, the ones arising from the distal part of LAA are difficult to ablate due to higher risk of LAA perforation and thromboembolism. We hereby present a patient with LAA tachycardia mapped to the tip of LAA with the help of the CARTO system and ablated. This case highlights the inherent challenges faced in such a scenario.

Focal atrial tachycardia ablation: Highly successful with conventional mapping

BACKGROUND/OBJECTIVE

Radiofrequency catheter ablation (RFCA) of focal atrial tachycardia (FAT) traditionally is guided by conventional endocardial mapping of earliest atrial activation; however, more recently electro-anatomical mapping is heralded as a more effective, albeit more expensive, tool to guide ablation. Herein we present the results of conventional mapping-guided RFCA. Apropos, we conducted a literature search of studies reporting > 10 FAT patients submitted to RFCA.

METHODS AND RESULTS

Conventional mapping-guided RFCA, performed in 63 FAT patients (aged 42.4 + 17.3 years; 14 with incessant tachycardia and 12 with tachycardiomyopathy (TCM)), was successful in 61 (96.8%) patients, applied for single foci in 59 (93.7%) and two foci in 4 patients, right (n = 46) or left sided (n = 17). The earliest atrial activation time at the ablation site was 41.3 ± 16.2 ms. Fluoroscopy time averaged 27.3 + 18.7 min, and procedure lasted 2.6 + 1.7 h. Complications occurred in two patients (sinus pauses in one needing a pacemaker and a large inguinal hematoma in one). Over 29.0 + 22.9 months, four patients (6.5%) had recurrences, of whom three were successfully re-ablated. All patients with TCM showed gradual improvement to normalization over 4-6 months. Literature search showed that RFCA success is equally high when guided with either conventional (88.5%) or electro-anatomical mapping (90%) with similar recurrences (9.6% vs. 9.5%).

CONCLUSION

Conventional mapping-guided RFCA of FAT had high success (96.8%) with low complication (3.2%) and recurrence rates (6.5%). TCM was fully reversible. These results are comparable to those achieved with the more expensive electro-anatomical mapping, which may be reserved for more complex cases or for those failing the conventional approach.

Sustained localized reentry within the left atrial appendage as a mechanism of recurrent arrhythmia following atrial fibrillation ablation

The current study investigated the electrophysiological characteristics and radiofrequency ablation in patients with localized reentry within the left atrial appendage during repeated ablation for recurrent atrial fibrillation (AF). A total of 76 patients (21 paroxysmal, 55 persistent) undergoing repeated catheter ablation for recurrent AF were enrolled in this study. Local reentry tachycardia within the left atrial appendage (LAA) was identified through combining activation and entrainment mapping. Left atriography was performed prior to radiofrequency ablation to identify the focus in the LAA. Three patients (1 paroxysmal, 2 persistent) with sustained atrial tachycardias (ATs) were identified during repeated ablation in this cohort. Combined activation and entrainment mapping were applied to localize the reentry. Postpacing interval-tachycardia cycle length differences were <30 msec at the possible site of reentry in varying segments with macro-reentry. This difference was only determined at the base of LAA for local reentry within the LAA. All 3 patients were free of atrial arrhythmias without any complications at the 6-month follow-up following the ablation in the LAA. Combining activation and entrainment mapping were necessary in approaching ATs within the LAA. Performing entrainments in opposite segments of possible loops were valuable in precluding macro-reentry. Focal ablation was safe and effective in this cohort. Therefore localized reentry within the LAA was not uncommon during repeat AF ablation. The present study may thus provide valuable information for clinicians to manage this type of arrhythmia.

Percutaneous alternative to the Maze procedure for the treatment of persistent or long-standing persistent atrial fibrillation (aMAZE trial): Rationale and design

BACKGROUND

Pulmonary vein antrum isolation (PVI) as a treatment of paroxysmal atrial fibrillation (AF) is associated with a high rate of success; however, outcomes for treating persistent and long-standing persistent AF with PVI alone are substantially lower and often require multiple procedures to maintain long-term freedom from atrial arrhythmias. Foci and/or substrate outside the pulmonary veins, particularly in the left atrial appendage (LAA), has been identified as a key mechanism in the maintenance of persistent AF and long-standing persistent AF.

OBJECTIVE

The goals of the study are to evaluate the safety and effectiveness of the LARIAT System to percutaneously isolate and ligate the LAA and to determine if LAA ligation as adjunctive therapy to PVI improves maintenance of sinus rhythm in patients with persistent and long-standing persistent AF.

STUDY DESIGN

The trial is a prospective, multicenter, randomized controlled study. The trial design incorporates a Bayesian adaptive design that will randomize a maximum of 600 patients with persistent or long-standing persistent AF to LAA ligation and PVI vs PVI alone in a 2:1 randomization. The primary end points include 30-day safety of the LARIAT procedure and freedom from documented AF, atrial flutter, or atrial tachycardia of more than 30 seconds at 12 months after the PVI off antiarrhythmic drugs. Key secondary outcomes include a composite of cardiovascular death and stroke, as well as quality of life.

CONCLUSION

The aMAZE trial will determine if LAA ligation as adjunctive therapy to PVI increases the efficacy of maintaining sinus rhythm in patients with persistent and long-standing persistent AF.

Atrial tachycardias arising from the atrial appendages and aortic sinus of valsalva

Focal atrial tachycardias arising from the atrial appendages and the aortic sinuses of Valsalva are less frequently encountered in clinical practice. This review article describes the clinical presentation, surface P wave morphology, electrophysiologic characteristics and treatment of these arrhythmias. Catheter ablation of these focal tachycardias has a high success rate. It is however important to be aware of specific anatomic considerations in these locations for optimal treatment outcomes with low complication rates.

Thoracoscopic resection of the left atrial appendage after failed focal atrial tachycardia ablation

BACKGROUND

This case series describes 3 patients with the unusual location of focal atrial tachycardia in the left atrial appendage who failed catheter ablation but were successfully treated by left atrial appendage resection by a totally thoracoscopic surgical technique.

METHODS

In all 3 cases, left atrial appendage resection was carried out by video-assisted thoracoscopic surgery using only 3 5- to 10-mm incisions, eliminating the need for median sternotomy or thoracotomy. An endoscopic stapler was used to resect the left atrial appendage at its base, successfully eliminating the source of the patients' focal atrial tachycardia.

RESULTS

The mean operative time was 84 minutes. All 3 patients tolerated the procedure without any complications and were discharged on postoperative day 3. At an average follow-up of 4.5 years, all patients remained asymptomatic and with normal ambulatory rhythm monitoring off all antiarrhythmic medications.

CONCLUSIONS

Surgical resection of the left atrial appendage using a totally thoracoscopic approach is a safe and successful treatment option for patients who have failed endocardial catheter ablation. This novel approach utilizes smaller incisions and shorter operative times than the more invasive surgical techniques previously described in the literature.

The effects of LAA ligation on LAA electrical activity

BACKGROUND

The arrhythmic role of the left atrial appendage (LAA) has been implicated in the maintenance of persistent atrial fibrillation. LAA isolation with catheter ablation has been successful but is limited by the risk of tamponade and electromechanical dissociation with the potential for LAA thrombus formation.

OBJECTIVE

To assess whether LAA ligation results in LAA electrical isolation.

METHODS

A total of 68 patients with contraindication or intolerance to oral anticoagulation therapy underwent LAA ligation with the LARIAT suture delivery device. Patients had unipolar [n = 30(44%)] or bipolar [n = 38(56%)] voltage measurements pre- and post-LAA ligation.

RESULTS

All 68 patients underwent successful LAA ligation. There was a statistically significant reduction in the mean LAA voltage from pre-ligation (unipolar pre-ligation voltage 1.1 ± 0.53 mV; bipolar pre-ligation voltage 4.7 ± 2.83 mV) to post-ligation (unipolar post-ligation voltage 0.3 ± 0.38 mV; bipolar post-ligation voltage 0.6 ± 0.27 mV). Ninety-four percent of the patients had a reduction in the LAA voltage after the closure of the snare, with 10 of 30 (33%) of the patients having complete elimination of LAA voltage with the initial tightening of the suture. Pacing from the LAA after the closure of the snare resulted in lack of capture of the left atrium in 28 of 31 patients.

CONCLUSIONS

The snare closure of the LAA using the LARIAT device produces an acute reduction in the LAA voltage and inhibits the capture of the left atrium during LAA pacing. Future studies are needed to determine whether LAA ligation affects atrial fibrillation burden.

An electrocardiography algorithm combined with clinical features could localize the origins of focal atrial tachycardias in adjacent structures

AIMS

It is difficult to differentiate the origins of focal atrial tachycardias (ATs) in adjacent structures by electrocardiography (ECG) alone. The aim of this study was to evaluate whether the clinical features of these ATs may help differentiate their origins.

METHODS AND RESULTS

One hundred and ninety-four patients (mean age, 43.5 ± 17.9 years; male, 53.6%) who underwent electrophysiological study for focal AT were included. We evaluated accuracy in differentiating the origin of AT by using ECG alone as well as with the addition of the clinical features. Electrocardiographs of ATs originating from the left superior pulmonary vein (LSPV, n = 24) vs. the left atrial appendage (LAA, n = 6), and from the right superior pulmonary vein (RSPV, n = 14) vs. the superior vena cava (SVC, n = 8) showed similar patterns. However, while no ATs from the LAA were found to be related to paroxysmal atrial fibrillation, 22 out of 24 ATs from the LSPV were associated with this condition. After localizing AT by using ECG, this clinical feature helped differentiate the ATs from the LSPV vs. the LAA with 93% accuracy. Moreover, while an on-and-off tachycardia (initiated and terminated more than 10 times per day) was observed in 4 of 8 ATs from the SVC, this pattern was observed in 13 of 14 ATs from the RSPV. After localizing the ATs by using ECG, on-and-off tachycardia helped differentiate the ATs from the RSPV vs. the SVC with 82% accuracy.

CONCLUSION

The clinical features and Holter monitoring can give additional information for differentiating the focal ATs originating from the adjacent structures.

Management of focal atrial tachycardias originating from the atrial appendage with the combination of radiofrequency catheter ablation and minimally invasive atrial appendectomy

BACKGROUND

Focal atrial tachycardias (ATs) originating from the left and the right atrial appendage (AA) were the most difficult to eliminate.

OBJECTIVE

To evaluate the safety and long-term efficacy of minimally invasive surgical atrial appendectomy in combination with radiofrequency catheter ablation (RFCA) in the management of focal atrial appendage tachycardias (AATs).

METHODS

We included 42 consecutive patients with 42 AATs confirmed by activation mapping and contrast venography. Thirty of them were successfully managed with RFCA (RFCA-successful group), while the remaining 12 (28.6%) finally resorted to video-assisted thoracoscopic atrial appendectomy owing to RFCA failure (resort-to-surgery group). We searched for predictors of RFCA failure, and the need for surgery by using a binomial logistic regression model.

RESULTS

In the RFCA-successful group, 6 (20.0%) patients experienced recurrence and re-do ablation and 11 (36.7%) AATs originated from distal AAs. In the resort-to-surgery group, the tachycardias involved exclusively distal AAs and required more RFCA attempts compared with those of the RFCA-successful group (1.58 ± 0.51 vs 1.20 ± 0.41; P = .0165). During atrial appendectomy, incessant ATs were terminated immediately after resection of the AA at the base. Long-term success was achieved in all 42 patients with a follow-up of 29.1 ± 17.5 months. No complications occurred. Fourteen patients with tachycardia-induced cardiomyopathy recovered fully. We identified origin at distal AATs and longer time to tachycardia termination by ablation as predictors of RFCA failure and the need for surgical intervention.

CONCLUSION

ATs originating from the distal portion of AA were more refractory to RFCA. The combination of catheter ablation and video-assisted thoracoscopic atrial appendectomy was an effective strategy to manage AATs.

Transcatheter left atrial appendage occlusion

Occlusion of the left atrial appendage (LAA) may reduce the risk of stroke in patients with atrial fibrillation (AF). Trials comparing LAA occlusion to warfarin anticoagulation in patients with nonvalvular AF showed a reduction in hemorrhagic stroke, although an increase in safety events due to procedural complications. Long-term follow-up suggests possible superiority of LAA occlusion due to fewer strokes and bleeding events. The superior dosing and safety profiles of the novel oral anticoagulants raise the accepted threshold for safety and efficacy of LAA occlusion procedures, and underscore the need for randomized studies comparing LAA occlusion with these newer anticoagulants.

Radiofrequency Ablation of a Left Atrial Appendage Tachycardia on ECMO Support

Extracorporeal membrane oxygenation (ECMO) has been utilized in the pediatric population for cardiogenic shock secondary to medically intractable arrhythmias. There is limited experience with cardiac radiofrequency ablation (RFA) on these patients while on ECMO. A 7-year-old girl presented with a tachycardia-mediated cardiomyopathy secondary to a left atrial appendage tachycardia. She suffered a cardiac arrest due to pulseless electrical activity and was placed on ECMO. Due to elevated left atrial pressures and the refractoriness of her arrhythmia to cardioversion and antiarrhythmic therapy, while on ECMO, blade atrial septostomy and radiofrequency ablation were performed. The patient tolerated the procedure well and was successfully decannulated. Her cardiac function normalized within four weeks of the ablation procedure. Twelve months after the procedure, she remains completely well, with no symptoms or tachycardia.

Focal atrial tachycardia originating from the distal portion of the left atrial appendage: characteristics and long-term outcomes of radiofrequency ablation

AIMS

The characteristics and response to ablation therapy of focal atrial tachycardia (AT) originating from the distal portion of left atrial appendage (LAAd) are still not quite clear up to now. The goal of this study is to characterize electrocardiographic and electrophysiological features and radiofrequency ablation (RFA) outcomes in patients with focal AT originating from the LAAd.

METHODS AND RESULTS

Fourteen patients (2.1%) (mean age, 25 ± 10 years; nine women; mean symptom duration, 5 ± 5 years) undergoing RFA of focal AT originating from the LAAd were included out of 668 RFA patients. Activation mapping was performed. P waves were classified as negative, positive, isoelectric, or biphasic. Tachycardia that was incessant in all, demonstrated a characteristic P-wave morphology and endocardial activation pattern: P wave was negative in leads I and aVL, highly positive in the inferior leads, and broad and positive in lead V₁. Radiofrequency ablation was acutely successful in 13 of 14 patients. The endocardial activation time of the successful RFA sites was 47.1 ± 4.3 ms before the onset of P wave. There were no complications in any of the 14 patients and long-term success was achieved in 13 of 13 successful RFA patients during follow-up (5 ± 2 years).

CONCLUSION

The LAAd is an uncommon site of origin for focal AT (2.1% incidence). In this case series, focal ATs originating from the LAAd had typical electrophysiological and electrocardiographic characteristics. Focal ablation yielded high acute success rate with low rate of recurrence during follow-up.

Localized reentry within the left atrial appendage: arrhythmogenic role in patients undergoing ablation of persistent atrial fibrillation

BACKGROUND

Left atrial appendage (LAA) is implicated in maintenance of atrial fibrillation (AF) and atrial tachycardia (AT) associated with persistent AF (PsAF) ablation, although little is known about the incidence and mechanism of LAA AT.

OBJECTIVE

The purpose of this study was to characterize LAA ATs associated with PsAF ablation.

METHODS

In 74 consecutive patients undergoing stepwise PsAF ablation, 142 ATs were encountered during index and repeat procedures. Out of 78 focal-source ATs diagnosed by activation and entrainment mapping, 15 (19%) arose from the base of LAA. Using a 20-pole catheter, high-density maps were constructed (n = 10; age 57 ± 6 years) to characterize the mechanism of LAA-AT. The LAA orifice was divided into the posterior ridge and anterior-superior and inferior segments to characterize the location of AT.

RESULTS

Fifteen patients with LAA AT had symptomatic PsAF for 17 ± 15 months before ablation. LAA AT (cycle length [CL] 283 ± 30 ms) occurred during the index procedure in four and after 9 ± 7 months in 11 patients. We could map 89% ± 8% AT CLs locally with favorable entrainment from within the LAA, which is suggestive of localized reentry with centrifugal atrial activation. ATs were localized to inferior segment (n = 4), anterior-superior segment (n = 5), and posterior ridge (n = 6) with 1:1 conduction to the atria. Ablation targeting long fractionated or mid-diastolic electrogram within the LAA resulted in tachycardia termination. Postablation, selective contrast radiography demonstrated atrial synchronous LAA contraction in all but one patient. At 18 ± 7 months, 13/15 (87%) patients remained in sinus rhythm without antiarrhythmic drugs.

CONCLUSION

LAA is an important source of localized reentrant AT in patients with PsAF at index and repeat ablation procedures. Ablation targeting the site with long fractionated or mid-diastolic LAA electrogram is highly effective in acute and medium-term elimination of the arrhythmia.

Left atrial appendectomy after failed catheter ablation of a focal atrial tachycardia originating in the left atrial appendage

This report describes a case of left atrial appendectomy after a failed endocardial catheter ablation of a continuous drug-refractory left atrial appendage (LAA) tachycardia in a 9-year-old boy. Electrophysiologic study showed atrial tachycardia (AT) originating in the LAA. Numerous radiofrequency applications with an irrigated-tip catheter were ineffective. During surgery, direct pressure on the apex of the LAA by forceps immediately terminated the AT and restored sinus rhythm. After a left atrial appendectomy, the patient remained free of any arrhythmias during a follow-up period of 18 months.

Using the 12-lead ECG to localize the origin of ventricular and atrial tachycardias: part 1. Focal atrial tachycardia

Focal atrial tachycardia is an unusual form of supraventricular tachycardia arising from defined anatomic locations and sites within the atria. Although recent advances in mapping technology have facilitated successful ablation, the surface ECG remains an important aid in localizing the focus. This review discusses the use of P-wave morphology on surface ECG to localize the site of focal atrial tachycardia.

Electrophysiologic and electrocardiographic characteristics and radiofrequency catheter ablation of focal atrial tachycardia originating from the left atrial appendage

BACKGROUND

The left atrial appendage (LAA) is one of the major sources of focal atrial tachycardias (ATs).

OBJECTIVE

The purpose of this study was to investigate the detailed electrophysiologic characteristics and catheter ablation of focal ATs originating from the LAA.

METHODS

The study population consisted of 47 consecutive patients with 50 focal ATs originating from the left atrium (LA): LAA in 13, left pulmonary veins (PVs) in 14, right PVs in 12, and mitral annulus in 11. Programmed electrical stimulation and pharmacologic testing were performed to examine the mechanism of LAA AT. Left atriography was performed prior to radiofrequency ablation to identify the focus in the LAA.

RESULTS

The mechanism of LAA AT was automaticity in 11 and triggered activity in 2. The 13 LAA foci were located mainly at the LAA base: 11 on the medial side and 2 on the lateral side. Atrial activation sequences within the distal coronary sinus were helpful in differentiating these LAA foci. The criterion of a negative P wave in leads I and aVL indicating an LAA AT focus was associated with sensitivity of 92.3%, specificity 97.3%, positive predictive value 92.3%, and negative predictive value 97.3%. No complications occurred in any of the 13 patients. All 13 patients were free of atrial arrhythmias without any antiarrhythmic drugs during follow-up of 8 +/- 3 years.

CONCLUSION

LAA ATs have typical electrophysiologic and electrocardiographic characteristics that are helpful in guiding radiofrequency catheter ablation.