Pulmonary vein disconnection using the LocaLisa three-dimensional nonfluoroscopic catheter imaging system

INTRODUCTION: Catheter ablation for atrial fibrillation (AF) is associated with prolonged fluoroscopy times. We prospectively evaluated the use of the LocaLisa three-dimensional nonfluoroscopic catheter imaging system with the aim of reducing fluoroscopy times during pulmonary vein (PV) disconnection. METHODS AND RESULTS: Fifty-two patients with AF (47 men and 5 women, mean age 53 +/- 9 years) underwent disconnection of all four PVs guided by a circumferential mapping catheter. The LocaLisa navigation system was used for real-time three-dimensional nonfluoroscopic imaging of the circumferential mapping catheter and ablation catheter electrodes in 26 patients. Procedural parameters were compared with those of a control group consisting of 26 patients in whom only standard fluoroscopy was used. PV disconnection was performed similarly in both groups by circumferential ablation around the ostia, with the endpoint of disconnecting left atrium to PV breakthroughs. The cumulative duration of radiofrequency (RF) energy delivery, procedural time, and fluoroscopy time required for PV disconnection were compared. Successful disconnection was achieved in all PVs, without acute complications. There was no significant difference in cumulative RF energy delivery: 34.8 +/- 11.4 minutes for the nonfluoroscopic imaging group versus 38.2 +/- 10.5 minutes for the control group. The fluoroscopy time required for disconnection of all four PVs was significantly lower in the LocaLisa group than in the control group: 8.4 +/- 4.3 minutes versus 23.7 +/- 9.7 minutes (P < 0.0001). There also was a significant difference in the mean time taken for PV disconnection: 46.5 +/- 12.0 minutes for the nonfluoroscopic imaging group versus 66.3 +/- 18.9 minutes for the control group (P < 0.0001). CONCLUSION: By allowing continuous three-dimensional monitoring of ablation and mapping catheter position and orientation, the LocaLisa nonfluoroscopic imaging system significantly reduces fluoroscopy and PV disconnection times.     

Catheter ablation of atrial flutter guided by electroanatomic mapping (CARTO): a randomized comparison to the conventional approach

INTRODUCTION: Three-dimensional electroanatomic (CARTO) activation mapping of the cavotricuspid isthmus can be helpful to guide atrial flutter ablation, but to date has not been investigated in comparison to conventional strategies. The aim of the present study was to assess the efficacy of the CARTO navigation system, especially with respect to the fluoroscopy time required for successful atrial flutter ablation. METHODS AND RESULTS: Eighty patients with recurrent common-type atrial flutter were randomly assigned to temperature-controlled radiofrequency (RF) catheter ablation, either guided by conventional criteria (group 1) or additionally oriented on electroanatomic mapping (group 2). In all patients, similar multipolar catheters were inserted into the coronary sinus and placed at the tricuspid annulus, respectively. In group 2, positioning of the mapping electrode and delivery of RF pulses within the cavotricuspid isthmus was mainly oriented on the CARTO map to achieve the most linear and continuous RF lesions. Abolition of intra-atrial conduction verified by conventional criteria (group 1) and electroanatomic mapping (group 2) could be verified in all patients. The overall number of RF pulses (group 1: 16.7+/-6.5; group 2: 13.2+/-5.3) and mean procedure duration (group 1: 172.5+/-47.4 min; group 2: 169.3+/-47.3 min) were not different between the two groups, but mean fluoroscopy time was significantly shorter when the CARTO technology was used (group 1: 29.2+/-9.4 min; group 2: 7.7+/-2.8 min; P = 0.0001). Recurrence of atrial flutter was observed in 3 (9%) patients in each group after a mean follow-up of 8.5+/-2.8 months. CONCLUSION: Atrial flutter can be abolished effectively using the conventional technique as well as oriented on electroanatomic mapping. However, overall X-ray exposure can be significantly reduced by the CARTO-guided approach without prolongation of procedure duration.     

Tracking dynamic conduction recovery across the cavotricuspid isthmus

OBJECTIVES: We sought to assess the dynamic temporal course of conduction recovery during and after radiofrequency (RF) catheter ablation of the cavotricuspid isthmus. BACKGROUND: Although cavotricuspid isthmus block is accepted as the best end point of ablation for typical flutter, conduction recovery is thought to underlie many eventual recurrences. Its time course and frequency have not been determined. METHODS: In a prospective group of 30 patients (26 men and 4 women, age 64 +/- 12 years) undergoing ablation of typical flutter in the cavotricuspid isthmus, the morphology of the P wave during pacing from the low lateral right atrium after achievement of complete isthmus block was identified as a reference. Regression of this morphologic P wave change was confirmed to be associated with intracardiac evidence of the recovery of cavotricuspid isthmus conduction and was observed throughout the procedure both during ablation in sinus rhythm (n = 15, group B) and just after flutter termination (n = 15, group A). RESULTS: Stable complete isthmus block was achieved in all patients; 29 had a terminal positivity of the paced P wave. Flutter termination resulted in stable block and terminal P wave positivity in three patients, transient terminal P wave positivity and transient block despite continuing RF at the same site in five patients and no block in the remaining seven patients. Conduction recovery identified by recovery of P wave changes was nearly as common (48%) during ablation in sinus rhythm. Multiple recoveries were noted in some patients, and 72% of all recoveries occurred within 1 min. Conduction recovery was only rarely associated with coagulum, impedance elevation or pops. CONCLUSIONS: Conduction recovery in the cavotricuspid isthmus is common during and after ablation and can be accurately, dynamically and continuously observed by monitoring the recovery of the low lateral right atrial paced P wave change.     

LocaLisa catheter navigation reduces fluoroscopy time and dosage in ablation of atrial flutter: a prospective randomized study

INTRODUCTION: Catheter ablation has become a well-established therapy for isthmus-dependent right atrial flutter (AFL). Recently, mapping and ablation of AFL have been performed using sophisticated three-dimensional mapping systems, such as electroanatomic and noncontact mapping systems. The LocaLisa system enables nonfluoroscopic navigation of intracardiac electrode catheters based on impedance changes related to catheter movements in transthoracic current fields. The aim of this randomized prospective study was to compare the efficacy of the LocaLisa system with the conventional mapping/ablation approach for radiofrequency ablation of AFL. METHODS AND RESULTS: Fifty consecutive patients with AFL (39 men and 11 women; age 65 +/- 10 years) were studied. The patients were randomly assigned to undergo radiofrequency ablation guided by a conventional fluoroscopy-based approach (24 patients) or by the LocaLisa system (26 patients). Ablation success rate and documentation of bidirectional isthmus block were 100% in both groups. Compared with fluoroscopy-guided approaches, LocaLisa-guided procedures demonstrated a reduction in total fluoroscopy time from 15.9 +/- 10.6 minutes to 7.5 +/- 6.5 minutes (P < 0.005). Total fluoroscopy dosage was reduced from 21.0 +/- 19.8 to 8.7 +/- 9.5 Gycm2 (P < 0.05). Fluoroscopy time required for ablation was significantly shortened in the LocaLisa group (2.6 +/- 2.6 min) compared with the conventional approach group (11 +/- 10 min, P < 0.0005). In 9 (35%) of 26 patients, the ablation could be performed with a fluoroscopy time < or = 1 minute. There were no significant differences with regard to the number of radiofrequency applications, fluoroscopy time needed for diagnostic reasons, total procedure time, or other ablation data. CONCLUSION: Compared with the conventional approach, the LocaLisa system significantly reduces the fluoroscopy times needed for ablation of typical AFL.     

Left atrial ablation versus biatrial ablation for persistent and permanent atrial fibrillation: a prospective and randomized study.

OBJECTIVES: The aim of this study was to compare--in patients with persistent and permanent atrial fibrillation (AF)--the efficacy and safety of left atrial ablation with that of a biatrial approach. BACKGROUND: Left atrium-based catheter ablation of AF, although very effective in the paroxysmal form of the arrhythmia, has an insufficient efficacy in patients with persistent and permanent AF. METHODS: Eighty highly symptomatic patients (age, 58.6 +/- 8.9 years) with persistent (n = 43) and permanent AF (n = 37), refractory to antiarrhythmic drugs, were randomized to two different ablation approaches guided by electroanatomical mapping. A procedure including circumferential pulmonary vein, mitral isthmus, and cavotricuspid isthmus ablation was performed in 41 cases (left atrial ablation group). In the remaining 39 patients (biatrial ablation group), the aforementioned approach was integrated by the following lesions in the right atrium: intercaval posterior line, intercaval septal line, and electrical disconnection of the superior vena cava. RESULTS: During follow-up (mean duration 14 +/- 5 months), AF recurred in 39% of patients in the left atrial ablation group and in 15% of patients in the biatrial ablation group (p = 0.022). Multivariable Cox regression analysis showed that ablation technique was an independent predictor of AF recurrence during follow-up. CONCLUSIONS: In patients with persistent and permanent AF, circumferential pulmonary vein ablation, combined with linear lesions in the right atrium, is feasible, safe, and has a significantly higher success rate than left atrial and cavotricuspid ablation alone.     

Randomized comparison of two targets in typical atrial flutter ablation

Typical atrial flutter ablation has become anatomically guided to 2 separate sites within the isthmus at the inferior right atrium: (1) between the inferior vena cava and the tricuspid annulus (anterior side of the isthmus [A]), (2) between the eustachian crest, the coronary sinus ostium and tricuspid annulus (posterior side of the isthmus [P]). We prospectively compared ablation results at these sites in 72 consecutive patients. Patients were randomized in group P or A according to the initial target site. If ablation failed at 1 site after 15 radiofrequency (RF) pulses, the other side of the isthmus was targeted. Before 15 RF pulses, complete bidirectional isthmus block was achieved in 30 of 36 group A patients and in 25 of 36 group P patients, with similar mean RF pulses number, procedure time, and fluoroscopy time. After shifting to the other target, success was finally obtained at P in 2 of 6 group A patients, and at A in 8 of 11 group P patients before a maximum of 30 RF pulses. Among successful patients, number of RF pulses, procedure time, and fluoroscopy time were significantly lower in group A (7.2 +/- 5.4 vs 11.0 +/- 8.1 pulses, p = 0.03; 131 +/- 44 vs 163 +/- 66 minutes, p = 0.03; 31 +/- 19 vs 46 +/- 24 minutes, p = 0.01, respectively). Impairment of atrioventricular (AV) nodal conduction occurred in 5 patients only during ablation at P. AV block was transient in 4 patients and permanent in 1. Although atrial flutter ablation is equally effective at P and A, success seems easier to obtain when A is first targeted. Ablation at P is associated with a significant risk of AV block.     

Identification and ablation of atypical atrial flutter. Entrainment pacing combined with electroanatomic mapping

Differentiation between typical and atypical atrial flutter solely based upon surface ECG pattern may be limited. However, successful ablation of atrial flutter depends on the exact identification of the responsible re-entrant circuit and its critical isthmus. Between August 2001 and June 2003, we performed conventional entrainment pacing within the cavotricuspid isthmus in 71 patients with sustained atrial flutter. In patients with positive entrainment we considered the arrhythmia as typical flutter and treated them with conventional ablation of the cavotricuspid isthmus. As a consequence of negative entrainment we performed 3D-electroanatomic activation mapping (CARTO trade mark ). Conventional ablation of the right atrial isthmus was successful in all patients (n = 54) with positive entrainment. We performed electroanatomic mapping in the remaining 17 patients (14 male; age 60.9 +/- 16 years) resulting in the identification of 6 cases with typical and 11 cases with atypical flutter. Therefore, entrainment pacing was able to predict the true presence of typical atrial flutter in 91.5%. Atypical flutter was right sided in 4 patients and left sided in 7 cases. Electrically silent ("low voltage") areas probably demonstrating atrial myopathy were identified in all cases with left sided and in 2 patients with right sided flutter. In these patients targets for ablation lines were located between silent areas and anatomic barriers (inferior pulmonary veins, mitral respectively tricuspid annulus, or vena cava inferior). In 1 patient, the investigation was stopped due to variable ECG pattern and atrial cycle lengths. In the remaining cases, ablation was acutely successful. One patient, after surgical closure of a ventricular septal defect, demonstrated a dual-loop intra-atrial reentry tachycardia dependent on two different isthmuses. This arrhythmia required ablation of those distinct isthmuses to be interrupted. After a mean follow-up of 8.8 +/- 3.4 months, there was one patient with a recurrence of left-sided atrial flutter. Another patient developed permanent atrial fibrillation shortly after the procedure. Mean duration time of the procedure was 235.6 +/- 56.4 min (right atrium: 196 +/- 17.3 min; left atrium: 267.2 +/- 59.5 min), and average fluoroscopy time was 21.8 +/- 11.7 min (right atrium: 9.5 +/- 6 min; left atrium: 28.9 +/- 7 min). There was no incidence of serious complications associated with these procedures. In conclusion, conventional pacing in the cavotricuspid isthmus combined with electroanatomic mapping was an effective method to differentiate between typical and atypical atrial flutter. Electroanatomic mapping was a powerful tool both for identification of different atrial re-entrant circuits including their critical isthmuses as well as for effective application of individual ablation line strategies.     

Catheter ablation of long-lasting persistent atrial fibrillation: critical structures for termination

BACKGROUND: The relative contributions of different atrial regions to the maintenance of persistent atrial fibrillation (AF) are not known. METHODS: Sixty patients (53 +/- 9 years) undergoing catheter ablation of persistent AF (17 +/- 27 months) were studied. Ablation was performed in a randomized sequence at different left atrial (LA) regions and comprised isolation of the pulmonary veins (PV), isolation of other thoracic veins, and atrial tissue ablation targeting all regions with rapid or heterogeneous activation or guided by activation mapping. Finally, linear ablation at the roof and mitral isthmus was performed if sinus rhythm was not restored after addressing the above-mentioned areas. The impact of ablation was evaluated by the effect on the fibrillatory cycle length in the coronary sinus and appendages at each step. Activation mapping and entrainment maneuvers were used to define the mechanisms and locations of intermediate focal or macroreentrant atrial tachycardias. RESULTS: AF terminated in 52 patients (87%), directly to sinus rhythm in 7 or via the ablation of 1-6 intermediate atrial tachycardias (total 87) in 45 patients. This conversion was preceded by prolongation of fibrillatory cycle length by 39 +/- 9 msec, with the greatest magnitude occurring during ablation at the anterior LA, coronary sinus and PV-LA junction. Thirty-eight atrial tachycardias were focal (originating dominantly from these same sites), while 49 were macroreentrant (involving the mitral or cavotricuspid isthmus or LA roof). Patients without AF termination displayed shorter fibrillatory cycles at baseline: 130 +/- 14 vs 156 +/- 23 msec; P = 0.002. CONCLUSION: Termination of persistent AF can be achieved in 87% of patients by catheter ablation. Ablation of the structures annexed to the left atrium-the left atrial appendage, coronary sinus, and PVs-have the greatest impact on the prolongation of AF cycle length, the conversion of AF to atrial tachycardia, and the termination of focal atrial tachycardias.     

Atrial flutter ablation: efficacy and cost-effectiveness of a single decapolar electrode to demonstrate bidirectional isthmus block.

AIMS: To evaluate whether a single decapolar electrode is a reliable and cost-effective substitute for the 'Halo' catheter to map the circuit and detect bidirectional isthmus block during atrial flutter (AFL) ablation. METHODS AND RESULTS: Twenty-four patients underwent AFL ablation by using the decapolar electrode in the infero-lateral wall of right atrium (group A) while a 'Halo' catheter was used in 11 patients (group B). Both groups had similar clinical characteristics. Anti-clockwise rotation (20 patients), clockwise (3 patients) or both forms of AFL (1 patient) were detected in group A. All patients in group B had anti-clockwise AFL. Bidirectional isthmus block was completed in 22 patients of group A and in 9 of group B (P=NS) while incomplete isthmus block was detected in 2 patients in each group (P=NS). Mean fluoroscopy and procedure time was 27 +/- 47 min, 107 +/- 36 min in group A and 14 +/- 19 min, 114 +/- 65 min in group B (P=NS). AFL relapsed in 3 patients of group A (follow-up 7 +/- 4 months) and in 2 of group B (4 +/- 2 months). CONCLUSION: A single decapolar electrode is a reliable method to map the circuit and demonstrate bidirectional isthmus block during AFL ablation. The cost of the decapolar electrode is a quarter of that of the 'Halo' catheter. This represents a significant saving particularly for centres with a substantial number of AFL ablations.     

Use of the LocaLisa mapping system during ablation procedures in patients with atrioventricular nodal reentrant tachycardia

INTRODUCTION: LocaLisa is a novel system for anatomical mapping. It enables an assessment of the three-dimensional position of electrodes within cardiac chambers without fluoroscopy. With this technique it may be possible to reduce radiation exposure during catheter-based ablation procedures. AIM: To evaluate the efficacy and safety of ablation procedures performed using the LocaLisa mapping system in patients with atrioventricular nodal reentrant tachycardia (AVNRT). METHODOLOGY: This study evaluated the course of the first 26 ablations performed using the LocaLisa system (studied group). The control group involved 30 consecutive patients with AVNRT treated with the conventional ablation technique that was routinely used prior to the introduction of the novel system into clinical practice. RESULTS: In the studied group procedural duration was 72.4+/-24.9 minutes, in the control group 80.1+/-18.2 minutes (NS). However, radiation exposure was significantly lower in the examined group -- 74.4+/-109.2 mGy compared to 184.8+/-59.9 mGy in the control group (p <0.05). All procedures were successful. No complications related to the ablation were observed. CONCLUSIONS: Employment of the LocaLisa mapping system enables the reduction of fluoroscopic exposure without any decrease of efficacy or elevation of risk of any complications during AVNRT ablations.     

Prospective randomized comparison of closed cooled-tip versus 8-mm-tip catheters for radiofrequency ablation of typical atrial flutter

INTRODUCTION: Cooled-tip and 8-mm-tip catheters have been found to be more effective than conventional 4-mm-tip catheters for radiofrequency (RF) ablation of common atrial flutter. The aim of this study was to compare the efficacy and safety of cooled-tip and 8-mm-tip catheters for flutter ablation in a randomized, prospective study. METHODS AND RESULTS: In 100 consecutive patients referred for ablation of common atrial flutter, cavotricuspid ablation was performed with a closed cooled-tip catheter (n = 50) or an 8-mm-tip ablation catheter (n = 50). RF current was applied for 60 to 120 seconds at powers of 40 to 50 W with the closed cooled-tip catheter and in a temperature-controlled mode (65 degrees C/70 W) with the 8-mm-tip catheter. The endpoint was achievement of a bidirectional isthmus conduction block. Cross-over was performed after 15 unsuccessful RF applications for each of the catheters. Complete bidirectional isthmus block was achieved in 99% of patients. Cross-over was performed in 11 patients after primary use of the cooled-tip catheter and in 9 patients after primary ablation with the 8-mm-tip catheter. No significant differences were found in the procedure parameters, such as overall RF applications (12.4 +/- 11.3 vs 12.9 +/- 8.6), ablation duration (42 +/- 43 min vs 39 +/- 27 min), and fluoroscopy time (17.0 +/- 18.7 min vs 15.7 +/- 10.7 min). In a mean follow-up of 8.3 months, 1 patient in the cooled-tip group and 3 patients in the 8-mm-tip group had recurrence of common atrial flutter. CONCLUSION: Use of the closed cooled-tip ablation catheter and the 8-mm-tip catheter have equal and high efficacy for RF ablation of common atrial flutter.     

Prevalence of typical atrial flutter with reentry circuit posterior to the superior vena cava: use of entrainment at the atrial roof.

AIMS: Upper turn-around of the reentry circuit in typical atrial flutter (AF) is classically described to be located in front of the superior vena cava (SVC), but circuits posterior to the SVC as well as lower loop reentry (LLR) involving only the lower part of the right atrium have been described. However, true prevalence of such AF circuits remains unknown. METHODS AND RESULTS: Fifty consecutive patients (46 men, 68 +/- 9 years old) undergoing radiofrequency (RF) ablation of typical counter-clockwise AF were prospectively investigated. Prior to RF deliverance, AF was entrained by pacing 10 ms shorter than the AF cycle length (AFCL). Post-pacing interval (PPI) at the cavotricuspid isthmus (CTI) and at the atrial roof (AR)-between SVC and the high tricuspid annulus-were determined. AR was considered to be part of the AF circuit when local PPI-AFCL was < or =20 or 30 ms or, in case of long PPI at the CTI isthmus, if difference between AR-PPI and CT-PPI was < or =10 ms. In 47 patients, CTI-PPI-AFCL was < or =30 ms (94%). Among them, AR-PPI-AFCL was >30 ms in 12 cases (25%). In the remaining three patients, AR-PPI-AFCL did not exceed CTI-PPI-AFCL by more than 10 ms. In 42 patients, CTI-PPI-AFCL was < or =20 ms (84%). Among them, AR-PPI-AFCL was >20 ms in 16 cases (39%). In the remaining eight patients, AR-PPI-AFCL was more than 10 ms longer than CTI-PPI-AFCL in only one instance. Taken together, AR PPI was >20 or >30 ms longer than AFCL or >10 ms longer than CTI PPI when prolonged in 17 (34%) and 12 patients (24%), respectively. CONCLUSION: In around a quarter to one-third of patients referred for RF ablation of typical AF, the atrial roof is not part of the circuit, thus they may present a 'posterior' variant of the typical counter-clockwise AF reentry circuit.     

Randomized comparison of anatomical versus voltage guided ablation of the cavotricuspid isthmus for atrial flutter.

OBJECTIVES: The purpose of this prospective study was to compare radiofrequency catheter ablation of the cavotricuspid isthmus using a strictly anatomic approach to an approach guided by a bipolar voltage map to avoid high voltage zones in the cavotricuspid isthmus. BACKGROUND: It is not clear whether local atrial electrogram amplitude influences the achievement of complete cavotricuspid isthmus block during radiofrequency catheter ablation for atrial flutter. METHODS: Thirty-two patients with atrial flutter were randomized to cavotricuspid isthmus ablation using an anatomical approach (group I, 16 patients) or guided by a bipolar voltage map (group II, 16 patients). A 3-dimensional electroanatomic mapping system and an 8-mm-tip ablation catheter were used in all patients. With the anatomical approach, an ablation line was created in the cavotricuspid isthmus at a 6 o'clock position in the 45 degree left anterior oblique projection. During voltage-guided ablation, a high-density bipolar voltage map of the cavotricuspid isthmus was created, and then contiguous applications of radiofrequency energy were delivered to create an ablation line through the cavotricuspid isthmus sites with the lowest bipolar voltage. RESULTS: Complete cavotricuspid isthmus conduction block was achieved in 100% of patients in each group. The mean maximum voltages along the line were 3.6 +/- 1.5 mV in group I, and 1.2 +/- 0.9 mV in group II (P < .01). Creating a high-density voltage map was associated with approximately 15-minute increase in the total procedure time (P = .2). During a mean follow-up of 177 +/- 40 days, there were no recurrences of atrial flutter in either group. There were no complications in either group. CONCLUSIONS: When cavotricuspid isthmus ablation for atrial flutter is performed with an 8-mm-tip catheter, complete block can be achieved in all patients regardless of local voltage. Ablation of high voltage zones is not associated with a higher recurrence rate. Therefore, anatomic ablation without voltage mapping is the preferred initial approach for cavotricuspid isthmus ablation.     

Computed tomography-fluoroscopy image integration-guided catheter ablation of atrial fibrillation

Introduction: This study examines the feasibility of atrial fibrillation (AF) ablation using registered three-dimensional computed tomography (CT) images of the left atrium with fluoroscopy.
Methods and Results: A total of 50 consecutive patients with symptomatic AF refractory to medical therapy (32 paroxysmal, 18 persistent, age 55 ± 10 years) were randomized to undergo a catheter-based AF ablation procedure with or without the CT-fluoroscopy guidance system. All patients underwent preprocedural contrast-enhanced CT imaging and segmentation of the left atrium. For the CT-fluoroscopy group, circumferential lesions encompassing the pulmonary vein (PV) antrum and linear lesions along the roof of the left atrium between the superior PVs and the mitral isthmus were created on the CT image, which was registered with real-time fluoroscopy. The registered images were then used to navigate the ablation catheters to the sites of planned ablation. After the ablation sites were completed, any remaining PV potentials were isolated with electrophysiological guidance. In the control patients, the same technique was performed without using the CT-fluoro guidance system. CT scans were accurately registered to fluoroscopic images with minimal manual correction. Operators could navigate catheters on the registered images to preplanned, extraostial sites for ablation. CT-fluoroscopy guidance decreased procedure duration and fluoro times (P < 0.05). At a mean follow-up of 9 ± 2 months, 21 patients (84%) in the CT-fluoro guidance group and 16 patients (64%) in the control group have had no recurrence of AF.
Conclusion: CT-fluoroscopic-guided left atrial ablation is feasible and allows appropriate catheter manipulation in the left atrium.     

Ventricular tachycardia ablation guided by LocaLisa system in patients with structural heart disease

INTRODUCTION: The ablation of ventricular tachycardia is limited by a number of factors that reduce the effectiveness of this intervention in patients with structural heart disease compared to other types of arrhythmia. Recent years have seen the development of several nonfluoroscopic navigation techniques that facilitate the mapping of complex arrhythmogenic substrates. One such technique, the LocaLisa system, has not previously been tested for the ablation of ventricular tachycardia. PATIENTS AND METHOD: A total of 32 patients with structural heart disease were treated at our center with ablation for sustained ventricular tachycardia. In 10 patients the LocaLisa system was used to visualize the catheters during the procedure. We compared the results in the LocaLisa group with those in a control group of 22 patients treated with conventional fluoroscopy-guided ablation. RESULTS: The success rate of ablation was 75% (9/12 procedures) in the LocaLisa group and 68% (17/25 procedures) in the control group (P=NS). In the LocaLisa group, mean total duration of the procedure (243 +/- 84), duration of ablation (86 +/- 56) and fluoroscopy time (46 +/- 19) did not differ significantly from those in the control group (244 +/- 72 min, 79 +/- 58 min, and 43 +/- 27 min, respectively). In the LocaLisa group the trend toward greater hemodynamic intolerance in ventricular tachycardia approached significance (42% in the LocaLisa group vs 24% in the control group, P=.05) and the number of mapping procedures performed during sinus rhythm was significantly higher in the former (33% in the LocaLisa group vs 4% in the control group, P=.03). With the LocaLisa system it was possible to locate and reposition the ablation catheter accurately at the target endocardial sites, as confirmed by electrographic recordings and fluoroscopic verification. CONCLUSIONS: The LocaLisa system helps to delineate the reentry circuit and facilitates accurate catheter repositioning in patients with structural heart disease and ventricular tachycardia.     

Effects of cavotricuspid isthmus catheter ablation on paroxysmal atrial fibrillation

It has been demonstrated that successful cavotricuspid isthmus ablation of typical atrial flutter combined with atrial fibrillation (AF) sometimes influences the preablation history of paroxysmal AF. However, the effectiveness of only isthmus ablation on AF itself is unclear. Endocardial catheter mapping during induced AF was performed around the tricuspid annulus using duodecapolar clectrode catheters in 39 patients with drug-refractory paroxysmal AF. Isthmus ablation was performed in 16 patients (41%) in whom catheter mapping during AF showed an organized activation pattern around the tricuspid annulus. During a mean follow-up of 12.3 months, isthmus ablation was successful in preventing AF in 12 (75%) patients, 8 without medication and 4 with a previously ineffective drug. This success group had a significantly higher F wave amplitude in lead V1 (0.29+/-0.10 vs 0. 15+/-0.04 mV, p < 0.01), a higher left ventricular ejection fraction (74+/-9 vs 58+/-2%, p < 0.05), and a smaller left atrial dimension (35+/-6 vs 43+/-4 mm, p < 0.05) than the failure group. Isthmus ablation may be effective in preventing paroxysmal AF with an organized activation pattern around the tricuspid annulus. F wave amplitude, left ventricular ejection fraction, and left atrial dimension were significant predictors of success.     

Catheter ablation of long-lasting persistent atrial fibrillation: clinical outcome and mechanisms of subsequent arrhythmias

BACKGROUND: Catheter ablation of atrial fibrillation (AF) is challenging in patients with long-standing persistent AF. The clinical outcome and subsequent arrhythmia recurrence after using an ablation method targeting multiple left atrial sites with the aim of achieving acute AF termination has not been characterized. METHODS: Sixty patients (mean age: 53 +/- 9 years) with persistent AF (mean duration: 17 +/- 27 months) were prospectively followed after catheter ablation. Catheter ablation targeting the following sites was performed in a random sequence: (i) electrical isolation of all pulmonary veins (PV); (ii) disconnection of other thoracic veins; (iii) atrial ablation at sites possessing complex electrical activity, activation gradients, or short cycle lengths. Finally, linear ablation of the LA roof and mitral isthmus was performed if sinus rhythm was not restored following energy delivery to the above sites. At 1, 3, 6, and 12 months after ablation, patients underwent clinical review and 24-hour ambulatory ECG monitoring to identify asymptomatic arrhythmia. Repeat mapping and catheter ablation was performed in any patient experiencing recurrent atrial tachycardia (AT). Clinical success was defined as the absence of any sustained atrial arrhythmia. RESULTS: AF terminated during ablation in 52 patients (87%). The fluoroscopy and procedural durations were 84 +/- 30 minutes and 264 +/- 77 minutes, respectively. Three months after ablation, sustained ATs were documented in 24 patients (associated with AF in 2). Mapping in 23 patients showed a single AT in 7 while multiple ATs were observed in 16. Macroreentry was confirmed to be due to gaps in the ablation lines, while focal ATs originated from discrete sites or isthmuses near the left atrial appendage, coronary sinus, pulmonary veins, or fossa ovalis; these sites were similar to those at which the greatest impact was observed on the fibrillatory process during the initial ablation procedure. After repeat ablation, at 11 +/- 6 months of follow-up, 57 patients (95%) were in sinus rhythm and 3 developed recurrent AF or AT. All patients in sinus rhythm demonstrated improved exercise capacity and all but 2 had evidence of atrial transport as assessed by Doppler echocardiography (mitral A wave velocity 34 +/- 17 cm/sec) by 6 months. CONCLUSION: Catheter ablation of long-lasting persistent AF associated with acute AF termination achieves medium to long-term restoration and maintenance of sinus rhythm in 95% of patients. Arrhythmia recurrence in the majority of patients is AT.     

Mechanism of conversion of atypical right atrial flutter to atrial fibrillation

The purpose of this study was to explore the mechanisms of conversion from atypical atrial flutter (AFL) to atrial fibrillation (AF), and the long-term results of cavotricuspid isthmus ablation in these patients. We retrospectively reviewed the records of 221 patients with typical AFL referred to our hospital for ablation. A total of 25 patients had atypical AFL, and cavotricuspid isthmus ablation was performed in 23 with isthmus-dependent atypical AFL, as well as in 180 patients with typical counterclockwise and/or clockwise AFL. In all, 13 spontaneous transitions from atypical AFL to AF were documented in 11 of 17 patients. Before AF, a pattern of lower loop reentry was observed in 11 of 13 patients (85%) and upper loop reentry in 3 (1 had both). Multiple early breaks along the tricuspid annulus during AFL were noted in 6 of 13 patients (46%). Among the 13 transitions, discrete atrial premature complexes before AF were found in 5 patients with lower loop reentry and in 1 with upper loop reentry (46%). In the remaining patients, a more rapid atrial rhythm was involved in the development of AF with a pulmonary venous focus in 2. In some cases, additional "breaks" in the functional line of block occurred before the development of AF. There was a significant increased incidence of AF (68%) in those with atypical AFL compared with those with typical AFL (38%) (p = 0.004). After a mean follow-up of 28 +/- 9 months for the atypical group and 18 +/- 11 months for the typical group, the AF recurrence rate was similar (57% vs 48%, p = 0.4). Discrete atrial premature complexes or atrial tachycardia may initiate AF either directly or by producing further breaks in lines of functional block. Bidirectional cavotricuspid isthmus block is associated with cure or control of AF in approximately 50% of patients with AFL.     

心房颤动射频消融术后继发房性心律失常的机制和对策

目的 研究心房颤动(AF)患者环肺静脉射频消融术后继发房性快速性心律失常(ATA)的机制和对策.方法 继发ATA 15例.左房各肺静脉逐一标测,对恢复心房-肺静脉传导的静脉补点消融,达到心房-肺静脉电隔离.成功后仍然存在或诱发ATA的则进行CARTO激动标测和拖带标测,并行辅线消融或局灶消融,直到不能诱发.结果 经电生理标测发现14例恢复了心房-肺静脉传导.相应补点消融后电隔离,9例不能再诱发,3例诱发了左房大折返心动过速,左房顶部/峡部消融后终止,1例诱发左房局灶心动过速,局灶消融后成功.2例诱发右房大折返心动过速,右房峡部消融后消失.术后随访1～16(5.5±4.4)个月,13例无复发,2例发作明显减少.结论 左房-肺静脉传导恢复是继发ATA的重要机制;其他机制还包括左房顶部、峡部、右房峡部依赖的大折返心动过速以及局灶房性心动过速等.对继发ATA,先检查肺静脉并补点消融很重要,但不能完全解决问题,尚需根据CARTO激动标测和拖带标测进行个体化的消融.     

Partial cavotricuspid isthmus block before ablation in patients with typical atrial flutter

OBJECTIVES

The purpose of this study was to prospectively evaluate preexisting partial isthmus block in the context of an electrophysiologically directed linear ablation strategy for typical atrial flutter (AF).

BACKGROUND

Double potentials (DPs) separated by an isoelectric interval have been recognized as markers of local block. However, the presence and significance of DPs in the cavotricuspid isthmus during AF before ablation have not been evaluated.

METHODS

Thirty consecutive patients with AF (counterclockwise: 24, clockwise: 6) were studied during AF. Sequential withdrawal mapping was performed in the cavotricuspid isthmus from the tricuspid valve (TV) to the inferior vena cava (IVC) edge with electrograms coinciding with the center of the surface electrocardiographic plateau during counterclockwise AF or with the initial downslope of the positive flutter wave during clockwise AF. Atrial electrograms along this line were categorized as double, single or fractionated potentials (SPs or FPs). After demarcation of the zone of contiguous DPs, radiofrequency (RF) catheter ablation was performed during AF only at sites with SPs or FPs (other than DPs) on the mapped line. If isthmus conduction still persisted after AF termination, additional RF applications were delivered using the same electrophysiologic strategy of avoiding DPs with an isoelectric interval during low lateral right atrial pacing for filling in the gap of residual conduction.

RESULTS

Before ablation, no DPs were recorded in the isthmus in 19 patients (63%); DPs were recorded only at the IVC edge in five patients, and only at the TV edge in one patient. A contiguous line of DPs extending through more than half the isthmus to the IVC edge was documented in five patients (17%: group DP). In group DP, AF was terminated with 1.4 ± 0.5 applications (vs. 5.8 ± 3.5 in the remaining patients: p < 0.01). Complete isthmus block was achieved with a total of 3.4 ± 0.5 applications (vs. 12 ± 6 in the remaining patients: p < 0.01).

CONCLUSIONS

Seventeen percent of patients undergoing ablation of AF have preexisting partial isthmus block indicated by a large contiguous zone of DPs separated by an isoelectric interval. Electrophysiologically directed linear ablation avoiding confluent DPs can prevent unnecessary applications for effective cure of AF.