Higher Rate of Recurrent Atrial Flutter and Atrial Fibrillation Following Atrial Flutter Ablation After Cardiac Surgery

Atrial Flutter After Cardiac Surgery . Introduction: Atrial flutter (AFL) is common after cardiac surgery. However, the types of post‐cardiac surgery AFL, its response to catheter‐based radiofrequency ablation, and its relationship to atrial fibrillation (AF) are unknown. Methods and Results: We retrospectively studied all patients who underwent mapping and ablation for AFL after cardiac surgery from January 1990 to July 2004. One hundred randomly selected patients without prior cardiac surgery (PCS) who underwent mapping and ablation of AFL served as the control population. A total of 236 patients formed the study population (mean age 62 + 13 years, 22% female) and 100 patients formed the control population (mean age 60 + 13 years, 25% female). The majority of patients without PCS had cavo‐tricuspid isthmus (CTI)‐dependent AFL when compared to patients with PCS (93% vs 72%, respectively, P < 0.0001). In contrast, scar‐related AFL was more common in patients with PCS as compared to patients without PCS (22% vs 3%, P < 0.0001). Predictors of scar related AFL in multivariable regression analysis included PCS and left‐sided AFL. Acute success rates and complications were similar between the groups. When compared to patients with AFL ablation without PCS, those that had AFL after PCS had higher rates of recurrence of both AFL (1% vs 12%, P < 0.0001; mean time to recurrence 1.85 years) and AF (16% vs 28%, P = 0.02; mean time to recurrence 2.67 years). Conclusion: Despite ablation of AFL, patients with PCS have a higher rate of AFL and AF when compared to patients without PCS who underwent ablation of atrial flutter during long‐term follow‐up. (J Cardiovasc Electrophysiol, Vol. pp. 760‐765, July 2010)     

Ablation of Atrial Fibrillation at the Time of Cavotricuspid Isthmus Ablation in Patients With Atrial Flutter Without Documented Atrial Fibrillation Derives a Better Long‐Term Benefit

AF Ablation in Patients With Only Documentation of Atrial Flutter. Objectives: The aim of the study was to evaluate whether isolation of the pulmonary veins (PVs) at the time of cavotricuspid isthmus (CTI) ablation is beneficial in patients with lone atrial flutter (AFL). Background: A high proportion of patients with lone persistent AFL have recurrent episodes of atrial fibrillation (AF) after CTI ablation. However, the benefit of AF ablation in patients with only documentation of AFL has not been determined. Methods: Forty‐eight patients with typical lone persistent AFL (age 56 ± 6; 90% male) were randomized to CTI ablation (Group A; n = 25) or to CTI + PV isolation (PVI) (Group B; n = 23). In addition to PVI, some patients in group B underwent ablation of complex fractionated electrograms and/or creation of left atrial roof and mitral isthmus ablation line in a stepwise approach when AF was induced and sustained for more than 2 minutes. Mean follow‐up was 16 ± 4 months with a 48‐hour ambulatory monitor every 2 months. Results: There were no recurrences of AFL in either group. Six patients in group B (22%) underwent a stepwise ablation protocol. AF organized and terminated in 5 patients during ablation (83%). Complication rate was not significantly different among the groups. Twenty patients in group B (87%) and 11 patients in group A (44%) were free of arrhythmias on no medications at the end of follow‐up (P < 0.05). Conclusions: Ablation of AF at the time of CTI ablation results in a significantly better long‐term freedom from arrhythmias. (J Cardiovasc Electrophysiol, Vol. 22, pp. 34‐38, January 2011)     

Incremental Pacing for the Diagnosis of Complete Cavotricuspid Isthmus Block During Radiofrequency Ablation of Atrial Flutter

Incremental Pacing for the Diagnosis of Cavotricuspid Isthmus Block.   Background: Complete conduction block of the cavotricuspid isthmus (CTI) reduces atrial flutter recurrences after ablation. Incremental rapid pacing may distinguish slow conduction from complete CTI conduction block.
Methods and Results: Fifty-two patients (67 ± 9 years) undergoing 55 CTI ablation procedures were included. With ablation, double potentials (DPs) separated by an isoelectric line of ≥30 ms were obtained. Incremental atrial pacing (600–250 ms) was performed from coronary sinus (CS) and low lateral right atrium (LLRA). A <20 ms increase in the DPs distance during incremental pacing was indexed as complete CTI block. In 8 patients, an initial <20 ms DPs distance increase was noted; direct complete isthmus block was suggested and no additional ablation performed. In the remaining, the CTI line was remapped for conduction gaps and additional radiofrequency energy pulses applied. Complete block, as indexed by incremental pacing, occurred in 46 of 55 procedures, with one flutter recurrence (follow-up 8 ± 2 months): DPs interval variation of 116 ± 20 to 123 ± 20 ms (CS), P = 0.21; and 122 ± 25 to 135 ± 35 ms (LLRA), P = 0.17. The remaining 9 patients (persistent rate-dependent DPs increase) presented 3 flutter recurrences, P = 0.01: DP distance from 127 ± 15 to 161 ± 18 ms (CS), P < 0.001; and 114 ± 24 to 142 ± 10 ms (LLRA), P = 0.007.
Conclusion: Incremental pacing distinguishes complete CTI block from persistent conduction. Such identification, accompanied by additional ablation to achieve block, should minimize flutter recurrences after ablative therapy. (J Cardiovasc Electrophysiol, Vol. 21, pp. 33–39, January 2010)     

Early versus Late Atrial Fibrillation after Atrial Flutter Ablation

Introduction: Radiofrequency catheter ablation of atrial flutter (AFl) has high initial success with a 10–15% recurrence. Atrial fibrillation (AFib) after radiofrequency catheter ablation of AFl can occur but may be transient (lasting no more than four weeks). Methods: Of one hundred seventeen consecutive patients studied, one hundred and four consecutive patients with sustained, symptomatic AFl, as the predominant rhythm disturbance (some of whom had transient pre-ablation AFib), referred for radiofrequency catheter ablation, had clinical follow-up. All had evidence for successful AFl ablation. Patients were followed prospectively. Results: Over a mean follow-up of 28 months, 28 patients developed AFib after ablation of AFl [12 early AFib (<2 months) and 16 late AFib (>2 months)]. Seven of 12 (58%) patients in the early onset group reverted to normal sinus rhythm; none required long-term antiarrhythmic therapy. Only one (8%) developed permanent AFib. No patient in the late onset group remained in sinus rhythm without an antiarrhythmic drug. Three (19%) developed permanent AFib despite therapy among those with late onset AFib. Two (17%) patients with early onset AFib reverted to normal sinus rhythm with treatment versus 5 (31%) in the late onset group. Finally, only 2 patients (17%) with paroxysmal/persistent episodes of Afib from the early onset group stayed in normal sinus rhythm despite therapy, while 8 patients ( ± %) with paroxysmal/persistent AFib episodes from the late onset group required therapy to maintain normal sinus rhythm. Conclusion: Early onset AFib after ablation of AFl is likely to be transient and self-limited. Late onset AFib after ablation of AFl can persist and require chronic therapy.     

Randomized Comparison of Multipolar,Duty‐Cycled,Bipolar‐Unipolar Radiofrequency Versus Conventional Catheter Ablation for Treatment of Common Atrial Flutter

Comparison of Radiofrequency Versus Conventional Catheter Ablation. Introduction: Radiofrequency (RF) catheter ablation has been established as an effective and curative treatment for atrial flutter (AFL). Approved methods include a drag‐and‐drop method, as well as a point‐by‐point ablation technique. The aim of this study was to compare the acute efficacy and procedural efficiency of a multipolar linear ablation catheter with simultaneous energy delivery to multiple catheter electrodes against conventional RF for treatment of AFL. Methods: Patients presenting to our department with symptomatic, typical AFL were enrolled consecutively and randomized to conventional RF ablation with an 8‐mm tip catheter (ConvRF) or a duty‐cycled, bipolar‐unipolar RF generator delivering power to a hexapolar tip‐versatile ablation catheter (T‐VAC) group. For both groups, the procedural endpoint was bidirectional cavotricuspid isthmus block. Results: Sixty patients were enrolled, 30 patients each assigned to ConvRF and T‐VAC groups. Total procedure time (40.2 ± 15.8 min vs 60.5 ± 12.7 min), energy delivery time (8.5 ± 3.7 min vs 14.7 ± 5.2 min), radiation dose (14.5 ± 3.5 cGy/cm² vs 31.7 ± 12.1 cGy/cm²), and the minimum number of RF applications needed to achieve block (4.2 ± 2.4 vs 8.9 ± 7.2) were significantly lower in the T‐VAC group. In 7 patients treated with the T‐VAC catheter, bidirectional block was achieved with less than 3 RF applications, versus no patients with conventional RF energy delivery. Conclusion: The treatment of typical AFL using a hexapolar catheter with a multipolar, duty‐cycled, bipolar‐unipolar RF generator offers comparable effectiveness relative to conventional RF while providing improved procedural efficiency. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1109‐1113)     

Right Coronary Artery Occlusion During RF Ablation of Typical Atrial Flutter

RCA Occlusion During RF Ablation . Right coronary artery (RCA) occlusion and acute myocardial infarction are rare during radiofrequency (RF) ablation of the cavotricuspid isthmus. Ventricular fibrillation (VF) or cardiac arrest in the periprocedural period may be the initial or only clinical manifestation. Septal or lateral RF delivery may increase the risk. We report 2 cases of RCA occlusion during ablation of typical atrial flutter (AFL). Angiographic and anatomical correlations are illustrated. One patient was ablated with a septal approach, the other with a lateral approach, and in each instance the RCA occluded near the ablative lesions. If septal or lateral ablation lines are contemplated during ablation of isthmus‐dependent atrial flutter, fluoroscopic or electroanatomic confirmation of catheter position is pivotal. Smaller tipped catheters, energy titration (to minimally effective dose), saline irrigation, or cryoablation should also be considered to help avoid this serious complication. (J Cardiovasc Electrophysiol, Vol. pp. 818‐821, July 2010)     

Identification of Extremely Slow Conduction in the Cavotricuspid Isthmus During Common Atrial Flutter Ablation

Introduction: Complete isthmus block has been used as an endpoint for radiofrequency ablation for common atrial flutter (AF). We sought to systematically evaluate extremely slow conduction (ESC), which is easily misinterpreted as complete block. Methods and Results: We studied 107 consecutive patients (92 men, 15 women, 58 ± 11 years) who had undergone a successful AF ablation procedure. A 24-pole catheter was positioned along the tricuspid annulus spanning the isthmus. Complete isthmus block was defined as the presence of a complete corridor of double potentials along the ablation line. Activation delay time (AT), activation difference (A) between two adjacent dipoles, maximum activation difference (A _max), change in polarity (CP) and change in amplitude (CA) of the bipolar atrial electrogram were recorded and P-wave morphology in the surface electrocardiogram was analyzed. ESC was observed in 16 patients. Between ESC and complete block, differences were found on the two lateral dipoles adjacent to the ablation line (AT: 148 ± 17 vs. 183 ± 27 ms and 155 ± 18 vs. 170 ± 28 ms, P < 0.01; A: –91 ± 22 vs. –126 ± 28 ms and –7 ± 13 vs. 13 ± 6 ms, P < 0.01). Statistically significant differences in CP were detected on the relevant dipoles (7/16 vs. 14/16 and 6/16 vs.13/16, P < 0.05). No significant difference was found either in CA or in terminal P wave positivity. Mean A _max were 13.8 ± 5.0 and 27.8 ± 9.5 ms (P < 0.001) respectively in ESC and complete block. Two types of ESC, regular and irregular, were demonstrated during the ablation procedure. Conclusions: (1) ESC was observed in 15% of the patients during the AF ablation procedure. (2) The parameters of AT, A, and CP may help to differentiate ESC from complete block. A _max might be the most powerful indicator. (3) To verify complete block, it is essential to position the mapping catheter across the CTI in order to demonstrate the activation sequence up to the ablation line.     

Radiofrequency Ablation of Atrial Flutter

RF Ablation of Atrial Flutter. Activation mapping in common atrial flutter has shown circular (reentrant) activation of the right atrium around anatomic structures and areas of functional block. The direction of rotation is counterclockwise (in a frontal view), and in the low right atrium the myocardium between the inferior vena cava (IVC) and the tricuspid valve (TV) is critical to close the activation circle. The circuit can be interrupted by radiofrequency ablation of the myocardium between the TV and the IVC, and, in some cases, by ablation between the coronary sinus and TV. Flutter interruption does not mean complete isthmus ablation, as it may remain inducible, requiring further ablation. Despite attaining noninducibility, flutter may recur, and new procedures may be needed for complete ablation. Atrial fibrillation occurs in up to 30% of the cases during follow-up but is generally well controlled with antiarrhythmic drugs that were ineffective in treating flutter before ablation. Some noncommon atrial flutters show circular right atrial activation in a reversed (clockwise) direction, with the same critical areas in the low right atrium, and in these isthmus ablation is effective. Other noncommon flutters have different substrates in the right or left atrium, and mapping has to define specific critical isthmuses as ablation targets in each case. Left atrial flutter circuits remain inaccessible to ablation.     

Spontaneous Transition from Atrial Fibrillation to Typical Atrial Flutter during Catheter Ablation of the Pulmonary Vein

A 71-year-old male patient was admitted for catheter ablation of the pulmonary veins to treat paroxysmal atrial fibrillation. Atrial fibrillation originating from the left superior pulmonary vein was induced after a pause of atrial pacing under isoproterenol infusion and became sustained. Spontaneous transition from atrial fibrillation to typical atrial flutter was noted after complete isolation of the pulmonary vein focus from the left atrium. Subsequently linear ablation of the cavotricuspid isthmus was created with completely bi-directional isthmus conduction block. We hypothesized that ectopic pulmonary vein focus played an important role in the spontaneous conversion of atrial fibrillation to typical atrial flutter, and complete isolation of the pulmonary vein could stop the spontaneous transition between the two atrial tachyarrhythmias.     

Percutaneous Microwave Ablation with a Long Side-Firing Antenna Array Can Successfully Treat a Nonsurgical Chronic Ovine Atrial Flutter Model

Introduction: Long side-firing microwave (MW) arrays can deliver energy uniformly over its length without the need for intimate endocardial contact. We hypothesize that a novel 6 Fr 20 mm long percutaneous high-efficiency MW antenna array ablation catheter can rapidly create long, continuous, and transmural linear ablation lesions.
Methods and Results: Cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) was created in 11 sheep by a line of radiofrequency ablation lesions in the posterior right atrium (RA) linking the venae cavae. After 4–6 weeks recovery, CTI-dependent AFL was still inducible in all 11 sheep (cycle length 178 ± 13 ms). MW ablation of the CTI at 100 W for 30 seconds was then performed with an endpoint of AFL noninducibility. AFL was not inducible in all 11 sheep after 4.3 ± 3.3 MW applications (129 ± 99 seconds). The last 6 animals needed fewer ablations (2.2 ± 1.5) and 3 of these sheep required only a single ablation. Although conduction times from proximal coronary sinus to lateral RA and vice versa increased postablation (51 ± 14 ms to 118 ± 31 ms [P = 0.0002] and 60 ± 13 ms to 119 ± 28 ms [P = 0.0001], respectively), AFL was still inducible in 2 sheep and further ablation was needed to reach the endpoint.
Conclusions: High-efficiency side-firing MW array ablation can rapidly create long linear and electrically intact lesions in an ovine AFL model. AFL noninducibility may be a more reliable indicator than CTI conduction times of an intact line of ablation in this animal model.     

Long-Term Outcome of Radiofrequency Catheter Ablation for Topical Atrial Flutter: Risk Prediction of Recurrent Arrhythmias

RF Catheter Ablation for Atrial Flutter. Introduction: Little is known about the predictors of recurrent atrial flutter or fibrillation after successful radiofrequency ablation of typical atrial flutter. In addition, there is only limited evidence suggesting that elimination of atrial flutter would modify the natural history of atrial fibrillation in patients who experienced both of these arrhythmias. The aims of the present study were to investigate the long-term results of radiofrequency catheter ablation and to examine the predictors for late occurrence of atrial fibrillation in a large population with typical atrial flutter. Methods and Results: The study population consisted of 144 patients (mean age 56 ± 18 years) with successful ablation of clinically documented typical atrial flutter. In the first 50 patients, successful ablation was defined as termination and noninducibility of atrial flutter; for the subsequent 94 patients, successful ablation was defined as achievement of bidirectional isthmus conduction block and no induction of atrial flutter. The clinical and echocardiographic variables were analyzed in relation to the late occurrence of atrial flutter or fibrillation. Over the follow-up period of 17 ± 13 months, 14 (9.7%) patients had recurrence of typical atrial flutter. In the first 50 patients, 8 (16%) had recurrence of atrial flutter, compared with only 6 (6%) of the following 94 patients. Patients with incomplete isthmus block had a significantly higher incidence of recurrent atrial flutter than those with complete isthmus block (6/16 vs 0/78, P < 0.0001) in the following 94 patients. There was no predictor for recurrence of atrial flutter after successful ablation as determined by univariate and multivariate analysis. Although successful ablation of atrial flutter eliminated atrial fibrillation in 45% of patients with a prior history of atrial fibrillation, 31 (21.5%) of 144 patients undergoing this procedure developed atrial fibrillation during the follow-up period. Univariate analysis revealed that three clinical variables were related to the occurrence of atrial fibrillation: (1) the presence of structural heart disease; (2) a history of atrial fibrillation before ablation; and (3) inducible sustained atrial fibrillation after ablation. By multivariate analysis, only a history of atrial fibrillation and inducible sustained atrial fibrillation could predict the late development of atrial fibrillation after atrial flutter ablation. Conclusion: Radiofrequency catheter ablation of typical atrial flutter is highly effective and associated with a low recurrence rate of atrial flutter, but atrial fibrillation continues to be a long-term risk for patients undergoing this procedure. The presence of structural heart disease and prior spontaneous or inducible sustained atrial fibrillation increases the risk of developing atrial fibrillation.     

Effects of High-Frequency Atrial Pacing in Atypical Atrial Flutter and Atrial Fibrillation

Atypical atrial flutter has, hitherto, been relatively refractory totermination by rapid atrial pacing. High-frequency pacing (HFP) in theatrium, for termination of atrial flutter or atrial fibrillation (AF), andthe electrophysiologic effects related to it have not been examined. Weexamined the clinical efficacy, safety, and electrophysiologic mechanisms ofHFP using 50-Hz bursts at 10 mA applied at the high right atrium in patientswith atypical atrial flutter (group 1) or AF (group 2), using a prospectiverandomized study protocol. Four burst durations (500, 1000, 2000, and 4000ms) were applied at the high right atrium repetitively in random sequence in22 patients with spontaneous atrial flutter or AF. Local and distant rightand left atrial electrogram recordings were analyzed during and after HFP.HFP resulted in local and distant right and left atrial electrogramacceleration in 8 of 10 patients (80%) in group 1 but caused lessfrequent local atrial electrogram acceleration (6 of 12 patients) and nodistant atrial electrogram effects in group 2 (p < .05 versus group 1).The HFP protocol was effective in arrhythmia termination in 6 of 10patients in group 1 but in no patient in group 2 (p < .05 versus group1). Standard HFP protocol applied at the high right atrium can frequentlyalter atrial activation in both atria and can terminate atypical atrialflutter. Efficacy in AF is limited, probably due to limitedelectrophysiologic actions beyond the local pacing site.     

Organized Left Atrial Tachyarrhythmia During Stepwise Linear Ablation for Atrial Fibrillation

Introduction: This study attempted to delineate the mechanism of organized left atrial tachyarrhythmia (AT) during stepwise linear ablation for atrial fibrillation (AF) using noncontact mapping.
Methods and Results: Eighty patients in whom organized ATs developed or induced during stepwise linear ablation for AF were enrolled. Left atrial (LA) activation during ATs was mapped using noncontact mapping. Radiofrequency (RF) energy was delivered to the earliest activation site or narrowest part of the reentrant circuit of ATs. A total of 146 ATs were mapped. Four ATs were characterized as a focal mechanism (cycle length (CL): 225 ± 49 ms). A macroreentrant mechanism was confirmed in the remaining 142 ATs. LA activation time accounted for 100% of CL (205 ± 37 ms). All 142 ATs used the conduction gaps in the basic figure-7 lesion line. There were three types of circuits classified based on the gap location. Type I (n = 68) used gaps at the ridge between left atrial appendage (LAA) and left superior pulmonary vein (LSPV). Type II (n = 50) used gaps on the LA roof. Type III (n = 24) passed through gaps in the mitral isthmus. Ablation at these gaps eliminated 130 ATs. During the follow-up period of 16.2 ± 6.7 months, 82.5% of the 80 patients were in sinus rhythm.
Conclusion: The majority of left ATs developed during stepwise linear ablation for AF are macroreentrant through conduction gaps in the figure-7 lesion line, especially at the LAA–LSPV ridge. Noncontact activation mapping can identify these gaps accurately and quickly to target effective catheter ablation.     

Validation of Coronary Sinus Activation Pattern During Left Atrial Appendage Pacing for Beat‐to‐Beat Assessment of Mitral Isthmus Conduction/Block

Assessment of Mitral Isthmus . Introduction: Mitral isthmus (MI) ablation for treatment of perimitral flutter is often performed during atrial fibrillation (AF) ablation but is technically challenging. Traditional assessment of MI conduction by left atrial activation mapping while pacing from either side of the line is time‐consuming, and cannot be performed during ongoing ablation. Analysis of the coronary sinus (CS) activation pattern during left atrial appendage (LAA) pacing has been proposed as a simpler technique for evaluating MI conduction, enabling beat‐to‐beat assessment of conduction during ablation procedures and prompt identification of conduction block. Methods: MI conduction was evaluated in 40 patients undergoing MI ablation using both: ((i) endocardial activation mapping and other standard techniques, and (ii) CS activation pattern during LAA pacing (change from distal‐to‐proximal activation to proximal‐to‐distal taken to signify the onset of MI block) Results: CS activation sequence was used to assess conduction in 39 of 40 patients (unable to advance CS catheter distally in one case). MI block was achieved in 36 of 39 cases. The mean MI conduction time (LAA to distal CS) was 92.9 ± 25.9 ms prior to ablation and 178.4 ± 59.9 ms after MI block was confirmed. The mean step‐out in conduction time at point of block was 80.8 ± 40.6 ms. In all individuals in whom CS activation indicated block, there was concordance with endocardial activation, differential pacing and, where detectable, presence of widely split double potentials. CS lesions were required to achieve block in 24 of 36 (67%) successful cases. Radiofrequency application time and procedure time to achieve MI block were 10.8 ± 6.0 minutes and 21.1 ± 15.3 minutes, respectively. (J Cardiovasc Electrophysiol, Vol. 21, pp. 418–422, April 2010)     

Nonpharmacologic Approaches to the Treatment of Atrial Fibrillation and Atrial Flutter

Nonpharmacologic Approaches to Atrial Fibrillation and Flutter. The high prevalence of atrial fibrillation, the associated morbidity and mortality, the absence of safe and effective drug therapy, and an increased understanding of the pathophysiologic basis of atrial fibrillation and flutter have collectively led to the development of novel nonpharmacologic treatments for the management of these arrhythmias, including the CORRIDOR and MAZE surgical procedures, catheter-based ablation and modification of AV conduction, catheter-based ablation of atrial flutter and fibrillation, and internal atrial defibrillation. These surgical and catheter-based techniques offer potentially curative therapy while sparing the long-term risks of antiarrhythmic drug therapy. For patients with typical atrial flutter, catheter ablation affords cure rates in excess of 70%. As technological innovations further facilitate identification and ablation of the critical isthmus in the floor of the right atrium, success rates should improve substantially. For patients with atrial fibrillation, AV junction ablation with implantation of a rate-responsive ventricular pacemaker should be considered palliative therapy, as should modification of AV junction conduction. The MAZE procedure offers very high cure rates, but because it currently involves open heart surgery, patient selection is critical. Catheter-based procedures emulating aspects of the MAZE procedure may one day offer cure rates comparable to those of the surgery itself, but additional research and technological development are necessary to further define and refine the minimal effective procedure, and then to facilitate the placement of contiguous, full-thickness lesions in precise three-dimensional configurations. In the interim, the implantable automatic atrial defibrillator may offer a means for rapidly restoring sinus rhythm without the risks of long-term antiarrhythmic drug therapy.     

Further Evidence for the “Muscle Bundle” Hypothesis of Cavotricuspid Isthmus Conduction: Physiological Proof,with Clinical Implications for Ablation

Two Line Flutter Ablation . Introduction: It has been suggested that the cavotricuspid isthmus (CTI) is composed of discrete muscle bundles with preferred paths of conduction. An ablation technique targeting high‐voltage local electrograms (maximum voltage guided or MVG technique) has been described with the aim of preferentially targeting the muscle bundles. We hypothesized that the MVG technique could provide isthmus block even if the high voltage targets were clearly separated on different ablation lines. In contrast, conduction over a continuous sheet of muscle would require a single continuous ablation line. Methods: Twenty‐two consecutive patients (mean age 65 ± 11.7, 5 females) underwent ablation using the MVG technique on 2 noncontiguous lines in the CTI. Ablation lesions were first applied at the septal aspect of the CTI, targeting only the ventricular (anterior) aspect of the annulus. A line distinctly lateral and noncontiguous to the first was then chosen to target high voltage potentials on the atrial (posterior) aspect of the CTI. Results: Complete CTI block was achieved in all study patients without complication. A mean of 7.8 ± 3.7 ablation lesions were required. Mean ablation time was 401.0 ± 414.5 seconds. Conclusion: Two nonoverlapping incomplete lines of ablation in the CTI consistently lead to bidirectional conduction block. This further supports the hypothesis that conduction over the CTI occurs over discrete muscle bundles. These bundles can be targeted individually for ablation without the need to ablate a continuous line over the CTI. (J Cardiovasc Electrophysiol, Vol. 24, pp. 47‐52, January 2013)     

Structural and Functional Inverse Cardiac Remodeling After Cavotricuspid Isthmus Ablation in Patients With Typical Atrial Flutter

Introduction and objectives

The purpose of the present study is to determine the structural and functional cardiac changes that occur in patients at 1-year follow-up after ablation of typical atrial flutter.

Methods

We enrolled 95 consecutive patients referred for cavotricuspid isthmus ablation. Echocardiography was performed at ≤6 h post-procedure and 1-year follow-up.

Results

Of 95 patients initially included, 89 completed 1-year follow-up. Hypertensive cardiopathy was the most frequently associated condition (39%); 24% of patients presented low baseline left ventricular systolic dysfunction. We observed a significant reduction in right and left atrial areas, end-diastolic and end-systolic left ventricular diameters, and interventricular septum. We observed substantial improvement in right atrium contraction fraction and left ventricular ejection fraction, and a reduction in pulmonary hypertension. Changes in diastolic dysfunction pattern were observed: 60% of patients progressed from baseline grade III to grade I; at 1-year follow-up, this improvement was found in 81%. We found no structural differences between paroxysmal and persistent atrial flutter at baseline and 1-year follow-up, exception for basal diastolic function.

Conclusions

In patients with typical atrial flutter undergoing cavotricuspid isthmus catheter ablation, we found inverse structural and functional cardiac remodeling at 1-year follow-up with much improved left ventricular ejection fraction, right atrium contraction fraction, and diastolic dysfunction pattern.     

三尖瓣峡部消融对心房颤动导管消融术后复发的影响

目的:评估三尖瓣峡部消融对伴有典型心房扑动(房扑)和不伴典型房扑发作的心房颤动(房颤)患者术后复发的影响.方法:连续入选房颤射频消融治疗患者113例,根据有无典型房扑分为三尖瓣峡部消融组(CTI组)和未行三尖瓣峡部消融组(Non-CTI组),比较临床特征及手术特点,并随访术后典型房扑和房颤发生率.结果:Non-CTI组左房内径更大,持续性和永久性房颤的比例、左房线性消融的比例更高.而CTI组射频消融时间较Non-CTI组更长.术后典型房扑和房颤发生率2组无显著区别.结论:无典型房扑发作的房颤患者,不行三尖瓣峡部消融,不会升高术后典型房扑发生率和房颤复发率,同时射频消融时间缩短.     

Catheter Ablation of Atrial Tachycardia Following Atrial Fibrillation Ablation

Atrial tachycardias represent the second front of atrial fibrillation (AF) ablation. They are frequently encountered during the index ablation for patients with persistent AF and are common following ablation of persistent AF, occurring in half of all patients who have had AF successfully terminated. An atrial tachycardia is rightly seen as a failure of AF ablation, as these tachycardias are poorly tolerated by patients. This article describes a simple, practical approach to diagnosis and ablation of these atrial tachycardias.     

Right Atrial Mapping and Linear Ablation for Paroxysmal Atrial Fibrillation

Objective: Catheter ablation techniques to cure atrial fibrillation (AF) are under investigation. This study evaluates a mapping-based, individualized approach to right atrial (RA) linear ablation in patients with paroxysmal AF. Methods: In this prospective observational study, 29 patients with recurrent symptomatic AF refractory to medical therapy, underwent linear ablation between May 1998 and December 1999. Inclusion criteria were symptomatic paroxysmal AF, failure of at least 2 antiarrhythmic medications, and informed consent. Radiofrequency ablation was performed in the RA using a 3.3 French multielectrode catheter, ablating through sequential electrodes to establish linear lesions. Lesions were delivered during sustained AF, guided by an empiric mapping scheme, targeting arrhythmogenic areas noted during electrophysiologic testing in sinus rhythm and areas of most disorganization during AF. Reinduction of AF was attempted at the end of successful ablation. Results: The mean age was 58 years. There were 15 male and 14 female patients. Sustained AF was inducible in all patients at electrophysiology study. Acute success was achieved in 24 patients (83%). Long term success (maintaining sinus rhythm off antiarrhythmic medications) was seen in 23 (79%) over a mean follow-up of 19.7 months. Ablation lines varied from patient to patient. There were no complications. Conclusions: Individualized linear ablation in the RA using a multielectrode catheter system can produce effective suppression of paroxysmal AF. Ablation during AF, and testing to reinduce AF at the end of the procedure, make this study unique.