Treatment Of Common Atrial Flutter Research Articles

Usefulness of the Noncontact Mapping System to Elucidate the Conduction Property for the Treatment of Common Atrial Flutter

The functional role of the cavotricuspid isthmus (CTI) for common atrial flutter (cAFL) remains to be elucidated. In the present study, we examined whether the EnSite system (St. Jude Medical, St. Paul, MN, USA), a noncontact mapping system, is useful to evaluate the conduction properties of CTI to minimize radiofrequency (RF) ablation applications for cAFL. We enrolled 22 consecutive patients with cAFL (64.1 ± 9.5 years old, M/F 21/1) treated with the EnSite system and examined the conduction properties during cAFL and during atrial pacing. In addition, the effectiveness of the system was evaluated in comparison with the conventional ablation group (67 ± 8.9 years old, n = 15, M/F 13/2). In 11 out of the 22 patients, CTI block line was achieved by fewer RF applications on a presumed single activation pathway which the EnSite system showed (point ablation [PA] group), and the remaining 11 patients needed additional linear ablation (additional ablation [AA] group). The number of RF applications in the PA group was significantly smaller than that in the conventional group. During the lower lateral right atrial pacing at a cycle length of 600 ms, the CV of the CTI in the PA group was smaller compared to that in the AA group (1.36 ± 0.61 vs 2.17 ± 0.66 m/s, P < 0.05), although the CV during cAFL (averaged cycle length 245 ± 34 ms) was not different in both groups. These results indicate that targeting the presumed single line identified by EnSite could be an optional therapy for cAFL RF ablation, and diverse conduction properties in CTI are related to the success rate of this procedure. (PACE 2012;35:1464-1471).

Comparison of a 6.5, 10, and 15 mm cryoablation catheter-tip for the treatment of common atrial flutter

Only a few studies have investigated the effect of large tip sizes for catheter-based cryoablation (cryo). This study evaluates the safety and efficacy of cryo of the cavotricuspid isthmus (CTI) using three cryocatheter-tip sizes. Forty-five consecutive patients with common atrial flutter (AFL) underwent cryo of the CTI using a 6.5, a 10, or a novel 15 mm catheter-tip. Single applications of 3 min were delivered at each site along the CTI. Baseline characteristics of the three groups were comparable. The overall acute success rate was 89% and there was no difference with respect to the tip electrode size (P > 0.05). Fewer applications were required for a 10 mm (6 ± 2, range 3-7) and a 15 mm (6 ± 1, range 4-8) compared with a 6.5 mm catheter-tip (8 ± 3, range 4-14; P < 0.05). Procedure time was significantly shorter with the largest tip electrode (89 ± 26 min vs. 132 ± 28 min (6.5 mm tip), P < 0.05). No complications occurred. After a mean follow-up of 51 ± 5 months, 43 patients (96%) were without recurrence of AFL. A large (10 or 15 mm) cryoablation catheter-tip requires significantly fewer applications to create bidirectional CTI block compared with a 6.5 mm tip. A significant decrease in procedure time with preservation of the overall safety and efficacy supports the preference of a 15 over a 6.5 mm catheter-tip for cryoablation of AFL.

Cavotricuspid Isthmus Catheter Ablation Without the Use of Fluoroscopy as a First-Line Treatment

The use of intracardiac navigation systems has enabled a significant reduction of the radiation dose in the majority of ablation procedures. The purpose of this study is to evaluate the feasibility and safety of cavotricuspid isthmus ablation without the use of fluoroscopy as a first-line treatment. An observational study without a control group in patients referred for treatment of common atrial flutter. In all of the procedures, Ensite-NavX™ was the only guidance system used to visualize the catheters. One or two diagnostic catheters and a cooled-tip ablation catheter were used in each procedure. Bidirectional cavotricuspid isthmus block was considered to indicate a successful procedure. Eighty-three ablation procedures were performed in 80 patients (82.5% men, 61 ± 10 years of age). The procedure was repeated in 3 patients (3.75%) due to flutter recurrence. Success was obtained in 98.8% of the procedures; in 1 patient it was necessary to implant a pacemaker for sinus node dysfunction and 4 patients experienced minor complications. In 75 procedures (90.4%), fluoroscopy was not required. Visualization of the diagnostic catheters was the most common reason for using fluoroscopy. The time required to perform the ablation procedure was similar to that published in other series. Cavotricuspid isthmus ablation using a nonfluoroscopic three-dimensional (3D) navigation system is effective and safe.

Relation entre l’anatomie de l’isthme cavo-tricuspide étudiée par échocardiographie trans-œsophagienne et les résultats immédiats de l’ablation par radiofréquence du flutter auriculaire commun

Radiofrequency ablation is the only curative treatment of common atrial flutter. The aim of the treatment is to create a line of bidirectional block at the level of the cavo-tricuspid isthmus. This objective can be achieved in the vast majority of the patients. However, it may difficult or even not possible to create an isthmus block. The anatomy of the right atrium is subject to important variations, especially at the isthmus level. We therefore tested the hypothesis that these anatomic variations might influence the immediate outcome of cavo-tricuspid isthmus ablation. The anatomy of cavo-tricuspid isthmus was studied by trans-oesophageal echocardiography. The shape of the isthmus (concave or not), the presence of diverticula and the degree of development of the Eustachian ridge were analysed. From these data, the cavo-tricuspid anatomy was classified as simple or complex. The immediate outcome of radiofrequency ablation was reviewed in 94 patients (mean age of 63 years) according to the anatomy, simple or complex. When the anatomy was classified as simple, the success rate of radiofrequency ablation was 95.6%; when the anatomy was complex, the success rate was 76.9% (overall success rate for the entire population equal to 90.4%). The length of the cavo-tricuspid isthmus did not influence the outcome of radiofrequency ablation. In summary, it appears that the anatomy of cavo-tricuspid isthmus seems to play a role in the immediate outcome of radiofrequency ablation of cavo-tricuspid isthmus.

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

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. 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. 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. 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.

Prospective randomized comparison of durability of bidirectional conduction block in the cavotricuspid isthmus in patients after ablation of common atrial flutter using cryothermy and radiofrequency energy: The CRYOTIP study

Recent studies have shown that cryoablation and radiofrequency (RF) ablation are comparable with regard to success rates and safety in the treatment of common atrial flutter (AFL). Long-term success requires persistence of bidirectional conduction block (BCB) in the inferior cavotricuspid isthmus (CTI). The purpose of this study was to determine the persistence of BCB in a prospective randomized multicenter trial of the two ablation techniques. A total of 191 patients were randomized to RF ablation or cryoablation of the CTI using an 8-mm-tip catheter. In all patients, BCB was defined as the ablation end-point. Primary end-point of the study was nonpersistence of achieved BCB and/or ECG-documented relapse of common AFL within 3-month follow-up. Acute success rates were 91% (83/91) in the RF group and 89% (80/90) in the cryoablation group (P = NS). Invasive follow-up after 3 months with repeated electrophysiologic study was available for 60 patients in the RF group and 64 patients in the cryoablation group. Persistent BCB could be confirmed in 85% of the RF group versus 65.6% of the cryoablation group. The primary end-point was achieved in 15% of the RF group and 34.4% of the cryoablation group (P = .014). As a secondary end-point, pain perception during ablation was significant lower in the cryoablation group (P <.001). Persistence of BCB in patients treated with cryoablation reinvestigated after 3 months is inferior to that patients treated with RF ablation, as evidenced by the higher recurrence rate of common AFL seen in this study.

Long term outcome of cavotricuspid isthmus cryoablation for the treatment of common atrial flutter in 180 patients: A single center experience

ObjectiveRecent literature has shown that common type atrial flutter (AFL) can recur late after cavotricuspid isthmus (CTI) catheter ablation using radiofrequency energy (RF). We report the long term outcome of a large group of patients undergoing CTI ablation using cryothermy for AFL in a single center.MethodsPatients with AFL referred for CTI ablation were recruited prospectively from July 2001 to July 2006. Cryoablation was performed using a deflectable, 10.5 F, 6.5 mm tip catheter. CTI block was reassessed 30 min after the last application during isoproterenol infusion. Recurrences were evaluated by 12-lead ECG and 24 h Holter recording every clinic visit (1/3/6/9 and 12 months after the procedure and yearly thereafter) or if symptoms developed.ResultsThe 180 enrolled patients had the following characteristics: 39 women (22%), mean age 58 years, no structural heart disease in 86 patients (48%), mean left atrium diameter 44 ± 7 mm and mean left ventricular ejection fraction 57 ± 7%. The average number of applications per patient was 7 (3 to 20) with a mean temperature and duration of −88°C and 3 min, respectively. Acute success was achieved in 95% (171) of the patients. There were no complications. After a mean follow-up of 27 ± 17 (from 12 to 60) months, the chronic success rate was 91%. The majority of the recurrences occurred within the first year post ablation. One hundred and twenty three patients had a history of atrial fibrillation (AF) prior to CTI ablation and 85 (69%) of those remained having AF after cryoablation. In 20 of 57 (35%) patients without a history of AF prior to CTI ablation, AF occurred during follow-up.ConclusionsThis prospective study showed a 91% chronic success rate (range 12 to 60 months) for cryoablation of the CTI in patients with common type AFL and ratified the frequent association of AF with AFL.

Low clinical recurrence and procedure benefits following treatment of common atrial flutter by electrogram-guided hot spot focal cryoablation

The study sought to evaluate whether electrogram-aided identification of hot spot targets produces additional clinical and/or procedure benefits when using a non-traditional focal cryo ablation method to treat common atrial flutter. A preliminary study identified a specific electrogram criterion (e.g., a stimulus to onset of electrogram time of 74 [+/- 5] ms) that produced successful cryo testing plus subsequent cryoablation with demonstrable bi-directional isthmus block created at intervention site. In the present study, 26 consecutive patients with symptomatic common atrial flutter were ablated with a 9FR 8 mm tip cryo catheter using electrogram-aided identification of hot spot targets with a stimulus to onset of electrogram time of > or =70 ms. Outcomes measured were bi-directional isthmus block at intervention, symptom and conduction recurrence at 3 month follow-up, symptom recurrence at 6 month follow-up, and procedure characteristics. Acute success rate at intervention was 100%. The percentage of patients with symptom recurrence by 3 month follow-up was 4.5% and no additional patients had arrhythmia symptoms documented by 12 month follow-up. Repeat electrophysiological study (EPS) at 3 month follow-up identified 44% of patients with conduction recurrence. The mean +/- SD number of cryo tests and ablations were 11 +/- 9 and 2 +/- 1, respectively. Procedure, fluoroscopy and cryoapplication times were 77 +/- 29 min, 11 +/- 7 min, and 28 +/- 11 min, respectively. A high acute success rate, plus low long-term clinical recurrence rate and procedure benefits may be achieved with electrogram-aided identification of hot spots for focal cryo ablation treatment of common atrial flutter using a 9FR 8 mm tip cryo catheter. The population of patients who were asymptomatic and had demonstrated conduction recurrence on repeat EPS at 3 month follow-up require close scrutiny over the long-term to ascertain whether they eventually experience arrhythmic symptoms. However, should these patients remain symptom-free over the long-term it would suggest that the entire isthmus may not be needed to support symptomatic common atrial flutter.

Acute Success and Persistence of Bidirectional Conduction Block in the Cavotricuspid Isthmus One Month Post Cryocatheter Ablation of Common Atrial Flutter

Cryoablation is successful in the treatment of common atrial flutter. Long-term clinical success is mainly dependent on persistence of bidirectional conduction block (BCB) in the inferior cavotricuspid isthmus (CTI). Only few data on persistence of BCB post cryoablation with the reported technique are available. This prospective study aimed to test efficacy of cryo energy and persistence of BCB in the CTI 1 month post cryoablation. Cryoablation of the CTI was performed in 50 consecutive patients (64 +/- 12 years, 40 males) with symptomatic common atrial flutter using a novel 9 Fr 8-mm-tip catheter. BCB in the CTI 30 minutes following the final cryoapplication was the ablation endpoint. Thirty days post ablation, persistence of BCB was controlled by repeat electrophysiological study (EPS). In all patients BCB was achieved with a mean of 9 (IQR 7-17.5) cryo applications and a mean cryo time of 2,378 seconds (IQR 1,680-3,474 seconds). In 5 of 50 patients, common atrial flutter recurred within 1 month post cryoablation. In 30 of 32 recurrence-free patients, persistence of BCB was verified. In 2 patients, resumption of isthmus conduction was detectable. Including relapses, 81.1% of patients (30/37) showed persistence of BCB. No patients reported pain during cryoapplication. No procedural complications were observed. Cryoablation of the CTI using a large-tip catheter is feasible and safe in the treatment of common atrial flutter. Acute and short-term success rates are comparable to those reported for radiofrequency (RF) ablation. Besides short-term clinical success, the persistence of BCB demonstrates efficacy of the cryoablation technique.

Comparison Between a 7 French 6 MM Tip Cryothermal Catheter and a 9 French 8 MM Tip Cryothermal Catheter for Cryoablation Treatment of Common Atrial Flutter

Larger tipped cryothermal catheters may deliver efficacy and procedure benefits in the treatment of patients with atrial flutter. To compare 7 French 6 mm and 9 French 8 mm tip cryothermal catheters (Freezor, Xtra or Freezor, MAX, CryoCath Technologies Inc., Kirkland, Canada) in terms of acute and chronic efficacy, and procedure characteristics in the treatment of atrial flutter. This non-randomized clinical investigation determined bi-directional isthmus block at intervention, procedure characteristics, and symptom and conduction recurrence rates post procedure in consecutive patients with symptomatic atrial flutter ablated either with the 7 French 6 mm tip cryothermal catheter (n = 43) at -75 degrees C for 4 minutes or the 9 French 8 mm tip cryothermal catheter (n = 51) at -75 degrees C for 8 minutes. Clinical data showed a higher acute success rate for the larger tipped catheter (100% vs. 88%). Symptom recurrence rates were 0% for both catheters at 3, 6, and 9 month follow-up. Conduction recurrence rates were similar for both catheters on repeat electrophysiological study at 3 months post procedure (35% vs. 32%). Procedure benefits were fewer cryotests (20 +/- 17 vs. 26 +/- 21) and ablations (4 +/- 4 vs. 12 +/- 18), and shorter procedure (80 +/- 61 min vs. 87 +/- 48 min), fluoroscopy (14 +/- 9 min vs. 24 +/- 10 min), and cryoapplication times (37 +/- 18 min vs. 44 +/- 23 min) with the larger tipped catheter. There were no adverse events reported. Clinical results showed differences in catheter performance that favoured the larger tipped catheter. However, increased acute success rate did not translate into reduced conduction recurrence rate post ablation, although clinical recurrence was completely absent long-term.

Influence of pacing on the left ventricular electrogram in patients with ischemic cardiomyopathy: Implications for substrate mapping

a mean procedure time of 122 42 min (range 75-246 min). In 5/50 patients common atrial flutter reoccured within one month after cryoablation. Successful reablation using radiofrequency (RF) energy was performed in all of them. In 30/32 recurrence free patients, who gave final consent to invasive control stimulation, persistency of BCB was verified. In 2 patients recovery of isthmus conduction was detectable. Including the relapses 81.1% of the patients (30/37) showed persistency of BCB. Cryo applications were painless in general. No procedural complications were observed. Conclusions: Cryoablation of the CTI using the large tip catheter is feasible and safe in the treatment of common atrial flutter. Acute and short-term success rates are comparable to those reported for RF ablation. Besides short term clinical success the persistency of BCB one month after cryoablation proves efficacy of cryoablation technique.

Various routes of septal propagation in common atrial flutter.

Although in the treatment of common atrial flutter, the isthmus between the tricuspid valve annulus and the eustachian ridge is often chosen as the site for conduction block by radiofrequency ablation, the precise path of the flutter circuit remains unknown. We therefore investigated the propagation of the atrial flutter wave front around the coronary sinus ostium and how its path is altered by application of radiofrequency current. To assess activation pattern, activation in the region surrounding the coronary sinus ostium was mapped using a deflectable decapolar catheter under basal conditions and while applying radiofrequency current to the septal isthmus, between the tricuspid valve annulus and the eustachian ridge. In five of eleven patients studied, the eustachian ridge side, below the coronary sinus ostium, was activated earlier, and the flutter wave exited from either the tricuspid valve annulus side or the eustachian ridge side, above the coronary sinus ostium. In four patients, a partial line of block created by applying radiofrequency current between the tricuspid valve annulus and the coronary sinus ostium or between the coronary sinus ostium and the eustachian ridge led to a shift in the direction of propagation of the flutter wave front from anterior to posterior or from posterior to anterior of the coronary sinus ostium, and prolongation of the cycle length. Application of radiofrequency current to the septal isthmus, between the tricuspid valve annulus and the eustachian ridge, can shift both the anterior and posterior propagation of flutter around the coronary sinus ostium.

Nonpharmacologic treatment of common atrial flutter guided by transient entrainment.

We attempted nonpharmacologic treatment for common atrial flutter in 7 patients, with direct current catheter ablation (CA) in 5 cases and cryoablation in 2 cases under the guidance of transient entrainment. Transient entrainment during common atrial flutter by pacing from the mid or low lateral right atrium (LLRA) revealed a long conduction time between the LLRA and the orifice of the coronary sinus (CSo) (73% to 121% of flutter cycle length). In 2 cases, fragmented electrograms were recorded at the low right atrial septum with durations of 150 msec and 155 msec, respectively. Because these fragmented electrograms were transiently entrained by rapid atrial pacing in the same manner as other atrial electrograms and were recorded in an area of long conduction, we believe that fragmented electrograms represent critical slow conduction. In 5 cases, CA was directed at this area. Three cases were successfully treated with 3 to 4 DC shocks of 100 J (follow up periods of 11.3, 4.5 and 3 months). Two cases which received 1 to 2 DC shocks of 100 J had recurrence of atrial flutter 6 and 4.7 months later, respectively. Two cases which showed atrial septal defect received surgical treatment. They were successfully treated with extended cryoablation in this same area (follow up periods of 26 and 9.2 months). In conclusion, extended ablation of an area of fragmented electrograms using transient entrainment may be an effective treatment for common atrial flutter.