Ablation Of Isthmus-dependent Atrial Flutter Research Articles

Familial cardiolaminopathy due to a previously undescribed LMNA gene mutation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Cardiolaminopathies are rare genetic alterations, which present diverse mechanical and electrical alterations. OBJECTIVE To present a family carrying an LMNA gene mutation that although not described manifest clinical and electrocardiographic characteristics of the disease. Methods We present the case of two sisters and one brother, aged 65, 57 and 51 years, respectively. At the beginning of their fourth decade, all of them debuted with atrial flutter associated with second and third degree atrioventricular block. Two of them (one or the sisters and the brother) underwent ablation of isthmus-dependent atrial flutter. However, in both, the flutter recurred and no new interventional treatment was further offered. The male subject received a pacemaker implant for treatment of AV block; some years later, he presented a cerebrovascular event and subsequently a recurrence, both while in oral anticoagulation and, actually remains with moderate motor deficit and dysarthria. The youngest woman suffered an embolic cerebrovascular event when she was 50 y/o; she remained asymptomatic in relation to the rhythm disorder and refused a pacemaker. The oldest sister who is asymptomatic, received a pacemaker when she was 45 y/o and now is anticoagulated. By echocardiography, all siblings presented left ejection fraction in between 40 and 50% with decreased strain values and normal left ventricular geometry. Results Recently in our country it is possible to carry out a genetic test, for which the three were subjected to it. In this family, the genetic testing was done using a comercial kit for 172 genes. The result was a Frameshift Indels (non misense) mutation NM_170707.3 c.1526del p.(Pro509LeufsTer39) Exon:9/12, in all three. The caveat is that this LMNA gene mutation has not been previously described. In light of these results, the youngest woman with total AV block and sequelae of cerebrovascular disease and mild left ventricular dysfunction, received an implantable cardiac defibrillator (ICD) implant for primary prevention of sudden death and her siblings are undergoing an upgrade to ICD. Conclusion The mutation found in this family is unique and for the first time reported in the LMNA gene in the world. Genetic diagnosis is limited in our country, which makes it difficult to determine this type of pathology. However, given the clinical presentation of an electrical disorder in all the siblings of a family, in this particular case, it was mandatory to perform this test. These results allow us to better understand the prognosis and intervene appropriately to prevent sudden death, even though there is no treatment to avoid the progression of the disease.

Magnetic resonance imaging-guided conventional catheter ablation of isthmus-dependent atrial flutter using active catheter imaging.

Interventional cardiac magnetic resonance (iCMR) has been established as a radiation-free alternative compared to standard fluoroscopy-guided catheter ablation for cavotricuspid isthmus (CTI)-dependent atrial flutter to image anatomy, structural alterations, and further catheter guidance. The purpose of this study was to explore the safety, feasibility, and efficacy of CTI ablations performed completely in the iCMR suite using active catheter imaging. Consecutive patients underwent iCMR-guided catheter ablation for CTI-dependent atrial flutter. Procedures were performed in a 1.5-T magnetic resonance (MR) imaging unit with MR-conditional ablation catheters. Catheter guidance was achieved using active catheter imaging via integrated MR receive tip coils. Acute success, periprocedural complications, and short-term follow-up were collected for further analysis. All patients (N = 15; 73% male; median age 70 years; interquartile range [67-82]) achieved acute procedural success without any complication. Median procedural time was 43 minutes [33-58] with median radiofrequency delivery time of 18 minutes [12-26]. Postprocedural lesion visualization scanning was completed in a median of 32 minutes [10-42]. None of the patients with 6-month follow-up had atrial flutter recurrence. In the iCMR suite, CTI-dependent atrial flutter ablation could be achieved safely using active catheter imaging without any complication. It further allows detailed anatomic visualization of the CTI, intraprocedural lesion visualization, and exclusion of pericardial effusion.

Acute Success and Long-term Follow-up of Catheter Ablation of Isthmus-dependent Atrial Flutter; A Comparison of 10 mm Tip Standard, 6 mm Tip Irrigated Radiofrequency, and Cryotherapy Catheters

Radiofrequency (RF) ablation of cavotricuspid isthmus (CTI) is an effective treatment for atrial flutter (AFL). This prospective, randomized study aimed to compare cryoablation (CRYO) with 10 mm tip RF catheter ablation (10RF) and 4.0 mm tip RF irrigated catheter ablation (IRRF) regarding the efficacy, safety, and long-term prognosis.

Efficacy and complications of cavo-tricuspid isthmus-dependent atrial flutter ablation in patients with and without structural heart disease: results from the German Ablation Registry.

The impact of structural heart disease (SHD) on safety and efficacy of catheter ablation of cavo-tricuspid isthmus-dependent atrial flutter (AFLU) is unclear. In addition, recent data suggest a higher complication rate of AFLU ablation compared to the more complex atrial fibrillation (AF) ablation procedure. Within our prospective multicenter registry, 3526 consecutive patients underwent AFLU ablation at 49 German electrophysiological centers from 2007 to 2010. For the present analysis, the patients were divided into a group with SHD (n= 2164 [61.4%]; median age 69years; 78.5% male) and a group without SHD (n= 1362 [38.6%]; 65years; 70.3% male). In our study, SHD mainly encompasses coronary artery disease (52.6%), left ventricular ejection fraction ≤ 50% (47.6%), and hypertensive heart disease (28.0%). The primary ablation success (97%) and the incidence of major (0.2%) or moderate (1.2%) complications did not differ significantly between the two groups (P= 1.0 and 0.87, respectively). Vascular access site complications (0.6%), AV block III° (0.2%), and bleeding (≥ BARC II: 0.2%) were most common. After a median 562days of follow-up, we observed a 2.92-fold higher one-year mortality (P< 0.0001) in patients with SHD. Patients' satisfaction with the ablation therapy (72.0% satisfied) was close to the overall subjective tachyarrhythmia-free rate (70.7%). The present analysis demonstrates that ablation of cavo-tricuspid isthmus dependent AFLU in patients with SHD has a comparable, excellent risk-benefit profile in our large "real-world" registry. Mortality rates expectedly are higher in patients with SHD and AFLU compared to patients without SHD. CLINICALTRIALS.GOV: NCT01197638, http://clinicaltrials.gov/ct2/show/NCT01197638.

Significance of fragmented QRS complexes for predicting new-onset atrial fibrillation after cavotricuspid isthmus–dependent atrial flutter ablation

Atrial fibrillation (AF) and cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) are 2 separate entities that coexist in a significant proportion of patients. In patients with CTI ablation of AFL, the decision to hold anticoagulation often becomes an issue. This study aimed to describe the incidence of the development of AF after CTI ablation in patients without a history of AF and to identify the risk predictors of the occurrence of AF. The present study included 120 consecutive patients (106 men; mean age 68 ± 12 years) who underwent radiofrequency catheter ablation (RFCA) of typical AFL since 2010. Patients with a history of AF before RFCA were excluded. The P-wave and QRS morphology, characteristics, and duration were evaluated by 12-lead electrocardiography the day after ablation. During 3.6 ± 2.6 years of follow-up after RFCA, 49 patients (41%) developed new-onset AF. A univariate analysis revealed that the presence of fragmented QRS (fQRS) complexes (hazard ratio [HR], 4.63; 95% confidence interval [CI] 2.31-9.29; P < .001) and advanced interatrial block (IAB), defined as P-wave duration > 120 ms and biphasic morphology in the inferior leads (HR 4.44; 95% CI 2.45-8.01; P < .001), were predictors of new-onset AF. A multivariate analysis revealed that fQRS complexes (HR 3.35; 95% CI 1.58-7.10; P = .002) and advanced IAB (HR 2.64; 95% CI 1.38-5.07; P < .004) were independent predictors. The present study indicated that new-onset AF developed in a significant proportion of patients undergoing AFL ablation. The presence of fQRS complexes and advanced IAB were predictors of new-onset AF.

Atrial Tachyarrhythmias and Atrial Flutter: the Basics of Diagnostics and Modern Opportunities of Therapy

The article is devoted to the description of all types of atrial tachyarrhythmias, including inappropriate sinus tachycardia, which, as a rule, is not paid enough attention in the domestic literature, sinoatrial node reentrant tachycardia, focal and multifocal atrial tachycardia, atrial flutter, and atrial fibrillation. The electrophysiological mechanisms of development and electrocardiographic criteria for the diagnosis of these cardiac rhythm disturbances are presented. Along with this, the article discusses the modern view of the strategy and tactics of pharmacological cardioversion and preventive therapy in patients with the main types of atrial tachyarrhythmias and atrial flutter. It is noted that the prognosis for inappropriate sinus tachycardia, as a rule, is favorable, and therefore, aim of treatment is to reduce the symptoms, and in their absence medical treatment is not necessary. Much attention is paid to drug and interventional treatment of atrial flutter. It is emphasized that catheter ablation of isthmus-dependent atrial flutter in most cases is preferred over long-term pharmacotherapy. However, in prolonged observation (more than 3 years), nearly 1/3 of patients may develop paroxysmal atrial fibrillation. At the same time, catheter ablation of atypical atrial flutter is, in most cases, substantially less effective. The indications and side effects of catheter ablation of the sinus node are also discussed. The authors provide a critical analysis of traditional approaches to the treatment of atrial tachyarrhythmias and analyze new recommendations for the management of these patients presented in Europe and the USA. Based on these recommendations, clear algorithms for the management of patients with atrial tachyarrhythmias are given. The need to prevent thromboembolic complications in some types of atrial tachyarrhythmias is emphasized.

Atrial fibrillation inducibility during cavo-tricuspid isthmus dependent atrial flutter ablation for the prediction of clinical atrial fibrillation

BackgroundAtrial fibrillation (AF) and cavo-tricuspid isthmus (CTI) dependent atrial flutter (AFL) are two separate entities that coexist in a significant percentage of patients. MethodsWe sought to investigate whether AF inducibility during CTI AFL ablation predicted the occurrence of AF at follow up after AFL ablation. Univariate and multivariate analyses were performed. ResultsA total of 154 patients (male: 72%, age: 61±13) with AFL and without history of AF were included. All patients underwent successful CTI dependent AFL ablation demonstrated by bidirectional block. During ablation, AF was seen or induced in 28 (18%) patients. After a mean follow up of 34±24months a total of 50 patients (32%) were noted with clinically manifest AF. From the patients who had inducible AF during AFL ablation, 50% developed post-procedural AF. From those in whom AF could not be induced, only 29% were documented with AF after ablation. Univariate and multivariate analyses revealed that only age and AF inducibility during AFL ablation were predictors of AF. Univariate analysis (age p=0.038 and inducible AF p=0.032 with odds ratio of 1.030 [95% CI (1.002–1.059)] and 2.500 [95% CI (1.084–5.765)], respectively) and multivariate analyses (age p=0.011 and inducible AF p=0.016 with adjusted odds ratio of 1.043 [95% CI (1.010–1.077)] and 3.293 [95% CI (1.250–8.676)], respectively). ConclusionAF inducibility in patients undergoing CTI AFL without history of AF is a strong predictor of AF occurrence in the future. Appropriate cardiology follow-up must be encouraged in this high-risk population as stroke prevention strategies can be appropriately introduced in a timely matter especially in patients with elevated CHA2DS2-VASc scores (≥2).

Predictors of acute inefficacy and the radiofrequency energy time required for cavotricuspid isthmus-dependent atrial flutter ablation.

Although cavotricuspid isthmus-dependent atrial flutter (CTI-AFL) ablation is a highly efficacious treatment, a bidirectional CTI block cannot be achieved in some patients. In this study, we sought to determine the predictors of acute inefficacy of CTI-AFL ablation and the predictors of the radiofrequency (RF) energy time required to achieve a complete bidirectional CTI block. All consecutive patients who underwent stand-alone CTI-AFL ablation in our institution, except patients with congenital heart disease, were included in this retrospective study. Clinical, echocardiographic, and ablation data were collected from the Arrhythmia Unit and Imaging Unit databases and medical charts. Three hundred and fifty-five patients, with a mean age 63 ± 12years, were included. The ablation was acutely inefficacious in 30 patients (9%). Tricuspid regurgitation was the only independent predictor of acute inefficacy of CTI-AFL ablation (OR 3.161, 95% CI 1.084-9.220, p = 0.035) and was associated with a longer RF time required to achieve CTI bidirectional block (p = 0.031). Age was inversely correlated with the RF time required to achieve a bidirectional CTI block (r = -0.133, p = 0.025). A previous CTI RF ablation, chronic obstructive pulmonary disease (COPD), the use of an irrigated catheter, and advanced age were the independent predictors for requiring less RF energy time to achieve a bidirectional CTI block. Tricuspid regurgitation is associated with less acute efficacy in CTI-AFL ablation. Prior CTI ablation, COPD, use of an irrigated catheter, and advanced age are independent predictors for needing less RF energy time to achieve a complete bidirectional CTI block.

Atrial fibrillation inducibility during cavotricuspid isthmus-dependent atrial flutter ablation as a predictor of clinical atrial fibrillation. A meta-analysis.

Atrial fibrillation (AF) and cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) are two separate entities that coexist in a significant percentage of patients. We sought to investigate whether AF inducibility during CTI AFL ablation predicted the occurrence of AF at follow-up after successful AFL ablation. A systemic review of Medline, Cochrane, and Embase was done for all the clinical studies in which assessment of AF inducibility in patients undergoing ablation for CTI AFL was performed. Given the low heterogeneity (i.e., I 2 <25), we used a fixed effect model for our analysis. A total of 10 studies (4 prospective and 6 retrospective) with a total of 1299 patients (male, 73%; mean age 59 ± 11years) fulfilled the inclusion criteria. During a mean follow-up period of 23 ± 7.6months, 407 patients (31%) developed AF during AFL ablation. The overall incidence for new-onset AF during follow-up was 29% (47% in the group with inducible AF vs. 21% in the non-inducible group). The odds ratio (OR) for developing AF after AFL ablation in patients with AF inducibility for all studies combined was 3.72, 95% CI 2.83-4.89 [prospective studies (OR 5.52, 95% CI 3.23-9.41) vs. retrospective studies (OR 3.23, 95% CI 2.35-4.45)]. Although ablation for CTI AFL is highly effective, AF continues to be a long-term risk for individuals undergoing this procedure. AF induced by pacing protocols in patients undergoing CTI AFL predicts for future AF. Inducible AF is a clinically relevant finding that may help guide decisions for long-term anticoagulation after successful typical AFL ablation especially in patients with elevated CHADS-VASc scores (≥2) and in considering prophylactic PVI during CTI AFL ablation.

Impact of previous cardiac surgery on long-term outcome of cavotricuspid isthmus-dependent atrial flutter ablation.

The aim of this study was to determine the acute and long-term outcome of radiofrequency catheter ablation (RFCA) for cavotricuspid isthmus-dependent atrial flutter (CTI-AFL) in adults with and without previous cardiac surgery (PCS), and predictors of these outcomes. Structural alterations of the anatomical substrate of the CTI-AFL are observed in post-operative patients, and these may have an impact on the acute success of the ablation and in the long-term. Clinical records of consecutive adults undergoing RFCA of CTI-AFL were analysed. Two main groups were considered: No PCS and PCS patients, who were further subdivided into acquired heart disease (AHD: ischaemic heart disease and valvular/mixed heart disease) and congenital heart disease [CHD: ostium secundum atrial septal defect (OS-ASD) and complex CHD]. Multivariate analysis identified clinical and procedural factors that predicted acute and long-term outcomes. A total of 666 patients (73% men, age 65 ± 12 years) were included: 307 of them with PCS. Ablation was successful in 647 patients (97%), 96% in the PCS group and 98% in the No PCS group (P = 0.13). Regression analysis showed that surgically corrected complex CHD was related to failure of the procedure [odds ratio 5.6; 95% confidence interval (CI) 1.6-18, P = 0.008]. After a follow-up of 45 ± 15 months, recurrences were observed in 90 patients (14%), more frequently in the PCS group: absolute risk of recurrence 18 vs. 10.5%, relative risk 1.71, 95% CI: 1.2-2.5, P = 0.006. Multivariate analysis indicated that the types of PCS [OS-ASD vs. No PCS: hazard ratio (HR) 2.57; 95% CI: 1.1-6.2, P = 0.03 and complex CHD vs. No PCS: HR 2.75; 95% CI: 1.41-5.48, P = 0.004], female gender (HR 1.55; 95% CI: 1.04-2.4, P = 0.048), and severe LV dysfunction (HR 1.36; 95% CI: 1.06-1.67, P = 0.04) were independent predictors of long-term recurrence. Radiofrequency catheter ablation of CTI-AFL after surgical correction of AHD and CHD is associated with high acute success rates. The severity of the structural alterations of the underlying heart disease and consequently the type of surgical correction correlates with higher risk for recurrence.

Risk and outcome after ablation of isthmus-dependent atrial flutter in elderly patients.

Purpose of the researchTo study the influence of age on the clinical presentation and long-term outcome of patients referred for atrial flutter (AFL) ablation. Age-related differences have been reported regarding the prognosis of arrhythmias.MethodsA total of 1187 patients with a mean age 65±12 years consecutively referred for AFL ablation were retrospectively analyzed in the study.Results445 (37.5%) patients were aged ≥70 (range 70 to 93) among which 345 were aged 70 to 79 years (29.1%) and 100 were aged ≥80 (8.4%). In multivariable analysis, AFL-related rhythmic cardiomyopathy and presentation with 1/1 AFL were less frequent (respectively adjusted OR = 0.44, 0.27–0.74, p = 0.002 and adjusted OR = 0.29, 0.16–0.52, p<0.0001). AFL ablation-related major complications were more frequent in patients ≥70 although remained lower than 10% (7.4% in ≥70 vs. 4.2% in <70, adjusted OR = 1.74, 1.04–2.89, p = 0.03). After 2.1±2.7 years, AFL recurrence was less frequent in patients ≥70 (adjusted OR = 0.54, 0.37–0.80, p = 0.002) whereas atrial fibrillation (AF) occurrence was as frequent in the 70–79 and ≥80 age subsets. As expected, cardiac mortality was higher in older patients. Patients aged ≥80 also had a low probability of AFL recurrence (5.0%) and AF onset (19.0%).ConclusionsOlder patients represent 37.5% of patients referred for AFL ablation and displayed a <10% risk of ablation-related complications. Importantly, AFL recurrences were less frequent in patients ≥70 while AF occurrence was as frequent as in patients <70. Similar observations were made in patients ≥80 years. AFL ablation appears to be safe and efficient and should not be ruled out in elderly patients.

Prophylactic pulmonary vein isolation during isthmus ablation for atrial flutter: the PReVENT AF Study I.

Although catheter ablation of isthmus-dependent atrial flutter (AFL) is successful at eliminating the target arrhythmia, many patients subsequently experience new-onset atrial fibrillation (AF). The aim of this study was to determine whether AF can be prevented by prophylactic pulmonary vein ablation in patients with AFL. A prospective, single-blind, randomized clinical trial in patients whose sole arrhythmia was AFL without AF was conducted. Patients were randomized to cavotricuspid isthmus ablation alone or with concomitant pulmonary vein isolation. All patients received an implantable cardiac monitor. Fifty patients completed the trial, and patients were well matched. Isthmus ablation was successful in all patients; pulmonary vein isolation was successful in 25 (100%) randomized patients. Procedure (P < .0001) and fluoroscopy (P < .0001) times were longer in the combined ablation group. More patients in the isthmus ablation-only group experienced new-onset AF during follow-up (52% vs. 12%; P = .003). The 1-year AF burden also favored the combined ablation group compared with the isthmus ablation-only group (8.3% vs. 4.0%; P = .034). In the isthmus ablation-only group, 8 (32%) patients subsequently underwent another ablation for AF. The performance of pulmonary vein isolation and male sex were independent predictors of freedom from AF. In the PREVENT-AF Study I randomized clinical trial of patients in whom only typical AFL had been observed clinically, the addition of pulmonary vein isolation to cavotricuspid isthmus ablation resulted in a marked reduction of new-onset AF during clinical follow-up as assessed with a continuous implantable cardiac monitor.

Value of Real-Time Transesophageal 3-Dimensional Echocardiography in Guiding Ablation of Isthmus-Dependent Atrial Flutter and Pulmonary Vein Isolation

In the past decade, both the range of indications and the efficacy and safety of interventional electrophysiology has improved considerably. This progress is attributed to both the accumulating experience of electrophysiologists and the advances in technological tools facilitating the diagnosis and treatment of cardiac arrhythmias. Real-time 3-dimensional transesophageal echocardiography (RT 3D TEE) has emerged as a new imaging tool in the clinical arena. Its ability to image in "real time" cardiac structures "en face" and the almost entire length of intracardiac catheters has made this technique a promising imaging tool to guide percutaneous catheter-based procedures. More recently it has been used in monitoring ablation procedures. In this review, the advantages and current limitations of RT 3D TEE during ablation of cavotricuspid isthmus-dependent atrial flutter and pulmonary vein isolation are described.

Usefulness of Pre-Procedure Cavotricuspid Isthmus Imaging by Modified Transthoracic Echocardiography for Predicting Outcome of Isthmus-Dependent Atrial Flutter Ablation

Anatomic characteristics of the cavotricuspid isthmus (CTI) have been reported to be related to the outcome of atrial flutter ablation therapy. However, preprocedural evaluation of CTI anatomy using modified transthoracic echocardiography to guide atrial flutter ablation has not been well described. Transthoracic echocardiography was prospectively performed before atrial flutter ablation in 42 patients with typical CTI-dependent atrial flutter. A modified apical long-axis view was designed to visualize and evaluate anatomic characteristics of the CTI and Eustachian ridge (ER). A prominent ER, extending from the inferior vena cava to the interatrial septum, is defined as an extensive ER. Twenty-eight patients had straightforward ablation procedures, and 14 patients had difficult ablation procedures. Two patients with difficult procedures had unsuccessful ablation. Multivariate analysis (using CTI length, the presence of a pouch or recess, ER morphology, and significant tricuspid regurgitation as variables) showed that the presence of extensive ER was the only independent predictor of a difficult ablation procedure. The ablation time in patients with extensive ER (n= 13) was significantly longer than in those patients with nonextensive ER (n= 29) (1,638.4 ± 1,548.3 vs 413.8 ± 195.5 sec, P= .015). The incidence of difficulty in achieving bidirectional isthmus block was also higher in patients with extensive ER (10 of 13 vs four of 29, P < .001). Preprocedural transthoracic echocardiography using a modified apical long-axis view is useful to characterize the morphology of the CTI and the ER. An extensive ER is a strong predictor for difficult ablation of CTI-dependent atrial flutter.

Atrial Flutter in a Patient with Postoperative AV Block and Right Infero‐Septal Accessory Pathway: How to Preserve AV Conduction

We report a case of postoperative acquired atrioventricular (AV) block and successful ablation of isthmus-dependent atrial flutter using "cryomapping" in combination with a mapping system preserving AV conduction via right infero-septal accessory pathway.

Right Coronary Artery Occlusion During RF Ablation of Typical Atrial Flutter

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.

MRI of Right Atrial Function after Catheter Ablation of Atrial Flutter

Catheter ablation of the cavotricuspid isthmus (CTI) is an effective treatment of right atrial flutter. The objective of this study was to evaluate the changes in CTI length and right atrial (RA) function after radiofrequency ablation of isthmus-dependent atrial flutter (isthmus ablation). Magnetic resonance imaging was obtained in 14 patients (2 female, mean age 59 +/- 9) before and after isthmus ablation (mean delay 80 +/- 175 days) using steady-state free precession cine magnetic resonance imaging in right anterior oblique view orientation. Right atrial function (maximum/minimum right atrial volumes, stroke volume, ejection fraction) and maximum/minimum length of the CTI were measured. After isthmus ablation, maximum RA volume decreased by 13% (P = .02) and minimum RA volume by 22% (P = .01), whereas stroke volume and ejection fraction did not increase significantly (P = .4 and .2, respectively). After ablation, the maximum length of the CTI showed a significant decrease of 19% (P < .001) and the minimum length a decrease of 24% (P < .001). A linear correlation between change in CTI length and number of energy applications during ablation could not be observed (r = .605, P = .22 for minimum length; r = .384, P = .18 for maximum length). After eliminating the outliers in the number of energy applications, a significant correlation between energy applications and change in CTI systolic length was found (r = .808, P = .008). Magnetic resonance imaging to visualize right atrial size and function in right anterior oblique orientation was successfully performed and easy to evaluate for volumetric analysis and determination of CTI length. Scarring of the CTI with the use of catheter ablation leads to a significant and linear decrease in its length and to a subsequent reduction of right atrial volumes, whereas functional parameters such as stroke volume/ejection fraction did not change significantly.

The change in the tissue characterization detected by magnetic resonance imaging after radiofrequency ablation of isthmus-dependent atrial flutter

Radiofrequency (RF) ablation produces thermal necrosis and electrophysiological conduction block when lesions are transmural. However, the phenomenon of endocardial edema may prevent the ablative energy from reaching the deeper layers of the myocardium. Sixty-seven patients underwent RF ablation of the cavotricuspid isthmus (CTI) for isthmus-dependent atrial flutter (AFL; 54 males, 61±9 years). Cardiac magnetic resonance (CMR) imaging was performed 1 day before ablation, and the length and morphology of the CTI were determined. In addition, 1 day and 1 month after ablation, the change in the wall thickness, prevalence of a high signal in the delayed enhancement (DE) and T2-weighted images at the CTI were evaluated. Before ablation, DE regions at the CTI were found in 2 patients with a concave type and 1 with a pouch type. No region with a high T2 signal at the CTI was observed in any of the 67 patients. One day after ablation, high T2 signals were detected at the CTI, and the wall thickness was significantly augmented (p<0.0001). CMR also revealed a DE at the CTI in 46 patients (69%). One month after ablation, the thickened wall with a high T2 signal recovered to baseline, and a DE at the CTI was found in 56 patients (84%). CMR is useful for assessing the creation of endocardial edema and scar tissue resulting from CTI ablation. These results may correlate with the anatomical isthmus block after ablation in a large portion of the patients with isthmus-dependent AFL.

Real-time integration of intracardiac echocardiography and 3D electroanatomical mapping to guide catheter ablation of isthmus-dependent atrial flutter in a patient with complete situs inversus and interruption of the inferior vena cava with azygos continuation

Atrial tachycardias are relatively common in patients with congenital heart disease. However, complex anomalies involving the heart and the great vessels might compromise the results of the ablation procedure. This report describes a clinical application of the new Cartosound™ module as an adjunctive technology to understand the mechanism of the arrhythmia and to guide successfully the ablation in a complex anatomy. Isthmus-dependent atrial flutter was diagnosed in a patient with complete situs inversus and interruption of the inferior vena cava with azygos continuation. Under these unusual circumstances, Cartosound facilitates interventional navigation within the right atrium and its adjacent structures and minimizes radiation exposure.

Comparison of 8-mm-tip and Irrigated-tip Catheters in the Ablation of Isthmus-Dependent Atrial Flutter: A Prospective Randomized Trial

Both 8-mm-tip and irrigated-tip catheters improve outcomes in typical atrial flutter ablation. However, it is not yet known which is preferable. The objective was to compare the effectiveness of 8-mm-tip (Group 1) and open irrigated-tip (Group 2) catheters in the first ablation attempt. A prospective randomized trial with a long-term follow-up was performed in patients with documented typical atrial flutter. For both types of catheter, the power was initially set to 50 W. The primary endpoint was ablation of the cavotricuspid isthmus in a procedure lasting, at most, 600 s. Group 1 contained 65 patients and Group 2 contained 66, with no significant intergroup difference in baseline characteristics. Their mean age was 63+/-12 years, 80% were men, and 65% had structural heart disease. The primary endpoint was achieved in 48 patients (73.8%) in Group 1 and 49 (74.2%) in Group 2 (P=NS). In the remaining patients, the procedure was continued at the physician's discretion and ablation was finally achieved in all cases. In the intention-to-treat analysis, there was no significant difference between the groups in the number of applications of the ablation device or in the duration of the ablation procedure, radioscopy or the total procedure. By 16+/-5 months of follow-up (>1 year in 98%), 8 (6.3%) patients had experienced recurrence and 95 (74.2%) were free from any arrhythmia. There was no differences between the groups. No difference was found between the effectiveness of 8-mm-tip and open irrigated-tip catheters in the first attempt at ablation of typical atrial flutter.