Is a Cooled Tip Catheter the Solution for the Ablation of the Cavotricuspid Isthmus?

SCAVÉE, C., et al. : Is a Cooled Tip Catheter the Solution for the Ablation of the Cavotricuspid Isthmus? To test the theoretical superiority of irrigated tip catheters to achieve complete cavotricuspid isthmus block, a 4-mm cooled tip catheter was compared to a conventional 8-mm tip catheter with a double temperature sensor in the cavotricuspid isthmus (CTI) ablation. The study prospectively enrolled 60 patients (47 men, mean   65 ± 10   years) with common flutter divided in group 1   (n = 30)   assigned to an 8-mm tip catheter versus group 2   (n = 30)   , assigned to an internal circuit, irrigated tip catheter. Linear radiofrequency applications were performed in a point-by-point protocol to achieve complete CTI block. Complete CTI block was achieved in 29 patients in each group. Mean durations of procedure and fluoroscopy were 91 versus 90 and 40 versus 33 minutes in group 1 versus 2, respectively, (NS). The mean number/patient of RF pulses to interrupt atrial flutter was four in group 1 and eight in group 2   (P = 0.034)   , and 11 and 13, respectively, to interrupt CTI conduction (NS). The total energy delivered was similar in both groups (29,237 vs 23,236 W/s, NS). CTI ablation with a conventional 8-mm tip catheter versus an irrigated tip catheter was associated with similar success rates, procedure duration, and fluoroscopic exposure. The technical complexity of the cooled tip catheter renders it less competitive. (PACE 2003; 26[Pt. II]:328–331)     

Atrial Flutter Ablation using a Technique for Detection of Conduction Block within the Posterior Isthmus

Catheter ablation orientated on the induction of a functional intraatrial block within the posterior isthmus of the tricuspid annulus has been shown to effectively abolish atrial flutter. In order to improve and simplify the current technique, a strategy based on an electrode catheter for combined right atrial and coronary sinus mapping and stimulation was explored prospectively. Twenty-four consecutive patients referred for catheter ablation of recurrent type I atrial flutter were included. A steerable 7 Fr catheter (Medtronic/Cardiorhythm) composed of two segments with 20 electrodes was used for right atrial and coronary sinus activation mapping and stimulation. Multiple steering mechanisms allowing intubation and positioning of the distal part within the coronary sinus were incorporated into the device. Adequate positioning of the mapping catheter was achieved solely via a transfemoral approach in all patients after 7.7 +/- 4.6 minutes, providing stable electrogram recordings during the entire ablation procedure. Radiofrequency current ablation (16.3 +/- 9.6 pulses) caused a significant bidirectional increase of the mean intraatrial conduction times via the posterior isthmus irrespective to the stimulation interval. Significant changes of intraatrial conduction properties were induced during ablation in 22 of 24 patients (bidirectional block: n = 18, unidirectional block: n = 3, conduction delay: n = 1, unchanged conduction: n = 2). Following ablation atrial flutter was noninducible in all patients. Twenty-two of 24 patients (92%) remained free of atrial flutter episodes during a follow-up of 12.5 +/- 5.7 months. Two of six patients without a bidirectional conduction block had a recurrence of atrial flutter. Atrial flutter ablation guided by the induction of an intraatrial conduction block can be effectively performed with this novel strategy for combined mapping of the posterior tricuspid isthmus, including coronary sinus and right atrial free wall. This transfemoral approach has a high accuracy with respect to the detection of radiofrequency current-induced changes of intraatrial conduction patterns.     

Late Recurrence of Atrial Flutter Following Radiofrequency Catheter Ablation

The success rate for catheter ablation of atrial flutter has been reported to be approximately 90%, but recurrences are common and can be seen in up to 20% of cases. Most of these recurrences are seen within a few weeks following ablation. We report on a patient who developed a recurrence of type I atrial flutter 2 years after an initially successful radiofrequency catheter ablation procedure. Whether the recurrent atriai flutter is due to a new reentrant circuit resulting from slow progression of atrial disease or due to the changes produced by radiofrequency energy in the nearby myocardium is not clear. Further work to define the electrophvsiological changes in the atrial myocardium produced by radiofrequency energy, as well as long-term follow-up of patients undergoing radiofrequency catheter ablation for atrial flutter may help in answering these questions.     

Complete Atrioventricular Block during Ablation of Atrial Flutter

We report the case of a 51‐year‐old patient who developed a complete atrioventricular (AV) block during the isthmic radiofrequency catheter ablation of a typical atrial flutter. The cause was an acute occlusion of the segment three of the right coronary artery. His recanalization was associated with the immediate restoration of a normal AV conduction. The complication is exceptional (one of 740 consecutive atrial flutter ablations). (PACE 2010; 516–519)     

Using Intracardiac Catheter Recordings from the His and Proximal Coronary Sinus to Distinguish Isthmus Conduction Block During Catheter Ablation of Type I Atrial Flutter

Isthmus conduction block, demonstrated with the use of multipolar catheter recordings, is considered the preferred endpoint for ablation of type I atrial flutter. This study investigated the feasibility of using recordings from the His and coronary sinus (CS) to document isthmus conduction block. Isthmus conduction block was produced with linear radiofrequency (RF) ablation in 27 patients with type I atrial flutter. In 13 patients (group I), RF was delivered until bidirectional isthmus conduction block was demonstrated with multipolar Halo catheter recordings. In 14 patients (group II), RF was delivered during pacing from the lateral isthmus at 600 ms until a reversal in activation of the proximal CS and His occurred. At this point, data from the Halo recordings were reviewed to see if reversal correlated with conduction block; if not, further ablation was performed until block was demonstrated. The initial reversal in His and CS activation during RF energy delivery correlated with isthmus block in only 4 (28.6%) of 14 patients in group II. Additional RF delivery produced isthmus block in the other ten patients resulting in a further increase in the St-CS interval of 35 ± 20 ms. A His-CS interval of at least -40 ms signified isthmus block with a sensitivity and specificity of 48% and 100%, respectively. Reversal in His-CS activation during pacing from the lateral margin of the isthmus is not specific for the creation of isthmus block. While activation of the proximal CS bipole > 40 ms after activation of the His appears specific for isthmus block, the low sensitivity of this finding limits its clinical use.     

Catheter Ablation of Atrial Flutter Circuits

Atrial flutter (AF) mapping has shown circular activation in the right atrium (RA), wilh a "counterclockwise" rotation in a frontal view. The myocardial isthmus between the inferior vena cava and the tricuspid valve (IVC-T) closes the activation circuit in its caudal end. The reproducibility of this activafion pattern, and the fact that some "rare" AF with a "clockwise" rotation of activation use the same circuit, suggests that reentry is greatly facilitated by the anatomical arrangement of the caudal end of the RA. This suggested that ablation of the IVC-T isthmus may interrupt AF and prevent its recurrence. We have applied radiofrequency (RF) current to the IVC-T isthmus in nine patients, producing sudden interruption of activation at this point in five (all those treated with large surface electrode catheters). in three others, RF produced acceleration or disorganization, leading to interruption. Preliminary follow-up data suggest a favorable effect on AF recurrence, either by preventing it, or by making antiarrhythmic drugs effective.     

Relation Between Left Atrial Size and Secondary Atrial Arrhythmias After Successful Catheter Ablation of Common Atrial Flutter

Catheter ablation ptovides an effective cure for patients with typical atrial flutter. However, these patients may have the potential to develop atrial tachyarrhythmias other than common atrial flutter. This study examines clinical and echocardiographic predictors for the occurrence of uncommon atrial flutter or atrial fibrillation after abolition of common atrial flutter. The study population comprised 17 patients (12 men, 5 women, age 32–74 years) who underwent successful radiofrequency catheter ablation of common atrial flutter. Common atrial flutter did not recur in any patient during a median follow-up time of 8 (range 1–25) months. Within a median of 7 (range 1–223) days, however, symptomatic atrial tachyarrhythmias occurred in 8 of 17 patients (47%): uncommon atrial flutter (n = 4); atrial fibrillation (n = 3); and both uncommon atrial flutter and atrial fibrillation in one patient. Preablation left atrial volume was significantly larger in patients who developed secondary arrhythmias compared with patients who remained in sinus rhythm (57.9 ± 15.6 vs 43.7 ± 16.4 cm³, P < 0.05). Enlarged left atrial volume dichotomized at 51 cm³ independently predicted postablation atrial arrhythmias (x²=5.11, rel. risk = 5.3, P < 0.05). On Kaplan-Meier analysis, time to occurrence of postablation atrial arrhythmias was significantly shorter in patietits with enlarged left atrium (P < 0.02). In conclusion, symptomatic uncommon atrial flutter and atrial fibrillation develops in a substantial proportion of patients after successful ablation of common atrial flutter. Out of a series of clinical and echocardiographic parameters, preablation left atrial size is the best predictor for the occurrence of these postablation atrial arrhythmias.     

Atrial Flutter Ablation in Inducible Patients during Pulmonary Vein Atrum Isolation: A Randomized Comparison

Background: The incidence of atrial flutter (AFL) post pulmonary vein antrum isolation (PVAI) in patients with atrial fibrillation (AF) is reported to be between 8% and 20%. The need for right or left AFL ablation during the initial PVAI procedure remains controversial. We prospectively compared mapping and ablation versus no ablative treatment of inducible AFL during PVAI. Methods and Results: In 220 patients (167 men, mean age 56 ± 15 years) with symptomatic AF presenting for PVAI, burst pacing from the high right atrium and coronary sinus was performed to determine AFL inducibility. A total of 25 patients with sustained (17 patients) or reproducible (eight patients) AFL were included in this study. Patients were randomized to mapping and ablation of AFL using the CARTO 3D mapping system (Biosense Webster, Diamond Bar, CA, USA) versus no further ablation. Typical AFL was induced in 48% of the patients. During a follow‐up of 12 ± 4 months, recurrences were determined by serial 48‐h Holter and event monitors. Recurrence rates, time to recurrence, and AFL cycle length differences between both groups were not statistically significant. Conclusion: These data suggest that inducibility of AFL post PVAI does not predict long‐term incidence of AFL. Moreover, this study demonstrates little benefit to mapping and ablation of these arrhythmias during the PVAI procedures.     

Use of a Three-Dimensional, Nonfluoroscopic Mapping System for Catheter Ablation of Typical Atrial Flutter

Recent studies have shown that typical atrial flutter (AFL) results from right atrial reentry around the tricuspid annulus (TA), constrained between the TA and crista terminalis (CT) on the free-wall and the TA and eustachian ridge (ER) on the septum. Creation of a complete line of conduction block across the subeustachian isthmus, between the TA and ER, elminates AFL. The accuracy of fluoroscopy in localizing the anatomical boundaries and previous radiofrequency application sites is limited. This article describes an approach for utilizing a new three-dimensional nonfluoroscopic electroanatomical mapping system (CARTO) to examine the global right atrial activation pattern in patients during AFL, localize the anatomical boundaries, and create a complete line of conduction block by ablation across the subeustachian isthmus. During AFL, the locations of CT and ER are identified by double atrial potentials recorded along the intercaval region and between the inferior vena cava and coronary sinus ostium, respectively. Radiofrequency ablation across the subeustachian isthmus is performed during coronary sinus pacing. Beginning at TA, the ablation electrode is moved toward ER in 2–3 mm increments. Each movement is marked on the right atrial map to visualize the ablation line. In the event of residual conduction across the ablation line, defects in the ablation line are located by mapping along the previous ablation sites guided by CARTO system to locate the transition from the double atrial potentials (indicating block) to a single atrial potential (indicating conduction). Radiofrequency ablation to the site showing the single atrial potential along the ablation line produces complete conduction block across the subeustachian isthmus. In conclusion, the new electroanatomical mapping system allows precise 3-D localization of the anatomical boundaries of the AFL reentrant circuit, and facilitates ablation by accurately locating defects in the ablation line.(PACE 1998; 21:1279–1286)     

Cavotricuspid Isthmus Ablation with Large-Tip Gold Alloy Versus Platinum-Iridium-Tip Electrode Catheters

Background: Gold has excellent electrical conductive properties and creates deeper and wider lesions than platinum-iridium during radiofrequency (RF) ablation in vitro . We tested the maximum voltage-guided technique (MVGT) of cavotricuspid isthmus (CTI) ablation using two 8-mm tip catheters containing gold (group G) or platinum-iridium (group PI).
Methods: We enrolled 31 patients who underwent CTI ablation. In group G (n = 15) CTI ablation was performed with a gold-tip ablation catheter, while in group PI (n = 16) a platinum-iridium tip was used. Ablation was guided by CTI potentials with the highest amplitude until achievement of bidirectional block (BIB). If BIB was not achieved after 10 RF applications, RF was delivered via a 3.5-mm irrigated-tip catheter. Success rate, procedure duration, duration of fluoroscopic exposure, and number of RF applications were measured.
Results: BIB was achieved in all patients in group G, while in group PI an irrigated tip was used in four patients (0% vs 25%, P < 0.001). These four patients required a total of 21 additional RF applications (5.25 ± 2.22). Procedure time (56.4 ± 12 vs 73.1 ± 15 minutes P < 0.05) and fluoroscopic explosure (4.9 ± 2.3 vs 7.1 ± 3.8 minutes, P < 0.01) were shorter in group G than in group PI. Mean number of RF applications was lower (4.6 ± 1.9 vs 6.6 ± 3.1 P < 0.001) and total RF duration shorter (280 ± 117 vs 480 ± 310 seconds) in group G than in group PI. No difference was observed in the number of recurrences at a 6 month-follow up (1 in group G vs 1 in group PI).
Conclusion: Using the MVGT of CTI ablation, gold-tip catheters were associated with shorter procedural and fluoroscopic times, and fewer RF applications.     

Catheter Ablation for Paroxysmal Atrial Fibrillation: A Randomized Comparison between Multielectrode Catheter and Point‐by‐Point Ablation

Introduction: Catheter ablation for paroxysmal atrial fibrillation is widely used for patients with drug‐refractory paroxysms of arrhythmia. Recently, novel technologies have been introduced to the market that aim to simplify and shorten the procedure. Aim: To compare the clinical outcome of pulmonary vein (PV) isolation using a multipolar circular ablation catheter (PVAC group), with point‐by‐point PV isolation using an irrigated‐tip ablation catheter and the CARTO mapping system (CARTO group; CARTO, Biosense Webster, Diamond Bar, CA, USA). Methods: Patients with documented PAF were randomized to undergo PV isolation using PVAC or CARTO. Atrial fibrillation (AF) recurrences were documented by serial 7‐day Holter monitoring. Results: One hundred and two patients (mean age 58 ± 11 years, 68 men) were included in the study. The patients had comparable baseline clinical characteristics, including left atrial dimensions and left ventricular ejection fraction, in both study arms (PVAC: n = 51 and CARTO: n = 51). Total procedural and fluoroscopic times were significantly shorter in the PVAC group (107 ± 31 minutes vs 208 ± 46 minutes, P < 0.0001 and 16 ± 5 minutes vs 28 ± 8 minutes, P < 0.0001, respectively). The AF recurrence was documented in 23% and 29% of patients in the PVAC and CARTO groups, respectively (P = 0.8), during the mean follow‐up of 200 ± 13 days. No serious complications were noted in both study groups. Conclusions: Clinical success rates of PV isolation are similar when using multipolar circular PV ablation catheter and point‐by‐point ablation with a three‐dimensional (3D) navigation system in patients with PAF, and results in shorter procedural and fluoroscopic times with a comparable safety profile. (PACE 2010; 33:1039–1046)     

Atrial Flutter Mapping and Ablation II. Radiofrequency Ablation of Atrial Flutter Circuits

The definition of the anatomical substrate of reentry in at rial flutter has allowed the recognition of narrow, critical areas of the circuit, where radiofrequencv ablation can interrupt reentry. In common flutter the isthmus between the inferior vena cava and the tricuspid valve appears the best target, but ablation between the coronary sinus and tricuspid valve can also be effective in some cases. In atypical flutter using the same circuit as common flutter in a “clockwise” direction, ablation of the same isthmus is effective. Flutter interruption is the main objective, but it does not mean complete isthmus ablation. If flutter remains inducible, new applications are delivered in the isthmus, until it is made noninducible. Complications are rare. Despite attaining noninducibility, flutter may recur, and new procedures may he needed to prevent recurrence. Atrial fibrillation can occur in up to 30% of the cases during follow-up, but it is generally well controlled with antiarrhythmic drugs, that were ineffective to treat flutter before ablation. In reentry circuits based on surgical atrial scars, ablation of an isthmus between the scar and the inferior vena cava can also be effective. Left atrial circuits are not known well enough to guide successful ablation.     

Simplified Demonstration of Cavotricuspid Isthmus Block After Catheter Ablation in Patients After Mustard's Operation

Background: The Mustard operation is a complex atrial rerouting performed in patients with transposition of the great arteries (TGA). Cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) is an important problem in these patients. While catheter ablation (CA) is successful, three-dimensional (3D) mapping is necessary to prove block at the CTI. 3D mapping, however, requires baffle puncture. We tested a simplified concept to prove isthmus block after CA for AFL in Mustard patients.
Methods: During electrophysiology study, catheters were placed in the high and low systemic venous atrium (HSVA and LSVA) and in the low pulmonary venous atrium (LPVA). LPVA and then LSVA were paced while recording in the HSVA and the alternate site. While pacing from one low site, the time taken to activate the other low site and the HSVA was compared before and after successful ablation.
Results: Three patients with Mustard operation and AFL underwent successful CA. Involvement of the CTI in AFL was proved by entrainment mapping. AFL was terminated during ablation and no longer inducible after ablation in all. LSVA pacing showed LPVA activation preceded HSVA activation preablation and activation pattern reversal after ablation. Likewise, LPVA pacing showed LSVA activation preceding HSVA preablation with reversal after ablation.
Conclusion: This study provides a simple method to demonstrate bidirectional block at the CTI in patients with CTI-based AFL after Mustard operation for TGA.     

Radiofrequency Catheter Ablation of Atrial Flutter That Elicits Inappropriate Implantable Cardioverter Defibrillator Discharge

The case of a patient with recurrent VT and an ICD is reported. After appropriate device discharges, the patient experienced 40 episodes of inappropriate shock therapy due to atrial arrhythmias confirmed as type I atrial flutter. Since programmed stimulation could reliably initiate atrial flutter, catheter ablation was performed. During delivery of RF current, atrial flutter terminated and was no longer inducible. The patient had no further inappropriate device discharges during 12 months of follow-up. In patients with ICDs suffering from recurrences of atrial flutter leading to inappropriate shock therapy, RF catheter ablation is an effective and curative approach.     

Persistent Atrial Fibrillation Converts to Common Type Atrial Flutter during CFAE Ablation

Background: Catheter ablation of persistent and long‐standing persistent atrial fibrillation (AF) is still challenging. So far different ablation techniques have been reported, including pulmonary vein isolation, additional linear lesions, ablation of complex fractionated atrial electrograms (CFAE), and combinations of these techniques. During ablation of CFAE, the occurrence of left atrial (LA) tachycardia is well known. The occurrence of right atrial flutter on the other hand is less well described. Methods: Here, we report three patients who had been ablated because of symptomatic persistent atrial fibrillation. Summary: In all patients, AF changed into a cavotricuspid isthmus = dependent right atrial flutter during ablation of CFAE in the LA. (PACE 2010; 33:304–308)     

Left‐Sided Atrial Flutter Originating in the Coronary Sinus after Radiofrequency Ablation of Atrial Fibrillation

We describe a case of atypical atrial flutter presenting 1 year after radiofrequency ablation for atrial fibrillation (AF). Electrophysiologic study showed a reentry circuit involving the inferolateral aspect of the mitral annulus and the coronary sinus (CS); however, a mitral isthmus line did not terminate the arrhythmia. Participation of the proximal CS musculature in the circuit suggested a possible target for ablation. Radiofrequency energy applications from within the CS terminated the tachycardia. Mapping and ablation within the CS should be considered in patients with post‐AF ablation arrhythmias, particularly when the mitral annulus appears to be involved in the tachycardia circuit. (PACE 2010; 33:e96–e99)     

Successful Catheter Ablation of Typical Atrial Flutter in a Patient with a Long Vertical and Diverticulum‐Like Cavotricuspid Isthmus

A long vertical vestibule with a diverticulum‐like morphology of cavotricuspid isthmus (CTI) was demonstrated by right atrial angiogram in a 47‐year‐old male patient in whom his typical atial flutter was difficult to be ablated. Compatible with the right atrial angiography, the diverticulum‐like CTI with a long vertical vestibule, pouch‐like recess, and a long transverse posterior component was also demonstrated on volume‐rendering reconstruction computed tomography and the virtual endoscopy showed prominent trabeculation inside the diverticulum‐like part of CTI. The bidirectional CTI conduction block was successfully achieved after ablating along the CTI guided by the right atrial angiography.     

Ablation of Atrial Flutter in a Patient with a Tricuspid Valve Replacement after Endocarditis

Myocardial scars from heart surgery are a source of tachycardia, eventually causing late morbidity and sudden death. In general, catheter ablation has been shown to be an effective therapy for various rhythm disorders, but it has been rarely described after atrioventricular valve replacement. We report on a 45-year-old man who developed atrial flutter after implantation of a tricuspid valve bioprosthesis. An electrophysiological investigation revealed typical type-I counterclockwise atrial flutter that was successfully terminated by catheter ablation. A sinus rhythm was restored and remained stable during the course of treatment; the valvular function was not diminished. It is demonstrated that safe mapping and ablation of typical atrial flutter is possible after a tricuspid valve replacement.     

Thromboembolic Risk of Patients Referred for Radiofrequency Catheter Ablation of Typical Atrial Flutter Without Prior Appropriate Anticoagulation Therapy

GRÖNEFELD, G.C., et al.: Thromboembolic Risk of Patients Referred for Radiofrequency Catheter Ablation of Typical Atrial Flutter Without Appropriate Prior Anticoagulation Therapy. Background: Radiofrequency catheter ablation of isthmus dependent atrial flutter is considered the therapy of choice. There is, however, controversy with regard to the thrombogenicity of atrial flutter in comparison with atrial fibrillation. Methods: Consecutive patients scheduled for catheter ablation of documented typical atrial flutter receiving insufficient (INR < 2.0) or no anticoagulation during the three weeks preceding the procedure underwent multiplane transesophageal echocardiography (TEE). Patients with exclusive documentation of atrial flutter were classified as group I, whereas patients with additional documentation of atrial fibrillation were classified as group II. Results: The study included 201 patients, 62 of whom were not on therapeutic anticoagulation (mean age   64 ± 9   years, 87% men). In 10 of these 62 patients (16%), TEE detected a left atrial (LA) appendage thrombus in 4, or dense spontaneous echo contrast (SEC) in 6 patients. Comparison of patients with versus without SEC or thrombus, revealed a higher incidence of valvular heart disease (60% vs 26%,   P = 0.05   ), but no differences with respect to age, gender, LA diameter, left ventricular end-diastolic diameter, or left ventricular ejection fraction. The incidence of positive TEE findings in group I was 1 in of 36 versus 9 of 26 in group II (3% vs 35%, P < 0.001), and the relative risk for thromboembolism in group II versus group I was 12.5 (95% CI: 3-55, P < 0.001). Conclusion: There is a significant risk for thromboembolism in patients referred for ablation of typical atrial flutter who have not been appropriately anticoagulated. (PACE 2003; 26[Pt. II]:323–327)