Sequential ultrahigh-density contact mapping of persistent atrial fibrillation: An efficient technique for driver identification.

INTRODUCTION: Literature supports the existence of drivers as maintainers of atrial fibrillation (AF). Whether ultrahigh density (UHD) contact mapping may detect them is unknown. METHODS: We sequentially mapped the left atrial (LA) activation during spontaneous persistent AF and performed circumferential pulmonary vein isolation (CPVI), followed by remapping and ablation of potential drivers (rotational and focal propagation sites) with Rhythmia™ in 90 patients. The time reference was an LA appendage (LAA) electrogram (EGM). Regions with uniform color were defined as "organized." Only patients (51) with no previous ablation were considered for acute results and follow-up reporting. RESULTS: LA maps (175 ± 28 ml, 43578 ± 18013 EGM) were acquired in 23 ± 7 min. In all post-CPVI maps potential drivers (7.3 ± 3.2/patient) were visualized: 85% with rotational propagation and continuous low voltage in the center; the remaining with focal propagation and an organized EGM at the site of earliest activation. The RF delivery time for extra-PV driver ablation was 12.2 ± 7.9 min. There was a progressive increase of AF organization: the LAA cycle length prolonged, the number of potential drivers decreased, and the organized LA surface in AF increased from 14 ± 6% to 28 ± 16% (p = .0007). Termination of AF without cardioversion was obtained in 67%. AF recurrence rate at 15 ± 7.3 months was 17.6% after the first procedure. CONCLUSIONS: Sequential UHD contact activation mapping of persistent AF allows visualization of potential drivers. A sequential strategy of CPVI followed by ablation of potential drivers with limited RF time resulted in an increasing organization of AF and good acute and long-term results.

Electrophysiologic evidence of epicardial connections between low right atrium and remote right atrial region or coronary sinus musculature: Relevance for catheter ablation of typical atrial flutter.

BACKGROUND: The coronary sinus (CS) is surrounded by a myocardial coat with extensive connections to the left and right atria that contributes to the interatrial electrical connection. Whereas epicardial connections between CS musculature and the left atrium have largely been demonstrated, clinically relevant epicardial connections from the CS musculature toward the low right atrium (LRA) and epicardial connections between two regions of the right atrium remain questionable. METHODS: Five patients underwent electrophysiology (EP) study for typical atrial flutter (AFl) using either conventional multipolar catheters (four patients) or three-dimensional high-density mapping system (one patient). RESULTS: All five patients had a similar sequence of events during the EP studies. After several cavotricuspid isthmus (CTI) radiofrequency (RF) applications, double potentials were recorded along the ablation line while tachycardia persisted. The right atrial activation pattern strongly suggested the presence of a complete endocardial CTI line of the block. Based on the detailed conventional atrial mapping, RF applications at the middle cardiac vein/CS ostium allowed sinus rhythm restoration in four patients. High-density mapping showed an early breakthrough site at the septal side of the ablation line, close to the CS ostium during counterclockwise AFl, in the fifth patient. RF applications at this site resulted in tachycardia termination. CONCLUSION: Our observations suggested the existence of epicardial fibers connecting the LRA with either the CS musculature or a remote right atrial region. When AFl ablation fails whereas evidence for the local endocardial block is observed, the operators should integrate this finding in the diagnosis and ablation strategy.

Cavotricuspid isthmus is constantly a zone of slow conduction: Data from ultra-high-resolution mapping.

BACKGROUND: Whether cavotricuspid isthmus (CTI) is a region of conduction slowing during typical flutter has been discussed with conflicting results in the literature. We aimed to evaluate conduction velocity (CV) along the different portions of the typical flutter circuit with a recently proposed method by means of ultra-high-resolution (UHR) mapping. METHODS: Consecutive patients referred for typical atrial flutter (AFL) ablation underwent UHR mapping (Rhythmia, Boston Scientific). CVs were measured in the CTI as well as laterally and septally, respectively, from its lateral and septal borders. RESULTS: A total of 33 patients (mean age: 65 ± 13 years; right atrial volume: 134 ± 57 mL) were mapped either during ongoing counterclockwise (n = 25), or clockwise (n = 3) AFL (mean cycle length: 264 ± 38 ms), or during coronary sinus pacing at 400 ms (n = 1), 500 ms (n = 1), or 600 ms (n = 3). A total of 13 671 ± 7264 electrograms were acquired in 14 ± 9 min. CTI CV was significantly lower (0.56  ± 0.18 m/s) in comparison with the lateral CV (1.31 ± 0.29 m/s; P < .0001) and the septal border CV of the CTI (1.29 ± 0.31 m/s; P < .0001). CONCLUSION: UHR mapping confirmed that CTI CV was systematically twice lower than atrial conduction velocities outside the CTI.

Ultrasound-guided axillary vein puncture for cardiac devices implantation in patients under antithrombotic therapy.

BACKGROUND: Ultrasound-guided axillary venous puncture (UGAVP) for cardiac devices implantation has been developed because of its rapidity, safety and potential long-term lead protection. Early work excluded defibrillators (ICD), cardiac resynchronization therapy (CRT) and upgrade procedures. Compared to the cephalic approach, in previous studies, there was a greater use of pressure dressings with this technique, suggesting a higher risk of bleeding. AIMS: To assess UGAVP in patients under antithrombotic therapy (ATT) undergoing cardiac devices implantation including CRT/ICD. METHODS: Prospectively, consecutive patients eligible for a pacemaker or ICD implantation were included. All procedures were performed by a single operator, experienced with UGAVP for femoral access, and fluoroscopy-guided axillary vein access. Guidewires insertion time (from lidocaïne administration), and complications were systematically studied. RESULTS: From 457 cardiac device implantations, 200 patients (77.8 ± 10 y, male 58%) 360 leads were implanted by UGAVP including 36 ICD, 54 CRT and 14 upgrade procedures. A majority (90%) was under ATT: Vitamin K Antagonist or Heparin (n = 58, 29%), direct oral anticoagulant (n = 46, 23%), dual antithrombotic therapy (n = 18, 9%) and single antiplatelet drug (n = 82, 41%). UGAVP was successful in 95.78%. Mean insertion time for 1.8 guidewires per patient was 4.68 ± 3.6 min. No complication (no hematoma) was observed during the follow-up (mean of 45 ± 10 months). Guidewires insertion time reached its plateau after 15 patients. CONCLUSION: UGAVP is fast, feasible and safe for patients under ATT undergoing device implantation including CRT/ICD and upgrade procedures, with a short learning curve.

Scar identification, quantification, and characterization in complex atrial tachycardia: a path to targeted ablation?

Successful catheter ablation of scar-related atrial tachycardia depends on correct identification of the critical isthmus. Often, this is a represented by a small bundle of viable conducting tissue within a low-voltage area. It's identification depends on the magnitude of the signal/noise ratio. Ultra-high density mapping, multipolar catheters with small (eventually unidirectional) and closely-spaced electrodes improves low-voltage electrogram detection. Background noise limitation is also of major importance for improving the signal/noise ratio. Electrophysiological properties of the critical isthmus and the characteristics of the local bipolar electrograms have been recently demonstrated as hallmarks of successful ablation sites in the setting of scar-related atrial tachycardia.

Radiofrequency catheter ablation of atrial fibrillation: Electrical modification suggesting transmurality is faster achieved with remote magnetic catheter in comparison with contact force use.

BACKGROUND: Remote magnetic navigation (RMN) and contact force (CF) sensing catheters are available technologies for radiofrequency (RF) catheter ablation of atrial fibrillation (AF). Our purpose was to compare time to electrogram (EGM) modification suggesting transmural lesions between RMN and CF-guided AF ablation. METHODS AND RESULTS: A total of 1,008 RF applications were analyzed in 21 patients undergoing RMN (n = 11) or CF-guided ablation (n = 10) for paroxysmal AF. All procedures were performed in sinus rhythm during general anesthesia. Time to EGM modification was measured until transmurality criteria were fulfilled: (1) complete disappearance of R if initial QR morphology; (2) diminution > 75% of R if initial QRS morphology; (3) complete disappearance of R' of initial RSR' morphology. Impedance drop as well as force time integral (FTI) were also assessed for each application. Mean CF at the beginning of each RF application in the CF group was 11 ± 2 g and mean FTI per application was 488 ± 163 gs. Time to EGM modification was significantly shorter in the RMN group (4.52 ± 0.1 seconds vs. 5.6 ± 0.09 seconds; P < 0.00001). There was no significant difference between other procedural parameters. CONCLUSION: Remote magnetic AF ablation is associated with faster EGM modification suggesting transmurality than optimized CF and FTI-guided catheter ablation.

Electroanatomic characteristics of the mitral isthmus associated with successful mitral isthmus ablation.

AIMS: The success of mitral isthmus (MI) ablation has been related to CT scan defined MI anatomy. We sought to correlate electroanatomical MI characteristics with MI ablation success in patients with perimitral flutter (PMF). METHODS AND RESULTS: In 53 consecutive patients (46 males, 61 ± 10 years) with PMF, MI was ablated with endocardial ± coronary sinus (CS) linear radiofrequency (RF) ablation lesion. Acute (termination of PMF during ablation) and long-term procedural success were studied. Mitral isthmus characteristics (thickness--minimal endocardial to CS distance, length, maximal MI bipolar voltage), as well as MI ablation line length and width, RF duration, and delivered energy were analysed. In 43 of the 53 patients (81%), acute success was observed. This was more frequently achieved in patients with thinner MI (2.4 ± 3.1 vs. 7 ± 3.2 mm; P = 0.0009). Mitral isthmus thickness predicted ablation failure with a ROC area of 0.84. The best threshold to predict MI ablation failure was 8.3 mm with a sensitivity of 67% and a specificity of 97%. Left atrial size was of greater importance in failed cases (2D echo surface: 24.1 ± 2.5 vs. 32.5 ± 6.9 cm2, P = 0.005; electroanatomic volume: 124 ± 32 vs. 165 ± 23 mL, P = 0.02). None of the other electroanatomical characteristics were associated with outcome. After a mean follow-up of 28 ± 15 months, 21 patients (39%) had atrial fibrillation (AF) or atypical flutter (PMF recurrence in four). CONCLUSION: Smaller MI thickness is associated with acute success in PMF ablation. Mitral isthmus electroanatomical characteristics might be used for decision-making on strategy during persistent AF ablation and for selecting the best location for interrupting PMF.

Pacemakers implantation and radiofrequency catheter ablation procedures during medical missions in Morocco: an 8-year experience.

AIMS: Radiofrequency catheter ablation (RFCA) for arrhythmias in the context of short-term medical missions (MM) in a developing country has not been reported so far. We describe here our experience with RFCA and pacemaker implantation in Morocco with a fully portable electrophysiological (EP) system under the auspice of the Monaco-Morocco Cardiology Association. METHODS AND RESULTS: Since November 2007, two to three MM (mean duration 4 days including transportation) per year were conducted (including two physicians and one nurse from Monaco) and were alternately located in Marrakech, Fes, Agadir, Casablanca, Rabat, Essaouira, and Oujda. All patients' files were sent by local teams and/or referring Moroccan cardiologists before MM. Each case was discussed with the Monaco EP team before the MM. Pacemakers and leads were donated by companies (Sorin Group, Medtronic, Saint-Jude Medical). The EP system (EP Tracer, CardioTek) as well as diagnostic/ablation catheters were brought for RFCA procedures. After the procedures, follow-up was performed by local teams. Procedures took place in gynaecological or orthopaedic operating room, or, when available, in the interventional cardiology cathlab. Thirty-one RFCA were performed during 11 MM (atrioventricular node re-entrant tachycardia = 12; atrioventricular re-entrant tachycardia/Mahaïm fibre = 15; typical atrial flutter = 3; ventricular ectopy = 1). Acute success was 93.5% for RFCA. Two major RFCA-related complications occurred (air embolism and complete atrioventricular block). No complication was related to pacemaker implantations (n = 44; mean 4 pacemakers per mission). CONCLUSION: Radiofrequency catheter ablation for arrhythmias in developing countries is technically challenging but feasible, despite technical and cultural difficulties.

Ultra-High-Definition Mapping of Atrial Arrhythmias.

The advantages of ultra-high-definition (UHD) mapping are presented in the context of different atrial arrhythmias, whether focal or macroreentrant. Not only are these sophisticated systems time-saving, but they also allow accurate identification of the substrate (scar quantification), as well as a more precise characterization of the critical isthmuses or focal sources of the atrial circuits. UHD mapping may become a standard approach for their curative treatment. This new technology allows automatic acquisition and accurate annotation of the electrograms, without the need for manual correction. Owing to better resolution, critical isthmuses and low-voltage regions of interest may now be successfully targeted without the need for entrainment maneuvers. Finally, the system also allows rapid assessment of the completeness of the lesions once delivered. (Circ J 2016; 80: 579-586).

Atrial flutter: more than just one of a kind.

Since its first description about one century ago, our understanding of atrial flutter (AFL) circuits has considerably evolved. One AFL circuit can have variable electrocardiographic (ECG) manifestations depending on the presence of pre-existing atrial lesions, or impaired atrial substrate. Conversely, different (right sided or even left sided) atrial circuits including different mechanisms (macroreentrant, microreentrant, or focal) can present with a very similar surface ECG manifestation. The development of efficient high-resolution electroanatomical mapping systems has improved our knowledge about AFL mechanisms, as well as facilitated their curative treatment with radiofrequency catheter ablation. This article will review ECG features for typical and atypical flutters, and emphasize the limitations for circuit location from the surface ECG.

Remotely controlled steerable sheath improves result and procedural parameters of atrial fibrillation ablation with magnetic navigation.

AIMS: The magnetic navigation (MN) system may be coupled with a new advancement system that fully controls both the catheter and a robotic deflectable sheath (RSh) or with a fixed-curve sheath and a catheter-only advancement system (CAS). We aimed to compare these approaches for atrial fibrillation (AF) ablation. METHODS AND RESULTS: Atrial fibrillation ablation patients (45, 23 paroxysmal and 22 persistent) performed with MN-RSh (RSh group) were compared with a control group (37, 18 paroxysmal and19 persistent) performed with MN-CAS (CAS group). Setup duration was measured from the procedure's start to operator transfer to control room. Ablation step duration was defined as the time from the beginning of the first radiofrequency (RF) pulse to the end of the last one and was separately acquired for the left and the right pulmonary vein (PV) pairs. Clinical characteristics, left atrial size, and AF-type distribution were similar between the groups. Setup duration as well as mapping times was also similar. Ablation step duration for the left PVs was similar, but was shorter for the right PVs in RSh group (46 ± 9 vs. 63 ± 12 min, P < 0.0001). Radiofrequency delivery time (34 ± 9 vs. 40 ± 11 min, P = 0.007) and procedure duration (227 ± 36 vs. 254 ± 62 min, P = 0.01) were shorter in RSh group. No complication occurred in RSh group. During follow-up, there were five recurrences (11%) in RSh group and 11 (29%) in CAS group (P = 0.027). CONCLUSION: The use of the RSh for AF ablation with MN is safe and improves outcome. Right PV isolation is faster, RF delivery time and procedure time are reduced.

Comparison between radiofrequency with contact force-sensing and second-generation cryoballoon for paroxysmal atrial fibrillation catheter ablation: a multicentre European evaluation.

AIMS: Whether pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) using contact force (CF)-guided radiofrequency (RF) or second-generation cryoballoon (CB) present similar efficacy and safety remains uncertain. METHODS AND RESULTS: We performed a multicentre study comparing procedural safety and arrhythmia recurrence after standardized PVI catheter ablation for PAF using CF-guided RF ablation (Thermocool(®) SmartTouch™, Biosense Webster; or Tacticath™, St Jude Medical) (CF group) with second-generation CB ablation (Arctic Front Advance™, Medtronic) (CB group). Overall, 376 patients (mean age 59.8 ± 10.4 years, 280 males) were enrolled in 4 centres: 198 in CF group and 178 in CB group. Procedure was shorter for CB group than for CF group (109.6 ± 40 vs. 122.5 ± 40.7 min, P = 0.003), but fluoroscopy duration and X-ray exposure were not statistically different (P = 0.1 and P = 0.22, respectively). Overall complication rate was similar in both groups: 14 (7.1%) in the CF group vs. 13 (7.3%) in the CB group (P = 0.93). However, transient right phrenic nerve palsy occurred only in CB group (10 patients, 5.6%; P = 0.001 vs. CF group) and severe non-lethal complications (embolic event, tamponade, or oesophageal injury) occurred only in CF group (5 patients, 2.5%; P = 0.03 vs. CB group). No periprocedural death occurred in either group. Single-procedure freedom from any atrial arrhythmias at 18 months post-ablation was comparable in CF group and CB group (76 vs. 73.3%, respectively, log rank P = 0.63). CONCLUSION: Pulmonary vein isolation using CF-guided RF and second-generation CB leads to comparable single-procedure arrhythmia-free survival at up to 18 months with similar overall complication rate.

General anesthesia is not superior to local anesthesia for remote magnetic ablation of atrial fibrillation.

BACKGROUND: Remote magnetic navigation is an emerging technology for atrial fibrillation (AF) ablation. General anesthesia (GA) has shown to be superior to local anesthesia (LA) for manual AF ablation in terms of catheter stability and lesion formation. We aimed at comparing GA with LA for remote magnetic AF ablation procedures. METHODS: All patients eligible for a remote magnetic ablation of AF were included in this study. Ninety patients (70% of the patients were male; age: 60 ± 10 years; CHA2 DS2 -VASC : 1.6 ± 1.2; paroxysmal AF: 60%, persistent AF: 40%), including 45 patients with GA, and 45 patients with LA were enrolled consecutively. RESULTS: There was no significant difference in total procedure time between the two groups (237 ± 50 minutes in the GA group vs 240 ± 61 minutes in the LA group; P = 0.84). Fluoroscopy time was significantly increased in the GA group (14.6 ± 6 minutes vs 11.6 ± 6 minutes, P = 0.018). Ablation time was not different between the two groups (2,320 ± 984 seconds in the GA group vs 2,055 ± 1,023 seconds in the LA group; P = 0.25). After a mean follow-up of 1 year (including repeat procedures), 39/45 patients (86.6%) within the GA group were free from recurrences versus 40/45 patients (88.8%) in the LA group (P = 0.74) without antiarrhythmic drugs. CONCLUSION: For remote magnetic AF ablation, procedures under LA have similar results to GA in terms of efficacy and safety after 1-year follow-up.

Contact force and force-time integral in atrial radiofrequency ablation predict transmurality of lesions.

AIMS: During radiofrequency (RF) delivery, lesion volume is highly dependent on contact force (CF). It has recently been shown that changes of bipolar electrogram (EGM) predict transmurality. We hypothesized that there is a correlation between CF and EGM criteria of transmural lesion (TL) during RF. METHODS AND RESULTS: We prospectively studied consecutive 512 RF applications from atrial fibrillation ablation procedures. A force-sensing ablation catheter (Tacticath(®), Endosense) was used to continuously measure CF and force-time integral (FTI) during each RF application. Distal bipolar EGM was analysed before, during, and after each RF application. Depending on initial EGM morphology, transmurality of lesions was defined by: (i) disappearance of the positivity after RF when there was QR morphology, (ii) diminution >75% of the positivity when there was QRS morphology, or (iii) disappearance of the R' positivity when there was RSR' morphology. Electrogram criteria were validated by electrophysiologists blinded to force measurements. Force-time integral was higher in TL than in non-transmural lesions (NTLs): 652 ± 248 vs. 212 ± 140 gs (P < 0.001). Mean CF per RF pulse was higher in TL than in NTL: 26.3 ± 12.5 vs. 11.3 ± 10.3 g (P < 0.001). The best cut-off to predict TL was an FTI ≥ 392 gs [sensitivity 0.89, specificity (Sp) 0.93, positive predictive value (PPV) 0.98, and negative predictive value 0.67] and a higher FTI (>700 gs) warrants transmurality of RF atrial lesions (100% Sp and PPV). CONCLUSION: Contact force and FTI during RF are correlated with TL. During RF delivery, a target FTI > 392 gs can be used as an endpoint.

Ultrasound-guided venous puncture in electrophysiological procedures: a safe method, rapidly learned.

BACKGROUND: We sought to determine the feasibility and learning curve associated with systematic use of real-time ultrasound-guided venous puncture (UGVP) in patients undergoing electrophysiological (EP) procedures. METHODS: Four operators performed UGVP in consecutive patients undergoing EP procedures (group I). Puncture time was defined as the time from ultrasound (US) visualization of the femoral vein to the insertion of all sheaths. A learning curve as defined by UGVP evolution over the time was established for each operator. This population was compared to an historical group of patients in whom venous puncture was performed without US (group II). RESULTS: A total of 150 patients per group were included. UGVP was successfully achieved in all patients. Mean time for 2.8 ± 0.7 sheaths per patient insertion was 280 ± 151 seconds in group I. There was one minor vascular complication (VC) out of 150 patients (0.66%) without major VC in group I as compared with group II (2% major VC and 4.6% minor VC; P < 0.05). UGVP time reached a plateau at the sixth patient-case for each operator; thus, learning curve was estimated to six patients. CONCLUSION: UGVP is a short learning curve technique, significantly associated with a low incidence of minor VCs. This study supports wide use of UGVP in patients undergoing EP procedures.

Characteristics of recurrent clockwise atrial flutter after previous radiofrequency catheter ablation for counterclockwise isthmus-dependent atrial flutter.

AIMS: Isthmus-dependent (ID) clockwise (CW) atrial flutters (AFl) are rare in comparison with counterclockwise (CCW) AFl. Little is known about clinical and electrophysiological characteristics of CW AFl occurring after previous radiofrequency (RF) catheter ablation of CCW AFl. We sought to compare CW AFl de novo vs. CW AFl occurring after previous CCW AFl RF ablation. METHODS AND RESULTS: A total of 246 procedures of RF catheter ablation for AFl from January 2009 to January 2011 were reviewed. Clinical and electrophysiological data were analysed. Patients were excluded if they were in sinus rhythm at the beginning of the procedure, if they had concomitant/previous atrial fibrillation ablation, or if AFl was not ID. Twenty-seven patients presented CW AFl (10.9% of all ID AFl), including 10 CW AFl occurring after a previous RF catheter ablation for CCW AFl. Mean time for recurrence after the previous procedure of CCW AFl RF ablation was 3.5 years. They were younger (61.6 ± 11 years) than patients with CW AFl de novo (74.0 ± 7.2 years; P = 0.005). Bidirectional isthmus block was obtained in all patients. There was a significant difference in terms of double potential separation after ablation (155 ± 31 ms for CW AFl de novo vs. 111 ± 7 ms for recurrent CW AFl; P = 0.028). No differences were observed concerning CHADS score, AFl cycle length, and electrocardiogram typical pattern for CW AFl between the two groups. CONCLUSION: Patients with CW AFl occurrence after CCW AFl RF catheter ablation are younger than patients with CW AFl de novo. They also have a smaller interspike interval after block completion.

Hepatico-tricuspid isthmus ablation for typical-like atrial flutter by femoral approach in absence of the inferior vena cava: use of magnetic navigation and three-dimensional mapping with image integration.

The previously unknown congenital absence of inferior vena cava, an otherwise benign condition, may create difficulties for catheter ablation of arrhythmias. We describe a case of a typical-like atrial flutter, in which magnetic navigation was important for conserving the femoral approach. Electroanatomic mapping with image integration helped define the critical isthmus between the ostia of the suprahepatic veins and the tricuspid valve.