Peak frequency mapping of atypical atrial flutter.

INTRODUCTION: Peak frequency (PF) mapping is a novel method that may identify critical portions of myocardial substrate supporting reentry. The aim of this study was to describe and evaluate PF mapping combined with omnipolar voltage mapping in the identification of critical isthmuses of left atrial (LA) atypical flutters. METHODS AND RESULTS: LA omnipolar voltage and PF maps were generated in flutter using the Advisor HD-Grid catheter (Abbott) and EnSite Precision Mapping System (Abbott) in 12 patients. Normal voltage was defined as ≥0.5 mV, low-voltage as 0.1-0.5 mV, and scar as <0.1 mV. PF distributions were compared with ANOVA and post hoc Tukey analyses. The 1 cm radius from arrhythmia termination was compared to global myocardium with unpaired t-testing. The mean age was 65.8 ± 9.7 years and 50% of patients were female. Overall, 34 312 points were analyzed. Atypical flutters most frequently involved the mitral isthmus (58%) or anterior wall (25%). Mean PF varied significantly by myocardial voltage: normal (335.5 ± 115.0 Hz), low (274.6 ± 144.0 Hz), and scar (71.6 ± 140.5 Hz) (p < .0001 for all pairwise comparisons). All termination sites resided in low-voltage regions containing intermediate or high PF. Overall, mean voltage in the 1 cm radius from termination was significantly lower than the remaining myocardium (0.58 vs. 0.95 mV, p < .0001) and PF was significantly higher (326.4 vs. 245.1 Hz, p < .0001). CONCLUSION: Low-voltage, high-PF areas may be critical targets during catheter ablation of atypical atrial flutter.

Baseline left atrial low-voltage area predicts recurrence after pulmonary vein isolation: WAVE-MAP AF results.

AIMS: Electro-anatomical mapping may be critical to identify atrial fibrillation (AF) subjects who require substrate modification beyond pulmonary vein isolation (PVI). The objective was to determine correlations between pre-ablation mapping characteristics and 12-month outcomes after a single PVI-only catheter ablation of AF. METHODS AND RESULTS: This study enrolled paroxysmal AF (PAF), early persistent AF (PsAF; 7 days-3 months), and non-early PsAF (>3-12 months) subjects undergoing de novo PVI-only radiofrequency catheter ablation. Sinus rhythm (SR) and AF voltage maps were created with the Advisor HD Grid™ Mapping Catheter, Sensor Enabled™ for each subject, and the presence of low-voltage area (LVA) (low-voltage cutoffs: 0.1-1.5 mV) was investigated. Follow-up visits were at 3, 6, and 12 months, with a 24-h Holter monitor at 12 months. A Cox proportional hazards model identified associations between mapping data and 12-month recurrence after a single PVI procedure. The study enrolled 300 subjects (113 PAF, 86 early PsAF, and 101 non-early PsAF) at 18 centres. At 12 months, 75.5% of subjects were free from AF/atrial flutter (AFL)/atrial tachycardia (AT) recurrence. Univariate analysis found that arrhythmia recurrence did not correlate with AF diagnosis, but LVA was significantly correlated. Low-voltage area (<0.5 mV) >28% of the left atrium in SR [hazard ratio (HR): 4.82, 95% confidence interval (CI): 2.08-11.18; P = 0.0003] and >72% in AF (HR: 5.66, 95% CI: 2.34-13.69; P = 0.0001) was associated with a higher risk of AF/AFL/AT recurrence at 12 months. CONCLUSION: Larger extension of LVA was associated with an increased risk of arrhythmia recurrence. These subjects may benefit from substrate modification beyond PVI.

Confirmation of the achievement of linear lesions using "activation vectors" based on omnipolar technology.

BACKGROUND: Although differential pacing conventionally has been used to confirm the achievement of block across linear lesion sets, high-resolution mapping demonstrates that pseudo-block is observed in 20%-30% of cases. OBJECTIVES: The purpose of this study was to examine the reliability and versatility of a method using "activation vectors" based on omnipolar technology to confirm the block line. METHODS: Linear ablation was performed during pacing, with the HD Grid catheter (Abbott) placed beside the linear lesion opposite the pacing site. The endpoint of complete linear lesion was complete inversion of the activation vectors to the opposite direction. When inversion of the activation vectors was not observed after 10 minutes of radiofrequency (RF) application, high-resolution mapping was performed to assess whether complete block was achieved. RESULTS: In 33 patients, 24 cavotricuspid isthmus lines, 11 mitral isthmus (MI) lines, 16 posterior lines, and 2 intercaval lines were performed using this method. Of the total of 53 lines, 10 (18.9%) required intermediate evaluation of the block line with high-resolution mapping because of the absence of inversion of activation vectors despite 10 minutes of RF application, resulting in incomplete block with endocardial gaps or epicardial conductions. Additional RF applications finally achieved inversion in direction of activation vectors in the 10 lines. In total, the present method can diagnose achievement of complete block line with 100% accuracy, whereas conventional differential pacing misdiagnosed incomplete block with epicardial conduction in posterior lines in 3 cases and in MI lines in 2 cases. CONCLUSION: Confirmation of complete linear lesions using "activation vectors" based on omnipolar technology is a reliable and versatile method.

A simplified differential pacing technique for the evaluation of bidirectional cavo-tricuspid isthmus block during ablation of typical atrial flutter.

PURPOSE: Bidirectional block of the cavo-tricuspid isthmus (CTI) is an established endpoint of CTI-dependent atrial flutter (AFl) ablation. Differential pacing has been used to evaluate the CTI block. The purpose of this study is to describe a modified differential pacing technique to evaluate the CTI block. METHODS: Sixty-two patients underwent radiofrequency (RF) ablation of CTI-dependent AFl. The acute endpoints were non-inducibility of the AFl, and verification of the bidirectional CTI block by our methodology. Pacing was performed in the CS with an ablation catheter positioned immediately lateral to the CTI ablation line, and then 1-2 cm more laterally. The stimulus-to-ablation catheter atrial electrogram intervals were measured at these sites (StimCS-Abl1 and StimCS-Abl2, respectively). Pacing with the ablation catheter also was performed at these 2 sites, and the stimulus-to-CS electrogram intervals (StimABL1-CS and StimABL2-CS) were measured. The criteria for the bidirectional block were StimCS-Abl1 > StimCS-Abl2, and StimABL1-CS > StimABL2-CS. Clinical efficacy was defined as freedom from recurrent AFl during follow-up. RESULTS: Following 12.2 ± 3.7 min of RF delivery across the CTI, intervals were StimCS-Abl1 = 181.2 ± 22.7 ms and StimABL1-CS = 181.0 ± 23.6 ms, and StimCS-Abl2 = 152.2 ± 26.5 ms and StimABL2-CS = 151.2 ± 22.7 (P < 0.001). Atrial flutter was rendered not inducible in all patients, and no procedural complications were encountered. During the next 15.9 ± 0.7 months, two patients were lost to follow-up, and among the 62 other patients, one (1.7%) had flutter recurrence. CONCLUSIONS: The bidirectional CTI block can be assessed quickly and easily using only the ablation and CS catheters for differential pacing.

Spectrum of arrhythmogenic substrate post minimally invasive maze surgery in patients with recurrent.

BACKGROUND: Advancements in minimally invasive surgical ablation (MISA) have focused on improving pulmonary vein isolation. Additional ablation targets have been developed (such as posterior wall isolation). The mid- and long-term effects of current techniques (including electrophysiologic findings and recurrent arrhythmia mechanisms) have not previously been reported. METHODS: Twenty eight patients with recurrent atrial arrhythmias after bipolar clamp ablation of the pulmonary vein antrum, ganglionated plexi, posterior wall isolation (roof and floor lines to create a posterior box), and ligament of Marshall ligation/cauterization and left atrial appendage clipping underwent follow up electrophysiology study including left atrial mapping an average of 2.3 years postoperatively. RESULTS: Atrial fibrillation was the most common recurrent arrhythmia (n = 18) followed by micro-reentrant atrial tachycardia (n = 5), macro-reentry left atrial flutter (n = 3), and typical cavo-tricuspid isthmus atrial flutter (n = 2). Eighty six of 112 (77%) PVs mapped were electrically isolated, 16 (57%) patients had all four pulmonary veins (PVs) isolated. The posterior wall (PW) was completely isolated in only four (14%) patients, seven (25%) patients had normal PW voltage, while 17 (61%) patients had abnormal delayed or fractionated electrograms in the posterior wall (incomplete isolation). Abnormal PW electrograms were more frequently found in patients with complex recurrent left atrial arrhythmia (micro-reentry or left atrial macro-reentry flutter). CONCLUSION: With current surgical techniques PV isolation has improved, but PW isolation remains challenging. Incomplete PW isolation may produce arrhythmogenic substrate.

Electrophysiological characteristics of epicardial to endocardial breakthrough in intractable cavotricuspid isthmus-dependent atrial flutter.

BACKGROUND: Epicardial to endocardial breakthrough (EEB) exists widely in atrial arrhythmia and is a cause for intractable cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL). This study aimed to investigate the electrophysiological features of EEB in EEB-related CTI dependent AFL. METHODS: Six patients with EEB-related CTI-dependent AFL were identified among 142 consecutive patients who underwent CTI-dependent AFL catheter ablation with an ultra-high-density, high-resolution mapping system in three institutions. Activation maps and ablation procedure were analyzed. RESULTS: A total of seven EEBs were found in six patients. Four EEBs (including three at the right atrial septum and one in paraseptal isthmus) were recorded in three patients during tachycardia. The other three EEBs were identified at the inferolateral right atrium (RA) during pacing from the coronary sinus. The conduction characteristics through the EEB-mediated structures were evaluated in three patients. Two patients only showed unidirectional conduction. Activation maps indicated that CTI-dependent AFL with EEB at the atrial septum was actually bi-atrial macro-reentrant atrial tachycardia (BiAT). Intensive ablation at the central isthmus could block CTI bidirectionally in four cases. However, ablation targeted at the inferolateral RA EEB was required in two cases. Meanwhile, local potentials at the EEB location gradually split into two components with a change in activation sequence. CONCLUSIONS: EEB is an underlying cause for intractable CTI-dependent AFL. EEB-mediated structure might show unidirectional conduction. CTI-dependent AFL with EEB at the atrial septum may represent BiAT. Intensive ablation targeting the central isthmus or EEB at the inferolateral RA could block the CTI bidirectionally.

Hypnosis Versus Placebo During Atrial Flutter Ablation: The PAINLESS Study: A Randomized Controlled Trial.

OBJECTIVES: The aim of this study was to assess the superiority of hypnosis versus placebo on pain perception and morphine consumption during typical atrial flutter (AFL) ablation. BACKGROUND: AFL ablation commonly requires intravenous opioid for analgesia, which can be associated with adverse outcomes. Hypnosis is an alternative technique with rising interest, but robust data in electrophysiological procedures are lacking. METHODS: This single center, randomized controlled trial compared hypnosis and placebo during AFl ablation. In addition to the randomized intervention, all patients were treated according to the institution's standard of care analgesia protocol (administration of 1 mg of intravenous morphine in case of self-reported pain ≥5 on an 11-point numeric rating scale or on demand). The primary endpoint was perceived pain quantified by patients using a visual analog scale. RESULTS: Between October 2017 and September 2019, 113 patients (mean age 70 ± 12 years, 21% women) were randomized to hypnosis (n = 56) or placebo (n = 57). Mean pain score was 4.0 ± 2.2 in the hypnosis group versus 5.5 ± 1.8 in the placebo group (p < 0.001). Pain perception, assessed every 5 min during the whole procedure, was consistently lower in the hypnosis group. Patients' sedation scores were also better in the hypnosis group than in the placebo group (8.3 ± 2.2 vs. 5.4 ± 2.5; p < 0.001). Finally, morphine requirements were significantly lower in the hypnosis group (1.3 ± 1.3 mg) compared with the placebo group (3.6 ± 1.8 mg; p < 0.001). CONCLUSIONS: In this first randomized trial, hypnosis during AFL ablation was superior to placebo for alleviating pain and reducing morphine consumption.

Electrophysiological findings in patients with isolated veins after cryoablation for paroxysmal atrial fibrillation.

AIMS: The main cause of atrial fibrillation recurrence after catheter ablation is pulmonary vein reconnection. The purpose of this retrospective study was to analyse the electophysiological findings in patients undergoing repeat procedures after an index cryoballoon ablation (CB-A) and presenting with permanency of pulmonary vein isolation (PVI) in all veins. In addition, we sought to compare the latter with a similar group of patients with reconnected veins at the redo procedure. METHODS: A total of 132 patients (81 men, 60.7 ±â€Š12.4 years) who underwent CB-A for paroxysmal atrial fibrillation (PAF) were enrolled. Indication for the redo procedure was symptomatic PAF in 83 (63%), persistent atrial fibrillation (PerAF) in 32 (24%) or persistent regular atrial tachycardia (RAT) in 17 (13%) patients. RESULTS: Seventy-five (57%) patients presented a pulmonary vein reconnection (pulmonary vein group) during the redo procedure, whereas 57 (43%) had no pulmonary vein reconnection (non-pulmonary vein group). The non-pulmonary vein group exhibited significantly more non-pulmonary vein foci and atrial flutters than the pulmonary vein group after induction protocol (51 vs. 24%, P = 0.002 and 67 vs. 36%, P = 0.003, respectively). Twenty-two (29.3%) patients of the pulmonary vein group and 20 (35%) patients of the non-pulmonary vein group had atrial fibrillation/RAT recurrence after a mean follow-up of 12.5 ±â€Š8 months. The survival analysis demonstrated no statistical significance in recurrence between both groups (log rank P = 0.358). CONCLUSION: Atrial fibrillation/RAT recurrence in patients after CB-A with durable PVI is significantly associated with non-pulmonary vein foci and atrial flutters. No statistically different success rate regarding atrial fibrillation/RAT freedom was detected between the pulmonary vein and non-pulmonary vein groups after redoing RF-CA.

Mapping potentials adjacent to the cavo-tricuspid isthmus ablation line during incremental pacing: A feasible and highly accurate maneuver to confirm complete CTI conduction block.

BACKGROUND: The diagnostic accuracy of incremental atrial pacing (IP) to determine complete cavo-tricuspid isthmus (CTI) block during typical atrial flutter (AFL) ablation is limited by both an extensive/nonlinear ablation and/or the presence of intra-atrial conduction delay elsewhere in the right atrium. We examined the diagnostic performance of an IP variant based on the assessment of the atrial potentials adjacent to the ablation line which aims at overcoming both limitations. METHODS: From a prospective population of 108 consecutive patients, 15 were excluded due to observation of inconclusive CTI ablation potentials precluding for a straight comparison between the IP maneuver and its variant. In the remaining 93, IP was performed from the low lateral right atrium and the coronary sinus ostium, with the ablation catheter positioned both at the CTI line and adjacent (<5 mm) to its septal and lateral aspect. The IP variant consisted of measuring the interval between the two atrial electrograms situated on the same side of the ablation line, opposite to the pacing site, a ≤10 ms increase indicating complete CTI block. RESULTS: The IP maneuver and its variant were consistent with complete CTI block in 82/93 (88%) and 87/93 (93%) patients, respectively. Four patients had AFL recurrence during follow-up: 2/4 and 4/4 had been adequately classified as incomplete block by the IP maneuver and its variant, respectively. Twenty-three patients (24%) had significant intra-atrial conduction delay elsewhere in the right atrium. The IP maneuver and its variant were suggestive of an incomplete CTI block in 11/23 and 4/23 in this setting (P = .028), with the later best predicting subsequent AFL relapses (2/12 vs 2/4, P = .01). CONCLUSIONS: The IP variant, which was designed to overcome the limitations of the conventional IP maneuver, accurately distinguishes complete from incomplete CTI block and helps to predict AFL recurrences after ablation.

Predictors of zero X ray procedures in supraventricular arrhythmias ablation.

To evaluate predictors of zero-X ray procedures for supraventricular arrhythmias (SVT) using minimally fluoroscopic approach (MFA). Patients referred for RF catheter ablation of SVT were admitted for a MFA with an electro-anatomical navigation system or a conventional fluoroscopic approach (ConvA). Exclusion criterion was the need to perform a transseptal puncture. 206 patients (98 men, age 53 ± 19 years) underwent an EP study, 93 (45%) with an MFA and 113 (55%) with a ConvA. Fifty-five had no inducible arrhythmias (EPS). Fifty-four had AV nodal reentrant tachycardia (AVNRT), 49 patients had typical atrial flutter (AFL), 37 had AV reciprocating tachycardia (AVRT/WPW), 11 had focal atrial tachycardia (AT), and underwent a RF ablation. X-ray was not used at all in 51/93 (58%) procedures (zero X ray). MFA was associated with a significant reduction in total fluoroscopy time (5.5 ± 10 vs 13 ± 18 min, P = 0.01) and operator radiation dose (0.8 ± 2.5 vs 3 ± 8.2 mSV, P < 0.05). The greatest absolute dose reduction was observed in AVNRT (0.1 ± 0.3 vs 5.1 ± 10 mSV, P = 0.01, 98% relative dose reduction) and in AFL (1.3 ± 3.6 vs 11 ± 16 mSV, P = 0.003, 88% relative dose reduction) groups. Both AVNRT or AFL resulted the only statistically significant predictors of zero x ray at multivariate analysis (OR 4.5, 95% CI 1.5-13 and OR 5, 95% CI 1.7-15, P < 0.001, respectively). Success and complication rate was comparable between groups (P = NS). Using MFA for SVT ablation, radiological exposure is significantly reduced. Type of arrhythmia is the strongest predictor of zero X ray procedure.

Electrogram voltage and pacing threshold before ablation, measured by mini-electrodes, predict parameters indicative of transmural lesions in the human atrium.

PURPOSE: An important attenuation of the atrial signal recorded with mini-electrodes (ME) embedded in an 8-mm tip was associated with a transmural radiofrequency lesion. Our aim was to assess if parameters obtained from ME or conventional bipoles before applications predict successful atrial lesions. METHODS: We prospectively included 33 consecutive patients undergoing cavotricuspid isthmus (CTI) ablation. Electrogram voltages and pacing thresholds were measured with ME and conventional bipoles before and after radiofrequency (RF) applications. The time before the loss of capture during applications was recorded. Lesions were considered successful, in accordance with preclinical data, if ME voltage decreased > 54%. RESULTS: Of 207 applications, 107 could be analyzed. During applications, voltages decreased more in the ME than in the conventional bipoles (66.8 ± 26.1% vs 37.5 ± 42.5%, P = 0.001). Likewise, pacing threshold increased significantly more using the ME (86.3 ± 22.9% ME, 52.6 ± 35.6% conventional, P = 0.001). ME pre-ablation voltages were significantly higher and pacing thresholds significantly lower in successful lesions (voltage 0.88 ± 0.71 vs 0.26 ± 0.18 mV, P = 0.0001; threshold 1.6 ± 1.7 vs 2.8 ± 3.0, P = 0.04). Neither of these parameters with conventional bipoles nor time to loss of capture showed differences. A ME voltage > 0.33 mV and a pacing threshold < 1.5 mA predicted a successful lesion with 0.78 and 0.6 sensitivity and 0.78 and 0.59 specificity. CONCLUSIONS: Certain pre-ablation parameters derived from ME such as electrogram voltage and pacing threshold differ from those obtained by a conventional configuration and can predict a successful atrial lesion.

Use of the cryoballoon to ablate pulmonary vein-dependent left atrial flutter.

New atrial flutter (AFL) that arises after pulmonary vein isolation (PVI) by catheter or surgical ablation can originate from reconnection of a pulmonary vein (PV). Reisolation of PVs with cryoballoon ablation (CBA) for treatment of peri-PV AFL after Maze or PVI has not previously been reported. The present case series describes use of CBA to treat post-PVI and post-Maze PV-dependent AFL. In these cases, CBA was used to reisolate the PVs and terminate AFL without requiring additional lesion sets for treatment of AFL.

A constant postpacing interval in response to overdrive pacing with variable number of beats: An aid in the identification of entrainment for a particular pacing train during macroreentrant atrial tachycardias.

BACKGROUND: When pacing trains with a constant cycle length (CL) but increasing number of beats are introduced during a macroreentrant atrial tachycardia (MAT), the postpacing interval (PPI) is expected to increase if entrainment does not occur but could be stable if entrainment occurs. We tested the ability of PPI analysis to detect entrainment. METHODS: Synchronized pacing trains with increasing number of beats (1-20) were delivered from the coronary sinus (CS) and lateral right atrium (RA) at a CL 20 ms shorter than the MAT CL. Pacing trains were grouped in pairs differing by one-paced beat, and the ∆PPI measured. RESULTS: In an initial prospective cohort of 21 patients (48% had left atrial flutter) the mean ∆PPI was 21.3 ± 5.6 ms for pairs of pacing trains in which neither entrained the MAT and 2.8 ± 1.4 ms for those in which both entrained the MAT (P < .0001). Results were similar for common vs atypical flutter, PPI-TCL ≤30 ms vs PPI-TCL >30 ms, presence vs absence of antiarrhythmic drugs and faster vs slower MAT. When an index pacing train was compared to one with two-paced beats less, a PPI difference of <19 ms identified entrainment with 95% sensitivity and 98% specificity. In a validation cohort of 16 patients, this cut-off value resulted in sensitivity and specificity of 90% and 94%. CONCLUSIONS: A relatively constant ∆PPI in response to overdrive pacing with identical CL but different number of beats allows accurate discrimination between trains that entrained vs those which did not entrain a MAT.

From near-zero to zero fluoroscopy catheter ablation procedures.

AIMS: The use of electroanatomical mapping (EAM) systems can reduce radiation exposure (RX) and it can also completely eliminate the use of RX. Radiation exposure related to conventional radiofrequency ablation procedures can have a stochastic and deterministic effect on health. The main aim of this study was to evaluate the safety and feasibility of an entirely nonfluoroscopic approach to catheter ablation (CA) using EAM CARTO3. METHODS: In 2011 we started an RX-minimization programme in all procedures using the CARTO system with the deliberate intention to not resort to the aid of RX unless strictly necessary. We divided procedures into two groups (group 1: from 2011 to 2013; group 2: from 2014 to 2017). The only exclusion criteria were the need for transseptal puncture, and nonidiopathic ventricular tachycardia (VT). RESULTS: From a total of 525 procedures, we performed CA entirely without RX in 78.5% of cases. From 2011 to 2013, we performed CA without RX in 38.5% of cases; from 2014 to 2017, we performed 96.2% of cases with zero RX. The use of RX was significantly reduced in group 2 (group 2: 1.4 ± 19.6 seconds vs group 1: 556.92 ± 520.76 seconds; P < .001). These differences were irrespective of arrhythmia treatment. There were no differences between the two groups in acute success, complications, or duration of procedures. CONCLUSION: CA of supraventricular tachycardia and VT entirely without RX, guided by the CARTO system, is safe, feasible, and effective. After an adequate learning curve, CA can be performed entirely without RX.

Achieving durable mitral isthmus block: Challenges, pitfalls, and methods of assessment.

BACKGROUND AND OBJECTIVES: Macroreentrant atrial tachycardias often occur following atrial fibrillation ablation, most commonly due to nontransmural lesions in prior ablation lines. Perimitral atrial flutter is one such arrhythmia which requires ablation of the mitral isthmus. Our objectives were to review the literature regarding ablation of the mitral isthmus and to provide our approach for assessment of mitral isthmus block. METHODS: We review anatomical considerations, ablation strategies, and assessment of conduction block across the mitral isthmus, which is subject to several pitfalls. Activation sequence and spatial differential pacing techniques are discussed for assessment of both endocardial and epicardial bidirectional mitral isthmus block. RESULTS: Traditional methods for verifying mitral isthmus block include spatial differential pacing, activation mapping, and identification of double potentials. Up to 70% of cases require additional ablation in the coronary sinus (CS) to achieve transmural block. Interpretation of transmural block is subject to six pitfalls involving pacing output, differentiation of endocardial left atrial recordings from epicardial CS recordings, identification of a slowly conducting gap in the line, and catheter positioning during spatial differential pacing. Interpretation of unipolar electrograms can identify nontransmural lesions. We employ a combined epicardial and endocardial assessment of mitral isthmus block, which involves using a CS catheter for epicardial recording and a duodecapolar Halo catheter positioned around the mitral annulus for endocardial recording. CONCLUSIONS: The assessment of transmural mitral isthmus block can be challenging. Placement of an endocardial mapping catheter around the mitral annulus can provide a precise assessment of conduction across the mitral isthmus.