Multielectrode Basket Catheter Research Articles

Impact of number of co-existing rotors and inter-electrode distance on accuracy of rotor localization

BackgroundConflicting evidence exists on the efficacy of focal impulse and rotor modulation on atrial fibrillation ablation. A potential explanation is inaccurate rotor localization from multiple rotors coexistence and a relatively large (9–11mm) inter-electrode distance (IED) of the multi-electrode basket catheter. Methods and resultsWe studied a numerical model of cardiac action potential to reproduce one through seven rotors in a two-dimensional lattice. We estimated rotor location using phase singularity, Shannon entropy and dominant frequency. We then spatially downsampled the time series to create IEDs of 2–30mm. The error of rotor localization was measured with reference to the dynamics of phase singularity at the original spatial resolution (IED=1mm). IED has a significant impact on the error using all the methods. When only one rotor is present, the error increases exponentially as a function of IED. At the clinical IED of 10mm, the error is 3.8mm (phase singularity), 3.7mm (dominant frequency), and 11.8mm (Shannon entropy). When there are more than one rotors, the error of rotor localization increases 10-fold. The error based on the phase singularity method at the clinical IED of 10mm ranges from 30.0mm (two rotors) to 96.1mm (five rotors). ConclusionsThe magnitude of error of rotor localization using a clinically available basket catheter, in the presence of multiple rotors might be high enough to impact the accuracy of targeting during AF ablation. Improvement of catheter design and development of high-density mapping catheters may improve clinical outcomes of FIRM-guided AF ablation.

Ablation as targeted perturbation to rewire communication network of persistent atrial fibrillation.

Persistent atrial fibrillation (AF) can be viewed as disintegrated patterns of information transmission by action potential across the communication network consisting of nodes linked by functional connectivity. To test the hypothesis that ablation of persistent AF is associated with improvement in both local and global connectivity within the communication networks, we analyzed multi-electrode basket catheter electrograms of 22 consecutive patients (63.5 ± 9.7 years, 78% male) during persistent AF before and after the focal impulse and rotor modulation-guided ablation. Eight patients (36%) developed recurrence within 6 months after ablation. We defined communication networks of AF by nodes (cardiac tissue adjacent to each electrode) and edges (mutual information between pairs of nodes). To evaluate patient-specific parameters of communication, thresholds of mutual information were applied to preserve 10% to 30% of the strongest edges. There was no significant difference in network parameters between both atria at baseline. Ablation effectively rewired the communication network of persistent AF to improve the overall connectivity. In addition, successful ablation improved local connectivity by increasing the average clustering coefficient, and also improved global connectivity by decreasing the characteristic path length. As a result, successful ablation improved the efficiency and robustness of the communication network by increasing the small-world index. These changes were not observed in patients with AF recurrence. Furthermore, a significant increase in the small-world index after ablation was associated with synchronization of the rhythm by acute AF termination. In conclusion, successful ablation rewires communication networks during persistent AF, making it more robust, efficient, and easier to synchronize. Quantitative analysis of communication networks provides not only a mechanistic insight that AF may be sustained by spatially localized sources and global connectivity, but also patient-specific metrics that could serve as a valid endpoint for therapeutic interventions.

Onset of Reentrant Ventricular Tachycardia Modulated by Variable Impulse Propagation through the Zone of Slow Conduction

We report an 18-year-old woman, who had undergone surgical repair of tetralogy of Fallot, and then underwent successful intracardiac recordings within the zone of slow conduction (ZSC) of the reentry circuit on the initiation of premature ventricular contractions (PVC) and reentrant ventricular tachycardia (VT), obtained with multielectrode basket catheter. PVC a) were caused by wavefronts of sinus cycles entering and exiting the ZSC, and b) were not repetitive because the wavefront of the PVC could not reenter the ZSC. Similarly, VT developed after delayed potentials of sinus cycles, and was sustained because the wavefront following the 1st cycle of VT was able to repetitively reenter and exit the ZSC. Thus, spontaneous changes in the conductivity of the ZSC, like an on-off switch, appeared to determine the onset and sustenance of reentrant VT.

Usage of spline interpolation in catheter-based cardiac mapping

Due to their minimal invasiveness catheters are highly preferred in cardiac mapping techniques used in the source localization of rhythm disturbances in the heart. In cardiac mapping, standard steerable catheters and multielectrode basket catheters are the two alternatives for the characterization of the underlying tissue on the inner (endocardium) and outer (epicardium) surfaces of the heart. As with any discrete sampling technique, an important question for catheter-based cardiac mapping is how to determine values at locations from which direct measurements are not available. Interpolation is the most common approach for providing values at unmeasured sites using the available measurements. In this study, the usage of spline interpolation technique in catheter-based cardiac mapping was introduced for the first time in the literature and compared with the existing approaches such as the nearest-neighbor, Laplacian, and Hardy's interpolation techniques. For different sampling resolutions on the endocardium and epicardium, we reconstructed the activation-time values on unmeasured sites using measured values. To provide quantitative validation, we have applied these methods to high resolution simulated activation-time values from a realistic heart model using Aliev-Panfilov mathematical modeling approach. The results show that spline, Laplacian, and Hardy interpolation methods performed successfully and also better than nearest-neighbor method. Among all interpolation schemes except for the nearest-neighbor method the average correlation coefficient (CC) values were greater than 0.985.

Purkinje activation precedes myocardial activation following defibrillation after long-duration ventricular fibrillation

While reentry within the ventricular myocardium (VM) is responsible for the maintenance of short-duration ventricular fibrillation (SDVF; VF duration <1 minute), Purkinje fibers (PFs) are important in the maintenance of long-duration ventricular fibrillation (LDVF; VF duration >1 minute). The purpose of this study was to test the hypothesis that the mechanisms of defibrillation may also be different for SDVF and LDVF. A multielectrode basket catheter was deployed in the left ventricle of eight beagles. External defibrillation shocks were delivered with a ramp-up protocol after SDVF (20 seconds) and LDVF (150 seconds). Earliest VM and PF activations were identified after the highest energy shock that failed to terminate VF and the successful shock. Defibrillation was successful after 36 +/- 12 and 181 +/- 14 seconds for SDVF and LDVF, respectively. The time after shock delivery until earliest activation was detected for failed shocks and was significantly longer after LDVF (138.7 +/- 24.1 ms) than after SDVF (75.6 +/- 8.7 ms). Earliest postshock activation after SDVF typically initiated in the VM (14 of 16 episodes), while it always initiated in the PF (16 of 16 episodes) after LDVF. Sites of earliest activity during sinus rhythm correlated with sites of earliest postshock activation for PF-led cycles but not for VM-led cycles. Earliest recorded postshock activation is in the Purkinje system after LDVF but not after SDVF. This difference raises the possibility that the optimal defibrillation strategy is different for SDVF and LDVF.

Vagal Modification Can Also Help Prevent Late Recurrence of Atrial Fibrillation After Segmental Pulmonary Vein Isolation

The relationship between vagal modification and paroxysmal atrial fibrillation (PAF) recurrence after segmental pulmonary vein (PV) isolation (S-PVI) was investigated. S-PVI was performed in 77 PAF patients using a multielectrode basket or circular catheter to achieve electrical disconnection of all 4 PVs independent of eliminating vagal reflexes. Serial Holter-recordings were obtained at baseline, immediately and 1, 3, 6, and 12 months after S-PVI to analyze the heart rate variability. Fifty-one patients were free from symptomatic PAF (Group A) and 26 had late PAF recurrences (Group B) at 12-month follow-up. Immediately after S-PVI, the root mean square of the successive differences (rMSSD) and high-frequency (HF) power, which reflected parasympathetic nervous activity, were significantly lower in Group A than in Group B (rMSSD: 33.6+/-26.0 vs 60.6+/-23.2 ms, P<0.05; ln HF: 8.73+/-0.84 vs 9.31+/-0.95 ms2, P<0.05). There were no significant differences in the average heart rate or ratio of the low-frequency to HF powers between the 2 groups. By multivariate analysis, only the HF immediately after S-PVI was an independent predictor of PAF recurrence (hazard ratio 1.707, 95% confidence interval 1.057-2.756, P<0.05). Vagal modification after S-PVI could also help prevent late recurrence of PAF.

ST Segment Changes Associated with the Use of a Multi-Electrode Basket Catheter during Atrial Fibrillation Ablation

ST Segment Changes Associated with the Use of a Multi-Electrode Basket Catheter during Atrial Fibrillation Ablation

Abstract 642: Effect of Acute and Chronic Stretch on the Pulmonary Veins in Humans: Implications for Arrhythmogenic Triggers

Introduction Stretch is characteristic of most conditions predisposed to atrial fibrillation (AF). However, there is no human data on effect of atrial stretch on pulmonary veins (PV), the dominant trigger of AF Method Two groups were studied; Group A (n=12; 31±7 yrs) undergoing left sided accessory pathway ablation and Group B (n=12; 29±7 yrs) undergoing percutaneous valvuloplasty for mitral stenosis (MVA 0.9±0.3 cm 2 ). Multi-electrode basket catheter was positioned in the PVs to perform high-density mapping using NavX system to determine: proximal/ distal effective refractory period (ERP); conduction time (CT); intra-PV conduction block (CB; ≥30ms between adjacent poles) resulting in circuitous conduction during the drive (S 1 ) and pre-excited stimulus (S 2 ); and intra-PV voltage. Effect of acute stretch was determined in Group A by simultaneous RV and PV pacing and chronic stretch in Group B Results Twenty-four PVs were studied in each group. Acute stretch (Group A) resulted in ERP shortening (240±33 to 225±39 ms; p=0.03), prolonged CT with S 2 , which increased further with stretch (77±30 to 88±37ms; p=0.02). Intra-PV CB became prominent with S 2 and accentuated with stretch (40±23 to 59±32ms; p&lt;0.0001). The changes were not site specific. Left atrial volume (p=0.001) and pressure (p=0.04) were elevated in Group B. Unlike acute stretch, ERP was prolonged, conduction delayed in sinus rhythm (p=0.005) and S 1 which further accentuated with S 2 (refer Table ). Intra-PV CB was seen at S 2 . Additionally, mean bipolar voltage was reduced (0.8[0.3–3.5] mV vs 1.4[0.8–3.7] mV; p=0.005) Conclusion Acute stretch results in abbreviation of PV ERP while chronic prolongs it. Nevertheless, both cause marked PV conduction abnormalities that are pronounced with chronic stretch and extra-stimuli. Additionally, structural remodeling was seen with chronic stretch. These abnormalities implicate stretch in the milieu for re-entry and PV arrhythmogenesis in conditions predisposed to AF Electrophysiological characteristics

Non‐Pulmonary Vein Epicardial Foci of Atrial Fibrillation Identified in the Left Atrium after Pulmonary Vein Isolation

Pulmonary vein (PV) isolation (PVI) has been demonstrated to be an effective technique for curing atrial fibrillation (AF). AF foci that cannot be isolated by PVI (non-PV foci) can become the cause of AF recurrence. The purpose of this study was to investigate the characteristics of non-PV AF foci. Two hundred consecutive patients with symptomatic AF underwent electrophysiologic studies. In all patients, successful ostial or antral PVI was achieved with a multielectrode basket catheter (MBC). In 45 patients, spontaneous AF was induced even after PVI. In 23 of those patients, 30 AF foci were found in the left atrium (LA) (12 in the PV antrum, and 18 in the LA wall). Twenty-six of those foci were eliminated by focal ablation guided by an MBC. Five of those foci (four in the PV antrum and one in the LA posterior wall) were speculated to be located epicardially because a small potential preceding the LA potential was recorded from the MBC electrodes during AF initiation at the successful ablation site where single large potentials were recorded during sinus rhythm and a longer duration of radiofrequency energy delivery was needed to eliminate them. MBC mapping with induction of spontaneous AF may be useful for identifying non-PV AF foci in the LA after PVI. In some of those non-PV foci, mainly around the PVI lesions, a few electrophysiologic findings suggesting an epicardial location were observed. This may be a rationale for the efficacy of extensive PV ablation.

Successful ablation of atrioventricular node reentry tachycardia in a patient with crisscross heart and situs inversus levocardia

Crisscross heart is a complex congenital anomaly that is rarely seen in the absence of important associated structural defects. We describe a 41-year-old woman with recurrent dizziness and tachycardia but no previous cardiovascular symptoms. Narrow-QRS tachycardia was detected, and magnetic resonance imaging showed situs inversus levocardia with a circulatory pattern typical of crisscross heart. Electrophysiologic study revealed atypical atrioventricular (AV) node reentry tachycardia of the "fast-slow" type. Despite the unusual anatomy, we successfully modified the AV node physiology by ablating the "slow AV node inputs" with the guidance of a multielectrode basket catheter in the anatomic right atrium.

Pulmonary Vein Antrum Not Always Coaxial to the Pulmonary Vein A Dimensional Pitfall to the Circumferential Isolation Technique

The dimensions and electrophysiological characteristics of the antral region of human pulmonary veins (PVs) were investigated. Fifty-five consecutive patients with symptomatic paroxysmal atrial fibrillation underwent PV isolation targeting the PV antrum potentials with a 31 mm multielectrode basket catheter (MBC). The most distal and proximal electrode pairs along the MBC spline where radiofrequency ablation was carried out were identified and the longitudinal distance between those ablation sites (Ld) was measured. When the Ld was > or =6 mm, the PV antrum was defined as noncoaxial. In 56% of the left superior PVs, 42% of the right superior PVs, 63% of the left inferior PVs and 56% of the right inferior PVs, a noncoaxial PV antrum was identified. In each PV, the radiofrequency ablation delivery duration and energy to complete the PV antrum isolation were significantly larger in the PVs with a noncoaxial PV antrum than in those with a coaxial PV antrum. The PV antrum is noncoaxial to the PV in >50% of the PVs, a feature that may increase the complexity of the circumferential isolation technique.

Descriptors of wavefront propagation

This article presents two signal processing techniques for the analysis of intracardial electrograins in patients with atrial fibrillation (AF). The first, number of occurrences (NO), is aimed at quantifying the level of organization of the signal. The second, index of synchronization (IS), quantifies the degree of synchrony of electrograms from adjacent atrial sites. The proposed indexes are applied to multielectrode basket catheter recordings in patients with chronic or electrically induced AF

Electrophysiological pulmonary vein antrum isolation with a multielectrode basket catheter is feasible and effective for curing paroxysmal atrial fibrillation: Efficacy of minimally extensive pulmonary vein isolation

How extensive should an appropriate pulmonary vein (PV) ablation be is a matter of controversy. The study's aim was to investigate the efficacy of minimally extensive PV ablation for isolating the PV antrum (PVA) with the guidance of electrophysiological parameters. Fifty-five consecutive symptomatic paroxysmal atrial fibrillation (PAF) patients underwent PV mapping with a multielectrode basket catheter (MBC). A 31-mm MBC was deployed in 3-4 PVs as proximally as possible without dislodgement, and the longitudinal PV mapping enabled us to recognize single sharp potentials formed by the total fusion of the PV and left atrial potentials around the PV ostium or the transverse activation patterns that were observed. Those potentials were defined as PVA potentials. Radiofrequency ablation was performed circumferentially targeting PVA potentials with the end point being their elimination. After circumferential PVA ablation, electrical disconnection was achieved in 77% and residual PVA conduction gaps were observed in 23% of all targeted PVs. Those residual conduction gaps were mainly located at the border between ipsilateral PVs (42%) and between the left PVs and left atrial appendage (33%) and were eliminated by a mean of 3 +/- 2 minutes of local radiofrequency deliveries. During the follow-up period (11 +/- 5 months), 46 (84%) patients were free of symptomatic PAF without any anti-arrhythmic drugs. No PV stenosis or spontaneous left atrial flutter occurred. Electrophysiological PVA ablation with an MBC is feasible and effective for curing PAF because this minimally extensive PVA isolation technique targets the optimal sites, achieving both high efficacy and safety.

New Approach to Pulmonary Vein Isolation for Atrial Fibrillation Using a Multielectrode Basket Catheter

Pulmonary vein (PV) isolation using a circular catheter creates an entrance block from the left atrium (LA) to the PV, which eliminates paroxysmal atrial fibrillation (PAF). A new approach to PV isolation during distal PV pacing is to use a basket catheter. Fifty consecutive patients with PAF underwent basket-catheter-guided PV isolation. PV pacing was performed from the distal electrode pair of the basket catheter. The exit breakthrough point was targeted for segmental PV isolation. The endpoint was the elimination of bidirectional PV - LA conduction. A repeat ablation procedure was performed in 12 of 14 patients who had recurrence of AF. The recovery of PV -LA conduction was noted in 24 of the 48 PVs, and 5 PVs (21%) had unidirectional block. At 12 months, 80% of patients were free of AF without antiarrhythmic drugs. No PV stenosis >50% was detected at 12 months after the procedure. This new approach for PV isolation during distal PV pacing using a basket catheter is useful for confirming bidirectional PV - LA conduction block. PV isolation that creates not only an entrance block but also an exit block at the PV - LA junction may be required to cure paroxysmal AF.

Mechanisms of Ventricular Fibrillation in Canine Models of Congestive Heart Failure and Ischemia Assessed by In Vivo Noncontact Mapping

Much of the research performed studying the mechanism of ventricular fibrillation (VF) has been in normal ventricles rather than under a pathological condition predisposing to VF. We hypothesized that different ventricular substrates would alter the mechanism and characteristics of VF. Three groups of dogs were studied: (1) control (n=8), (2) pacing-induced congestive heart failure (n=7), and (3) acute ischemia produced by 30 minutes of mid left anterior descending artery ligation (n=5). A noncontact mapping catheter (Ensite 3000, ESI) was placed via transseptal into the left ventricle (LV), along with an electrophysiology catheter. A multielectrode basket catheter (EP Technologies) was placed in the right ventricle, along with an electrophysiology catheter. Several episodes of VF were recorded in each animal. In addition to constructing isopotential and isochronal maps of the VF episodes, signals underwent frequency domain analysis as a fast Fourier transform was performed over a 2-second window every 1 second. From the fast Fourier transform, the dominant frequency was determined, and the organization was calculated. In control dogs, meandering, reentrant spiral wave activity was the main feature of the VF. The congestive heart failure group showed evidence of a stable rotor (n=3), evidence of a focal source (n=3), or no evidence of a driver in the LV (n=1). The ischemic group showed evidence of an initial focal mechanism that transitioned into reentry. In the control and ischemic groups, the LV always had higher dominant frequencies than the right ventricle. Different ventricular substrates produced by the different animal models altered the characteristics of VF. Thus, different mechanisms of VF may be present in the LV, depending on the animal model.

Computerized Three-Dimensional Potential Mapping with a Multielectrode Basket Catheter Can be Useful for Pulmonary Vein Electrical Disconnection

Pulmonary vein (PV) isolation (PVI) has been recently proposed as an effective technique to cure atrial fibrillation (AF). The aim of this study was to investigate the efficacy of a novel technique utilizing a computerized three-dimensional mapping system (QMS2) with a multielectrode basket catheter (MBC) for PVI and to reveal the relation between the style of breakthrough and the network of the PV musculature. Sixty-five consecutive patients with frequent AF attacks underwent PV mapping with a 31-mm MBC, and a three-dimensional color animation of the potential map was constructed by the QMS2. The animation color schema was arranged to minimize the low-amplitude left atrial (LA) potentials and emphasize the high-amplitude PV potentials (PVPs). The longitudinal PVP map enabled us to recognize the true breakthroughs and reveal the network of the PV musculature. A total of 205 PVs (65 left superior PVs, 65 right superior PVs, 57 left inferior PVs and 18 right inferior PVs) were mapped and successful PVI was achieved in all PVs, except one that had no PVPs, with a mean radiofrequency duration of 7 +/- 5 minutes per PV. In about 90% of the PVs, a final radiofrequency application eliminated all the distal PVPs simultaneously because the PVI was performed at the appropriate LA-PV junction. A single segmental breakthrough was detected in 17 PVs, single broad breakthrough in 83 PVs, multiple separate breakthroughs with a distal connection between the PV musculatures extending from each separate breakthrough in 88 PVs and multiple separate breakthroughs without that connection in 16 PVs. During the follow-up period, fifty-one (78%) patients were free of symptomatic AF without any antiarrhythmic drugs after multiple procedures (thirty-three (51%) of those patients after the first procedure) and no PV stenosis was found. Computerized three-dimensional potential mapping can be useful for PVI because it can not only identify the true breakthrough, but can also confirm the elimination of the breakthroughs by the change in the activation sequence through the network of the PV musculature.

1014-211 Activation mapping of pulmonary veins during initiation of atrial fibrillation using a multielectrode basket catheter

1014-211 Activation mapping of pulmonary veins during initiation of atrial fibrillation using a multielectrode basket catheter

Properties of unipolar electrograms recorded with a multielectrode basket catheter

In the past few years, clinical trials with multielectrode “basket” catheters have provided unique recordings from the endocardium of intact in-situ human hearts. Analysis of these recordings is difficult because unipolar electrograms obtained from a basket catheter in the blood-filled cavity differ from those obtained by other mapping techniques such as endocardial balloons used during antiarrhythmic surgery. We investigated these differences using basket catheter recordings obtained in isolated porcine and canine hearts that could be filled with perfusion fluid and evacuated at will. The results indicated that the differences between basket and balloon recordings are largely attributable to the presence and absence of blood. Activation maps obtained in the presence and absence of blood were usually similar and only differed in a minority of cases at sites in which electrograms revealed multiple deflections. In conclusion, unipolar mapping using a basket catheter can be used with confidence for the creation of activation maps if appropriate care is taken in the interpretation of fractionated electrograms.

Mapping the organization of atrial fibrillation with basket catheters. Part I: Validation of a real-time algorithm.

The authors proposed a real-time algorithm to quantify AF organization from multielectrode basket catheter (MBC) recordings. The algorithm is based on a fast method to estimate the number of points along the baseline of a single bipolar electrogram (number of occurrences, NO). They have already proven this parameter to be effective at discriminating AF organization according to Wells' criteria. Special attention has been paid to ventricular far-field artifacts, as they proved they can significantly bias the degree of organization. To fulfill the constraints of a real-time application, a ventricular blanking procedure was implemented and validated. Bipolar electrograms were obtained from MBC in the right atrium in 17 informed patients with chronic AF. The results of NO computations were displayed as three-dimensional color-coded maps of organization by interpolating the measurements obtained at the locations of catheter bipoles. The proposed method allows real-time estimation of the organization of the atrial electrograms according to Wells' criteria. The estimation has a temporal resolution of 2 seconds, is robust to far-field ventricular artifacts, and interpolates the data available to furnish a single global map of the entire atrium. Further studies devoted to the analysis of individual and common patterns of the regional distribution of AF organization are needed to assess the usefulness of this approach for electrophysiological studies and therapeutic applications.

Nonlinear Ablation Targeting an Isthmus of Critically Slow Conduction Detected by High-Density Electro anatomical Mapping for Atypical Atrial Flutter

Focused high-density atrial endocardial mapping was performed with a three-dimensional electroanatomical mapping system or a multielectrode basket catheter in six men and two women (mean age = 54 years) with atypical atrial flutter (AFL) to characterize its reentry circuit and identify its isthmus of critically slow conduction (ICSC). Activation mapping revealed figure-8 reentry with ICSC between a surgical atrial scars in three atypical AFLs following atriotomy, and between the crista terminalis (CT) and the inferior (IVC) or superior (SVC) vena cavae in atypical right atrial (RA) AFL in absence of prior atriotomy. Figure-8 double loop reentry was documented in one RA atypical AFL. ICSC was characterized by concealed entrainment with a post-pacing interval identical to the AFL cycle length, and a mid-diastolic fractionated electrogram, 129 +/- 23 ms in duration, spanning the isoelectric line between double potentials on adjacent area of conduction block. All AFLs were successfully ablated with 4.9 +/- 4.3 RF pulses applied at ICSC. A possible mechanism of atypical AFL consists of figure-8 reentry with ICSC between surgical scars in postoperative AFL, and between the CT and the IVC/SVC in RA AFL not preceded by cardiac surgery. Late and partial regeneration of conduction across the atriotomy scar can create an ICSC. Nonlinear ablation targeting ICSC can cure atypical AFL, whether it follows surgery or not.