High-resolution, real-time, and nonfluoroscopic 3-dimensional cardiac imaging and catheter navigation in humans using a novel dielectric-based system.

BACKGROUND: Catheter navigation and 3-dimensional (3D) cardiac mapping are essential components of minimally invasive electrophysiological procedures. OBJECTIVE: The purpose of this study was to develop a novel 3D mapping system (KODEX - EPD, EPD Solutions, Best, The Netherlands) that measures changing electric field gradients induced on intracardiac electrodes to enable catheter localization and real-time 3D cardiac mapping. METHODS: We first validated the accuracy of the system's measurement and localization capabilities by comparing known and KODEX - EPD-measured distances and locations at 12 anatomical landmarks in both the atria and ventricles of 4 swine. Next, in vivo images of 3D porcine cardiac anatomy generated by KODEX - EPD and widely used CARTO 3 system (Biosense Webster, Inc., Diamond Bar, CA) were compared with gold standard computed tomography images acquired from the same animals. Finally, 3D maps of atrial anatomy were created for 22 patients with paroxysmal atrial fibrillation (Dielectric Unravelling of Radiofrequency ABLation Effectiveness trial). RESULTS: First, the mean error between known and measured distances was 1.08 ± 0.11 mm (P < .01) and the overall standard deviation between known and measured locations in 12 areas of the porcine heart was 0.35 mm (P < .01). Second, an expert comparison of 3D image quality revealed that KODEX - EPD is noninferior to CARTO 3. Third, the system enabled 3D imaging of atrial anatomy in humans, provided real-time images of atrioventricular valves, and detected important anatomical variations in a subset of patients. CONCLUSION: The KODEX - EPD system is a novel 3D mapping system that accurately detects catheter location and can generate high-resolution images without the need for preacquired imaging, specialty catheters, or a point-by-point mapping procedure.

Non-paroxysmal atrial fibrillation mapping: characterization of the electrophysiological substrate using a novel integrated mapping technique.

AIMS: Clinical outcomes after radiofrequency catheter ablation (RFCA) remain suboptimal in the treatment of non-paroxysmal atrial fibrillation (AF). Electrophysiological mapping may improve understanding of the underlying mechanisms. To describe the arrhythmia substrate in patients with persistent (Pers) and long-standing persistent (LSPers) AF, undergoing RFCA, using an integrated mechanism mapping technique. METHODS AND RESULTS: Patients underwent high-density electroanatomical mapping before and after catheter ablation. Integrated maps characterized electrogram (EGM) cycle length (CL) in regions with repetitive-regular (RR) activations, stable wavefront propagation, fragmentation, and peak-to-peak bipolar voltage. Among 83 patients (72% male, 60 ± 11 years old), RR activations were identified in 376 regions (mean CL 180 ± 31 ms). PersAF patients (n = 43) showed more RR sites per patient (5.3 ± 2.4 vs. 3.7 ± 2.1, P = 0.002) with faster CL (166 ± 29 vs. 190 ± 29 ms; P < 0.001) and smaller surface area of fragmented EGMs (15 ± 14% vs. 27 ± 17%, P < 0.001) compared with LSPersAF. The post-ablation map in 50 patients remaining in AF, documented reduction of the RR activities per patient (1.5 ± 0.7 vs. 3.7 ± 1.4, P < 0.001) and area of fragmentation (22 ± 17% vs. 8 ± 9%, P < 0.001). Atrial fibrillation termination during ablation occurred at RR sites (0.48 ± 0.24 mV; 170.5 ± 20.2 ms CL) in 31/33 patients (94%). At the latest follow-up, arrhythmia freedom was higher among patients receiving ablation >75% of RR sites (Q4 82.6%, Q3 63.1%, Q2 35.1%, and Q1 0%; P < 0.001). CONCLUSION: The integrated mapping technique allowed characterization of multiple arrhythmic substrates in non-paroxysmal AF patients. This technique might serve as tool for a substrate-targeted ablation approach.

Comparison between novel and standard high-density 3D electro-anatomical mapping systems for ablation of atrial tachycardia.

Ultra-high-density mapping allows very accurate characterization of circuits/mechanisms in atrial tachycardia (AT). Whether these advantages will translate into a better procedural or long-term clinical outcome is unknown. Sixty consecutive AT ablation procedures using ultra-high-density mapping (Rhythmia™, group 1) were retrospectively compared to 60 consecutive procedures using standard high-density mapping (Carto/NavX™, group 2) (total 209 AT, 79% left AT). A higher number of maps were performed in group 1 (4.8 ± 2.5 vs 3.2 ± 1.7, p = 0.0001) with similar acquisition duration (12 ± 5 vs 13 ± 6 min per map, p = ns), although with a greater number of activation points (10,543 ± 5854 vs 689 ± 1827 per map, p < 0.0001). AT location remained undetermined in 5 AT in group 1 vs 10 (p = 0.1). Mechanism remained undetermined in 5 AT from group 1 vs 11 (p = 0.06). Acute complete success was achieved in 77%, in both groups. At 1-year follow-up, AT recurred in 37% in group 1 vs 50% in group 2 (p = 0.046). There are less long-term recurrences after AT ablation using ultra-high-density mapping system compared to standard high-density 3D mapping, possibly because of a better comprehensive approach of AT mechanisms.

Identification of Repetitive Activation Patterns Using Novel Computational Analysis of Multielectrode Recordings During Atrial Fibrillation and Flutter in Humans.

OBJECTIVES: The purpose of this study was to assess computational analysis of 64-electrode basket catheter (BC) recordings of atrial fibrillation (AF) and atrial flutter using novel software, CARTOFINDER (CF). BACKGROUND: Repetitive patterns have been recorded during AF and reported to be an important mechanism of AF. CF was used to identify rotational repetitive activation patterns (RAPs) in the right (RA) and left atrium (LA). METHODS: To assess for presence of RAPs, multiple 1-min BC maps of the RA and LA were obtained before and after radiofrequency ablation (RFA) around the pulmonary veins in 14 patients undergoing AF ablation. Validation of the CF algorithm was based on analysis of BC recordings of the cavotricuspid isthmus flutter. RESULTS: There were 2.9 rotational RAPs per patient (1.3 RA; 1.6 LA). No RAPs were noted in 2 patients. RFA was delivered on top of (n = 10), within 5 mm (n = 5), or distant (n = 10) from any RAP. Reproducibility of the BC to identify the same RAP was 82%. Post-pulmonary vein (PV) isolation, there was a 45% reduction in RAP versus pre-RFA. CF was validated by 4 electrophysiologists blindly reviewing 32 RA CF maps. Electrophysiologists correctly categorized presence/absence of RAP in 122 of 128 maps (95%). CONCLUSIONS: CF is novel software incorporated into CARTO that identifies rotational RAP in the RA and LA with 82% reproducibility. PV RFA results in 45% reduction of RAP, suggesting that RFA beyond PV isolation is required to eliminate the bulk of RAP. Electrophysiologists who were first-time users of CF could readily identify RAPs.

High-Resolution Mapping of Ventricular Scar: Evaluation of a Novel Integrated Multielectrode Mapping and Ablation Catheter.

OBJECTIVES: This study sought to evaluate an investigational catheter that incorporates 3 microelectrodes embedded along the circumference of a standard 3.5-mm open-irrigated catheter. BACKGROUND: Mapping resolution is influenced by both electrode size and interelectrode spacing. Multielectrode mapping catheters enhance mapping resolution within scar compared with standard ablation catheters; however, this requires the use of 2 separate catheters for mapping and ablation. METHODS: Six swine with healed infarction and 2 healthy controls underwent mapping of the left ventricle using a THERMOCOOL SMARTTOUCH SF catheter with 3 additional microelectrodes (0.167 mm2) along its circumference (Qdot, Biosense Webster, Diamond Bar, California). Mapping resolution in healthy and scarred tissue was compared between the standard electrodes and microelectrodes using electrogram characteristics, cardiac magnetic resonance, and histology. RESULTS: In healthy myocardium, bipolar voltage amplitude was similar between the standard electrodes and microelectrodes, with a fifth percentile of 1.19 and 1.30 mV, respectively. In healed infarction, the area of low bipolar voltage (defined as <1.5 mV) was smaller with microelectrodes (16.8 cm2 vs. 25.3 cm2; p = 0.033). Specifically, the microelectrodes detected zones of increased bipolar voltage amplitude, with normal electrogram characteristics occurring at the end of or after the QRS, consistent with channels of preserved subendocardium. Identification of surviving subendocardium by the microelectrodes was consistent with cardiac magnetic resonance and histology. The microelectrodes also improved distinction between near-field and far-field electrograms, with more precise identification of scar border zones. CONCLUSIONS: This novel catheter combines high-resolution mapping and radiofrequency ablation with an open-irrigated, tissue contact-sensing technology. It improves scar mapping resolution while limiting the need for and cost associated with the use of a separate mapping catheter.

Evaluation of a novel high-resolution mapping system for catheter ablation of ventricular arrhythmias.

BACKGROUND: The mapping of ventricular arrhythmias in humans using a minibasket 64-electrode catheter paired with a novel automatic mapping system (Rhythmia) has not been evaluated. OBJECTIVE: The purpose of this study was to evaluate the safety and efficacy of mapping ventricular arrhythmias and clinical outcomes after ablation using this system. METHODS: Electroanatomic maps for ventricular arrhythmias were obtained during 20 consecutive procedures in 19 patients (12 with ventricular tachycardia [VT] and 2 with ventricular ectopy [VE]). High-density maps were acquired using automatic beat acceptance and automatic system annotation of electrograms. RESULTS: Forty-seven electroanatomic maps (including 3 right ventricular and 9 epicardial maps) were obtained. Left ventricular endocardial mapping by transseptal (n = 13) and/or transaortic (n = 11) access was safe with no complications related to the minibasket catheter. VT substrate maps (n = 14; median 10,184 points) consistently demonstrated late potentials with high resolution. VT activation maps (n = 25; median 6401 points) obtained by automatic annotation included 7 complete maps (covering ≥90% of the tachycardia cycle length) in 5 patients in whom the entire VT circuit was accurately visualized. VE timing maps (n = 8) successfully localized the origin of VEs in all, with all accepted beats consistent with clinical VEs. Over a median follow-up of 10 months, no arrhythmia recurrence was noted in 75% after VT ablation and 86% after VE ablation. CONCLUSION: In this first human experience for ventricular arrhythmias using this system, ultra-high-density maps were created rapidly and safely, with a reliable automatic annotation of VT and consistent recording of abnormal electrograms. Medium-term outcomes after ablation were encouraging. Further larger studies are needed to validate these findings.

Rapid high resolution electroanatomical mapping: evaluation of a new system in a canine atrial linear lesion model.

BACKGROUND: A canine right atrial (RA) linear lesion model was used to produce a complex pattern of RA activation to evaluate a novel mapping system for rapid, high resolution (HR) electroanatomical mapping. METHODS AND RESULTS: The mapping system (Rhythmia Medical, Incorporated) uses an 8F deflectable catheter with a minibasket (1.8 cm diameter), containing 8 splines of 8 electrodes (total 64 electrodes, 2.5 mm spacing). The system automatically acquires electrograms and location information based on electrogram stability and respiration phase. In 10 anesthetized dogs, HR-RA map was obtained by maneuvering the minibasket catheter during sinus rhythm and coronary sinus pacing. A right thoracotomy was performed, and either 1 or 2 (to create a gap) epicardial linear lesions were created on the RA free wall (surgical incision or epicardial radiofrequency lesions). RA maps during RA pacing close to the linear lesions were obtained. A total of 73 maps were created, with 44 to 729 (median 237) beats and 833 to 12 412 (median 3589) electrograms (≤2 to ≤5 mm from surface geometry), resolution 1.8 to 5.3 (median 2.7) mm, and 2.6 to 26.3 (median 7.3) minutes mapping time. Without manual annotation, the system accurately created RA geometry and demonstrated RA activation, identifying the location of lines of block and presence or absence of a gap in all 10 dogs. Endocardial radiofrequency catheter ablation of a gap (guided by activation map) produced complete block across the gap in all 3 dogs tested. CONCLUSIONS: The new HR mapping system accurately and quickly identifies geometry and complex patterns of activation in the canine RA, with little or no manual annotation of activation time.

Time- and frequency-domain analyses of atrial fibrillation activation rate: the optical mapping reference.

BACKGROUND: Time- and frequency-domain estimates of activation rate have been proposed to guide atrial fibrillation (AF) ablation in patients, but their electrophysiological correlates are unclear. OBJECTIVE: This study sought to examine the relative correlation of average electrical cycle length (CL) and dominant frequency (DF) during AF with reference optical mapping measures. METHODS: Eight sheep hearts were Langendorff-perfused and superfused with oxygenated Tyrode solution inside a tank representing the human thorax. Optical mapping (DI-4-ANEPPS) of 4 × 4 cm2 in the left atrium was performed at 0.5 mm/pixel and 600 fps. A 20-pole catheter was placed in the optical field of view to acquire 1.2-kHz unipolar recordings by the EnSite NavX System (ENS; St. Jude Medical, St. Paul, MN) optimized for CL and DF calculation. During AF, 5-second-long simultaneous optical and electrical signals were analyzed for CL and DF. RESULTS: During pacing, DF measurements had fewer false results than CL (6.6% to 2.5% vs. 21.5% to 4.4% depending on filtering, P <.001). During AF in regions showing periodic waves on both sides of the catheter optical 1,000/CL versus DF correlation showed 95% confidence identity and was better than unipolar measurements in the ENS (adjusted R(2): 0.58879 vs. 0.12902; P < 10(-6)). DFs of unipolar signals correlated better than CLs with DFs of optical signals. Similarly, bipolar DF correlation with optical DF was not different from identity (P >.157), but the bipolar CL showed smaller identity with the optical CL (P <.0004). CONCLUSION: DF values of unipolar and bipolar signals correlate with those of optical signals better than CL values for the respective signals.

Comparison of PV signal quality using a novel circular mapping and ablation catheter versus a standard circular mapping catheter.

PURPOSE: Recently, new catheter technologies have been developed for atrial fibrillation (AF) ablation. We investigate the diagnostic accuracy of a circular mapping and pulmonary vein ablation catheter (PVAC) compared with a standard circular mapping catheter (Orbiter) and the influence of filter settings on signal quality. METHODS: After reconstruction of the left atrium by three-dimensional atriography, baseline PV potentials (PVP) were recorded consecutively with PVAC and Orbiter in 20 patients with paroxysmal AF. PVPs were compared and attributed to predefined anatomical PV segments. Ablation was performed in 80 PVs using the PVAC. If isolation of the PVs was assumed, signal assessment of each PV was repeated with the Orbiter. If residual PV potentials could be uncovered, different filter settings were tested to improve mapping quality of the PVAC. Ablation was continued until complete PV isolation (PVI) was confirmed with the Orbiter. RESULTS: Baseline mapping demonstrated a good correlation between the Orbiter and PVAC. Mapping accuracy using the PVAC for mapping and ablation was 94% (74 of 79 PVs). Additional mapping with the Orbiter improved the PV isolation rate to 99%. Adjustment of filter settings failed to improve quality of the PV signals compared with standard filter settings. CONCLUSIONS: Using the PVAC as a stand-alone strategy for mapping and ablation, one should be aware that in some cases, different signal morphology mimics PVI isolation. Adjustment of filter settings failed to improve signal quality. The use of an additional mapping catheter is recommended to become familiar with the particular signal morphology during the first PVAC cases or whenever there is a doubt about successful isolation of the pulmonary veins.

Efficacy of bundle ablation for cavotricuspid isthmus-dependent atrial flutter: combination of the maximum voltage-guided ablation technique and high-density electro-anatomical mapping.

INTRODUCTION: Pathological studies have demonstrated that the cavotricuspid isthmus (CTI) is often composed of discrete muscle bundles, which are thought to be represented electrically as high-amplitude electrograms. Based on this observation, we visualized the bundles using an electro-anatomical mapping system (EAMS) and investigate the efficacy of bundle ablation which is an ablation method for selectively targeting high-voltage sites obtained by high-density electro-anatomical mapping along the CTI. METHODS: Sixty patients with atrial flutter were randomly assigned to cavotricuspid isthmus ablation using a conventional anatomical approach (Group 1) or bundle ablation approach (Group 2). In Group 2, CTI was mapped in detail with EAMS, and we visualized the bundles that were 1.5 mV or more on a bipolar voltage map. Radiofrequency (RF) ablation was delivered sequentially from the maximum voltage site at the shortest distance of the bundle until bidirectional block was achieved. RESULTS: Bidirectional block was achieved in all patients. Mean ablation times (Group 1, 1,392 + or - 960 s; Group 2, 638 + or - 342 s, p < 0.01), the mean number of RF applications (Group 1, 31.7 + or - 23.6; Group 2, 13.0 + or - 7.0, p < 0.01), and fluoroscopy times (Group 1, 50.4 + or - 28.3 min; Group 2, 42.3 + or - 21.3 min, p < 0.01) were significantly shorter in Group 2 than those in Group 1. CONCLUSION: Bundle ablation at CTI is highly effective for achieving a bidirectional block requiring shorter ablation times, shorter fluoroscopy times, and fewer RF applications.

A family of intracardiac ultrasound imaging devices designed for guidance of electrophysiology ablation procedures.

Our Bioengineering Research Partnership grant, -High Frequency Ultrasound Arrays for Cardiac Imaging", including the individuals cited at the end of this paper - Douglas N. Stephens (UC Davis), Matthew O'Donnell (UW Seattle), Kai Thomenius (GE Global Research), Aaron M. Dentinger (GE Global Research), Douglas Wildes (GE Global Research), Peter Chen (St. Jude Medical), K. Kirk Shung (University of Southern California), Jonathan M. Cannata (University of Southern California), Butrus (Pierre) T. Khuri-Yakub (Stanford University), Omer Oralkan (Stanford University), Aman Mahajan (UCLA School of Medicine), Kalyanam Shivkumar (UCLA School of Medicine) and David J. Sahn (Oregon Health & Science University) - is in its sixth year of NIH funding, having proposed to develop a family of high frequency miniaturized forward and side-looking ultrasound imaging devices equipped with electrophysiology mapping and localization sensors and eventually to include a family of capactive micromachined ultrasonic transducer (cMUT) devices - a forward-looking cMUT MicroLinear array and a ring array capable of 3-dimensional imaging and a 5Fr lumen large enough to admit an electrode and ablation devices.

Electroanatomic characterization of post-infarct scars comparison with 3-dimensional myocardial scar reconstruction based on magnetic resonance imaging.

OBJECTIVES: This study was designed to compare electroanatomic mapping (EAM) and magnetic resonance imaging (MRI) with delayed contrast enhancement (DCE) data for delineation of post-infarct scars. BACKGROUND: Electroanatomic substrate mapping is an important step in the post-infarct ventricular tachycardia (VT) ablation strategy, but this technique has not yet been compared with a gold-standard noninvasive tool informing on the topography and transmural extent of myocardial scars in humans. METHODS: Ten patients (9 men, age 71 +/- 10 years) admitted for post-infarct VT ablation underwent both a left ventricle DCE MRI and a sinus-rhythm 3-dimensional (3D) (CARTO) EAM (Biosense Webster, Johnson & Johnson, Diamond Bar, California). A 3D color-coded MRI-reconstructed left ventricular endocardial shell was generated to display scar data (intramural location and transmural extent). A matching process allocated any CARTO point to its corresponding position on the MRI map. Electrogram (EGM) characteristics were then evaluated in relation to scar data. RESULTS: A spiky EGM morphology, a reduced unipolar or bipolar EGM voltage amplitude (<6.52 and <1.54 mV, respectively), as well as a longer bipolar EGM duration (>56 ms) independently correlated with the presence of scar whatever its intramural position. Endocardial scars had a larger degree of signal reduction than intramural or epicardial scars. None of the parameters was correlated with transmural scar depth. A clear mismatch in infarct surface between CARTO and MRI maps was observed in one-third of infarct zones. CONCLUSIONS: Sinus-rhythm EAM helps identify the limits of post-infarct scars. However, the accuracy of EAM for precise scar delineation is limited. This limit might be circumvented using anatomical information provided by 3D MRI data.

Spatial and temporal stability of complex fractionated electrograms in patients with persistent atrial fibrillation over longer time periods: relationship to local electrogram cycle length.

BACKGROUND: Atrial fibrillation (AF) ablation guided by complex fractionated electrograms (CFE) has been described, but the spatial and temporal stability of the electrograms (EGMs) has been questioned. OBJECTIVE: The purpose of this study was to prospectively assess the spatial and temporal stability of CFE in patients with persistent AF. METHODS: Twenty-four patients were studied. For 12 patients, two high-density CFE maps were performed during AF at baseline (0 minute) and 20 minutes later using the EnSite NavX system. Six-second bipolar EGMs were collected throughout the left atrium (LA) using a circular mapping catheter. Automated software measured the time between discrete local EGM deflections yielding a mean local cycle length (CL). EGMs with mean CL <120 ms were considered CFE. The LA was divided into six regions. Spatial distribution of EGMs at 0 and 20 minutes was compared in each region across three different CL ranges (A = 50-120 ms, B = 121-200 ms, C = 200-500 ms). The 0- and 20-minute CFE maps were directly superimposed offline in MATLAB, and the mean CL value for each point that was sampled in both maps was compared in each CL range (A-C). For the other 12 patients, repetitive measurements (1-minute intervals for 5 minutes) of mean CL were obtained at a sample point for each CL range (A-C) in each patient and compared for consistency. RESULTS: A total of 324 +/- 65 points were collected per map. Globally in the LA, the distribution of CLs did not change from 0 to 20 minutes (A: 47.1% vs 45.0%; B: 35.3% vs 36.5%; C: 16.0% vs 16.9%; P = .6). The CL distribution in each of the six regions of the LA also did not change significantly from 0 to 20 minutes. There was no significant change in repetitive CL measures for range A (mean DeltaCL 12 +/- 4 ms, P = .4). However, there was significant variation over 5 minutes for ranges B and C (mean DeltaCL 39 +/- 19 ms and 48 +/- 22 ms, respectively, P <.05 for both). Superimposing maps showed 74.7% point-to-point match for range A, 39.3% for range B, and 14.2% for range C (within 30 ms), with a significant correlation seen only for range A (r = 0.82, P <.001). CONCLUSION: CFE show a high degree of spatial and temporal stability. Greater temporal variation is seen in progressively longer CL regions that are outside of the CFE region of interest.

Ventricular fibrillation in myopathic human hearts: mechanistic insights from in vivo global endocardial and epicardial mapping.

Ventricular fibrillation (VF) is an important cause of sudden cardiac death and cardiovascular mortality in patients with cardiomyopathy. Although it was generally believed that chaotic reentrant wavefronts underlie VF in humans, there is emerging evidence of spatiotemporal organization during early VF. The mechanism of this organization of electrical activity in early VF is unknown in myopathic hearts. We studied early VF in vivo, intraoperatively in five cardiomyopathic patients. Simultaneous electrograms were obtained from the epicardium and endocardium in left ventricular cardiomyopathy and from the endocardium in right ventricular myopathy. The Hilbert transform was used to derive the phase of the electrograms. Rotors were identified by isolating phase singularity points. Rotors were present in all of the myopathic hearts studied during VF and cumulatively lasted a mean of 3.2 +/- 2.0 s of the 7.0 +/- 4.0 s of the VF segments analyzed. For each surface mapped, 3.6 +/- 2.9 rotors were identified for the duration mapped. The average number of cycles completed by these rotors was 4.9 +/- 4.9. The longest rotor lasted 10.2 +/- 6.2 rotations and lasted 2.0 +/- 1.2 s. The rotors on the endocardium had a cycle length of 192 +/- 33 ms compared with 220 +/- 15 ms on the epicardium (P=0.08). There is centrifugal activation of electrical activity from these rotors, and they give rise to domains that activate at faster rates with evidence of conduction block at the border with slower domains. These rotors frequently localized to border regions of myocardium with bipolar electrogram amplitude of <0.5 mV. The organization of electrical activity during early VF in myopathic human hearts is characterized by wavefronts emanating from a few rotors.

Feasibility and safety of pulmonary vein isolation using a new mapping and navigation system in patients with refractory atrial fibrillation.

BACKGROUND: Ostial pulmonary vein (PV) isolation by radiofrequency (RF) catheter ablation can cure patients with atrial fibrillation (AF); however, this procedure carries the risk of PV stenosis. The aim of this study was to assess the feasibility of a new mapping and navigation technique using a multipolar basket catheter (BC) for PV isolation in patients with refractory AF and to analyze its safety with regard to PV stenosis at long-term follow-up. METHODS AND RESULTS: We studied 55 patients (mean age, 53+/-11 years; 40 male) with drug-refractory AF (paroxysmal, n=37; persistent, n=18). A 64-pole BC was placed transseptally into each of the accessible PVs. By use of a nonfluoroscopic navigation system, the ablation catheter was guided to the BC electrodes at the PV ostium, with earliest activation during sinus rhythm. RF was delivered by use of maximum settings of temperature at 50 degrees C and power at 30 W. The end point of the procedure was the complete elimination of all distal and fragmented ostial PV potentials. Of 165 targeted veins, 163 were successfully isolated with a mean RF duration of 720+/-301 seconds per vein. At 1-year follow-up, 62% of the patients were in sinus rhythm without antiarrhythmic drugs. Contrast-enhanced magnetic resonance angiography revealed 2 PV stenoses of >25% out of 165 treated vessels. CONCLUSIONS: The use of a multipolar BC allowed effective and safe PV isolation by combining 3D mapping and navigation. At 1-year follow-up, 62% of the patients were in sinus rhythm without antiarrhythmic drugs, and the incidence of relevant diameter reduction of the treated PVs was 1.2%.

Novel, magnetically guided catheter for endocardial mapping and radiofrequency catheter ablation.

BACKGROUND: Ablation of complex arrhythmias would be greatly facilitated by more precise control of ablation catheters. A feasibility study was performed in animals to evaluate a novel magnetic guidance system (MGS) that generates a magnetic field to control the movement and position of a magnetic ablation catheter. METHODS AND RESULTS: The MGS is composed of a digital biplanar fluoroscope within an array of superconducting electromagnets that surround the torso of the experimental animal and a computer control system that generates a composite magnetic field for directional catheter deflection. Magnetic catheter navigation was performed in dogs and pigs (20 to 30 kg). A 7F magnetic ablation catheter was used for intracardiac navigation and radiofrequency ablation. The performance of a standard 7F deflectable catheter was not affected by the MGS. The magnetic catheter was navigated successfully to 51 predefined targets throughout the heart in 6 animals. In 5 animals, the magnetic catheter, guided by a 3D computed tomogram, was successfully navigated to all pulmonary veins. Navigation accuracy was estimated as <1 mm displacement from the target. The magnetic catheter was used to ablate the atrioventricular node in 4 animals and to perform linear ablations across the endocardial surface underlying an epicardial multielectrode recording plaque in 4 animals. CONCLUSIONS: These results demonstrate that the MGS can navigate and stabilize an ablation catheter at endocardial targets. Linear or focal radiofrequency ablation with the magnetic catheter is not compromised by the magnetic field. This technology provides precise control of endocardial catheters.