Mapping and ablation of clinical spontaneous perimitral atrial tachycardias using an ultra-high-resolution mapping system.

BACKGROUND: Perimitral atrial tachycardias (PMATs) are common atrial tachycardias (ATs), yet their mechanisms vary. OBJECTIVE: The purpose of this study was to characterize clinical spontaneous PMATs using an ultra-high-resolution (UHR) mapping system. METHODS: The study included 32 consecutive PMATs in 31 patients who had undergone AT mapping/ablation using a UHR mapping system. RESULTS: Six, 10, 11, and 5 PMATs occurred in cardiac intervention-naïve (group A), post-lateral/posterior mitral isthmus linear ablation (group B), post-atrial fibrillation ablation without mitral isthmus linear ablation (group C), and post-cardiac surgery (group D) patients, respectively. Group A patients tended to be older, more likely were female, and had sinus node or atrioventricular conduction disturbances more frequently. A 12-lead synchronous isoelectric interval was observed in 15 PMATs (46.9%). Coronary sinus activation was proximal to distal or distal to proximal except in 3 PMATs with straight patterns due to epicardial gaps. Left atrial anterior/septal wall (LAASW) low-voltage areas were smallest in group B. Slow conduction areas (SCAs) were identified in 26 PMATs (81.2%) and were located on the LAASW in all group A and group D patients. Conduction velocity in the SCAs was slowest in group B. In group B, all PMATs were terminated by single applications, and the gaps were located epicardially in 5 of 10 (50%). Anterior (n = 23) or lateral/posterior (n = 9) mitral isthmus linear block was successfully created without any complications in all. Twenty-five concomitant ATs among 18 patients (58.1%) also were eliminated. During a median of 20.0 (11.0-40.0) months of follow-up, 28 patients (90.3%) were free from any atrial tachyarrhythmias. CONCLUSION: An UHR mapping-guided approach with identification of the individual tachycardia mechanism should be the preferred strategy given the distinct and complex arrhythmia mechanisms.

RADAR: A Multicenter Food and Drug Administration Investigational Device Exemption Clinical Trial of Persistent Atrial Fibrillation.

BACKGROUND: Pulmonary vein isolation is insufficient to treat all patients with persistent atrial fibrillation (AF), and effective adjunctive ablation strategies are needed. Ablation of AF drivers holds promise, but current technologies to identify drivers are limited by spatial resolution. In a single-arm, first-in-human, investigator-initiated Food and Drug Administration Investigational Device Exemption study, we used a novel system for real-time, high-resolution identification of AF drivers in persistent AF. METHODS: Patients with persistent or long-standing persistent AF underwent ablation using the RADAR (Real-Time Electrogram Analysis for Drivers of Atrial Fibrillation) system in conjunction with a standard electroanatomical mapping system. After pulmonary vein isolation, electrogram and spatial information was streamed to the RADAR system and analyzed to identify driver domains to target for ablation. RESULTS: Across 4 centers, 64 subjects were enrolled: 73% male, age, 64.7±9.5 years; body mass index, 31.7±6.0 kg/m2; left atrium size, 54±10 mm, with persistent/long-standing persistent AF in 53 (83%)/11 (17%), prior AF ablation (re-do group) in 26 (41%). After 12.6±0.8 months follow-up, 68% remained AF-free off all antiarrhythmics; 74% remained AF-free and 66% remained AF/atrial tachycardia/atrial flutter-free on or off AADs (antiarrhythmic drugs). AF terminated with ablation in 35 patients (55%) overall and in 23/38 (61%) of de novo ablation patients. For patients with AF termination during ablation, 82% remained AF-free and 74% AF/atrial tachycardia/atrial flutter-free during follow-up on or off AADs. Patients undergoing first-time ablation generally had higher rates of freedom from AF than the re-do group. CONCLUSIONS: This novel technology for panoramic mapping of AF drivers showed promising results in a persistent/long-standing persistent AF population. These data provide the scientific basis for a randomized trial. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03263702; IDE#G170049.

Prospective evaluation of entrainment mapping as an adjunct to new-generation high-density activation mapping systems of left atrial tachycardias.

BACKGROUND: Identification of atrial tachycardia (AT) mechanism remains challenging. OBJECTIVE: We sought to investigate the added value of entrainment maneuvers (EM) when using new high-density activation mapping (HDAM) technologies for the identification of complex left ATs. METHODS: Thirty-six consecutive complex ATs occurring after ablation of persistent atrial fibrillation were prospectively analyzed. The AT mechanism was diagnosed in 2 steps by 2 experts: (1) based on HDAM only (Coherent module, CARTO, Biosense Webster Inc., Irvine, CA) and (2) with additional analysis from EM. RESULTS: EM resulted in atrial fibrillation in 1 patient, who was excluded from the analysis. Ten of 11 single loop macroreentries identified by HDAM were confirmed by EM. Only 4 of 14 double loop macroreentries identified by HDAM wereconfirmed by EM (in 10 patients, EM unmasked passive activation of one of the visual circuits). One sole microreentry circuit identified by HDAM was confirmed by EM. A combination of macro- and microreentry circuits was visualized in 3 ATs using HDAM. However, EM revealed passive activation of the visual macroreentrant loop in 2 of these 3 cases. By using HDAM in 6 of 35 ATs (17%), no univocal mechanism could be identified, whereas EM finally enabled the diagnosis of 5 microreentry circuits and 1 macroreentrant AT. All the diagnoses made from EM in addition to HDAM were confirmed by ablation. CONCLUSION: Entrainment maneuvers are still useful during mapping of complex left ATs, mostly to differentiate active from passive macroreentrant loops and to demonstrate microreentry circuits.

Insight Into the Mechanism of Macroreentrant Atrial Tachycardia With Cycle Length Alternans Using Ultrahigh Density Mapping System.

BACKGROUND: Atrial tachycardia (AT) with cycle length (CL) alternans is a rare phenomenon. We aimed to identify the characteristics and precise mechanism of this special category of ATs by using an ultrahigh density mapping system. METHODS: We identified 7 ATs with alternating CL in a total of 478 ATs from 2 institutions mapped with an ultrahigh density mapping system. Activation maps were performed for long CL (289±35 ms; mapping points, 21 520±11 103) and short CL (251±18 ms; mapping points,17 594±8059) separately. RESULTS: We classified ATs with CL alternans into 2 types. Type 1: There existed 2 potential loops with different routes. CL alternans resulted from an intermittently 2:1 conducting block within the channel of the smaller loop. Type 2: CL alternans resulted from different conduction velocity through 2 closely spaced gaps within preexisting linear lesions. Catheter ablation successfully terminated all the 7 ATs. CONCLUSIONS: Ultrahigh density mapping provides an opportunity to delineate the precise mechanism of AT with CL alternans. Intermittent conduction block or slowing of a channel was essential for the maintenance of AT.

Grid Mapping Catheter for Ventricular Tachycardia Ablation.

BACKGROUND: A new grid mapping catheter (GMC)-allowing for bipolar recordings of the electrograms in each orthogonal direction-became available. The aim of the current study is to evaluate the utility of the GMC in creating substrate and ventricular tachycardia (VT) activation maps during VT ablation procedures. METHODS: From December 2017 to July 2018, 41 consecutive patients undergoing a VT ablation procedure using a GMC were studied. During the substrate mapping, 3 different maps were created using the 3 GMC bipolar configurations (along the spline, across the spline, HD wave solution); the low voltage area and late potential areas were compared. In case of inducible VTs, the GMC was used to create the VT activation maps focusing on the diastolic interval. The relation between diastolic activities during VT and substrate abnormality during sinus rhythm was also investigated. RESULTS: The median low-voltage area drawn by the HD wave configuration was 28.9 cm2, 13% and 15% smaller than the low-voltage areas identified by the along and across configuration, respectively (33.1 and 33.9 cm2; P<0.0001). The late potential areas obtained with the 3 GMC configuration did not differ (P>0.05). VT activation mappings using the GMC were performed in 40 VTs, visualizing the full diastolic pathway in 22 (55%) of them. While the latest late potential areas were included in VT diastolic pathway in 17 VTs, the other 6 VTs showed mismatching of them. Identifying the full diastolic pathway led to a higher ongoing VT termination rate during the ablation than in case of partial recordings (88% versus 45%; P=0.03); furthermore, in the former situation, the noninducibility of the targeted VTs was achieved in all cases. CONCLUSIONS: The GMC is a useful tool for performing substrate and VT activation mappings during the VT ablation procedure, precisely identifying the low-voltage areas and quickly visualizing the diastolic pathways.

How to perform electroanatomic mapping-guided cardiac resynchronization therapy using Carto 3 and ESI NavX three-dimensional mapping systems.

AIMS: To examine the feasibility and safety of a novel protocol for low fluoroscopy, electroanatomic mapping (EAM)-guided Cardiac resynchronization therapy with a defibrillator (CRT-D) implantation and using both EnSite NavX (St. Jude Medical, St. Paul, MN, USA) and Carto 3 (Biosense Webster, Irvine, CA, USA) mapping systems. METHODS AND RESULTS: Twenty consecutive patients underwent CRT implantation using either a conventional fluoroscopic approach (CFA) or EAM-guided lead placement with Carto 3 and EnSite NavX mapping systems. We compared fluoroscopy and procedural times, radiopaque contrast dose, change in QRS duration pre- and post-procedure, and complications in all patients. Fluoroscopy time was 86% lower in the EAM group compared to the conventional group [mean 37.2 min (CFA) vs. 5.5 min (EAM), P = 0.00003]. There was no significant difference in total procedural time [mean 183 min (CFA) vs. 161 min (EAM), P = 0.33] but radiopaque contrast usage was lower in the EAM group [mean 16 mL (CFA) vs. 4 mL (EAM), P = 0.006]. Likewise, there was no significant change in QRS duration with BiV pacing between the groups [mean -13 (CFA) vs. -25 ms (EAM), P = 0.09]. CONCLUSION: Electroanatomic mapping-guided lead placement using either Carto or ESI NavX mapping systems is a feasible alternative to conventional fluoroscopic methods for CRT-D implantation utilizing the protocol described in this study.

Comparison of ablation outcomes of the second ablation procedure for recurrent atrial fibrillation using an ultra-high-resolution mapping system and conventional mappings system.

BACKGROUND: The utility of an ultra-high-resolution electroanatomical mapping system (UHR-EAM, Rhythmia) for repeat atrial fibrillation (AF) ablation has not been evaluated. HYPOTHESIS: A second AF ablation procedure performed using UHR-EAM may demonstrate different outcomes compared with that using a conventional electroanatomical mapping system (C-EAM, CARTO3). METHOD: This observational study enrolled consecutive patients who underwent a second AF ablation procedure using UHR-EAM (n = 103) and C-EAM (n = 153). The second ablation procedure included re-isolation of reconnected pulmonary veins (PVs) and elimination of clinical or induced non-PV AF triggers and atrial tachycardia (AT). Other empirical ablations were additionally conducted at the discretion of the operators. RESULTS: Re-isolation of PVs was achieved in 196 patients who had ≥1 left atrial-PV reconnection. The elimination rate of AT was higher in the UHR-EAM group than the C-EAM group (87% vs 65%, P = .040), while that of non-PV AF triggers was similar (63% vs 63%, P = 1.00). The UHR-EAM demonstrated shorter radiofrequency application time (21.8 ± 16.8 vs 28.0 ± 21.3 minutes, P = .017), but longer fluoroscopic time (26.2 ± 12.6 vs 21.4 ± 9.3 minutes, P = .0001). No severe complication developed. The total 1-year AF/AT-free survival rates were similar between the two groups (off AADs, 59.2% vs 56.2%, P = .62; on AADs, 65.0% vs 69.3%, P = .49). CONCLUSION: The efficacy and safety outcomes of repeat AF ablation using UHR-EAM was comparable to those using C-EAM.

Impact of Spacing and Orientation on the Scar Threshold With a High-Density Grid Catheter.

BACKGROUND: Multipolar catheters are increasingly used for high-density mapping. However, the threshold to define scar areas has not been well described for each configuration. We sought to elucidate the impact of bipolar spacing and orientation on the optimal threshold to match magnetic resonance imaging-defined scar. METHOD: The HD-Grid catheter uniquely allows for different spatially stable bipolar configurations to be tested. We analyzed the electrograms with settings of HD-16 (3 mm spacing in both along and across bipoles) and HD-32 (1 mm spacing in along bipoles and 3 mm spacing in across bipoles) and determined the optimal cutoff for scar detection in 6 infarcted sheep. RESULTS: From 456 total acquisition sites (mean 76±12 per case), 14 750 points with the HD-16 and 32286 points with the HD-32 configuration for bipolar electrograms were analyzed. For bipolar voltages, the optimal cutoff value to detect the magnetic resonance imaging-defined scar based on the Youden's Index, and the area under the receiver operating characteristic curve (AUROC) differed depending on the spacing and orientation of bipoles; across 0.84 mV (AUROC, 0.920; 95% CI, 0.911-0.928), along 0.76 mV (AUROC, 0.903; 95% CI, 0.893-0.912), north-east direction 0.95 mV (AUROC, 0.923; 95% CI, 0.913-0.932), and south-east direction, 0.87 mV (AUROC, 0.906; 95% CI, 0.895-0.917) in HD-16; and across 0.83 mV (AUROC, 0.917; 95% CI, 0.911-0.924), along 0.46 mV (AUROC, 0.890; 95% CI, 0.883-0.897), north-east direction 0.89 mV (AUROC, 0.923; 95% CI, 0.917-0.929), and south-east direction 0.83 mV (AUROC, 0.913; 95% CI, 0.906-0.920) in HD-32. Significant differences in AUROC were seen between HD-16 along versus across (P=0.002), HD-16 north-east direction versus south-east direction (P=0.01), HD-32 north-east direction versus south-east direction (P<0.0001), and HD-16 along versus HD-32 along (P=0.006). The AUROC was significantly larger (P<0.01) when only the best points on each given site were selected for analysis, compared with when all points were used. CONCLUSIONS: Spacing and orientation of bipoles impacts the accuracy of scar detection. Optimal threshold specific to each bipolar configuration should be determined. Selecting one best voltage point among multiple points projected on the same surface is also critical on the Ensite-system to increase the accuracy of scar-mapping.

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.

High density mapping of aortic cusps improves near field detection of pre-potentials during premature ventricular contractions.

Recognition of pre-potentials during activation mapping of aortic cusp premature ventricular contractions is useful to localize the precise site of origin and is an indicator of successful ablation, but sometimes these electrograms can be blunt and have low amplitude. High resolution mapping in the aortic cusp region allows improved near field detection of these signals in very few beats.

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.

Effect of bipolar electrode orientation on local electrogram properties.

BACKGROUND: The direct effect of bipolar orientation on electrograms (EGMs) remains unknown. OBJECTIVE: The purpose of this study was to examine the variation of EGMs with diagonally orthogonal bipoles. METHODS: The HD-32 Grid catheter (Abbott, Minneapolis, MN) can assess the effect of bipolar orientation while keeping the interelectrode distance and center unchanged. Seven sheep with anterior myocardial infarction were analyzed using diagonally orthogonal electrode pairs across splines by comparing local EGMs from each pair of opposing electrodes {eg. A1-B3 (southeast direction [SE]) vs A3-B1 (northeast direction [NE])}. RESULTS: A total of 4084 EGMs (1 in each direction) were analyzed for 2042 sites (544 in the infarcted area, 488 in the border area, and 1010 in the normal area). The higher and lower voltages measured using each pair of opposing electrodes significantly differed (1.10 mV [0.43-2.56 mV] vs 0.69 mV [0.28-1.58 mV]; P < .0001), and the median variation was 0.28 mV (0.11-0.80 mV) (31.7% [16.0%-48.9%]). The voltage variation was maximized to 48.7% (37.7%-61.6%) (P < .0001) on sites where the activation wavefront was perpendicular to the one bipolar direction and parallel to the other. A total of 594 of 719 (82.6%) sites with the voltage <0.5 mV and 539 of 699 (77.1%) sites with the voltage >1.5 mV in NE stayed in the same voltage range as those in SE. However, only 348 of 624 (55.8%) sites with the voltage 0.5-1.5 mV in NE stayed in the same range as those in SE. Local ventricular abnormal activities (LAVAs) were detected in 592 of 2042 (29.0%) sites in total, frequently distributed in the border area. A total of 177 (29.9%) LAVAs were missed in one direction and 180 (30.4%) in the other. When 415 (70.1%) LAVAs detected in NE are defined as the reference, 235 of 415 (56.6%) matched with those detected in SE. CONCLUSION: The bipolar voltage and distribution of LAVAs may differ significantly between diagonally orthogonal bipolar pairs at any given site.

Evaluation of comfort associated with the use of a robotic mattress with an interface pressure mapping system and automatic inner air-cell pressure adjustment function in healthy volunteers.

AIM OF THE STUDY: A robotic mattress equipped with an interface pressure mapping system and an automatic inner air-cell pressure adjustment function had been developed to aid in the management of pressure ulcers, but its effects on comfort remained unclear. The present study aimed to investigate whether use of the mattress with continuous, automatic, interface pressure mapping-based regulation of inner air-cell pressure (i.e., robotic mattress) improves comfort over that provided by body weight-based pressure regulation (traditional approach) in healthy volunteers. MATERIALS AND METHODS: A robotic mattress was used with two settings (i.e., interface pressure-vs. body weight-based regulation). First, 20 healthy volunteers were recruited, and the level of comfort, interface pressure distribution, body immersion, and tissue oxygenation were measured and compared between the two settings. RESULTS: The level of comfort (20.5 vs 47.5, p = 0.014), contact area (2263.9 vs 2145.2 cm2, p = 0.002), and body immersion for healthy participants were significantly larger when using the interface pressure-based setting. CONCLUSION: The robotic mattress provided improved comfort, which might be caused by increased contact area, and improved body immersion. The robotic mattress is expected to be effective both for managing pressure ulcers and increasing comfort.

The best of two worlds? Pulmonary vein isolation using a novel radiofrequency ablation catheter incorporating contact force sensing technology and 56-hole porous tip irrigation.

AIMS: This study aimed to evaluate feasibility and safety as well as 1-year clinical outcome of pulmonary vein isolation (PVI) using a unique radiofrequency ablation catheter ("Thermocool SmartTouch SurroundFlow"; STSF) incorporating both, contact force (CF) sensing technology and enhanced tip irrigation with 56 holes, in one device. METHODS: A total of 110 patients suffering from drug-refractory atrial fibrillation underwent wide area circumferential PVI using either the STSF ablation catheter (75 consecutive patients, study group) or a CF catheter with conventional tip irrigation ("Thermocool SmartTouch", 35 consecutive patients, control group). For each ablation lesion, a target CF of ≥ 10-39 g and a force time integral (FTI) of > 400 g s was targeted. RESULTS: Acute PVI was achieved in all patients with target CF obtained in > 85% of ablation points when using either device. Mean procedure time (131.3 ± 33.7 min in the study group vs. 133.0 ± 42.0 min in the control group; p = 0.99), mean fluoroscopy time (14.0 ± 6 vs. 13.5 ± 6.6 min; p = 0.56) and total ablation time were not significantly different (1751.0 ± 394.0 vs. 1604.6 ± 287.8 s; p = 0.2). However, there was a marked reduction in total irrigation fluid delivery by 51.7% (265.52 ± 64.4 vs. 539.6 ± 118.2 ml; p < 0.01). The Kaplan-Meier estimate 12-month arrhythmia-free survival after the index procedure following a 3-month blanking period was 79.9% (95% CI 70.4%, 90.4%) for the study group and 66.7% for the control group (95% CI 50.2%, 88.5%). This finding did not reach statistical significance (p = 0.18). Major complications occurred in 2/75 patients (2.7%; one pericardial tamponade and one transient ischemic attack) in the study group and no patient in the control group (p = 18). CONCLUSION: PVI using the STSF catheter is safe and effective and results in beneficial 1-year clinical outcome. The improved tip irrigation leads to a significant reduction in procedural fluid burden.

Measuring the impact of cushion design on buttocks tissue deformation: An MRI approach.

AIM: To establish a research approach for describing how different wheelchair cushion designs impact buttocks tissue deformation during sitting. MATERIALS AND METHODS: The buttocks of 4 individuals with spinal cord injury and significant atrophy were scanned sitting in a FONAR Upright MRI. Scans were collected with the individuals' buttocks fully suspended without pelvic support, and seated on 3 different commercially available wheelchair cushions. Multi-planar scans were analyzed to provide 3D renderings and measurements of tissue thickness and shape. RESULTS: Bulk tissue thicknesses at the ischium, which rarely included muscle, were reduced by more than 60% on enveloping cushion designs studied (i.e., Roho HP and Matrx Vi), and more variably (23-60%) on an orthotic off-loading design (i.e., Java). Adipose was typically displaced posterior and superior from the unloaded condition, with more lateral displacement on the Roho HP and Matrx Vi and more medial displacement present on the Java. Large changes in angle at the sacro-coccygeal joint indicated significant loading on the region. Deformation at the greater trochanter was more consistent across surfaces. Greater interface pressures tended to be associated with greater deformation, but the relationship varied by individuals and was highly non-linear. CONCLUSIONS: The buttocks in this study all deformed significantly, but at different locations and in different manners across all 3 surfaces. Attention needs to be paid to the regions of greatest deformation. A future metric of shape compliance should consider cushion performance at all high risk regions, and changes to the amount and shape of tissue in the regions of interest.

The seamless integration of three-dimensional rotational angiography images into electroanatomical mapping systems to guide catheter ablation of atrial fibrillation.

It is important to visually confirm radiofrequency ablation lesions during atrial fibrillation (AF) ablation for procedural efficiency, which requires the integration of a three-dimensional (3D) left atrial image reconstructed from computed tomography (CT) or a magnetic resonance imaging. However, an EP Navigator allows seamless integration of 3D anatomy obtained through 3D rotational angiography (3D-ATG) into an electroanatomical mapping system. We hypothesized that 3D-ATG can be used during AF ablation while significantly reducing the effective dose (ED) and without compromising image morphology compared to a 3D-CT image. Organ dose was measured at 37 points with a radiophotoluminescence glass dosimeter inserted in an anthropomorphic Rando Phantom. The ED was calculated by multiplying the organ dose by the tissue weighting factor. The dose-area product (DAP)-to-ED conversion factor was calculated by measuring the DAP during radiation exposure. The ED for the CT examination was estimated from the dose-length product with a conversion factor of 0.014. ED was calculated from DAP measurements in 114 patients undergoing AF ablation using 3D-ATG. The DAP-to-ED conversion factor for 3D-ATG was 2.4 × 10-4 mSv/mGy cm2 in our hospital. The mean DAP for all patients was 7777 ± 1488 mGy cm2 for the 3D-ATG of the left atrium. The corresponding ED for 3D-ATG was 1.9 ± 0.4 mSv. The ED for CT examinations was 13.6 ± 4.2 mSv (P < 0.001). 3D-ATG can be used during AF ablation while significantly reducing the ED and without compromising image morphology.

Localization of ventricular activation origin using patient-specific geometry: Preliminary results.

BACKGROUND AND OBJECTIVES: Catheter ablation of ventricular tachycardia (VT) may include induction of VT and localization of VT-exit site. Our aim was to assess localization performance of a novel statistical pace-mapping method and compare it with performance of an electrocardiographic inverse solution. METHODS: Seven patients undergoing ablation of VT (4 with epicardial, 3 with endocardial exit) aided by electroanatomic mapping underwent intraprocedural 120-lead body-surface potential mapping (BSPM). Two approaches to localization of activation origin were tested: (1) A statistical method, based on multiple linear regression (MLR), which required only the conventional 12-lead ECG for a sufficient number of pacing sites with known origin together with patient-specific geometry of the endocardial/epicardial surface obtained by electroanatomic mapping; and (2) a classical deterministic inverse solution for recovering heart-surface potentials, which required BSPM and patient-specific geometry of the heart and torso obtained via computed tomography (CT). RESULTS: For the MLR method, at least 10-15 pacing sites with known coordinates, together with their corresponding 12-lead ECGs, were required to derive reliable patient-specific regression equations, which then enabled accurate localization of ventricular activation with unknown origin. For 4 patients who underwent epicardial mapping, the median of localization error for the MLR was significantly lower than that for the inverse solution (10.6 vs. 27.3 mm, P  =  0.034); a similar result held for 3 patients who underwent endocardial mapping (7.7 vs. 17.1 mm, P  =  0.017). The pooled localization error for all epicardial and endocardial sites was also significantly smaller for the MLR compared with the inverse solution (P  =  0.005). CONCLUSIONS: The novel pace-mapping approach to localizing the origin of ventricular activation offers an easily implementable supplement and/or alternative to the preprocedure inverse solution; its simplicity makes it suitable for real-time applications during clinical catheter-ablation procedures.