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Background: Catheter ablation of right-sided accessory pathways (APs) has lower success and higher recurrence rates compared to left-sided substrates. Irrigated-tip catheter (ITC) ablation might offer an advantage in this setting but data about its use in patients below 18 years are scarce. The aim of this study was to compare an ITC approach to conventional catheter ablation. Methods: A retrospective analysis of all patients <18 years undergoing radiofrequency ablation (RFA) for right-sided APs from 2004 to 2014 at our institution was performed. Patients either underwent an ITC approach in combination with 3-D mapping (Group 1; n = 53) or a conventional non-ITC approach (Group 2; n = 52). Study endpoints were acute procedural success, safety, and recurrence rate. A total of 105 mostly adolescent patients (56.2% male;median age 14 years) with 107 right-sided APs were included. Results: The prevailing anatomic AP locations were right posteroseptal (44.9%), right anterior/anterolateral (24.3%), and right lateral (13.1%). Acute success (94.3% vs 94.2%) did not differ between the groups. One major complication (pericardial effusion) occurred in the non-ITC group. Overall, freedom from AP recurrence was 94% at 4 years in the ITC group, and 81% at 4 years in the non-ITC group (P = 0.04). Conclusions: The use of ITCs in combination with 3-D mapping system for ablation of rightsided APs in adolescents has a high acute success rate, is safe, and associated with a significantly reduced recurrence rate compared to a non-ITC/conventional approach. It might be considered as alternative approach in this age group. [ABSTRACT FROM AUTHOR]

The purpose of this study is to examine a normal conduction pathway of the left atrium. During pulmonary vein isolation using a three-dimensional mapping system, we observed the characteristics of the conduction pattern. Subjects consisted of 15 patients with paroxysmal atrial fibrillation (mean age, 62.8 ± 8.4 years). Left atrial activation conduction begins in the interatrial septum, and moves toward the peak of the ridge between the left atrial appendage and left pulmonary vein. In coronary sinus or appendage pacing, conduction was in the opposite direction at the same location. The mean conduction velocity in this area was 2.03 ± 0.43 m/s. Features of decrement conduction were not present. Anatomical position of the appendage differed greatly between patients. A detailed observation using the inner-cavity view of a three-dimensional mapping system also showed that the peak of the ridge reached the center of the roof.

In this paper, a high-speed three-dimensional map generation method using direct estimation of the motion parameters of the sensor is proposed. The method aligns range images between frames after estimating the motion parameters of the sensor using two kinds of information. One is the relationship of the range images and the motion parameters of a small motion. The other is the relationship of the intensity gradient information of the color images and the motion parameters. The method can create three-dimensional maps quickly because the method does not need to obtain the correspondences of features. Both the processing time required for the motion parameter estimation and the accuracy of the map are verified by experiments using a developed fast RGB-D sensor. It is also shown that the method is applicable to the Kinect sensor.

An advanced three-dimensional mapping approach utilizing reflection high-energy electron diffraction (RHEED) is introduced. The application of the method is demonstrated in detail by resolving the crystal structure and epitaxial relations of individual components within epitaxially grown magnetically ordered Co/MnF2/CaF2/Si(001) heterostructures. The electron diffraction results are cross-checked using synchrotron X-ray diffraction measurements. A number of advantages of the three-dimensional mapping technique as compared to conventional electron diffraction are demonstrated. Not least amongst these is the possibility to build arbitrary planar cross sections and projections through reciprocal space, including the plan-view projection onto the plane parallel to the sample surface, which is otherwise impossible to obtain. [ABSTRACT FROM AUTHOR]

Abstract: The recent development of high‐density high‐spatial resolution three‐dimensional mapping has provided detailed information for understanding complicated atrial activation patterns at a level not previously possible. Using this technology, we report a case with recurrent common atrial flutter, demonstrating the presence of a bridging epicardial fiber that traveled across the previous cavotricuspid isthmus ablation lesion with apparent epicardial‐endocardial breakthrough (EEB) sites located on both sides of the ablation line. The entrainment study indicated that the EEB site, located adjacent to the coronary sinus ostium, was part of the recurrent circuit and a focal ablation targeting that site terminated the tachycardia. [ABSTRACT FROM AUTHOR]

The operation of nanoscale electronic devices is related intimately to the three-dimensional (3D) charge density distributions within them. Here, we demonstrate the quantitative 3D mapping of the charge density and long-range electric field associated with an electrically biased carbon fiber nanotip with a spatial resolution of approximately 5 nm using electron holographic tomography in the transmission electron microscope combined with model-based iterative reconstruction. The approach presented here can be applied to a wide range of other nanoscale materials and devices.

Purpose: Right atrial (RA) tachyarrhythmias are not rare in patients with congenital heart disease and a history of cardiac surgery. This study investigated the usefulness of a crista catheter for 3-dimensional electroanatomical mapping of RA tachyarrhythmias.Methods: We consecutively included 35 patients (age, 43.2 ± 15.6 years; 15 men) who underwent an electrophysiological study with 3-dimensional electroanatomical mapping for RA tachycardia or flutter. In 13 patients with atrial flutter, we recorded and compared the electrical sequence in the anterior and posterior portions of the RA lateral wall. We used a crista catheter as a mapping catheter for 3-dimensional mapping in 12 patients (crista group), a lasso catheter in 12 patients (lasso group), and an ablation catheter in 11 patients (ablation group). We compared the 3-dimensional mapping points, time, and speed (mapping points per minute) among the groups.Results: Atrial flutter was confirmed as cavotricuspid isthmus-dependent in all patients whose two atrial electrical sequences were the same direction and as atypical (including scar-related and dual-loop) in all patients whose sequences were in the opposite direction. Mapping speed in the crista group was significantly faster than in the lasso and ablation groups: median (interquartile range) 44.0 (35.5-69.4) points/min, 23.7 (17.8-29.8) points/min, and 8.2 (4.8-11.0) points/min, respectively (p = 0.001).Conclusions: A crista catheter is useful for high-density 3-dimensional electroanatomical mapping of complex RA tachyarrhythmias. Comparison of the electrical sequences in the anterior and posterior portions of the RA lateral wall is helpful for differentiating between cavotricuspid isthmus-dependent and atypical atrial flutter. [ABSTRACT FROM AUTHOR]

When performing epicardial ablation of ventricular tachycardia (VT), caution must be taken not to damage the coronary arteries. We report a case in which a new, nonfluoroscopic technique for incorporating an accurate, real-time reconstruction of the main coronary vessels into a three-dimensional electroanatomic map was used for epicardial VT ablation. [ABSTRACT FROM AUTHOR]

Background: Local abnormal ventricular activities (LAVA) in patients with scar-related ventricular tachycardia (VT) may appear at any time during or after the far-field electrogram. Although they may be separated from the far-field signal by an isoelectric line and extend beyond the end of surface QRS, they may also appear fused or buried within the QRS. Objective: The purpose of this study was to characterize LAVA in postinfarction VT patients with respect to their anatomic locations. Methods: Thirty-one patients with postinfarction VT underwent mapping/ablation during sinus rhythm with a three-dimensional electroanatomic mapping system. From a total of 18,270 electrograms reviewed in all study subjects, 1104 LAVA (endocardium 839, epicardium 265) were identified and analyzed. Results: The interval from onset of QRS complex to ventricular electrogram (EGM onset) on the endocardium was significantly shorter than the epicardium (P < .001). EGM onset was shortest in the septal endocardium and longest in the inferior and lateral epicardium. There was a significant positive correlation between EGM onset and LAVA lateness as estimated by the interval from surface QRS onset to LAVA (r = 0.52, P < .001). LAVA were more frequently detected after the QRS complex in the epicardium (241/265 [91%]) than in the endocardium (551/839 [66%], P < .001). Only 43% of endocardial septal LAVA were detected after the QRS complex. Conclusion: Lateness of LAVA is affected to a large extent by their locations. The chance of detecting late LAVA increases when electrogram onset is later. Substrate-based approach targeting delayed signals relative to the QRS complex may miss critical the arrhythmogenic substrate, particularly in the septum and other early-to-activate regions. [Copyright &y& Elsevier]

Background: Patients with CHD can be exposed to high levels of cumulative ionising radiation. Utilisation of electroanatomic mapping during catheter ablation leads to reduced radiation exposure in the general population but has not been well studied in patients with CHD. This study evaluated the radiation sparing benefit of using three-dimensional mapping in patients with CHD., Methods: Data were retrospectively collected from the Catheter Ablation with Reduction or Elimination of Fluoroscopy multi-institutional registry. Patients with CHD were selected. Those with previous ablations, concurrent diagnostic or interventional catheterisation and unknown arrhythmogenic foci were excluded. The control cohort was matched for operating physician, arrhythmia mechanism, arrhythmia location, weight and age. The procedure time, rate of fluoroscopy use, fluoroscopy time, procedural success, complications, and distribution of procedures per year were compared between the two groups., Results: Fifty-six patients with congenital heart disease and 56 matched patients without CHD were included. The mean total procedure time was significantly higher in patients with CHD (212.6 versus 169.5 minutes, p = 0.003). Their median total fluoroscopy time was 4.4 minutes (compared to 1.8 minutes), and their rate of fluoroscopy use was 23% (compared to 13%). The acute success and minor complication rates were similar and no major complications occurred., Conclusions: With the use of electroanatomic mapping during catheter ablation, fluoroscopy use can be reduced in patients with CHD. The majority of patients with CHD received zero fluoroscopy.

Copyright of Herzschrittmachertherapie und Elektrophysiologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: We performed retinal and choroidal thickness mapping by three-dimensional high-penetration optical coherence tomography (OCT) and evaluated the choroidal thickness distribution throughout the macula in healthy eyes. Methods: Forty-three eyes of 43 healthy Japanese volunteers were evaluated by 1060-nm swept-source OCT. The eyes were scanned with a three-dimensional raster scanning protocol, and the mean retinal and choroidal thicknesses of the posterior sectors were obtained. The sectors were defined by the Early Treatment Diabetic Study (ETDRS) layout. These data were compared by age (23-56 years), spherical equivalent refractive error (between +0.9 D and −10.3 D), and axial length (22.9-27.6 mm). Results: The mean retinal and choroidal thicknesses of the ETDRS area were 284 ± 14 μm and 348 ± 63 μm respectively. The mean regional choroidal thicknesses in the nasal inner macula and nasal outer macula were significantly smaller than those in all other sectors. The mean regional choroidal thickness in most sectors showed a significant negative correlation with axial length and a significant positive correlation with refractive error. In eyes with a long axial length (>25.0 mm), the mean regional choroidal thickness of five sectors showed a significant negative correlation with age. The coefficient of variation of choroidal thickness between sectors showed a significant negative correlation with axial length, and a positive correlation with refractive error. The mean retinal thickness in each sector was not significantly correlated with the mean choroidal thickness, age, axial length, or refractive error. Conclusions: The choroidal thickness map showed a distribution entirely different from the retinal thickness map. Choroidal thickness varies significantly with location, axial length, refractive error, and age. These variations should be considered when evaluating choroidal thickness. [ABSTRACT FROM AUTHOR]

Copyright of Archives of Cardiovascular Diseases is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Although the anterior and posterior boundaries of cavotricuspid isthmus-dependent atrial flutter (AFL) are reported to be located at the tricuspid annulus and sinus venosa region or crista terminalis, the exact upper turnaround point of the AFL circuit remains unclear. The aim of this study was to determine the upper turnaround site of the AFL circuit by means of three-dimensional (3D) mapping and entrainment pacing. Methods: Subjects were 21 patients with counter-clockwise AFL in whom high-density mapping of the high right atrium (RA) and superior vena cava (SVC) orifice was performed with an electroanatomical or non-contact mapping system. Entrainment pacing was performed around the SVC-RA junction. Results: In 20 of the 21 patients, the wavefront from the septal RA split into two wavefronts: one that traveled anterior to the SVC and another that traveled to the posterior RA where it was blocked. In the remaining patient, the wavefront from the septal RA split into two wavefronts: one that propagated through the anterior portion of the SVC orifice and another that propagated transversely across the posterior portion of the SVC orifice. The two wavefronts joined in the lateral RA. Entrainment pacing from the SVC-RA junction demonstrated that the anterior boundary was within the circuit in all patients, but the posterior boundary also constituted a circuit in four patients. Conclusions: We surmise that the upper turnaround site of the AFL circuit is located in the anterior portion of the SVC-RA junction in the majority of patients with AFL. [ABSTRACT FROM AUTHOR]

Knowledge of the innervation of interneurons within the striatum is critical to determining their role in the functioning of the striatal network. To this end, the synaptic innervation of a distal dendrite of a rat striatal cholinergic interneuron was quantified for the first time. These synaptic data were compared to three other dendrites from rat striatal interneurons and to published data from dendrites in the mammalian cerebral cortex. To label the cholinergic interneurons and their distal dendrites, a male Wistar rat was perfused and the striatum was double-immunolabelled with an antibody to choline acetyltransferase (ChAT) and an antibody to m2 muscarinic receptor. After processing for transmission electron microscopy, a cholinergic interneuron was located and an m2-labelled distal dendrite identified by tracing it through serial ultrathin sections to this double-immunolabelled soma. Two interneuronal distal dendrites in the same tissue, and another from a second rat, were used for comparison. The widths and lengths of the four distal dendrites, the total number and type of synapses, and the number of synapses per μm for each distal dendrite were measured. Symmetric synapses were the most common type on all four dendrites. There were 0.73 synapses per μm on the distal dendrite of the identified striatal cholinergic interneuron. Two other interneuronal dendrites that were positive for the m2 muscarinic receptor antibody showed similar synaptic densities of 0.62 and 0.83 synapses per μm of distal dendrite, respectively. On a third unlabelled interneuronal distal dendrite located in the lateral striatum, there were 2.17 synapses per μm. This interneuron was thought to be a parvalbumin interneuron rather than a calretinin interneuron, which would more likely be medially located. These data suggest that the number of synapses per μm on the distal dendrite of the cholinergic interneuron, and possibly two other cholinergic interneurons, is three times lower than that of a likely parvalbumin interneuron in the rat striatum. The number of synapses per μm of distal dendrite for a striatal cholinergic interneuron is also lower than the published 1.22–3.3 synapses per μm of dendrite for neurons in the mammalian cerebral cortex. Such anatomical data are important for the construction of new generation computer models that are better able to emulate the operation of striatal cholinergic interneurons. [ABSTRACT FROM AUTHOR]

The purpose of this study is to examine a normal conduction pathway of the left atrium. During pulmonary vein isolation using a three-dimensional mapping system, we observed the characteristics of the conduction pattern. Subjects consisted of 15 patients with paroxysmal atrial fibrillation (mean age, 62.8 ± 8.4 years). Left atrial activation conduction begins in the interatrial septum, and moves toward the peak of the ridge between the left atrial appendage and left pulmonary vein. In coronary sinus or appendage pacing, conduction was in the opposite direction at the same location. The mean conduction velocity in this area was 2.03 ± 0.43 m/s. Features of decrement conduction were not present. Anatomical position of the appendage differed greatly between patients. A detailed observation using the inner-cavity view of a three-dimensional mapping system also showed that the peak of the ridge reached the center of the roof. [Copyright &y& Elsevier]

Abstract: A method for depth sensing based on sensing the visibility associated with the coherence function of a laser source is presented. The setup is based on an electronic speckle pattern interferometric (ESPI) setup, where the object depth is encoded into the amplitude of the interference pattern without the need for depth scanning. After performing phase-shifting method, the object three-dimensional (3-D) shape is reconstructed by means as a range image from the visibility of the image set of interferograms and where each gray level represents a given object depth. Experimental results validate the proposed approach for reflective diffuse objects at different measurement distances. [Copyright &y& Elsevier]

Good situational awareness is an absolute must when operating mobile robots for planetary exploration. Three-dimensional (3-D) sensing and modeling data gathered by the robot are, hence, crucial for the operator. However, standard methods based on stereo vision have their limitations, especially in scenarios where there is no or only very limited visibility, e.g., due to extreme light conditions. Three-dimensional laser range finders (3-D-LRFs) provide an interesting alternative, especially as they can provide very accurate, high-resolution data at very high sampling rates. However, the more 3-D range data are acquired, the harder it becomes to transmit the data to the operator station. Here, a fast and robust method to fit planar surface patches into the data is presented. The usefulness of the approach is demonstrated in two different sets of experiments. The first set is based on data from our participation at the European Space Agency Lunar Robotics Challenge 2008. The second one is based on data from a Velodyne 3-D-LRF in a high-fidelity simulation with ground truth data from Mars. [ABSTRACT FROM AUTHOR]

Aims: Multisite atrial pacing has been suggested to be effective in suppressing atrial fibrillation (AF), however, the effect of linear triple-site atrial pacing (LTSP) in humans has not been evaluated. We compared the effects of LTSP to single-site atrial pacing (SSP) on the atrial activation and wavefront propagation pattern in patients with persistent AF. [ABSTRACT FROM PUBLISHER]

Copyright of Revista Española de Cardiología (18855857) is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We present the case of a female patient who previously underwent cardiac surgery for traumatic anterior right atrial perforation after a stabbing attack. Four years later the patient presented with right atrial common type flutter and isthmus ablation was performed subsequently. However, three years after isthmus ablation the patient was readmitted with atypical right atrial flutter. Electrophysiological study revealed persistent bidirectional isthmus block. Three-dimensional mapping (NavX, St. Jude Medical, St. Paul, MN, USA) demonstrated an incisional tachycardia with the critical isthmus at the border of the anterior area of scar in a close proximity to the superior tricuspid annulus. After ablation of this isthmus the patient was arrhythmia free after a follow-up of 9 months. This case illustrates that three-dimensional scar mapping may help to identify unusual isthmus sites that may be simultaneously responsible for both typical and atypical atrial flutter. [ABSTRACT FROM AUTHOR]

Background: Newer technologies such as three-dimensional mapping and echocardiography can decrease x-ray exposure during catheter ablation. Many right-sided tachycardias can now be ablated without fluoroscopy. Left-sided tachycardias, however, have not yet been ablated using a zero fluoroscopy approach. Objective: This study sought to examine the utility of trans-esophageal echocardiography (TEE) in providing adequate imaging as an alternative to fluoroscopy for transseptal puncture. When combined with NavX guidance (St. Jude Medical, St. Paul, MN, USA), fluoroscopy may not be necessary. Methods: Ten pediatric patients with supraventricular tachycardia (SVT) had accessory pathways mapped to the left side. Right atrial and coronary sinus geometries were created using NavX. Once a left-sided pathway was confirmed, a transseptal puncture was performed. A guide wire was placed in the SVC and confirmed by TEE. A transseptal sheath and dilator were advanced over the wire and positioned with TEE guidance so that the tip of the dilator was tenting the fossa ovalis. A transseptal needle was advanced across the fossa. Left atrial location of the needle tip was confirmed on TEE by saline contrast injection. The sheath and dilator were advanced over the needle with continuous pressure monitoring and TEE. Once the sheath was appropriately positioned, the ablation was completed using NavX guidance. Results: All patients had acutely successful ablations and none required the use of fluoroscopy. Number of cryo lesions ranged from five to 19, with a mean of 9. Mean procedure time was 4.4 hours, with a range of 3.2 hours to 7.2 hours. There were no complications. One patient had recurrence. Conclusions: Three-dimensional mapping combined with TEE shows potential for eliminating fluoroscopy use during catheter ablation. [ABSTRACT FROM AUTHOR]

Two female patients undergoing left atrial radiofrequency catheter ablation developed Tako-tsubo cardiomyopathy. This reversible form of left ventricular dysfunction is known to occur under conditions associated with marked sympathetic nervous activation. Radiofrequency catheter ablation in the left atrium can damage autonomic ganglionated plexi, leading to vagal withdrawal, thus resulting in enhanced sympathetic tone. Tako-tsubo cardiomyopathy has not been previously described following radiofrequency catheter ablation. [ABSTRACT FROM AUTHOR]

Abstract: Salt is widespread in the Australian landscape – in soil, regolith and groundwater – leading to concerns that land management practices may be putting much agricultural land and important water resources at risk of salinisation. Defining the location and nature of salt stores is an important first step in understanding the processes leading to salinity of soils, streams and groundwater resources, and predicting areas that may be at risk. Airborne geophysics can define subsurface salt stores and mobilisation pathways. Airborne electromagnetics (AEM) can map the three-dimensional conductivity structure of the landscape but does not, intrinsically, quantify the amount of salt. Salinity, moisture content, porosity and mineralogy all contribute to the electromagnetic signal, and each can vary significantly throughout the landscape. In the Lower Balonne catchment, Queensland, the relationship between AEM and the amount of salt in the landscape was quantified using laboratory analyses of pore fluids from core samples. A general statistical relationship was established between AEM conductivity and salt load (defined as the product of pore fluid salinity, porosity and moisture content)—with a significant positive correlation although data were generally widely dispersed. Comparison of calculated salt load with borehole electromagnetic logs gives insight into the factors contributing to dispersion in the AEM data. The relationship transforms bulk conductivity to salt load in 5m layers, allowing the generation of a three-dimensional map of the salt load. This is a powerful tool for identifying areas that may require monitoring and management interventions to reduce salinity risk. An example is given of salt loads beneath an established irrigation area in the Lower Balonne catchment, Queensland. [Copyright &y& Elsevier]

An amplitude modulated laser radar has been developed by the Italian Agency for New Technologies, Energy and the Environment for periodic in-vessel inspection in large fusion machines (International Thermonuclear Experimental Reactor). The system is able to obtain a complete three-dimensional mapping of the in-vessel surface. A first digital signal processing system was developed to modulate the laser beam and to detect both the amplitude of the backscattered light and the phase difference between it and the modulation signal. This system is based on commercial digital receiver and parallel digital signal processing boards on a VME bus. It reaches a speed of 100 K measures/s, showing good accuracy and stability. Starting from this, a further development has been done to increase the speed up to 2.328 M measures/s. Reaching the submicrosecond speed was necessary to implement the mathematical algorithm in a highly parallel hardware architecture using a field programmable gate array (FPGA). Based on the good results of the previously developed system, it was decided to maintain the same acquisition front-end though using the last release of analog-to-digital converters, to increase the operating frequency from 80 up to 200 MHz. The software algorithm previously used was completely redesigned and optimized to be used in the FPGA hardware architecture [ABSTRACT FROM PUBLISHER]

The gastrocolic trunk of Henle has not been described in detail in context with right hemicolectomy. The aim of this study was to define the caliber, length and three-dimensional position of the gastrocolic trunk of Henle (GTH). We studied 10 fresh (<24 h) cadavers. A corrosion cast method was employed. Cold polymerized methylacrylate was injected into the superior mesenteric vein (SMV) and artery. GTH diameter, length and point of confluence with the SMV were assessed. The GTH was present in all specimens originating from the confluence of the right gastroepiploic and superior-anterior pancreaticoduodenal veins. The GTH joined the SMV at an average distance of 2.2 cm (range, 1.6–3.2 cm) from the inferior pancreatic border and it coursed towards the right side in a ventral-cranial direction. The mean caliber and length of the GTH were 5.2 mm (range, 4.8–5.8 mm) and 16.1 mm (range, 10.1–20.7 mm), respectively. The GTH is a short, medium-sized vessel of potential clinical significance with a consistent ventral-cranial direction. [ABSTRACT FROM AUTHOR]

Introduction: Precise localization of target sites for radiofrequency catheter ablation (RFCA) of arrhythmias is hampered by the relative inaccuracy of X-ray localization procedures. This study evaluated the efficacy of a three-dimensional (3D) real-time position management system in guiding RECA procedures in patients. Methods and Results: Patients (n = 30, age 59 ± 20 years) referred for ablation of either atrial flutter (n = 10), ventricular tachycardia (n = 15), or accessory pathways (n = 5) were studied. The real-time position management system uses ultrasound ranging techniques to track the position of an ablation catheter relative to two multitransducer reference catheters, positioned in the right atrium or coronary sinus and the right ventricle. Each catheter contains three or four ultrasound transducers. The distance between the transducer(s) Is determined by calculating the time necessary for an ultrasound pulse to reach other transducers, assuming the speed of sound in blood is 1,550 m/sec. The proximal His bundle was marked at the beginning and the end of the procedure as an electrical landmark to verify reproducibility. After identification of target sites, the position of each lesion created with the ablation catheter was marked. Successful ablation was achieved in 94% of the patients. The distance between the location of the proximal His bundle as marked at the beginning and at the end of the procedure was 2.0 ± 1.2 mm (range 1.5 to 3.5). conclusion: The new 3D real-time position management system facilitated RFCA procedures as it allowed accurate and reproducible 3D tracking of the mapping and ablation catheter. [ABSTRACT FROM AUTHOR]

Introduction: Cesium chloride has widely been used in experimental models to produce various ventricular arrhythmias. The study was designed to evaluate whether type and mechanism of these arrhythmias are dose-dependent. Methods: In 7 dogs with acute AV-block, 60 pins containing 4 bipolar electrodes each were inserted into both ventricles to provide 240 endo-, epi- and midmyocardial recording sites. A computerized mapping system was used to determine three-dimensional activation patterns of ventricular arrhythmias induced by three injections of 1 mmol/kg cesium chloride at 20 minute intervals. Results:Out of all arrhythmias induced, 25 ventricular extrasystoles, 31 monomorphic and 47 polymorphic ventricular tachycardias were mapped. Nonsustained ventricular tachycardias were readily inducible by a single bolus of cesium chloride, whereas sustained episodes required repetitive injections (1.45 ± 0.61 vs. 2.61 ± 0.57 doses, p < 0.05). Polymorphic tachycardias were observed more commonly than monomorphic tachycardias (87 vs. 31). Initiation and maintenance of cesium induced arrhythmias were exclusively based on focal mechanisms originating from the subendocardium, irrespective of morphology and dosage. All monomorphic arrhythmias were caused by repetitive firing of single immobile foci located in either the right or the left ventricle. Bi- and multifocal mechanisms, however, were found to underlie the polymorphic episodes. Conclusions: Although there is a dose-dependence as to the sustenance of mono- or polymorphic tachycardias, this does not reflect on the three-dimensional activation pattern of cesium induced arrhythmias, which are due to mono- or multifocal activation originating from the subendocardium. [ABSTRACT FROM AUTHOR]

A trial was undertaken with an electromagnetic position-tracking (Tracker) system by mapping a small section of a lichen habitat near Cape Royds, Ross Island, Antarctica. This method facilitated the simultaneous collection of precise information about both the topography of the site and the distribution of lichen species. These data were used to produce accurate maps and three-dimensional reconstructions of the mapped area. The technique offers considerable savings in time over conventional methods used in plant and lichen surveys, and has potential to enhance the information collected from broader-scale transect surveys. [ABSTRACT FROM AUTHOR]

The CARTO electroanatomical mapping system represents a paradigm shift in the ability to map the three-dimensional anatomy of the heart and determine the cardiac electrical activity at any given mapped point. The system associates anatomical structure and electrophysiological data and displays the combined information in an easily readable, visual fashion. The system consists of a roving mapping catheter with small magnetic sensors in the tip, a fixed sensor that acts as a reference point, a low magnetic field generating pad, and a data acquisition and display system. When the roving catheter is moved in three-dimensional space, its location in relation to the fixed sensor is monitored by the system, with a resolution of < 1 mm. By gating the acquisition of points in space to the cardiac electrical activity, points that represent both location and electrical activity at that location can be acquired and displayed on a computer screen. After acquiring a number of points, a three-dimensional representation is constructed, and may be displayed from any viewing projection. Clinical applications of the system include defining the mechanisms of arrhythmias, designing ablation strategies, guiding ablations, and improving the safety of mapping and ablation procedures by allowing localization of critical cardiac structures such as the atrioventricular node and His bundle. The system holds the potential to both further our understanding of arrhythmias and increase the safety, efficacy, and efficiency of catheter ablation. [ABSTRACT FROM AUTHOR]

We report the use of the Abbott three-dimensional mapping system (EnSite Precision) for the placement of an atrial pacemaker lead in a patient after modified Fontan procedure. The mapping system was used for the identification of a promising pacing site in the complexly modified right atrium and to visualize the successful placement of an atrial lead at the same spot. [ABSTRACT FROM AUTHOR]