Noncontact Mapping Research Articles

Abstract 13901: Significance of Rotor Activation Observed Outside of the Pulmonary Vein for the Maintenance of Atrial Fibrillation: Three-dimensional Analysis Using a Non-contact Mapping System

Background: It has been suggested pulmonary vein (PV) acts as the driving sources of atrial fibrillation (AF). However, it is unclear whether the rotor, which is located outside the PV, also maintains the AF. Objectives: To define the prevalence and significance of rotor observed outside the PV in the left atrium (LA), LA activation sequence was analyzed during AF after PV isolation. Methods: Endocardial mapping of LA was performed in 25 AF patients (9 paroxysmal and 16 persistent AF) using a non-contact mapping system (EnSite 3000) during AF perpetuated after PV isolation. Presence of rotor activation was defined when the circular activation around the functional block line once completed its whole reentrant activation. To define the role of rotor for the maintenance of AF, the number of pivoting activation involved in the rotor activation was compared with that not involved in the rotor activation. Further, the activation time involved in the rotor activation was compared with that not involved in the rotor activation. Results: Rotor was identified in 14 (56%) patients (3 paroxysmal and 11 persistent AF patients). Rotor was observed at the septum (8 patients), roof (4 patients), anterior (3 patients) and posterior (1 patient), respectively. The number of rotor activation was 1.5±1.8 times/sec. Total number of pivoting activation was 9.2±6.5 times/sec. The number of pivoting activation involved in the rotor activation was significantly fewer than that not involved in the rotor activation (2.7±3.0 vs. 6.5±5.4 times/sec, p=0.0034). The activation time in which the rotor was observed in the LA occupied 18.5±21.1 % of the total recording intervals. Thus, the percentage of activation time involved in the rotor activation was significantly lower than that not involved in the rotor activation (18.5±21.1% vs. 81.5±21.1%, p<0.0001). Conclusions: Rotor activation was observed outside the PV in only half of AF patients. Further, most of pivoting activations were not involved in the rotor activation and the activation time involved in the rotor activation occupied a limited interval during AF. These suggest that AF after PV isolation was not maintained by the rotor, but was driven by the non-stationary random wave propagation associated with frequent pivoting activations.

Panoramic characterization of endocardial left atrial activation during human persistent AF: Insights from non-contact mapping

BackgroundThe relative importance of focal drivers, multiple wavelets, rotors and endocardial–epicardial circuits in the maintenance of persistent AF remains unclear. Our objective was to characterize AF wavefront (WF) dynamics during persistent AF. MethodsThe Ensite 3000 (St Jude Medical) non-contact mapping system was used to map the LA of 15 patients with persistent AF. Wavefronts were classified into planar WFs, rotors or focal WFs. For each new WF the site of origin, the unipolar electrogram, and propagation patterns were determined. ResultsAF was characterized by highly unstable patterns of activation with random combinations of 1–2 propagating planar wavefronts alternating with focal activations in a dynamic process. Stable reentry circuits and rotors were never seen. A total of 499 wavefront patterns were analyzed in this study (416 planar wavefronts and 83 focal wavefronts). In an individual patient planar WFs accounted for 67±35% of activations with lifespans of 98±86ms. Focal activations accounted for 29.7±33.5% of activations with lifespans of 76±95ms. The most common sites for new WF generation were the PVs (33%), LA roof (23%), anterior LA (15%), LAA (11%), and posterior LA (8%). The most common unipolar electrogram morphologies observed were QS pattern (34%), rS (29%), CFAE (26%), QR (7%) and Rs (4%), suggesting that WFs may originate from both the endocardial and epicardial surfaces. ConclusionHuman persistent AF is characterized by the formation of highly unstable WFs consisting of various combinations of one to two planar WFs and brief focal activations without any evidence of rotors or sustained focal sources.

Tribological Investigation of Two Different Layered Zirconium Phosphates as Grease Additives Under Reciprocating Sliding Test

The tribological properties of α-Zr(HPO4)·H2O and Cu(OH)2Zr(HPO4)2·2H2O (α-ZrP and Cu-α-ZrP, respectively) were investigated in lithium grease by using an optimol SRV-V oscillating reciprocating friction and wear tester (SRV). α-ZrP had excellent anti-wear and friction-reducing properties regardless of the applied load, frequency, and test duration. The applied load for α-ZrP reached 600 N, and the corresponding friction coefficient was 0.082. At 60 Hz, the wear volume rate was 11.16 × 10−9 mm3/Nm. The tribological properties of Cu-α-ZrP were dependent on the test conditions, especially at higher frequency. The α-ZrP worn steel surfaces were smooth and shallow as indicated from scanning electron microscopy and a three-dimensional non-contact surface mapping profiler. Related elements were detected by energy-dispersive X-ray spectroscopy on the rubbed surfaces. A boundary solid film may form on the worn surfaces after friction tests. In reciprocating mode, α-ZrP stuck on the contacting surfaces, which enabled it to form a stable solid lubricant film more effectively than Cu-α-ZrP. The crystal structure may be important for film strength under high loads, especially at high speed.

Infrared thermography based magnetic hyperthermia study in Fe3O4 based magnetic fluids

Owing to the immense clinical benefits, magnetic hyperthermia is likely to emerge as an alternate cancer therapeutic procedure in the near future. Presently, radio frequency immune fiber optic based sensors are being used to monitor temperature changes during magnetic hyperthermia measurements, which have inherent limitations due to the requirement of physical contact of the sensor with the sample, contamination and temperature monitoring at a single point. Here, we investigate the field induced heating of oil based oleic acid coated Fe3O4 nanofluid, synthesized using co-precipitation method, using infrared thermal imaging (IRT) camera and compare the results with those of fiber optic temperature sensor. Experiments were performed on nanofluid samples of four different concentrations and under five different external field amplitudes. The specific absorption rate (SAR) of the samples were determined from the initial rate of temperature rise measured using both the techniques. The SAR values determined from both the techniques were in very good agreement with each other, with in an accuracy of 5%, after incorporating convection loss correction on the infrared thermal imaging data. The consecutive thermal cycling on the samples showed good thermal stability and thermal recovery. The maximum SAR obtained was 95.9W/gFe for a sample concentration and field amplitude of 23wt.% and 57.3kAm−1, respectively. This study showed the efficacy and accuracy of temperature measurement using IRT during field induced heating of magnetic nanofluid and its advantages over conventional point measurements techniques for real-time, non-contact and wide area temperature mapping without sample contamination.

Prevalence and mechanism of rotor activation identified during atrial fibrillation by noncontact mapping: Lack of evidence for a role in the maintenance of atrial fibrillation

It remains unclear whether atrial fibrillation (AF) is maintained by the rotor. We evaluated the role of the rotor and examined its mechanism. Among 75 patients with AF (60 paroxysmal, 15 persistent AF) who underwent 3-dimensional noncontact left atrial mapping during AF, we examined the prevalence and location of rotor activation and elucidated its mechanism. Catheter ablation was performed in a stepwise fashion (linear roof lesion and complex fractionated atrial electrogram ablation after pulmonary vein [PV) isolation) until AF termination. Rotor activation was observed in 11 patients (14.7%; 10 paroxysmal and 1 persistent AF) (tachycardia cycle length 160.0 ± 19.8 ms). Rotors were observed transiently (duration 6128 ± 9094 ms) during AF at the roof (n = 5), septum (n = 3), and ostium of the left superior PV (n = 3). Five rotors circulated in clockwise and 6 in counterclockwise directions. The length of the block line at the center of the rotor was 15.2 ± 6.9 mm. The electrograms at the block line showed low-amplitude multiple deflections (n = 7) or double potentials (n = 4), and the amplitudes during rotor activation were significantly lower than those during sinus rhythm (0.27 ± 0.18 mV vs 1.22 ± 0.92 mV; P < .01). No conduction disturbances were found during sinus rhythm, suggesting that the central line of block was formed functionally. AF was terminated by PV isolation alone without additional lesions in patients with rotors. Functionally formed rotor activation was observed during AF in a limited number of patients. These rotor activations may not be related to AF maintenance, but rather may reflect a transient organization of random propagation.

Electroanatomical Mapping of the Urinary Bladder.

A noncontact mapping system (EnSite) was used for electroanatomical mapping of the bladder simultaneously with pressure flow study in three women with lower urinary tract symptoms. We selected the periods of obvious detrusor activity. Data were processed to remove baseline drift, and an envelope of electrovesicography (EVG) data was created. The correlation coefficient for the correlation between between the EVG envelope and the detrusor pressure (Pdet) was calculated. Bladder geometry was successfully created in all 3 patients. Simultaneous recording of EVG and pressure flow data was successful in 1 patient. Scatter plots were made of the highest correlation coefficient, showing a positive correlation between the Pdet and the envelope, and negative correlation between abdominal pressure (Pabd) and the envelope. Minimal electrical activity could be observed. Significant weak to moderate correlation coefficients were found for the correlations between Pdet and EVG and between Pabd and EVG.

Quality evaluation of food by thermal imaging

SUMMARY : Temperature estimation is an imperative wonder in all mechanical and agrarian divisions. A few instruments and techniques have been produced to quantify the temperature of items. Temperature estimations in the agrarian and sustenance commercial enterprises have for the most part depended on ordinary contact techniques, for example, thermocouples, thermometers, and thermistors, which give constrained data. Non-contact strategies and temperature mapping procedures are getting to be prominent because of higher transient and spatial resolutions. A few strategies, for example, xbeam tomography, infrared thermography, electrical impedance tomography, ultrasound imaging, microwave radiometry, and attractive reverberation imaging (MRI) are accessible to outline temperatures of organic materials. On the other hand, infrared thermal imaging has incredible potential for both pre-collect and post-harvest operations in horticulture because of the convey ability of the hardware and basic operational strategy. The decreases in expense of the hardware and basic operational method have made open doors for the application in a few fields of the agrarian and nourishment commercial enterprises. This innovation can be utilized as a part of every farming material and procedures, where warmth is created or lost in space and time. Little varieties (beneath 1 o C) can likewise be effectively measured with appropriate gear and system. On the off chance that the temperature distinction is too little, a suitable domain ought to be made, for example, expanding or diminishing the temperature of the specimen and measuring the rate of cooling or warming. Detection of bruise and maturity level of fruits and vegetables, overall quality evaluation can be done by the help of thermal imaging.

Radiofrequency catheter ablation of frequent premature ventricular contractions using ARRAY multi-electrode balloon catheter.

The noncontact mapping system facilitates the mapping of premature ventricular contractions (PVCs) and ventricular tachycardia (VT) using a 64-electrode expandable balloon catheter (ARRAY, St. Jude Medical). The aim of this study is to analyze the results and follow-up of the PVC ablation using this system. Prospective and consecutive patients with frequent PVCs (6,000 or more) or monomorphic VT, suspected to be originated on the right ventricular outflow tract (RVOT), were included. The balloon catheter was positioned in the RVOT. Eighteen patients, 9 women, mean age 48 years (youngest/oldest 19-65) were included. Sixteen patients presented no structural heart disease. The origin of the arrhythmia was RVOT (n = 15), right ventricular inflow tract (n = 1), and left ventricular outflow tract (n = 2). Acute success was achieved in 15 patients; in 2 patients radiofrequency was not applied due to security reasons (origin site close to left coronary artery origin). The mean follow-up was 15 months (min. 4, max. 26); 13 patients presented abolition of the arrhythmia without drugs and 1 patient required antiarrhythmic drugs for arrhythmia control (previously ineffective). As an only complication, a femoral artery-venous fistula was observed. The noncontact mapping system using a multielectrode balloon allows right ventricular arrhythmia treatment with a high rate of efficacy and safety.

Difference in the maintenance mechanism of atrial fibrillation perpetuated after pulmonary vein isolation between paroxysmal and persistent atrial fibrillation: Effects of subsequent stepwise ablation

BackgroundNeither the atrial fibrillation (AF) maintenance mechanism after pulmonary vein isolation (PVI) nor the mechanism of AF termination via stepwise ablation is clearly understood. MethodsAmong 226 consecutive AF patients (154 paroxysmal (P-AF) and 72 persistent AF (Per-AF) patients), left atrial endocardial non-contact mapping was performed after PVI in the initial 10 P-AF and 16 Per-AF patients to define the AF maintenance mechanism. Subsequently, effect of stepwise catheter ablation (linear roof lesion and complex fractionated atrial electrogram (CFAE) following PVI) was evaluated in all patients. ResultsAfter PVI, AF was maintained by the activation around isolated PV/mitral annulus, focal discharge and disorganized activations mostly observed over residual CFAE region (pivoting activation, wave break and fusion). CFAE region in P-AF was smaller than Per-AF after PVI (1.6±2.1 vs. 7.7±2.5cm2, p<0.0001). The frequency of pivoting activation, wave break and fusion in P-AF were lower than those in Per-AF (1.9±2.0 vs. 11.8±5.0 times/s; p<0.0001, 0.1±0.3 vs. 3.6±2.5 times/s; p<0.001, 5.8±3.6 vs. 9.8±3.2 times/s; p<0.01). AF termination was more frequent in P-AF than Per-AF (94.8% vs 81.9%, p=0.0019). AF termination by PVI alone was more frequent in P-AF than Per-AF (85.6% vs. 18.6%, p<0.0001). However, AF termination via roof line and/or CFAE ablation was less frequent in P-AF than Per-AF (14.4 vs. 81.4%, p<0.0001). ConclusionsDisorganized activations after PVI, more prominent in Per-AF, were associated with residual CFAE region. Most P-AF was terminated by PVI alone, however additional roof line lesion and CFAE ablation were necessary to terminate Per-AF, consistent with mapping results.

Noncontact Mapping of Intracellular Elasticity via Brillouin Microscopy

We present Brillouin optical microscopy for noncontact, label-free, and 3D interrogation of live cell mechanical properties. This technique is based on the interaction of light with spontaneous acoustic phonons. By measuring the optical frequency shift of the scattered light, the longitudinal modulus of the medium is determined. Mechanically, Brillouin interaction can be thought of as a test that measures the ratio of uniaxial stress and strain in confined compression conditions at high frequency. We show that Brillouin microscopy is sensitive to liquid-solid regulation within cells under different osmotic conditions and directly validate our measurements to gold-standard micro-indentation. Moreover, we show Brillouin microscopy can detect intracellular mechanical changes due to actin cytoskeletal changes such as polymerization, branching and network disruption. Finally, enabled by the non-contact nature of the technique, we investigate the mechanical behavior of cells cultured on 2D flat substrates vs when they are embedded in 3D meshwork of proteins.

Usefulness of combined CARTO electroanatomical mapping and manifest entrainment in ablating adenosine triphosphate-sensitive atrial tachycardia originating from the atrioventricular node vicinity

BackgroundBy using a noncontact mapping system, adenosine triphosphate (ATP)-sensitive atrial tachycardia (ATP-AT) originating from the atrioventricular (AV) node vicinity was successfully ablated at the entrance to the slow conduction zone indicated by the manifest entrainment technique. We aimed to prospectively validate the efficacy of the combination of CARTO electroanatomical mapping and manifest entrainment in ablating this ATP-AT. MethodsOf the 27 AT patients from January 2013 to March 2014, 6 patients with sustained ATP-AT were studied (age, 67±13 years; tachycardia cycle length, 350±95ms). We first created the CARTO map during AT, and performed rapid pacing from the anterior right atrial wall (ARAW) and cavotricuspid isthmus (CTI) approximately 30mm remote from the earliest activation site (EAS). We identified the site where manifest entrainment, defined as the orthodromic capture of the EAS with a long conduction time, was observed, and ablated the site approximately 20mm remote from the EAS, between the pacing site and the EAS. ResultsManifest entrainment was demonstrated in all patients paced from the ARAW (four patients) and from the CTI (two patients). Ablation at the prespecified site terminated AT in 6±3s, and AT became no longer inducible in all patients. At the successful ablation sites, discrete atrial electrograms were recorded; however, low-amplitude, fractionated electrograms suggestive of slow conduction were not observed in all patients. The atrio-His interval during sinus rhythm remained unchanged (from 96±12 to 89±7ms, p=NS). During 11±6 months, no patients showed AT recurrence and AV conduction abnormality. ConclusionCARTO mapping- and manifest entrainment-guided ablation strategy is effective and safe in the treatment of ATP-AT.

Wear resistance of superior structural WS2–Sb2O3/Cu nanoscale multilayer film

Transition metal dichalcogenides (TMDs) with layered structure exhibit very low friction coefficient but poor wear resistance in vacuum environments. To develop high wear resistance of WS2 film, its nanostructure was optimized by co-introducing of Sb2O3 dopant and Cu sublayer using sputtering technique. Effects of co-doping on film nano/microstructure, mechanical and tribological performance were investigated by GIXRD, FESEM, HRTEM, nano-indentation tester, AFM, 3D non-contact surface mapping profiler, scratch tester and vacuum ball-on-disk tribometer. The results showed that the growth of WS2 columnar platelets could be restricted by co-introducing of Sb2O3 dopant and thin Cu sublayer (about 1.6nm), but not single-doping of even 10.0at.% Sb2O3, leading to formation of amorphous WS2 phase. As compared to the loose WS2–Sb2O3 and pure WS2 films, the dense multilayer films possessed high hardness and high H3/E2, and those maximum values were 6.3GPa and 2.7×10−2GPa, respectively. The doping 10.0at.% Sb2O3 could double the film wear life to 2.7×105cycles in vacuum under high Hertzian contact pressure (about 1.0GPa), and further introduction of Cu sublayer would make the multilayer film much longer wear life about to 1.1×106cycles. Wear mechanisms were discussed in terms of wear track morphology after different sliding cycles.

Successful Ablation for Atrial Tachycardia Originated from Sinus Venosa with Tachycardia-Induced Cardiomyopathy.

A 74-year-old male suffering from congestive heart failure with atrial tachycardia (AT) with 2 : 1 atrioventricular conduction was admitted to our hospital. After the therapy with diuretics and β-blocker, his rapid AT was still sustained. He took the catheter ablation for his AT. Postpacing interval mapping from entrainment and noncontact mapping system revealed the mechanism of his AT, originated from sinus venosa. His AT was successfully terminated and eliminated by radiofrequency catheter ablation. After the successful ablation, he has been free from any AT, and his cardiac function was also improved.

Terahertz wafer-scale mobility mapping of graphene on insulating substrates without a gate.

We demonstrate wafer-scale, non-contact mapping of essential carrier transport parameters, carrier mobility (µdrift), carrier density (Ns), DC sheet conductance (σdc), and carrier scattering time (τsc) in CVD graphene, using spatially resolved terahertz time-domain conductance spectroscopy. σdc and τsc are directly extracted from Drude model fits to terahertz conductance spectra obtained in each pixel of 10 × 10 cm2 maps with a 400 µm step size. σdc- and τsc-maps are translated into µdrift and Ns maps through Boltzmann transport theory for graphene charge carriers and these parameters are directly compared to van der Pauw device measurements on the same wafer. The technique is compatible with all substrate materials that exhibit a reasonably low absorption coefficient for terahertz radiation. This includes many materials used for transferring CVD graphene in production facilities as well as in envisioned products, such as polymer films, glass substrates, cloth, or paper substrates.

Abstract 16807: Role of Rotor Activation Within the Pulmonary Vein as the Driving Sources for Atrial Fibrillation: Three-dimensional Analysis using a Non-contact Mapping System

Background: It has been suggested rotor which is located within the pulmonary vein (PV) acted as the driving sources of atrial fibrillation (AF). However, it has never been confirmed whether or not the rotor exists within PV in human. Objectives: We analyzed the activation sequence within the PV during AF and examined how the PV acted as the driving sources of AF. Methods: Selective endocardial mapping of left superior PV (LSPV) was performed during AF in 11 paroxysmal AF patients using a non-contact mapping system (EnSite 3000). Presence of rotor activation was defined when the circular activation around the functional block line once completed its whole reentrant activation. We analyzed the relation between the pivoting activation and the rotor activation. To define the preferable site of rotor and pivoting activation, we also analyzed the relation between the location of rotor and pivoting activation and region of the complex fractionated electrogram (CFE) recording site. Results: Rotor activation was observed with a mean number of 4.6±3.6 times/sec. CFE was observed at the roof (n=5), ridge (n=11) and carina (n=7) of the proximal half of LSPV with a mean area of 9.1±3.4 cm2. The number of rotor activation observed at the CFE area was significantly higher than that at the non-CFE area (4.1±3.9 vs. 0.7±1.2 times/sec, p=0.025). Total frequency of pivoting activation was 37.0±14.7 times/sec. Pivoting activation involved in the rotor activation was significantly lower than that not involved in the rotor activation (8.8±8.1 vs. 27.7±15.8 times/sec, p=0.0116). Regarding the CFE area, pivoting activation involved in the rotor activation was also significantly lower than that not involved in the rotor activation (8.4±8.2 vs. 24.1±12.0 times/sec, p=0.0105). However, there was no difference between the frequencies of pivoting activation with and without rotor activation in the non-CFE area (1.0±2.0 vs. 3.6±6.1 times/sec, p=NS). Conclusions: Rotor activation was observed at the proximal portion of the LSPV coincided with the location of CFE area. However, most of pivoting activation was not involved in the rotor activation. These suggest that AF was driven by the other meandering propagation associated with frequent non-stable pivoting activation over the CFE area.

Abstract 16789: Activation Sequence within the Pulmonary Vein as the Driving Sources of Atrial Fibrillation: Three-dimensional Analysis Using a Non-contact Mapping System

Background: The mechanisms how the activation within the pulmonary vein (PV) drives the atrial fibrillation (AF) has not been elucidated. Objectives: To define the AF maintenance mechanism by PV, we analyzed the activation sequence within the PV during AF. Methods: Selective endocardial mapping of the left superior PV (LSPV) was performed during AF in 11 patients with paroxysmal AF using a three-dimensional non-contact mapping system (EnSite 3000). In addition, we analyzed how the circumferential radiofrequency energy applications around the LSPV alter the activation of the LSPV and terminate AF. Results: Complex fractionated electrograms (CFE) were observed at the second half of the proximal LSPV at the roof (n=5), ridge (n=11) and carina (n=7). Mean CFE area was 9.1±3.4 cm2, which occupied the 19.8% of the LSPV area. Frequent episodes of pivoting activation associated with wave break and fusion was observed at this CFE area. The frequency of pivoting activation around the functional conduction block, wave break and fusion at the CFE region were significantly higher than those at the non-CFE region (32.5±12.2 vs. 4.6±5.8 times/sec; p&lt;0.0001, 9.2±5.1 vs. 1.4±3.1 times/sec; p=0.0007, and 12.9±4.8 vs. 6.4±4.4 times/sec, p=0.0044). After isolation of ipsilateral right PV, subsequent circumferential radiofrequency energy applications around the left PV terminate the AF with a mean number of 13.5±7.8 applications, including LSPV roof (n=3.0±2.2) and LSPV ridge (n=5.6±1.9) lesions. AF was terminated before left PV isolation in all patients. The frequency of pivoting activation, wave break and fusion at all PV area just before the AF termination were significantly lower than those before ablation (8.1±11.7 vs. 37.0±14.7 times/sec; p&lt;0.0001, 2.3±5.8 vs. 10.6±6.6 times/sec; p=0.005, 6.9±6.8 vs. 19.3±7.1 times/sec, p=0.0004), suggesting that linear lesion eliminate the random wave propagation over the CFE area. Conclusions: AF was driven by the high frequent episodes of pivoting activation associated with wave break and wave fusion observed over the CFE area at the proximal PV. Linear lesions along the left PV including CFE area of the LSPV eliminate the meandering activation over the CFE area, resulting in the termination of AF.

Catheter Ablation of Pediatric Focal Atrial Tachycardia: Ten-Year Experience Using Modern Mapping Systems.

Experience of catheter ablation of pediatric focal atrial tachycardia (FAT) is still limited. There are data which were gathered prior to the introduction of modern 3D mapping and navigation systems into the clinical routine. Accordingly, procedures were associated with significant fluoroscopy and low success rates. The aim of this study was to present clinical and electrophysiological details of catheter ablation of pediatric FAT using modern mapping systems. Since March 2003, 17 consecutive patients <20 years underwent electrophysiological study (EPS) for FAT using the NavX(®) system (n = 7), the non-contact mapping system (n = 6) or the LocaLisa(®) system (n = 4), respectively. Radiofrequency was the primary energy source; cryoablation was performed in selected patients with a focus close to the AV node. In 16 patients, a total number of 19 atrial foci (right-sided n = 13, left-sided n = 6) could be targeted. In the remaining patient, FAT was not present/inducible during EPS. On an intention-to-treat basis, acute success was achieved in 14/16 patients (87.5 %) with a median number of 11 (1-31) energy applications. Ablation was unsuccessful in two patients due to an epicardial location of a right atrial focus (n = 1) and a focus close to the His bundle (n = 1), respectively. Median procedure time was 210 (84-332) min, and median fluoroscopy time was 13.1 (4.5-22.5) min. In pediatric patients with FAT, 3D mapping and catheter ablation provided improved clinical quality of care. Catheter ablation may be considered early in the course of treatment of this tachyarrhythmia in symptomatic patients.

The Different Substrate Characteristics of Arrhythmogenic Triggers in Idiopathic Right Ventricular Outflow Tract Tachycardia and Arrhythmogenic Right Ventricular Dysplasia: New Insight from Noncontact Mapping.

BackgroundThe aim of this study was to investigate the different substrate characteristics of repetitive premature ventricular complexed (PVC) trigger sites by the non-contact mapping (NCM).MethodsThirty-five consecutive patients, including 14 with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC) and 21 with idiopathic right ventricular outflow tract tachycardia (RVOT VT), were enrolled for electrophysiological study and catheter ablation guided by the NCM. Substrate and electrogram (Eg) characteristics of the earliest activation (EA) and breakout (BO) sites of PVCs were investigated, and these were confirmed by successful PVC elimination.ResultsOverall 35 dominant focal PVCs were identified. PVCs arose from the focal origins with preferential conduction, breakout, and spread to the whole right ventricle. The conduction time and distance from EA to BO site were both longer in the ARVC than the RVOT group. The conduction velocity was similar between the 2 groups. The negative deflection of local unipolar Eg at the EA site (EA slope3,5,10ms values) was steeper in the RVOT, compared to ARVC patients. The PVCs of ARVC occurred in the diseased substrate in the ARVC patients. More radiofrequency applications were required to eliminate the triggers in ARVC patients.Conclusions/InterpretationThe substrate characteristics of PVC trigger may help to differentiate between idiopathic RVOT VT and ARVC. The slowing and slurred QS unipolar electrograms and longer distance from EA to BO in RVOT endocardium suggest that the triggers of ARVC may originate from mid- or sub-epicardial myocardium. More extensive ablation to the trigger site was required in order to create deeper lesions for a successful outcome.

Noncontact three-dimensional mapping of intracellular hydromechanical properties by Brillouin microscopy.

Current measurements of the biomechanical properties of cells require physical contact with cells or lack sub-cellular resolution. Here, we developed a label-free optical microscopy technique based on Brillouin light scattering capable of measuring intracellular longitudinal modulus with optical resolution. We obtained 3D Brillouin maps of cells in 2D and 3D microenvironments, which reveal mechanical changes due to cytoskeletal modulation and cell volume regulation.

Non-Contact Local Conductance Mapping of Individual Graphene Oxide Sheets during the Reduction Process

We used electrostatic force microscopy (EFM) to investigate local conducting states of atomically thin individual graphene oxide (GO) sheets and monitor the spatial evolution of their conducting properties during the reduction process. Because of the thinness of the GO sheets and finite carrier density, the electric field is partially screened in the reduced GO, which is manifested in the EFM phase signals. We found inhomogeneous oxidation states in as-prepared GO sheets and followed the evolution of reduction process in the individual GO sheets during both thermal and chemical reduction. We also compared the EFM measurement results with simultaneous IV characteristics to assess correlations between two measurements.