Low voltage zones detected by omnipolar Vmax map accurately identifies the potential atrial substrate and predicts the AF ablation outcome after PV isolation

Abstract Background It has been reported that low voltage areas and conduction abnormalities detected by electrophysiology catheters in the left atrium (LA) represent regional degeneration and fibrosis of the atrium and are related to a poor atrial fibrillation (AF) ablation outcome. Assessment of the local atrial function is clinically useful because atrial degeneration does not occur uniformly throughout the atrium. Though evaluating the global atrial function using speckle tracking imaging (STI) by transthoracic echocardiography (TTE) has been attempted, TTE does not have a sufficient image quality to assess local atrial STI. Purpose To evaluate the local atrial function by STI using intracardiac echocardiography (ICE) and to elucidate the characteristics of the STI in normal and abnormal voltage regions in the LA. Methods We included 9 patients undergoing AF ablation with written informed consent for this prospective observational study. After pulmonary vein isolation, we performed voltage mapping of the LA in sinus rhythm using a CARTO system (Biosense). Abnormal regions and normal regions were defined as those with low voltage areas (<0.5 mV) and those with normal voltages, respectively. Echo images were recorded by an ACUSON SC2000 (Siemens) and SOUNDSTAR catheter (Biosense). We inserted the SOUNDSTAR catheter into the LA to obtain clear images, recorded the STI of the anterior and inferior wall, and performed an offline analysis of the atrial strain with an eSie VVI work station (Siemens) and the LA voltage data with CARTO system at each site simultaneously (left figure). We compared the strain during the atrial contraction phase (Sct) between the normal and abnormal regions. Results Among the study population, 5 patients had low voltage areas in the LA. We evaluated the STI at 26 normal regions and 44 abnormal regions. The typical regional speckle tracking waveform in the normal region was similar to a jugular vein pressure waveform (right figure). There was a difference in the amplitude of the Sct between the groups; it was significantly smaller in the abnormal regions (normal and abnormal regions, 9.8±5.0% and 5.6±3.8%, p=0.0001). The duration of the Sct was significantly more prolonged in the abnormal regions than normal regions (98.8±26.3ms and 118.2±33.9ms, p=0.015). Conclusions This pilot study demonstrated that the local atrial function was evaluable by STI using ICE and that the regional strain tracking waveform during the atrial contraction phase in abnormal voltage regions was smaller and more prolonged than that in normal regions. An evaluation of the regional STI with an ICE may be useful to detect regional abnormalities of the atrium. Representative case Funding Acknowledgement Type of funding source: None

Download Full-text

P959Influence of complex reentrant atrial circuits on tachycardia cycle length

EP Europace ◽

10.1093/europace/euaa162.034 ◽

2020 ◽

Vol 22 (Supplement_1) ◽

Author(s):

C Alonso ◽

E Rodriguez Font ◽

J Guerra Ramos ◽

B Campos Garcia ◽

Z Moreno Weidman ◽

...

Keyword(s):

Heart Disease ◽

Left Atrial ◽

Cycle Length ◽

Low Voltage ◽

Structural Heart Disease ◽

Af Ablation ◽

Atrial Ablation ◽

Active Circuit ◽

The Right ◽

Activation Map

Abstract Funding Acknowledgements NA OnBehalf NA Background Ablation of left atrial reentrant tachycardias (ART) is challenging since they usually occur in the setting of complex diseased atrial tissue either in patients with structural heart disease or after ablation of atrial fibrillation. In these cases, scarred tissue or previous ablation lines make the circuits more complex. We have developed a mapping approach in which an activation map that only contains the active circuit is generated from entrainment maneuvers. Purpose To describe the electrophysiological characteristics of the circuits in patients with structural heart disease and previous left atrial ablation. Methods Consecutive patients with documented atypical flutter were included. A high density activation map was generated during the index arrhythmia and subsequently, entrainment maneuvers were performed to delineate the active circuit. Results Seventeen patients (82% males, average age 62+-7 years, 59% structural heart disease and 53% with a previous left atrial ablation) underwent 20 procedures. Twenty-one circuits were identified (20 in the left atrium and 1 in the right atrium). Of all LA circuits, 15 were macroreentrant (8 roof dependent, 4 perimitral and 3 related to a gap after AF ablation. Four out of 5 microreentrant circuits were related to the left atrial appendage and 1 was identified in the septum. Overall, procedural duration and fluoroscopy time was 176 ± 55 minutes and 27 ± 13 minutes, respectively. Roof-dependent ARTs and gap-related ARTs after AF ablation exhibited a significantly longer TCL (359 ± 99 ms and 331 ± 47 ms, respectively, p < 0,05) than perimitral, microreentrant and RA circuits (279 ± 50 ms; 277 ± 36 ms; and 260 ms, respectively). Extensive areas of low voltage (<0.3 mV) were identified in all patients with LA circuits. Conclusions The cycle length of complex atrial reentrant tachycardias is apparently related to the location and characteristics of the circuits. This feature can be of help at the time of approaching the mapping and ablation of this tachycardias.

Download Full-text

P983Long-standing persistent atrial fibrillation: what can we achieve with ablation?

European Heart Journal ◽

10.1093/eurheartj/ehz747.0576 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

A Nunes Ferreira ◽

N Cortez-Dias ◽

P Silverio Antonio ◽

G Lima Silva ◽

I Goncalves ◽

...

Keyword(s):

Atrial Fibrillation ◽

Success Rate ◽

Short Duration ◽

Cox Regression ◽

Low Voltage ◽

Success Rates ◽

Loop Recorder ◽

Af Ablation ◽

History Of

Abstract Introduction Atrial fibrillation (AF) ablation presents suboptimal results in patients (pts) with persistent long-lasting forms (LSPAF, AF ≥12 months). Recently, the STAR AF-II trial has shown that in these pts complex additional strategies do not improve success compared to only performing pulmonary vein isolation (PVI). Objectives To evaluate the success of AF ablation, particularly in long-standing persistent AF Methods Single-center prospective study of pts with AF submitted to ablation. The strategy, regardless of the type of AF, was based on PVI, complemented by cavo-tricuspid isthmus line (CTI) in pts with history of flutter. Additional ablation strategies were selectively considered in pts with stable atypical flutter conversion, persistent triggers or no electrograms in the VPs. Pts were monitored with Holter/7-day event loop recorder (3, 6, 12 months and annually up to 5 years). Success was assessed from the 90th day after ablation, with the absence of recurrences of any sustained atrial arrhythmias (>30 sec). Cox regression and Kaplan-Meier survival were used to compare the success of ablation as a function of the clinical type of AF in our population and with pts included in STAR-II AF trial. Results 620 patients were submitted to AF ablation, 67% male, 58±12 years, including 78 pts (13%) with LSPAF - pts with paroxysmal and persistent short duration AF represented 61% and 26% of the population. In LSPAF, VPI was performed with irrigated catheter (N=33), PVAC (N=44) or nMARQ (N=1), complemented by CTI ablation in 15, linear left atrial lesions in 3, ablation of areas of low voltage in 3 and elimination of fractionated electrograms in 1 patient. With a median follow-up of 426 days (94–989), the 3-year success rate after a single procedure was 53% in LSPAF, lower than that observed in patients with paroxysmal AF (69%) or short-duration persistent AF (61%) - LogRank P=0.002. The risk of arrhythmias was double in LSPAF vs paroxysmal AF (HR: 2.0; P=0.001). However, after an average of 1.2 procedures/patient, the success rate in LSPAF was 80% at 3 years, comparable to that observed for other types of AF (Log Rank 2.5, p=0.29). Effectively, the long-term success rate of our LSPAF pts treated with PVI and very selective additional strategies was higher than that observed in the STAR-II AF pts treated with PVI and indiscriminate complex ablations (80% vs. 69%, t-test p<0.001, with similar mean follow-up). Conclusions AF ablation is more effective if it is performed earlier in the natural history of the disease. However, even in LSPAF, high success rates are achieved through PVI-based ablation strategies, although more procedures are required.

Download Full-text

Find me if you can: lessons learned using the novel cartofinder algorithm in a routine workflow for catheter ablation of atrial fibrillation

EP Europace ◽

10.1093/europace/euab116.129 ◽

2021 ◽

Vol 23 (Supplement_3) ◽

Author(s):

C Sohns ◽

L Bergau ◽

R Unland ◽

M Piran ◽

M Chmelevsky ◽

...

Keyword(s):

Atrial Fibrillation ◽

Pulmonary Vein ◽

Low Voltage ◽

Lessons Learned ◽

The Novel ◽

Af Ablation ◽

Density Mapping ◽

Substrate Modification ◽

Close Relationship ◽

The Individual

Abstract Funding Acknowledgements Type of funding sources: None. Background CARTOFINDER allows for a simultaneous and automated detection of repetitive focal and rotational activations during electroanatomical mapping using a multi-electrode catheter in patients with atrial fibrillation (AF). Aim This study aimed to validate the CARTOFINDER algorithm for the detection of potential drivers for AF under routine clinical conditions and to access the effects of PVI and additional substrate modification on regions of interests (ROI) from CARTOFINDER mapping. Methods Forty-four consecutive patients underwent AF ablation for persistent AF using a 3D-mapping system with the novel integrated CARTOFINDER module. All patients presented with persistent AF and mapping was performed using a multi-electrode catheter. The ablation workflow was divided into the following steps: 1. 3D reconstruction of the right (RA) and left atrium (LA). 2. Identification of the individual ROIs separated for focal and rotational activity in the RA and LA. 3. Ablation index guided pulmonary vein isolation (PVI). 4. Repeat mapping for ROIs in the RA and LA. 5. Direct current electrical cardioversion. 6. Confirmation of persistent PVI and bipolar ultra-high density mapping of the RA and LA followed by substrate modification if there was evidence for local bipolar low-voltage in the LA. Results Acute PVI was achieved in all patients (100%). In 28% of these patients additional LA substrate modification was performed. AF termination was observed in 4 patients. Mean procedure duration was 137 ± 30 min, mapping time for ROIs in the RA was 8 ± 5 min and 11 ± 5 for the LA, respectively. A mean number of 149 ± 82 ROIs were revealed from CARTOFINDER. In the LA, focal activity was predominantly observed inside the LA appendage (LAA) and in close relationship to the pulmonary vein ostia. The majority of rotational activities was found along the mitral valve annulus. In the RA, the majority of ROIs was found at the septum and in close relationship to the RA appendage. During re-mapping for ROIs after AF ablation we observed the elimination of ROIs close to the linear ablation set for PVI. In addition, rotational activity could not be re-identified at repeat mapping. Conclusions ROIs could be discriminated and visualized utilizing CARTOFINDER in all patients. These ROIs might potentially be an additional and individual ablation target beyond PVI in patients with persistent AF.

Download Full-text

P441Targeted ablation of residual luminal pulmonary vein potentials through high density mapping: preliminary results from the CHARISMA registry

EP Europace ◽

10.1093/europace/euaa162.221 ◽

2020 ◽

Vol 22 (Supplement_1) ◽

Author(s):

F Solimene ◽

F M Cauti ◽

G Zucchelli ◽

V Schillaci ◽

P Rossi ◽

...

Keyword(s):

Pulmonary Vein ◽

De Novo ◽

Low Voltage ◽

Complete Characterization ◽

High Density ◽

Analysis Tool ◽

Temporal Consistency ◽

Af Ablation ◽

Density Mapping

Abstract Background A high incidence of pulmonary vein (PV) reconnection has been reported in patients (pts) with clinical recurrences of AF. Low-voltage activity beyond PVs (e.g. antral activity) may contribute to ablation failures in the long term. Detailed characterization of PV antra through high density mapping (HDM) and automated algorithm is still lacking. Purpose to characterize PV gaps and the low-voltage activity in tissue such as the PV antra during and after ablation of PVs in AF pts. Methods Consecutive pts undergoing AF ablation from the CHARISMA registry with complete characterization of residual PV antral activity were included. A complete map of the left atrium and PVs was performed prior and after ablation through the Rhythmia HDM system. A novel map analysis tool (Lumipoint - LM -) that automatically identifies split potentials and continuous activation was used sequentially on each PV component, in order to assess the presence of gaps (PVG) and residual potential within the antral scar (RAP, defined as any low voltage high frequency fractionated signal propagating within the antral scar without conduction into the vein) and characterize electrical propagation. After ablation we reassessed with repeat voltage and propagation maps that electrical quiescence was achieved. Ablation endpoint was PV isolation. Results Thirty-six cases of AF ablation were analyzed (11 de novo, 25 redo). A total of 36 PVG in 13 (36%) patients were detected after remap (1 case of de novo) or initial map of redo patients (12 cases). A total of 34 RAP in 20 cases (56%) were found: 4 (36%) cases of de novo (all after ablation and remap) and 16 (64%) cases of redo (all after initial map). In 7 (19%) cases we found at least one RAP in pts with complete absence of PV conduction. 100% of PVG (n = 36) and 89% of RAP (n = 29) were fully detected though a first pass automated annotation. In 5 RAPs (11%) an additional temporal consistency of low-voltage signal relative to neighboring activation was needed due to the very low voltage EGM (≤0.1 mV). PVGs were more common at right PV sites (n = 26, 72%) and anterior PV sites (n = 20, 55.6%) whereas RAPs were detected more frequently at left PV sites (n = 20, 59%) and anterior PV sites (n = 21, 62%). RAP showed a lower median voltage compared with PVG (0.22[0.2-0.3]mV for RAP vs 0.97[0.6-1.3]mV for PVG, p < 0.0001) whereas the median number of EGM peaks were higher (6.5[5-8] for RAP vs 3[2-4] for PVG, p < 0.0001). No complications during the procedures were reported. The acute procedural success was 100%, with all PVs successfully isolated and RAPs completely abolished in all study pts. Conclusion In our preliminary experience, local vulnerabilities in antral lesion sets were commonly discernible using HDM system both in de novo or redo patients when no PV conduction was present. The applied workflow seemed to be useful to quickly pinpoint and accelerate the search of local PV activity or concealed low-voltage activity.

Download Full-text

High incidence of left atrial dysfunction and low voltage zone in patients requiring multiple atrial fibrillation ablation

European Heart Journal ◽

10.1093/ehjci/ehaa946.0425 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

T Oka ◽

I Yoshimoto ◽

Y Koyama ◽

K Tanaka ◽

Y Hirao ◽

...

Keyword(s):

Atrial Fibrillation ◽

Sinus Rhythm ◽

Recurrence Rate ◽

Left Atrial ◽

Low Voltage ◽

Peak Voltage ◽

Af Ablation ◽

Recurrent Atrial Fibrillation ◽

Linear Ablation ◽

Left Atrial Dysfunction

Abstract Background While multiple catheter ablation for recurrent atrial fibrillation (AF) is effective for the maintenance of sinus rhythm, some of patients have ablation-refractory AF. Left atrial (LA) dysfunction and the presence of low voltage zone (LVZ) are associated with recurrence after AF ablation. The association between recurrence and LA dysfunction/ LVZ among patients undergoing multiple AF ablation remains unclear. Purpose We aimed to compare (i)LA function, (ii)the prevalence of LVZ among patients undergoing first, second and third or more AF ablation procedures. Further, we investigated whether LA dysfunction and LVZ are associated with recurrence after multiple procedures. Methods We retrospectively analyzed 460 patients undergoing AF ablation procedures including first, second and third or more sessions from January 2017 to October 2019 in our institute. Before each session, 256-slice MDCT was performed under sinus rhythm to measure pre-ablation LA emptying fraction (LAEF) as the representative of LA function. At the end of each session, we checked the presence of LVZ, which was defined as regions where bipolar peak-to-peak voltage was <0.5mV. All patients underwent pulmonary vein isolation (PVI). If necessary, additional ablation (e.g. linear ablation, non-PV foci ablation and LVZ ablation) was performed. Results Out of 460 sessions, 295 were first (follow-up years: 1.5 [0.8, 2.0]), 134 were second (1.0 [0.5, 1.8]), and 31 were third or more sessions (1.2 [0.7, 2.0]). As the number of sessions increased, the recurrence rate was increased (19% vs. 31% vs. 61%, first vs. second vs. ≥third, P<0.0001), LAEF decreased (39.7±10.5% vs. 32.6±10.1% vs. 25.3±11.8%, P<0.0001) and the incidence of LVZ increased (18% vs. 34% vs. 68%, P<0.0001) (Figure 1). In patients with recurrence (N=104) after multiple ablation (second or more sessions), LAEF was lower and the prevalence of LVZ was higher than those without recurrence (N=61) (LAEF: 27.3±10.3% vs. 33.5±10.5%, with vs. without, P=0.0003; LVZ: 57% vs. 31%, P=0.0014). Conclusions As the number of sessions increased, the recurrence rate was increased. The prevalence of LA dysfunction and LVZ was high in patients requiring multiple ablation procedure. LA dysfunction and LVZ possibly reflect arrhytmogenic substrate causing recurrence of ablation-refractory AF. We should carefully consider repeated AF ablation in patients with severe LA dysfunction and extensive LVZ. Figure 1 Funding Acknowledgement Type of funding source: None

Download Full-text

Processing of human melanoma cells for correlative TEM, LVSEM, and LM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100084831 ◽

1991 ◽

Vol 49 ◽

pp. 106-107

Author(s):

Marek Malecki ◽

J. Victor Small ◽

James Pawley

Keyword(s):

Electron Microscopy ◽

Low Voltage ◽

Fluorescent Microscopy ◽

Blood Stream ◽

Surface Topology ◽

Integrin Receptors ◽

Transmission Electron ◽

Develop Technology ◽

Voltage Scanning ◽

Mechanisms Of Adhesion

The relative roles of adhesion and locomotion in malignancy have yet to be clearly established. In a tumor, subpopulations of cells may be recognized according to their capacity to invade neighbouring tissue,or to enter the blood stream and metastasize. The mechanisms of adhesion and locomotion are themselves tightly linked to the cytoskeletal apparatus and cell surface topology, including expression of integrin receptors. In our studies on melanomas with Fluorescent Microscopy (FM) and Cell Sorter(FACS), we noticed that cells in cultures derived from metastases had more numerous actin bundles, then cells from primary foci. Following this track, we attempted to develop technology allowing to compare ultrastructure of these cells using correlative Transmission Electron Microscopy(TEM) and Low Voltage Scanning Electron Microscopy(LVSEM).

Download Full-text

High-pressure freezing of cells in suspension for low-voltage scanning electron microscopy (LVSEM)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100084624 ◽

1991 ◽

Vol 49 ◽

pp. 64-65

Author(s):

Marek Malecki ◽

James Pawley ◽

Hans Ris

Keyword(s):

Electron Microscopy ◽

High Pressure ◽

Low Voltage ◽

Culture Media ◽

Cell Structure ◽

Freeze Substitution ◽

Ice Crystal ◽

High Pressure Freezing ◽

Cell Culture Media ◽

Voltage Scanning

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.

Download Full-text

Development of a conical anode Fe-gun for low voltage SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106958 ◽

1988 ◽

Vol 46 ◽

pp. 978-979

Author(s):

T. Miyokawa ◽

S. Norioka ◽

S. Goto

Keyword(s):

High Resolution ◽

Field Emission ◽

Low Voltage ◽

Irradiation Damage ◽

Cold Cathode ◽

Virtual Source ◽

Source Position ◽

Electrostatic Lens ◽

Electrostatic Lenses ◽

Wide Range

Field emission SEMs (FE-SEMs) are becoming popular due to their high resolution needs. In the field of semiconductor product, it is demanded to use the low accelerating voltage FE-SEM to avoid the electron irradiation damage and the electron charging up on samples. However the accelerating voltage of usual SEM with FE-gun is limited until 1 kV, which is not enough small for the present demands, because the virtual source goes far from the tip in lower accelerating voltages. This virtual source position depends on the shape of the electrostatic lens. So, we investigated several types of electrostatic lenses to be applicable to the lower accelerating voltage. In the result, it is found a field emission gun with a conical anode is effectively applied for a wide range of low accelerating voltages.A field emission gun usually consists of a field emission tip (cold cathode) and the Butler type electrostatic lens.

Download Full-text

SEM analysis of DC magnetron sputtered beryllium films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106867 ◽

1988 ◽

Vol 46 ◽

pp. 960-961

Author(s):

E. F. Lindsey ◽

C. W. Price ◽

E. L. Pierce ◽

E. J. Hsieh

Keyword(s):

Fine Structure ◽

Electron Emission ◽

Secondary Electron ◽

Low Voltage ◽

Ion Beam ◽

Secondary Electron Emission ◽

Sem Analysis ◽

Fused Silica ◽

Grain Structure ◽

Silica Substrate

Columnar structures produced by DC magnetron sputtering can be altered by using RF biased sputtering or by exposing the film to nitrogen pulses during sputtering, and these techniques are being evaluated to refine the grain structure in sputtered beryllium films deposited on fused silica substrates. Beryllium is brittle, and fractures in sputtered beryllium films tend to be intergranular; therefore, a convenient technique to analyze grain structure in these films is to fracture the coated specimens and examine them in an SEM. However, fine structure in sputtered deposits is difficult to image in an SEM, and both the low density and the low secondary electron emission coefficient of beryllium seriously compound this problem. Secondary electron emission can be improved by coating beryllium with Au or Au-Pd, and coating also was required to overcome severe charging of the fused silica substrate even at low voltage. The coating structure can obliterate much of the fine structure in beryllium films, but reasonable results were obtained by using the high-resolution capability of an Hitachi S-800 SEM and either ion-beam coating with Au-Pd or carbon coating by thermal evaporation.

Download Full-text