scholarly journals Quantitative assessment of ventricular far field removal techniques for clinical unipolar electrograms

2021 ◽  
Vol 7 (2) ◽  
pp. 243-246
Author(s):  
Nick Johannes Lorenz ◽  
Laura Anna Unger ◽  
Armin Luik ◽  
Olaf Dössel
Keyword(s):  
Atrial Tachycardia ◽  
Electrophysiological Study ◽  
Clinical Settings ◽  
Data Sets ◽  
Clinical Validation ◽  
Far Field ◽  
Optimal Length ◽  
Electrophysiological Studies ◽  
Removal Technique ◽  
Unipolar Electrograms

Abstract The incidence of atrial tachycardia steadily increases in industrial nations. During invasive electrophysiological studies, a catheter measures electrograms within the atrium to assist detailed diagnosis and treatment planning. With unipolar and bipolar electrograms, two different acquisition modes are clinically available. Unipolar electrograms have several advantages over bipolar electrograms. However, unipolar electrograms are more affected by noise and the ventricular far field. Therefore, only bipolar electrograms are typically used in clinical settings. A recently published ventricular far field removal technique models the ventricular far field by a set of dipoles and yielded promising results in a simulation study. However, the method lacks quantitative clinical validation. Therefore, we adapted the technique to clinical needs and applied it to data sets of two patients using four different lengths of the removal window. Results were compared quantitatively by a tailored residual error measure. The used method resulted in a median reduction of the ventricular far field by approximately 89% using a removal window of optimal length for both patients. The results showed that the dipole method provides an alternative to other VFF removal techniques in clinical practice because it can reveal AA originally hidden by VFF without leading to a prolongation of the electrophysiological study.

The shape of things to come — Development and testing of a new marine vibrator source

2019 ◽  
Vol 38 (9) ◽  
pp. 680-690 ◽  
Author(s):  
Benoît Teyssandier ◽  
John J. Sallas
Keyword(s):  
Seismic Source ◽  
Test Facility ◽  
Data Sets ◽  
Far Field ◽  
Ocean Bottom ◽  
Air Gun ◽  
Seismic Image ◽  
Field Radiation ◽  
Technical Issues ◽  
To Come

Ten years ago, CGG launched a project to develop a new concept of marine vibrator (MV) technology. We present our work, concluding with the successful acquisition of a seismic image using an ocean-bottom-node 2D survey. The expectation for MV technology is that it could reduce ocean exposure to seismic source sound, enable new acquisition solutions, and improve seismic data quality. After consideration of our objectives in terms of imaging, productivity, acoustic efficiency, and operational risk, we developed two spectrally complementary prototypes to cover the seismic bandwidth. In practice, an array composed of several MV units is needed for images of comparable quality to those produced from air-gun data sets. Because coupling to the water is invariant, MV signals tend to be repeatable. Since far-field pressure is directly proportional to piston volumetric acceleration, the far-field radiation can be well controlled through accurate piston motion control. These features allow us to shape signals to match precisely a desired spectrum while observing equipment constraints. Over the last few years, an intensive validation process was conducted at our dedicated test facility. The MV units were exposed to 2000 hours of in-sea testing with only minor technical issues.

Measuring stress-induced martensite microstructures using far-field high-energy diffraction microscopy

2018 ◽  
Vol 74 (5) ◽  
pp. 425-446 ◽  
Author(s):  
Ashley Nicole Bucsek ◽  
Darren Dale ◽  
Jun Young Peter Ko ◽  
Yuriy Chumlyakov ◽  
Aaron Paul Stebner
Keyword(s):  
Phase Transformation ◽  
Three Dimensional ◽  
Infinite Plate ◽  
Direct Analysis ◽  
High Energy ◽  
Data Sets ◽  
Far Field ◽  
X Ray Diffraction ◽  
Parent Austenite ◽  
Diffraction Microscopy

Modern X-ray diffraction techniques are now allowing researchers to collect long-desired experimental verification data sets that are in situ, three-dimensional, on the same length scales as critical microstructures, and using bulk samples. These techniques need to be adapted for advanced material systems that undergo combinations of phase transformation, twinning and plasticity. One particular challenge addressed in this article is direct analysis of martensite phases in far-field high-energy diffraction microscopy experiments. Specifically, an algorithmic forward model approach is presented to analyze phase transformation and twinning data sets of shape memory alloys. In the present implementation of the algorithm, the crystallographic theory of martensite (CTM) is used to predict possible martensite microstructures (i.e. martensite orientations, twin mode, habit plane, twin plane and twin phase fractions) that could form from the parent austenite structure. This approach is successfully demonstrated on three single- and near-single-crystal NiTi samples where the fundamental assumptions of the CTM are not upheld. That is, the samples have elastically strained lattices, inclusions, precipitates, subgrains, R-phase transformation and/or are not an infinite plate. The results indicate that the CTM still provides structural solutions that match the experiments. However, the widely accepted maximum work criterion for predicting which solution of the CTM should be preferred by the material does not work in these cases. Hence, a more accurate model that can simulate these additional structural complexities can be used within the algorithm in the future to improve its performance for non-ideal materials.

scholarly journals Electrophysiological Studies in Patients with Pulmonary Hypertension: A Retrospective Investigation

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Dirk Bandorski ◽  
Jörn Schmitt ◽  
Claudia Kurzlechner ◽  
Damir Erkapic ◽  
Christian W. Hamm ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Atrial Flutter ◽  
Electrophysiological Study ◽  
Atrioventricular Nodal Reentrant Tachycardia ◽  
Reentrant Tachycardia ◽  
Group 4 ◽  
Electrophysiological Studies ◽  
Group 5 ◽  
Group 2 ◽  
Ventricular Tachycardias

Few studies have investigated patients with pulmonary hypertension and arrhythmias. Data on electrophysiological studies in these patients are rare. In a retrospective dual-centre design, we analysed data from patients with indications for electrophysiological study. Fifty-five patients with pulmonary hypertension were included (Dana Point Classification: group 1: 14, group 2: 23, group 3: 4, group 4: 8, group 5: 2, and 4 patients with exercised-induced pulmonary hypertension). Clinical data, 6-minute walk distance, laboratory values, and echocardiography were collected/performed. Nonsustained ventricular tachycardia was the most frequent indication (n=15) for an electrophysiological study, followed by atrial flutter (n=14). In summary 36 ablations were performed and 25 of them were successful (atrial flutter 12 of 14 and atrioventricular nodal reentrant tachycardia 4 of 4). Fluoroscopy time was 16±14.4 minutes. Electrophysiological studies in patients with pulmonary hypertension are feasible and safe. Ablation procedures are as effective in these patients as in non-PAH patients with atrial flutter and atrioventricular nodal reentrant tachycardia and should be performed likewise. The prognostic relevance of ventricular stimulations and inducible ventricular tachycardias in these patients is still unclear and requires further investigation.

Epidemiology, presentation, and therapy of supraventricular tachycardias

2016 ◽  
Author(s):  
Demosthenes G. Katritsis ◽  
Bernard J. Gersh ◽  
A. John Camm
Keyword(s):  
Atrial Tachycardia ◽  
Clinical Settings ◽  
Supraventricular Tachycardias

Supraventricular tachycardias (SVT) are traditionally considered as sinus nodal tachycardias, atrial tachycardia and flutter, AVNRT and other junctional arrhythmias, and AVRT. In this chapter, classification, epidemiology, and presentation of SVT in various clinical settings are presented.

scholarly journals Incessant Automatic Atrial Tachycardia in a Neonate Successfully Treated with Nadolol and Closely Spaced Doses of Flecainide: A Case Report

2020 ◽  
Vol 12 (3) ◽  
pp. 108-113
Author(s):  
Gilda Belli ◽  
Mattia Giovannini ◽  
Giulio Porcedda ◽  
Marco Moroni ◽  
Giancarlo la Marca ◽  
...  
Keyword(s):  
Case Report ◽  
Sinus Rhythm ◽  
Atrial Tachycardia ◽  
Electrophysiological Study ◽  
Common Type ◽  
Supraventricular Tachyarrhythmia ◽  
Risk Of Mortality ◽  
Wide Complex Tachycardia ◽  
Stable Sinus Rhythm ◽  
Narrow Complex Tachycardia

Supraventricular tachyarrhythmia (SVT) is the most common type of arrhythmia in childhood. Management can be challenging with an associated risk of mortality. A female neonate was diagnosed with episodes of SVT, controlled antenatally with digoxin. Flecainide was commenced prophylactically at birth. Despite treatment, the infant developed a narrow complex tachycardia at 5 days of age. The electrocardiogram features were suggestive of either re-entry tachycardia or of automatic atrial tachycardia (AAT). Following several unsuccessful treatments, a wide complex tachycardia developed. A transesophageal electrophysiological study led to a diagnosis of AAT. Stable sinus rhythm was finally achieved through increasing daily administrations of flecainide up to six times a day, in association with nadolol. The shortening of intervals to this extent has never been reported before and supports the evidence of a personal, age-specific variability in pharmacokinetics of flecainide. Larger studies are needed to better define the appropriate dose and timing of administration.

scholarly journals A fusion fuzzy model for detecting phony accounts in social networks

2018 ◽  
Vol 7 (4) ◽  
pp. 2738
Author(s):  
P. Srinivas Rao ◽  
Jayadev Gyani ◽  
G. Narsimha
Keyword(s):  
Social Network ◽  
Fuzzy Model ◽  
Machine Learning Techniques ◽  
Personal Attributes ◽  
Data Sets ◽  
Learning Techniques ◽  
The Social ◽  
Using Data ◽  
Removal Technique ◽  
Normal Rank

In online social network’s phony account detection is one of the major task among the ability of genuine user from forged user account. The fundamental objective of detection of phony account framework is to detect fake account and removal technique in Social network user sites. This work concentrates on detection of phony account in which it depends on normal basis framework, transformative Algorithms and fuzzy technique. Initially, the most essential attributes including personal attributes, comparability techniques and various real user review, tweets, or comments are extricated. A direct blend of these attributes demonstrates the significance of each reviews tweets comments etc. To compute closeness measure, a consolidated strategy in view of artificial honey bee state Algorithm and fuzzy technique are utilized. Second approach is proposed to alter the best weights of the normal user attributes utilizing the social network activities/transaction and inherited Algorithm. Finally, a normal rank rationale framework is utilized to calculate the final scoring of normal user activities. The decision making of proposed approach to find phony account are variation with existing techniques user behavioral analysis using data sets and machine learning techniques such as crowdflower_sample and genuine_accounts_sample dataset of facebook and Twitter. The outcomes demonstrate that proposed strategy overcomes the previously mentioned strategies. 

CLINICAL VALIDATION OF A NOVEL SPRING LOADED TENSIONING DEVICE AND COMPUTER ASSISTED NAVIGATION

2006 ◽  
Vol 06 (01) ◽  
pp. 13-18
Author(s):  
S. BIGNOZZI ◽  
S. ZAFFAGNINI ◽  
S. MARTELLI ◽  
M. MARCACCI
Keyword(s):  
Randomized Study ◽  
Computer Software ◽  
Constant Load ◽  
Computer Assisted ◽  
Data Sets ◽  
Clinical Validation ◽  
Qualitative Comparison ◽  
Assisted Navigation ◽  
Orthopedic Surgeons ◽  
Ligament Tension

This study presents the validation of the tensioning device that applies a constant load to the medial and lateral compartments of knee joint separately, which can collapse or expand on each side independently, and that should be able to provide a better evaluation of ligament tension and allow the computer software to better plan the appropriate bone cuts or ligament release, and reports the first phase of the clinical validation of the tensioning device, including first qualitative comparison with standard navigated technique and consideration on the use of the device. A randomized study, involving five experienced orthopedic surgeons with 58 complete data sets, revealed that there is no statistical difference between the gaps obtained with standard navigated technique and tensioning device in extension, while in flexion there is an average difference 1.4 mm.

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