scholarly journals The Impact of Filter Settings on Morphology of Unipolar Fibrillation Potentials

2020 ◽  
Vol 13 (6) ◽  
pp. 953-964
Author(s):  
Roeliene Starreveld ◽  
Paul Knops ◽  
Maarten Roos-Serote ◽  
Charles Kik ◽  
Ad J. J. C. Bogers ◽  
...  
Keyword(s):  
Clinical Practice ◽  
High Resolution ◽  
Ablative Therapy ◽  
Potential Source ◽  
Deflection Amplitude ◽  
Low Pass ◽  
Atrial Electrogram ◽  
The Impact ◽  
High Pass ◽  
Source Of Error

AbstractUsing unipolar atrial electrogram morphology as guidance for ablative therapy is regaining interest. Although standardly used in clinical practice during ablative therapy, the impact of filter settings on morphology of unipolar AF potentials is unknown. Thirty different filters were applied to 2,557,045 high-resolution epicardial AF potentials recorded from ten patients. Deflections with slope ≤ − 0.05 mV/ms and amplitude ≥ 0.3 mV were marked. High-pass filtering decreased the number of detected potentials, deflection amplitude, and percentage of fractionated potentials (≥ 2 deflections) as well as fractionation delay time (FDT) and increased percentage of single potentials. Low-pass filtering decreased the number of potentials, percentage of fractionated potentials, whereas deflection amplitude, percentage of single potentials, and FDT increased. Notch filtering (50 Hz) decreased the number of potentials and deflection amplitude, whereas the percentage of complex fractionated potentials (≥ 3 deflections) increased. Filtering significantly impacted morphology of unipolar fibrillation potentials, becoming a potential source of error in identification of ablative targets.

P436The impact of filter settings on morphology of unipolar fibrillation potentials

EP Europace ◽  
2020 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
R Starreveld ◽  
P Knops ◽  
M Roos-Serote ◽  
C Kik ◽  
A J J C Bogers ◽  
...  
Keyword(s):  
Low Voltage ◽  
Ablative Therapy ◽  
Deflection Amplitude ◽  
Low Pass ◽  
Atrial Electrogram ◽  
Notch Filtering ◽  
Activation Times ◽  
The Impact ◽  
High Pass ◽  
Source Of Error

Abstract Funding Acknowledgements N.M.S. de Groot, MD, PhD was supported by CVON-AFFIP (914728), NWO-Vidi (91717339) and Biosense Webster USA (ICD 783454). Background Using unipolar atrial electrogram morphology as guidance for ablative therapy is regaining interest. Although standardly used in clinical practice during ablative therapy, the impact of filter settings on morphology of unipolar AF potentials is unknown. Purpose This study aims to elucidate consequences of high-pass, low-pass and notch filtering on unipolar atrial fibrillation (AF) potentials. Methods Thirty different filter settings were applied to high-resolution epicardial AF potentials recorded from ten patients. . Local activation times were determined by marking deflections with slope ≤-0.05mV/ms and amplitude ≥0.3mV. Fibrillation potentials were analyzed for peak-to-peak amplitude (mV), number of deflections (f) and fractionation delay time (FDT, interval between first and last deflection), and classified as single potential (SP, f = 1), double potential (DP, f = 2) or complex fractionated potential (CP, f ≥ 3). Results In total, 3000 seconds of AF recordings were analyzed, containing 255,7045 fibrillation potentials. Changing high-pass filtering from 0.5 up to 100 Hz decreased the number of detected fibrillation potentials (with 25-65%), median deflection amplitude (min-max 0.59-0.96 to 0.44-0.57 mV), percentage of DP (25.8-32.9 to 22.5-31.6%) and CP (15.9-36.0 to 7.3-37.8%) as well as median FDT (16-25 to 11-15 ms) (all p < 0.01). Gradually changing low-pass filtering from 400 Hz to 20 Hz induced an exponential decrease in fibrillation potentials (to 0%), percentage of DP (25.8-32.9 to 0%) and CP (15.9-36.0 to 0%), whereas deflection amplitude, percentage of SP and median FDT exponentially increased (0.59-0.96 to 1.82-2.39 mV, 36.1-57.6 to 100%, 16-25 to 33-38 ms, respectively) (all p < 0.01). Notch filtering at 50 Hz decreased the number of detected fibrillation potentials (with ∼1%), median deflection amplitude (0.59-0.96 to 0.59-0.95 mV) (both p < 0.01), whereas the percentage of CP increased (15.9-36.0 to 16.2-37.0%, p = 0.016). Conclusions Filtering significantly impacted  of unipolar fibrillation potentials and decreased the number of detected potentials, becoming a potential source of error in identification of LATs, low-voltage areas, fractionated potentials and thus ablative targets during mapping. Potentials (%) Amplitude (mV) SP (%) DP (%) CFP (%) FDT (ms) Default (0.5-400 Hz) 100 0.59-0.96 36.1-57.6 25.8-32.9 15.9-36.0 16.0-25.0 High-pass filtering Decreased Decreased Increased Decreased Decreased Decreased Low-pass filtering Decreased Increased Increased Decreased Decreased Increased Notch filtering Decreased Decreased p = NS p = NS Increased p = NS Impact of filtering on morphology parameters Abstract Figure. Impact of filtering on AF morphology

Atomic resolution characterisation of interface structures by Electron Energy Loss Spectroscopy

1993 ◽  
Vol 51 ◽  
pp. 576-577
Author(s):  
N. D. Browning ◽  
M. M. McGibbon ◽  
M. F. Chisholm ◽  
S. J. Pennycook
Keyword(s):  
High Resolution ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Imaging Technique ◽  
Atomic Scale ◽  
Atomic Resolution ◽  
Reference Image ◽  
The Impact ◽  
Electron Energy Loss

The recent development of the Z-contrast imaging technique for the VG HB501 UX dedicated STEM, has added a high-resolution imaging facility to a microscope used mainly for microanalysis. This imaging technique not only provides a high-resolution reference image, but as it can be performed simultaneously with electron energy loss spectroscopy (EELS), can be used to position the electron probe at the atomic scale. The spatial resolution of both the image and the energy loss spectrum can be identical, and in principle limited only by the 2.2 Å probe size of the microscope. There now exists, therefore, the possibility to perform chemical analysis of materials on the scale of single atomic columns or planes.In order to achieve atomic resolution energy loss spectroscopy, the range over which a fast electron can cause a particular excitation event, must be less than the interatomic spacing. This range is described classically by the impact parameter, b, which ranges from ~10 Å for the low loss region of the spectrum to <1Å for the core losses.

Translating Principles of Speech Science to Clinical Practice: Current and Future Trends in Craniofacial Disorders

2008 ◽  
Vol 18 (1) ◽  
pp. 31-40 ◽  
Author(s):  
David J. Zajac
Keyword(s):  
Clinical Practice ◽  
Speech Intelligibility ◽  
Current Practice ◽  
Computer Assisted ◽  
Behavioral Management ◽  
Single Word ◽  
Future Directions ◽  
Speech Science ◽  
The Impact ◽  
Opinion Article

Abstract The purpose of this opinion article is to review the impact of the principles and technology of speech science on clinical practice in the area of craniofacial disorders. Current practice relative to (a) speech aerodynamic assessment, (b) computer-assisted single-word speech intelligibility testing, and (c) behavioral management of hypernasal resonance are reviewed. Future directions and/or refinement of each area are also identified. It is suggested that both challenging and rewarding times are in store for clinical researchers in craniofacial disorders.

The end of the laboratory developed test as we know it? Recommendations from a national multidisciplinary taskforce of laboratory specialists on the interpretation of the IVDR and its complications

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Paul C. D. Bank ◽  
Leo H. J. Jacobs ◽  
Sjoerd A. A. van den Berg ◽  
Hanneke W. M. van Deutekom ◽  
Dörte Hamann ◽  
...  
Keyword(s):  
Clinical Practice ◽  
The Netherlands ◽  
Medical Devices ◽  
Task Force ◽  
Large Impact ◽  
Guidance Document ◽  
Scientific Societies ◽  
Clinical Laboratories ◽  
The Impact

AbstractThe in vitro diagnostic medical devices regulation (IVDR) will take effect in May 2022. This regulation has a large impact on both the manufacturers of in vitro diagnostic medical devices (IVD) and clinical laboratories. For clinical laboratories, the IVDR poses restrictions on the use of laboratory developed tests (LDTs). To provide a uniform interpretation of the IVDR for colleagues in clinical practice, the IVDR Task Force was created by the scientific societies of laboratory specialties in the Netherlands. A guidance document with explanations and interpretations of relevant passages of the IVDR was drafted to help laboratories prepare for the impact of this new legislation. Feedback from interested parties and stakeholders was collected and used to further improve the document. Here we would like to present our approach to our European colleagues and inform them about the impact of the IVDR and, importantly we would like to present potentially useful approaches to fulfill the requirements of the IVDR for LDTs.

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