Ultrasonic measurements of local activation times: Toward the realization of a clinical intramural cardiac electrical mapping?

Heart Rhythm ◽  
2011 ◽  
Vol 8 (5) ◽  
pp. 760-761
Author(s):  
Sharon Zlochiver
Keyword(s):  
Local Activation ◽  
Ultrasonic Measurements ◽  
Electrical Mapping ◽  
Activation Times

scholarly journals Effects of local activation times on the tension development of human cardiomyocytes in a computational model

2018 ◽  
Vol 4 (1) ◽  
pp. 247-250
Author(s):  
Armin Müller ◽  
Ekaterina Kovacheva ◽  
Steffen Schuler ◽  
Olaf Dössel ◽  
Lukas Baron
Keyword(s):  
Human Heart ◽  
Maximum Pressure ◽  
Simulation Framework ◽  
Activation Time ◽  
Tension Development ◽  
Human Cardiomyocytes ◽  
Local Activation ◽  
Activation Times ◽  
The Right ◽  
Simulation Time

AbstractThe human heart is an organ of high complexity and hence, very challenging to simulate. To calculate the force developed by the human heart and therefore the tension of the muscle fibers, accurate models are necessary. The force generated by the cardiac muscle has physiologically imposed limits and depends on various characteristics such as the length, strain and the contraction velocity of the cardiomyocytes. Another characteristic is the activation time of each cardiomyocyte, which is a wave and not a static value for all cardiomyocytes. To simulate a physiologically correct excitation, the functionality of the cardiac simulation framework CardioMechanics was extended to incorporate inhomogeneous activation times. The functionality was then used to evaluate the effects of local activation times with two different tension models. The active stress generated by the cardiomyocytes was calculated by (i) an explicit function and (ii) an ode-based model. The results of the simulations showed that the maximum pressure in the left ventricle dropped by 2.3% for the DoubleHill model and by 5.3% for the Lumens model. In the right ventricle the simulations showed similar results. The maximum pressure in both the left and the right atrium increased using both models. Given that the simulation of the inhomogeneously activated cardiomyocytes increases the simulation time when used with the more precise Lumens model, the small drop in maximum pressure seems to be negligible in favor of a simpler simulation model

scholarly journals Probabilistic Interpolation of Uncertain Local Activation Times on Human Atrial Manifolds

2020 ◽  
Vol 67 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Sam Coveney ◽  
Richard H. Clayton ◽  
Cesare Corrado ◽  
Caroline H. Roney ◽  
Richard D. Wilkinson ◽  
...  
Keyword(s):  
Local Activation ◽  
Activation Times

scholarly journals Arrhythmia Mechanisms Revealed by Ripple Mapping

2018 ◽  
Vol 7 (4) ◽  
pp. 1 ◽  
Author(s):  
George Katritsis ◽  
Vishal Luther ◽  
Prapa Kanagaratnam ◽  
Nick WF Linton ◽  
◽  
...  
Keyword(s):  
Expert Opinion ◽  
Ventricular Tachyarrhythmias ◽  
Local Activation ◽  
Intracardiac Electrogram ◽  
Arrhythmia Mechanisms ◽  
Electrophysiological Procedures ◽  
Novel Method ◽  
Mapping Techniques ◽  
Activation Times ◽  
Prior Assignment

Ripple mapping is a novel method of 3D intracardiac electrogram visualisation that allows activation of the myocardium to be tracked visually without prior assignment of local activation times and without interpolation into unmapped regions. It assists in the identification of tachycardia mechanism and optimal ablation site, without the need for an experienced computer-operating assistant. This expert opinion presents evidence demonstrating the benefit of Ripple Mapping, compared with traditional electroanatomic mapping techniques, for the diagnosis and management of atrial and ventricular tachyarrhythmias during electrophysiological procedures.

Abstract 18650: Activation Mapping of Ventricular Ectopy: Characterization of a Threshold Value Predicting Successful Catheter Ablation

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Will Camnitz ◽  
Kenneth Bilchick ◽  
John Dimarco ◽  
Kevin Driver ◽  
John Ferguson ◽  
...  
Keyword(s):  
Catheter Ablation ◽  
Threshold Value ◽  
Accurate Method ◽  
Ventricular Ectopy ◽  
Activation Time ◽  
Local Activation ◽  
Successful Ablation ◽  
Activation Times ◽  
Local Activation Time ◽  
Activation Mapping

Background: Catheter ablation of ventricular ectopy is performed with increasing frequency. Activation mapping to determine the site with the earliest presystolic electrogram (EGM) is the most accurate method to locate the optimal ablation site. Despite this, activation mapping of ventricular ectopy has not been systematically reviewed in a large series, and the optimal activation time predicting successful ablation has not previously been determined. The goal of this study is to determine the local presystolic activation time most predictive of successful ablation. Methods and Results: We retrospectively reviewed 100 consecutive successful endocardial PVC ablations and analyzed the local activation time at each successful and unsuccessful ablation site. A total of 561 ablation lesions were reviewed. Activation time was calculated as the difference between the peak of the local bipolar EGM and the onset of the reference surface QRS complex. Acute success was defined as complete elimination of the target PVC during the procedure with no recurrence at 30 days by ECG and follow-up Holter. A local activation time 27 msec presystolic best predicted success with a sensitivity of 88%, specificity 85%, and an area under the ROC curve of 0.936 (95% CI 0.91 - 0.95; figure 1). The 27 msec presystolic activation time remained most predictive of success after sub-stratifying activation times by location (RVOT v LVOT, outflow v intracavitary). The odds ratio for success with each 1 msec increase in activation time (becomes more negative by 1 msec) is 1.24 (95% CI 1.19 - 1.29). Conclusion: In our experience, a local presystolic activation time of 27 msec is the threshold value most predictive of successful PVC ablation. Our review is the first to systematically characterize an activation time predicting success with PVC ablation in a large cohort. Figure 1

127Diastolic window of interest mapping for fast identification of the critical isthmus in re-entrant ventricular tachycardia

EP Europace ◽  
2020 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
M J B Kemme ◽  
M J Mulder ◽  
C P Allaart
Keyword(s):  
Ventricular Tachycardia ◽  
Ischemic Cardiomyopathy ◽  
Near Field ◽  
Negative Slope ◽  
Far Field ◽  
Local Activation ◽  
Scar Area ◽  
Vt Ablation ◽  
Activation Times ◽  
Manual Correction

Abstract Background/Introduction Identification of the critical isthmus in re-entrant ventricular tachycardia (VT) should be fast and accurate as the tachycardia is often tolerated for a limited period of time. Using the standard window of interest (WOI) setting with the beginning and end of the window set at mid diastole, mapping systems may incorrectly annotate far field systolic signals instead of smaller diastolic local bipolar signals. The resulting activation map may not show activation pathways through the scar area. Purpose We aimed to study if adjustment of the WOI to the diastolic part of the VT cycle during automatic annotated mapping could aid critical tachycardia isthmus identification. Methods Consecutive patients with ischemic cardiomyopathy undergoing endocardial VT ablation between January 2018 and July 2019 were studied. VT mapping was performed using a multipolar mapping catheter. All signals were automatically annotated using the algorithm provided by the 3D mapping system which uses the maximum negative slope of the unipolar signal (-dV/dT) concomitant with a bipolar signal to calculate local activation times. Location of the critical isthmus was either identified or confirmed by pacing showing concealed entrainment. Acquired maps were analysed retrospectively using three methods: (1) automatically annotated using conventional WOI settings with onset of the window fixed in mid-diastole and a window duration spanning the tachycardia cycle length minus 20 ms, (2) similar conventional WOI settings with manual correction assuring annotation of the near field signal and (3) automatically annotated with an adjusted WOI focused on the diastolic part of the VT, thus excluding its systolic part. Results Forty ischemic cardiomyopathy patients underwent endocardial VT ablation, of which 8 procedures were identified that included activation mapping of re-entrant VT’s. Using conventional WOI settings, local activation was automatically annotated on far field instead of the actual local bipolar activation signal in a mean of 92 (14%) points, range 17 to 260 (3 to 21 %). In all cases, the resulting map did not show diastolic pathways through the scar (Figure A). After manual correction of annotated signals, maps depicted pathways through the scar area (Figure B). All automatically annotated maps with a diastolic WOI indicated the location of the critical isthmus (Figure C). Diastolic pathways are shown by isochronals coloured red/yellow (early diastolic entry) going over in green to light blue (mid-diastolic) adjacent to blue (late diastolic) to pink (exit area), instead of blue/pink and red/yellow (‘early meets late’) during standard WOI mapping. Conclusions Diastolic WOI mapping improves rapid critical isthmus identification in re-entrant ventricular tachycardia, without the need for manual correction. Resulting activation maps may require familiarisation as colour coding differs from standard WOI maps. Abstract Figure. Standard versus diastolic WOI map

scholarly journals CVAR-Seg: An Automated Signal Segmentation Pipeline for Conduction Velocity and Amplitude Restitution

2021 ◽  
Vol 12 ◽  
Author(s):  
Mark Nothstein ◽  
Armin Luik ◽  
Amir Jadidi ◽  
Jorge Sánchez ◽  
Laura A. Unger ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Conduction Velocity ◽  
Matched Filter ◽  
Atrial Fibrillation Patient ◽  
Time Interval ◽  
Signal To Noise ◽  
Local Activation ◽  
Temporal Proximity ◽  
Atrial Activity ◽  
Activation Times

BackgroundRate-varying S1S2 stimulation protocols can be used for restitution studies to characterize atrial substrate, ionic remodeling, and atrial fibrillation risk. Clinical restitution studies with numerous patients create large amounts of these data. Thus, an automated pipeline to evaluate clinically acquired S1S2 stimulation protocol data necessitates consistent, robust, reproducible, and precise evaluation of local activation times, electrogram amplitude, and conduction velocity. Here, we present the CVAR-Seg pipeline, developed focusing on three challenges: (i) No previous knowledge of the stimulation parameters is available, thus, arbitrary protocols are supported. (ii) The pipeline remains robust under different noise conditions. (iii) The pipeline supports segmentation of atrial activities in close temporal proximity to the stimulation artifact, which is challenging due to larger amplitude and slope of the stimulus compared to the atrial activity.Methods and ResultsThe S1 basic cycle length was estimated by time interval detection. Stimulation time windows were segmented by detecting synchronous peaks in different channels surpassing an amplitude threshold and identifying time intervals between detected stimuli. Elimination of the stimulation artifact by a matched filter allowed detection of local activation times in temporal proximity. A non-linear signal energy operator was used to segment periods of atrial activity. Geodesic and Euclidean inter electrode distances allowed approximation of conduction velocity. The automatic segmentation performance of the CVAR-Seg pipeline was evaluated on 37 synthetic datasets with decreasing signal-to-noise ratios. Noise was modeled by reconstructing the frequency spectrum of clinical noise. The pipeline retained a median local activation time error below a single sample (1 ms) for signal-to-noise ratios as low as 0 dB representing a high clinical noise level. As a proof of concept, the pipeline was tested on a CARTO case of a paroxysmal atrial fibrillation patient and yielded plausible restitution curves for conduction speed and amplitude.ConclusionThe proposed openly available CVAR-Seg pipeline promises fast, fully automated, robust, and accurate evaluations of atrial signals even with low signal-to-noise ratios. This is achieved by solving the proximity problem of stimulation and atrial activity to enable standardized evaluation without introducing human bias for large data sets.

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