scholarly journals Spatial Distribution of Phase Singularities in Ventricular Fibrillation

Circulation ◽  
2003 ◽  
Vol 108 (3) ◽  
pp. 354-359 ◽  
Author(s):  
Miguel Valderrábano ◽  
Peng-Sheng Chen ◽  
Shien-Fong Lin
Keyword(s):  
Spatial Distribution ◽  
Ventricular Fibrillation ◽  
Phase Singularities

Spatiotemporal Correlation Between Phase Singularities and Wavebreaks During Ventricular Fibrillation

2003 ◽  
Vol 14 (10) ◽  
pp. 1103-1109 ◽  
Author(s):  
YEN‐BIN LIU ◽  
ANISH PETER ◽  
SCOTT T. LAMP ◽  
JAMES N. WEISS ◽  
PENG‐SHENG CHEN ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Spatiotemporal Correlation ◽  
Phase Singularities

Abstract 1356: Is Human Ventricular Fibrillation Different From Experimental Models?

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Martyn P Nash ◽  
Ayman Mourad ◽  
Chris P Bradley ◽  
David J Paterson ◽  
Richard H Clayton ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Ventricular Fibrillation ◽  
Phase Plane ◽  
Experimental Models ◽  
Epicardial Mapping ◽  
Voltage Versus ◽  
Wavefront Analysis ◽  
Phase Singularities ◽  
Contact Electrodes ◽  
Zero Phase

Introduction: There is a paucity of data on wavefront dynamics during human VF. Some experimental models show multiple small wavelets, whilst others implicate a single stationary rotor. We have studied human VF using phase and wavefront analysis based on global epicardial mapping. Methods: VF was induced by burst pacing in 10 patients undergoing routine cardiac surgery. For each subject, a 20 – 40 s episode of VF activity was sampled at 1 kHz using an epicardial sock containing 256 unipolar contact electrodes connected to a UnEmap system. Wavefronts were determined from the phase plane (based on de-trended voltage versus its Hilbert transform) using an active-edge algorithm to track the isolines of zero phase. Wavefront sizes and rotor statistics were tallied across all patients. Results: As illustrated, one or more wavefronts of at least 10 cm in size were present for 90% of the VF duration. Insert shows a polar projection of wavefronts between pairs of phase singularities. Large convoluted wavefronts were predominant with at least one wavefront of size > 20 cm present for over half of the VF duration. Persistent epicardial rotors (defined as those with lifetimes greater than 1000 ms, or approximately 5 rotations) were present for more than 78% of the total VF duration, whilst two or more persistent rotors were present more than half of the time. Conclusion: Epicardial mapping in humans suggests that neither multiple wavelets nor a single persistent stationary rotor, as seen in experimental models, drive VF. Instead, in all subjects the predominant characteristic was multiple mobile rotors of moderate duration (1000 –7000 ms), which generated large make and break wavefronts.

Synchronization of ventricular fibrillation with real-time feedback pacing: implication to low-energy defibrillation

2003 ◽  
Vol 285 (6) ◽  
pp. H2704-H2711 ◽  
Author(s):  
Hui-Nam Pak ◽  
Yen-Bin Liu ◽  
Hideki Hayashi ◽  
Yuji Okuyama ◽  
Peng-Sheng Chen ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
High Frequency ◽  
Cycle Length ◽  
Optical Potential ◽  
Spatial Dispersion ◽  
Optical Recording ◽  
Multisite Pacing ◽  
Phase Singularities ◽  
Overdrive Pacing ◽  
Excitable Gap

Wavefront synchronization is an important aspect preceding the termination of ventricular fibrillation (VF). We evaluated the defibrillation efficacy of a novel multisite pacing algorithm using optical recording-guided synchronized pacing (SyncP) in the excitable gaps. We compared the effects of SyncP with traditional overdrive pacing (ODP) at 90% of the VF cycle length (VFCL) and high-frequency pacing (HFP; 43–215 Hz) on spontaneous VF termination in isolated rabbit hearts. For SyncP, the pacing current was triggered by the activation of a reference site and was delivered when the optical potential of the pacing site was in an excitable gap. We measured VFCL and the spatial dispersion of VFCL (SDCL) from five points (3 points in the paced area and 2 points in the nonpaced area) and the distribution of phase singularities during the prepacing, pacing, and postpacing periods. The results showed that 1) the VF termination rate of SyncP (16.0%, n = 106) was higher than that of ODP (2.1%, n = 48, P < 0.01) or HFP (1.6%, n = 129, P < 0.0001); 2) energy consumption for SyncP (7.6 ± 9.3 mJ) was significantly lower than that of ODP (14.0 ± 14.8 mJ, P < 0.0001); and 3) SyncP, but not ODP or HFP, decreased SDCL in the paced area during the pacing ( P < 0.01) and postpacing ( P < 0.05) periods compared with the prepacing period. We conclude that SyncP is effective in inducing wavefront synchronization and is more effective at facilitating spontaneous VF termination than non-SyncP.

P1594Ventricular fibrosis spatial distribution and quantity is a key mechanistic determinant of ventricular fibrillation mechanisms

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
B S Handa ◽  
X Li ◽  
C A Mansfield ◽  
R J Jabbour ◽  
D Pitcher ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Ventricular Fibrillation ◽  
Critical Role ◽  
Underlying Mechanism ◽  
Dominant Frequency ◽  
Diffuse Fibrosis ◽  
Sprague Dawley ◽  
Average Maximum ◽  
Ventricular Fibrosis

Abstract Background Ventricular fibrosis is known to play a critical role in initiation and maintenance of ventricular fibrillation (VF). Post myocardial infarction the quantity of fibrosis negatively correlates with survival. There is a lack of data on how the quantity and degree of fibrosis influences the mechanisms of VF itself. VF mechanisms remain debated, there are data to support both critical areas sustaining rotational drivers (RDs) and the contrary hypothesis of disorganized myocardial activation driving VF. Purpose We hypothesized that the underlying mechanism of VF is influenced by the spatial distribution and quantity of ventricular fibrosis. Methods Thirty-five Sprague-Dawley rats underwent permanent left anterior descending (LAD) ligation (n=11), 20mins LAD territory ischaemia-reperfusion (n=13) or in-vivo angiotensin infusion (500ng/kg/min, n=11) to generate compact (CF), patchy (PF) and diffuse fibrosis (DF) models respectively. After a 4-week maturation period, the hearts were explanted, Langendorff perfused and VF induced with burst pacing and 30μM pinacidil. Fibrillation dynamics were quantified using phase analysis, phase singularity (PS) tracking and our novel method of global fibrillation organisation quantification, frequency dominance index (FDI), which is a power ratio of highest amplitude dominant frequency in the frequency spectrum. Results Ventricular fibrosis for each group was characterized and quantified (CF: 22.3±3.2%, PF: 18.4±4.2%, DF: 5.8±1.3%, p=0.046). VF was driven predominantly by disorganised activity in CF, PSs were detected 26±7% of time comparative to 51.2±4% in DF and 69.5±8% in PF group (p=0.001). PF stabilised RDs, average maximum rotations for a single RD in PF were 31.6±7.1 comparative to 12.5±1.7 in DF and 6.4±1.1 in CF, p<0.001. The average maximum duration for a single RDs was significantly longer in PF (PF: 1231±365ms, DF: 568±68ms, CF: 363±41ms, p=0.014). Similarly, average rotations per RD were greater in the PF group (PF: 4.5±0.7, DF: 3.3±0.2, CF: 2.41±0.3 rotations, p=0.013). Total number of RDs/second were much greater with PF (PF: 12.4±2.0, DF: 5.4±0.8, CF: 3.1±1.1, p<0.001). VF organisation measured by FDI was higher in PF (PF: 0.61±0.07, DF: 0.47±0.04, CF: 0.33±0.03, p=0.004). RDs in DF showed a greater degree of meander comparative to PF (DF: 12.6±1.4 vs PF: 9.3±0.8 pixels, p=0.024). Conclusion VF mechanisms occur along a spectrum between organised activity sustained by discrete drivers and disorganised myocardial activation. The underlying VF mechanism can differ significantly dependent on the quantity and pattern of fibrosis. Patchy fibrosis stabilises RDs with localization to discrete areas and sustains an organised form of VF comparative to CF where VF is largely disorganised. Characterising the degree and pattern of fibrosis in patient groups vulnerable to VF might be beneficial in identifying patients with suitable targets for ablation. Acknowledgement/Funding BHF Programme Grant PG/16/17/32069

scholarly journals Spatial Distribution of Phase Singularities in Optical Random Vector Waves

2016 ◽  
Vol 117 (9) ◽  
Author(s):  
L. De Angelis ◽  
F. Alpeggiani ◽  
A. Di Falco ◽  
L. Kuipers
Keyword(s):  
Spatial Distribution ◽  
Random Vector ◽  
Phase Singularities

scholarly journals Influence of Fibrosis Amount and Patterns on Ventricular Arrhythmogenesis and Pumping Efficacy: Computational Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Aulia Khamas Heikhmakhtiar ◽  
Abrha Abebe Tekle ◽  
Ki Moo Lim
Keyword(s):  
Spatial Distribution ◽  
Mechanical Performance ◽  
Computational Study ◽  
Diffuse Fibrosis ◽  
Computational Studies ◽  
Diffuse Type ◽  
Compact Type ◽  
Phase Singularities ◽  
The Mean ◽  
Ventricular Arrhythmogenesis

Myocardial fibrosis is an integral component of most forms of heart failure. Clinical and computational studies have reported that spatial fibrosis pattern and fibrosis amount play a significant role in ventricular arrhythmogenicity. This study investigated the effect of the spatial distribution of fibrosis and fibrosis amount on the electrophysiology and mechanical performance of the human ventricles. Seventy-five fibrosis distributions comprising diffuse, patchy, and compact fibrosis types that contain 10–50% fibrosis amount were generated. The spatial fibrosis distribution was quantified using the fibrosis entropy (FE) metric. Electrical simulations under reentry conditions induced using the S1–S2 protocol were conducted to investigate the fibrosis arrhythmogenicity. We also performed mechanical simulations to examine the influence of the fibrosis amount and the spatial distribution of fibrosis on the pumping efficacy of the LV. We observed that the mean FE of the compact type is the largest among the three types. The electrical simulation results revealed that the ventricular arrhythmogenicity of diffuse fibrosis depends on the fibrosis amount and marginally on the spatial distribution of fibrosis. Meanwhile, the ventricular arrhythmogenicity of the compact and patchy fibrosis pattern is more reliant on the spatial distribution of fibrosis than on the fibrosis amount. The average number of phase singularities (PSs) in the compact fibrosis pattern was the highest among the three patterns of fibrosis. The diffuse type of fibrosis has the lowest average number of PSs than that in the patchy and compact fibrosis. The reduction in the stroke volume (SV) showed high influence from the electrical instabilities induced by the fibrosis amount and pattern. The compact fibrosis exhibited the lowest SV among the three patterns except in the 40% fibrosis amount. In conclusion, the fibrosis pattern is as crucial as the fibrosis amount for sustaining and aggravating ventricular arrhythmogenesis.

Detection of Phase Singularities in Triangular Meshes

2007 ◽  
Vol 46 (06) ◽  
pp. 646-654 ◽  
Author(s):  
L. Wieser ◽  
M. C. Stühlinger ◽  
F. Hintringer ◽  
B. Tilg ◽  
G. Fischer ◽  
...  
Keyword(s):  
Ventricular Fibrillation ◽  
Topological Charge ◽  
Quantitative Data ◽  
Triangular Meshes ◽  
Phase Information ◽  
Time Step ◽  
Phase Singularity ◽  
Cardiac Fibrillation ◽  
Oriented Path ◽  
Phase Singularities

Summary Objectives : Phase singularities have become a key marker in animal and computer models of atrial and ventricular fibrillation. However, existing algorithms for the automatic detection of phase singularities are limited to regular, quadratic mesh grids. We present an algorithm to automatically and exactly detect phase singularities in triangular meshes. Methods : For each node an oriented path inscribing the node with one unit of spatial discretization is identified. At each time step the phase information is calculated for all nodes. The so-called topological charge is also computed for each node. A non-zero (± 2π) charge is obtained for all nodes with a path enclosing a phase singularity. Thus all charged nodes belonging to the same phase singularity have to be clustered. Results : With the use of the developed algorithm, phase singularities can be detected in triangular meshes with an accuracy of below 0.2 mm – independent of the type of membrane kinetics used. Conclusions : With the possibility to detect phase singularities automatically and exactly, important quantitative data on cardiac fibrillation can be gained.

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