Use of topological charge to determine filament location and dynamics in a numerical model of scroll wave activity

Bray, Mark-Anthony; Wikswo, John P.

doi:10.1109/tbme.2002.803516

Cited by 69 publications

(53 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…16,22 Trajectories in phase space were not markedly affected by global myocardial ischemia (see online-only Data Supplement for details). Phase singularities (PS) were identified by a method based on topological charge, 23 and wavefronts were identified as lines of zero phase. Wavefront lengths were estimated by adding together the distances between pixels located on the wavefronts.…”

Section: Phase Singularities and Wavefrontsmentioning

confidence: 99%

Human Ventricular Fibrillation During Global Ischemia and Reperfusion

Bradley

Clayton

Nash

et al. 2011

Circ: Arrhythmia and Electrophysiology

View full text Add to dashboard Cite

Background-Ischemic ventricular fibrillation in experimental models has been shown to progress through a series of stages. Progression of ischemic VF in the in vivo human heart has not been determined. Methods and Results-We studied 10 patients undergoing cardiac surgery. Ventricular fibrillation was induced by burst pacing.After 30 seconds, global myocardial ischemia was induced by aortic cross-clamp and maintained for 2.5 minutes, followed by coronary reflow. Epicardial activity was sampled (1 kHz) with a sock that contained 256 unipolar contact electrodes. Dominant frequencies were calculated with a fast Fourier transform with a moving window. The locations of phase singularities and activation wavefronts were identified at 10-ms intervals. Preischemic (perfused) ventricular fibrillation was maintained by a disorganized mix of large and small wavefronts. During global myocardial ischemia, mean dominant frequencies decreased from 6.4 to 4.7 Hz at a rate of Ϫ0.011Ϯ0.002 Hz s Ϫ1 (PϽ0.001) and then increased rapidly to 7.4 Hz within 30 seconds of reflow. In contrast, the average number of epicardial phase singularities increased during ischemia from 7.7 to 9.7 at a rate of 0.013Ϯ0.005 phase singularities per second (PϽ0.01) and remained unchanged during reflow, at 10.3. The number of wavefronts showed a similar time course to the number of phase singularities. Conclusions-In human ventricular fibrillation, we found an increase in complexity of electric activation patterns during global myocardial ischemia, and this was not reversed during reflow despite an increase in activation rate. (Circ Arrhythm Electrophysiol. 2011;4:684-691.)

show abstract

Section: Phase Singularities and Wavefrontsmentioning

confidence: 99%

Human Ventricular Fibrillation During Global Ischemia and Reperfusion

Bradley

Clayton

Nash

et al. 2011

Circ: Arrhythmia and Electrophysiology

View full text Add to dashboard Cite

show abstract

“…Given (t), the spatial phase maps can be created, and PSs can be identified. The PS is the spatial point at which all phase values converge (62) and may be localized by means of topological charge calculation (9,24), defined as (23,44),…”

Section: Experimental Preparationmentioning

confidence: 99%

Regional increase of extracellular potassium leads to electrical instability and reentry occurrence through the spatial heterogeneity of APD restitution

Sidorov¹,

Uzelac

Wikswo

2011

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

Sidorov VY, Uzelac I, Wikswo JP. Regional increase of extracellular potassium leads to electrical instability and reentry occurrence through the spatial heterogeneity of APD restitution. Am J Physiol Heart Circ Physiol 301: H209 -H220, 2011. First published May 2, 2011; doi:10.1152/ajpheart.01141.2010.-The heterogeneities of electrophysiological properties of cardiac tissue are the main factors that control both arrhythmia induction and maintenance. Although the local increase of extracellular potassium ([K ϩ ]o) due to coronary occlusion is a well-established metabolic response to acute ischemia, the role of local [K ϩ ]o heterogeneity in phase 1a arrhythmias has yet to be determined. In this work, we created local [K ϩ ]o heterogeneity and investigated its role in fast pacing response and arrhythmia induction. The left marginal vein of a Langendorff-perfused rabbit heart was cannulated and perfused separately with solutions containing 4, 6, 8, 10, and 12 mM of K ϩ . The fluorescence dye was utilized to map the voltage distribution. We tested stimulation rates, starting from 400 ms down to 120 ms, with steps of 5-50 ms. We found that local [K ϩ ]o heterogeneity causes action potential (AP) alternans, 2:1 conduction block, and wave breaks. The effect of [K ϩ ]o heterogeneity on electrical stability and vulnerability to arrhythmia induction was largest during regional perfusion with 10 mM of K ϩ . We detected three concurrent dynamics: normally propagating activation when excitation waves spread over tissue perfused with normal K ϩ , alternating 2:2 rhythm near the border of [K ϩ ]o heterogeneity, and 2:1 aperiodicity when propagation was within the high [K ϩ ]o area. [K ϩ ]o elevation changed the AP duration (APD) restitution and shifted the restitution curve toward longer diastolic intervals and shorter APD. We conclude that spatial heterogeneity of the APD restitution, created with regional elevation of [K ϩ ]o, can lead to AP instability, 2:1 block, and reentry induction. restitution heterogeneity; regional perfusion; optical mapping THE STATIONARY AND DYNAMIC heterogeneities of electrophysiological properties of cardiac tissue play a key role in the induction and maintenance of cardiac arrhythmias (1,10,16,59). Cardiac tissue heterogeneities increase drastically when acute regional ischemia occurs. The early stage of acute ischemia is characterized by abrupt metabolic and electrophysiological changes in the affected area (11). Among them, the more prominent are increased extracellular potassium ([K ϩ ] o ) (25, 26), decreased creatine phosphate (43, 63), elevated intracellular inorganic phosphate (63), acidosis (27, 46), catecholamine release (39), and partial depolarization of transmembrane potential (V m ) (28,36).Since an early change in V m closely relates to [K ϩ ] o accumulation (34, 60), the K ϩ imbalance is considered to be the major factor affecting excitability and is responsible for slow impulse propagation and induction of reentry (51) Although numerous studies have been devoted to investigation ...

show abstract

“…Phase was then calculated independently for each grid point using (t)ϭatan2[V(t),HV(t)], where V(t) and HV(t) represent the interpolated voltage and Hilbert transform, respectively. The spatial distributions of phase were analyzed with a topological charge technique 13 to locate the phase singularities (PSs) associated with the ends of wavefronts such as at the tip of a reentrant wave.…”

Section: Activation Times Phase Phase Singularities and Wavefrontsmentioning

confidence: 99%

Evidence for Multiple Mechanisms in Human Ventricular Fibrillation

et al. 2006

View full text Add to dashboard Cite

Background-The mechanisms that sustain ventricular fibrillation (VF) in the human heart remain unclear. Experimental models have demonstrated either a periodic source (mother rotor) or multiple wavelets as the mechanism underlying VF. The aim of this study was to map electrical activity from the entire ventricular epicardium of human hearts to establish the relative roles of these mechanisms in sustaining early human VF. Methods and Results-In 10 patients undergoing cardiac surgery, VF was induced by burst pacing, and 20 to 40 seconds of epicardial activity was sampled (1 kHz) with a sock containing 256 unipolar contact electrodes connected to a UnEmap system. Signals were interpolated from the electrode sites to a fine regular grid (100ϫ100 points), and dominant frequencies (DFs) were calculated with a fast Fourier transform with a moving 4096-ms window (10-ms increments). Epicardial phase was calculated at each grid point with the Hilbert transform, and phase singularities and activation wavefronts were identified at 10-ms intervals. Early human VF was sustained by large coherent wavefronts punctuated by periods of disorganized wavelet behavior. The initial fitted DF intercept was 5.11Ϯ0.25 (meanϮSE) Hz (PϽ0.0001), and DF increased at a rate of 0.018Ϯ0.005 Hz/s (PϽ0.01) during VF, whereas combinations of homogeneous, heterogeneous, static, and mobile DF domains were observed for each of the patients. Epicardial reentry was present in all fibrillating hearts, typically with low numbers of phase singularities. In some cases, persistent phase singularities interacted with multiple complex wavelets; in other cases, VF was driven at times by a single reentrant wave that swept the entire epicardium for several cycles. Conclusions-Our data support both the mother rotor and multiple wavelet mechanisms of VF, which do not appear to be mutually exclusive in the human heart. (Circulation. 2006;114:536-542.)

show abstract

Use of topological charge to determine filament location and dynamics in a numerical model of scroll wave activity

Cited by 69 publications

References 41 publications

Human Ventricular Fibrillation During Global Ischemia and Reperfusion

Human Ventricular Fibrillation During Global Ischemia and Reperfusion

Regional increase of extracellular potassium leads to electrical instability and reentry occurrence through the spatial heterogeneity of APD restitution

Evidence for Multiple Mechanisms in Human Ventricular Fibrillation

Contact Info

Product

Resources

About