Quantification of Effects of Global Ischemia on Dynamics of Ventricular Fibrillation in Isolated Rabbit Heart

Mandapati, Ravi; Asano, Yukio; Baxter, William T.; Gray, Richard A.; Davidenko, Jorge M.; Jalife, José

doi:10.1161/01.cir.98.16.1688

Cited by 97 publications

(107 citation statements)

References 26 publications

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“…Extracellular K ϩ accumulation is a prominent factor of myocardial ischemia (7). Reduced excitability resulting from hyperkalemia increases spatiotemporal periodicity and stabilizes sources of VF in isolated heart preparations (23,25,43). These effects have been explained in terms of the increase in the core size of the spiral wave (25) or flattening APDR (23).…”

Section: Discussionmentioning

confidence: 99%

“…Yet, the effects of ischemia on VF dynamics are complex and poorly understood. Reduced excitability resulting from hyperkalemia increases spatiotemporal periodicity and stabilizes sources of VF in isolated heart preparations perfused with physiological solutions (23,25,43). However, in the open-chest dog, Huang et al (19) have recently found a biphasic type of evolution of activation patterns during VF, with a transient phase of increased spatiotemporal organization between 1 and 1.5 min after VF onset followed by a decrease in the organization in later phases of VF.…”

mentioning

confidence: 99%

“…However, in the open-chest dog, Huang et al (19) have recently found a biphasic type of evolution of activation patterns during VF, with a transient phase of increased spatiotemporal organization between 1 and 1.5 min after VF onset followed by a decrease in the organization in later phases of VF. While the transient phase of increased organization may be attributed to the effect of hyperkalemia as found in isolated heart preparations (23,25,43), the mechanism of decreased organization during later phases of VF remains unknown.…”

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confidence: 99%

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Three distinct phases of VF during global ischemia in the isolated blood-perfused pig heart

Huízar¹,

Warren²,

Shvedko³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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Zaitsev AV. Three distinct phases of VF during global ischemia in the isolated blood-perfused pig heart. Am J Physiol Heart Circ Physiol 293: H1617-H1628, 2007. First published June 1, 2007; doi:10.1152/ajpheart.00130.2007.-Changes in ventricular fibrillation (VF) organization occurring after the onset of global ischemia are relevant to defibrillation and survival but remain poorly understood. We hypothesized that ischemia-specific dynamic instability of the action potential (AP) causes a loss of spatiotemporal periodicity of propagation and broadening of the electrocardiogram (ECG) frequency spectrum during VF in the ischemic myocardium. We recorded voltage-sensitive fluorescence of di-4-ANEPPS (anterior left ventricle, 35 ϫ 35 mm, 64 ϫ 64 pixels) and the volumeconducted ECG in six blood-perfused hearts during 10 min of VF and global ischemia. We used coefficient of variation (CV) to estimate variability of AP amplitude, AP duration, and diastolic interval (CV-APA, CV-APD, and CV-DI, respectively). We computed excitation median frequency (Median_F), spectral width of the AP and ECG (SpW-AP and SpW-ECG, respectively), wavebreak incidence (WBI), and recurrence of propagation direction (RPD). We found three distinct phases of local VF dynamics: "relatively periodic" (Յ1 min, high Median_F, moderate AP variability, high WBI, low RPD), "highly periodic" (1-2 min, reduced Median_F, low AP variability, low WBI, high RPD), and "aperiodic" (3-10 min, low Median_F, high AP variability, high WBI, low RPD). In one experiment, spontaneous conversion from the aperiodic to the highly periodic phase occurred after 5 min of ischemia. The SpW-ECG was correlated with SpW-AP, CV-APD, and CV-APA. We conclude that 1) at least three distinct phases of VF dynamics are present in our model, and 2) the newly described aperiodic phase is related to ischemia-specific dynamic instability of the AP shape, which underlies broadening of the ECG spectrum during VF evolution. ventricular fibrillation; action potential; electrocardiogram ONE IMPORTANT DECISION that an emergency care professional faces at the scene of cardiac arrest is whether to initiate cardiopulmonary resuscitation (CPR) before the application of a shock, or to defibrillate first. Population studies indicate that the "CPR first" strategy improves survival if the ventricular fibrillation (VF) duration exceeds 3-4 min ("circulatory phase") but not at the earlier "electrical" phase of VF (18). This observation motivated recent studies aimed at estimating VF duration based on the structure and spectral content of the electrocardiogram (ECG) waveform (6, 27, 34). Furthermore, various quantitative measures of "order" in the ECG waveform can predict the likelihood of rescue shock success, restoration of circulation, and survival to hospital discharge (4, 6). However, the relationship between the structure of the ECG waveform and the spatiotemporal dynamics of the fibrillatory waves in the myocardium remains unknown.VF organization evolves naturally after its onset as a result of glo...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Three distinct phases of VF during global ischemia in the isolated blood-perfused pig heart

Huízar¹,

Warren²,

Shvedko³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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“…To aid in the development of new approaches to defibrillation, 20,22 it would be invaluable to make available electrophysiological mapping data collected during VF in model systems. A more informed analysis of VF will lead to a deeper understanding of the mechanism of complex wave phenomena, which underlie not only sudden cardiac death 23,24 but possibly other pathophysiological dynamics, such as seizure disorders.…”

Section: Potential Benefitsmentioning

confidence: 99%

PhysioBank, PhysioToolkit, and PhysioNet

et al. 2000

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“…Therefore, we believe that the termination occurred because of the presence of a single rotor that maintained AF. Mandapati et al 13 reported that the size of the core of a stationary spiral wave in an isolated rabbit ventricle was significantly increased by the addition of small concentrations of sodium channel blocker. They suggested that a reduction of sodium current enlarges the core size and prolongs the rotation period, which is consistent with these findings.…”

Section: Effects Of Pilsicainide On Electrophysiological Action Durinmentioning

confidence: 99%

Widening of the Excitable Gap and Enlargement of the Core of Reentry During Atrial Fibrillation With a Pure Sodium Channel Blocker in Canine Atria

et al. 2003

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Background-This study aimed to assess the effects of pilsicainide, a pure sodium channel blocker, on electrophysiological action and wavefront dynamics during atrial fibrillation (AF). Methods and Results-In a newly developed model of isolated, perfused, and superfused canine atria (nϭ12), the right and left endocardia were mapped simultaneously by use of a computerized mapping system. AF was induced with 1 to 5 mol/L acetylcholine. The antifibrillatory actions of pilsicainide on AF cycle length (AFCL), refractory period (RP), conduction velocity (CV), excitable gap (EG), and the core of the mother rotor were studied. The RP was defined as the shortest coupling interval that could capture the fibrillating atrium. The EG was estimated as the difference between the AFCL and RP. At baseline, multiple wavefronts were observed. After 2.5 g/mL infusion of pilsicainide, all preparations showed irregular activity, and AF was terminated in 2 preparations. The AFCL and RP were prolonged, and CV was decreased significantly. The EG was widened (147%; PϽ0.01), and the core perimeter was increased (100%; PϽ0.01). Increasing the dosage either terminated AF (6 preparations) or converted to organized activity (ie, atypical atrial flutter) (4 preparations). On the maps, all "unorganized" AFs were terminated with the excitation of the core of the mother rotor by an outside wavefront, whereas in preparations with atrial flutter, pilsicainide did not terminate its activity. Conclusions-Widening

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Quantification of Effects of Global Ischemia on Dynamics of Ventricular Fibrillation in Isolated Rabbit Heart

Cited by 97 publications

References 26 publications

Three distinct phases of VF during global ischemia in the isolated blood-perfused pig heart

Three distinct phases of VF during global ischemia in the isolated blood-perfused pig heart

PhysioBank, PhysioToolkit, and PhysioNet

Widening of the Excitable Gap and Enlargement of the Core of Reentry During Atrial Fibrillation With a Pure Sodium Channel Blocker in Canine Atria

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