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Mechanisms of vortices termination in the cardiac muscle

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ABSTRACT

We propose a solution to a long-standing problem: how to terminate multiple vortices in the heart, when the locations of their cores and their critical time windows are unknown. We scan the phases of all pinned vortices in parallel with electric field pulses (E-pulses). We specify a condition on pacing parameters that guarantees termination of one vortex. For more than one vortex with significantly different frequencies, the success of scanning depends on chance, and all vortices are terminated with a success rate of less than one. We found that a similar mechanism terminates also a free (not pinned) vortex. A series of about 500 experiments with termination of ventricular fibrillation by E-pulses in pig isolated hearts is evidence that pinned vortices, hidden from direct observation, are significant in fibrillation. These results form a physical basis needed for the creation of new effective low energy defibrillation methods based on the termination of vortices underlying fibrillation.

No MeSH data available.


Success rate of two vortices termination. Success rate versus normalized frequency  where fd is the dominant frequency. On the image, ‘different’ and ‘close’ frequencies mean significant and insignificant difference in frequencies as per equation (2.2). Numerical calculations with the normalized  =0.2.
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RSOS170024F5: Success rate of two vortices termination. Success rate versus normalized frequency where fd is the dominant frequency. On the image, ‘different’ and ‘close’ frequencies mean significant and insignificant difference in frequencies as per equation (2.2). Numerical calculations with the normalized =0.2.

Mentions: Figure 5 shows the success rate of termination of two vortices as a function of the normalized frequency of E-pacing. The graphs represent results of Monte Carlo simulations of the axiomatic model described above, with random initial phases of vortices and two variants for the choice of frequencies: (i) normal distributions of parameters and (mean ± s.d.), ‘different frequencies’; and (ii) the same parameters for , and enforced very close to , namely , ‘close frequencies’, with other parameters fixed at , , D=0.25. The success rate of termination of two vortices with significant difference in frequencies as per equation (2.2) is seen in figure 5 to be threefold lower than that for vortices with insignificant difference in frequencies. This happens because when the leading (fastest) vortex is terminated first, the same E-pacing period T appears below the period T1 of the resting slower vortex, see equation (2.2). Thus, the resting vortex cannot be terminated (figure 2c).Figure 5.


Mechanisms of vortices termination in the cardiac muscle
Success rate of two vortices termination. Success rate versus normalized frequency  where fd is the dominant frequency. On the image, ‘different’ and ‘close’ frequencies mean significant and insignificant difference in frequencies as per equation (2.2). Numerical calculations with the normalized  =0.2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383855&req=5

RSOS170024F5: Success rate of two vortices termination. Success rate versus normalized frequency where fd is the dominant frequency. On the image, ‘different’ and ‘close’ frequencies mean significant and insignificant difference in frequencies as per equation (2.2). Numerical calculations with the normalized =0.2.
Mentions: Figure 5 shows the success rate of termination of two vortices as a function of the normalized frequency of E-pacing. The graphs represent results of Monte Carlo simulations of the axiomatic model described above, with random initial phases of vortices and two variants for the choice of frequencies: (i) normal distributions of parameters and (mean ± s.d.), ‘different frequencies’; and (ii) the same parameters for , and enforced very close to , namely , ‘close frequencies’, with other parameters fixed at , , D=0.25. The success rate of termination of two vortices with significant difference in frequencies as per equation (2.2) is seen in figure 5 to be threefold lower than that for vortices with insignificant difference in frequencies. This happens because when the leading (fastest) vortex is terminated first, the same E-pacing period T appears below the period T1 of the resting slower vortex, see equation (2.2). Thus, the resting vortex cannot be terminated (figure 2c).Figure 5.

View Article: PubMed Central - PubMed

ABSTRACT

We propose a solution to a long-standing problem: how to terminate multiple vortices in the heart, when the locations of their cores and their critical time windows are unknown. We scan the phases of all pinned vortices in parallel with electric field pulses (E-pulses). We specify a condition on pacing parameters that guarantees termination of one vortex. For more than one vortex with significantly different frequencies, the success of scanning depends on chance, and all vortices are terminated with a success rate of less than one. We found that a similar mechanism terminates also a free (not pinned) vortex. A series of about 500 experiments with termination of ventricular fibrillation by E-pulses in pig isolated hearts is evidence that pinned vortices, hidden from direct observation, are significant in fibrillation. These results form a physical basis needed for the creation of new effective low energy defibrillation methods based on the termination of vortices underlying fibrillation.

No MeSH data available.