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Reprint of 'Model of unidirectional block formation leading to reentrant ventricular tachycardia in the infarct border zone of postinfarction canine hearts'.

Ciaccio EJ, Coromilas J, Ashikaga H, Cervantes DO, Wit AL, Peters NS, McVeigh ER, Garan H - Comput. Biol. Med. (2015)

Bottom Line: The UBL leading edge coincided with the distal isthmus where the center-entrance boundary would be expected to occur. 3.The double-loop reentrant circuit pattern is a consequence of wavefront bifurcation around this UBL followed by coalescence, and then impulse propagation through the isthmus.The wavefront is blocked from propagating laterally away from the isthmus by sharp increases in border zone thickness, which results in critically convex wavefront curvature at VT cycle lengths.

View Article: PubMed Central - PubMed

Affiliation: Division of Cardiology, Department of Medicine, Columbia University Medical Center, New York, United States. Electronic address: ciaccio@columbia.edu.

No MeSH data available.


Related in: MedlinePlus

Schematic of the timing during the premature stimulus and during the first reentrant ventricular tachycardia cycle (A), stimulus sites for unidirectional block line formation at either isthmus end (B–D), and direction of propagation during reentrant ventricular tachycardia, shown by arrows (E–G).
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f0015: Schematic of the timing during the premature stimulus and during the first reentrant ventricular tachycardia cycle (A), stimulus sites for unidirectional block line formation at either isthmus end (B–D), and direction of propagation during reentrant ventricular tachycardia, shown by arrows (E–G).

Mentions: Based on the above paradigm, the timing relationship of the premature stimulation cycle versus the first reentrant VT cycle is depicted in Fig. 3A. Activation wavefront propagation direction during the premature excitation cycle is denoted with black arrows. Examples of approximate timing are given, with the actual timing depending in part on the distances between landmarks. The premature excitation wavefront arrives at time 50 ms at the opposite end of the isthmus and blocks around it on three sides due to the steep thin-to-thick transition in the forward wavefront direction. Toward the end of the premature stimulation cycle, the bifurcated wavefronts coalesce, and are facilitated to rapidly propagate in the travel direction at time 150 ms since the spatial transition is thick-to-thin. A single impulse then proceeds and enters the isthmus. Due in part to the wavefront curving a total of 180° in this region, there is a long delay for arrival at the reentry point (from time 50 ms to time 160 ms). This is a consequence of propagation of the wave about a pivot point, with convex wavefront curvature slowing the conduction velocity about such points [18,19]. A gray arrow shows the propagation direction as the wavefront breaks through the unidirectional block line on the opposite side to initiate the first reentry cycle (time 160 ms). The wavefront proceeds through the isthmus center (time 160 to 180 ms). It is constrained in this region as a narrow electrical impulse, and is prevented from propagating outwardly across the lateral boundaries due to the steep change in thin-to-thick transition there (see also Fig. 2B). The impulse then proceeds through the isthmus exit. There is a slight possibility of block at short VT cycle lengths at this location due to convex wavefront curvature, depending on the shortness of the cycle length. However, if the wavefront does propagate through the exit, it then bifurcates, the distinct wavefronts slowly pivot, then travel in the downward direction in the schematic away from the lateral boundaries (gray arrows, time 300 ms), and arrive at the isthmus entrance (time 320 ms), whereupon they coalesce, completing the first reentry cycle. Thus the double-loop pattern of reentry is established during premature stimulation and the first reentry cycle, with a VT cycle length of approximately 200 ms on average [20]. On subsequent cycles, due to the constraints of thin-to-thick transition and because of the refractory relationships forming during the first cycle, the pattern perpetuates, so long as wavefront breakthrough does not occur.


Reprint of 'Model of unidirectional block formation leading to reentrant ventricular tachycardia in the infarct border zone of postinfarction canine hearts'.

Ciaccio EJ, Coromilas J, Ashikaga H, Cervantes DO, Wit AL, Peters NS, McVeigh ER, Garan H - Comput. Biol. Med. (2015)

Schematic of the timing during the premature stimulus and during the first reentrant ventricular tachycardia cycle (A), stimulus sites for unidirectional block line formation at either isthmus end (B–D), and direction of propagation during reentrant ventricular tachycardia, shown by arrows (E–G).
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4593299&req=5

f0015: Schematic of the timing during the premature stimulus and during the first reentrant ventricular tachycardia cycle (A), stimulus sites for unidirectional block line formation at either isthmus end (B–D), and direction of propagation during reentrant ventricular tachycardia, shown by arrows (E–G).
Mentions: Based on the above paradigm, the timing relationship of the premature stimulation cycle versus the first reentrant VT cycle is depicted in Fig. 3A. Activation wavefront propagation direction during the premature excitation cycle is denoted with black arrows. Examples of approximate timing are given, with the actual timing depending in part on the distances between landmarks. The premature excitation wavefront arrives at time 50 ms at the opposite end of the isthmus and blocks around it on three sides due to the steep thin-to-thick transition in the forward wavefront direction. Toward the end of the premature stimulation cycle, the bifurcated wavefronts coalesce, and are facilitated to rapidly propagate in the travel direction at time 150 ms since the spatial transition is thick-to-thin. A single impulse then proceeds and enters the isthmus. Due in part to the wavefront curving a total of 180° in this region, there is a long delay for arrival at the reentry point (from time 50 ms to time 160 ms). This is a consequence of propagation of the wave about a pivot point, with convex wavefront curvature slowing the conduction velocity about such points [18,19]. A gray arrow shows the propagation direction as the wavefront breaks through the unidirectional block line on the opposite side to initiate the first reentry cycle (time 160 ms). The wavefront proceeds through the isthmus center (time 160 to 180 ms). It is constrained in this region as a narrow electrical impulse, and is prevented from propagating outwardly across the lateral boundaries due to the steep change in thin-to-thick transition there (see also Fig. 2B). The impulse then proceeds through the isthmus exit. There is a slight possibility of block at short VT cycle lengths at this location due to convex wavefront curvature, depending on the shortness of the cycle length. However, if the wavefront does propagate through the exit, it then bifurcates, the distinct wavefronts slowly pivot, then travel in the downward direction in the schematic away from the lateral boundaries (gray arrows, time 300 ms), and arrive at the isthmus entrance (time 320 ms), whereupon they coalesce, completing the first reentry cycle. Thus the double-loop pattern of reentry is established during premature stimulation and the first reentry cycle, with a VT cycle length of approximately 200 ms on average [20]. On subsequent cycles, due to the constraints of thin-to-thick transition and because of the refractory relationships forming during the first cycle, the pattern perpetuates, so long as wavefront breakthrough does not occur.

Bottom Line: The UBL leading edge coincided with the distal isthmus where the center-entrance boundary would be expected to occur. 3.The double-loop reentrant circuit pattern is a consequence of wavefront bifurcation around this UBL followed by coalescence, and then impulse propagation through the isthmus.The wavefront is blocked from propagating laterally away from the isthmus by sharp increases in border zone thickness, which results in critically convex wavefront curvature at VT cycle lengths.

View Article: PubMed Central - PubMed

Affiliation: Division of Cardiology, Department of Medicine, Columbia University Medical Center, New York, United States. Electronic address: ciaccio@columbia.edu.

No MeSH data available.


Related in: MedlinePlus