| TITLE |
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Induction of Ventricular Arrhythmias Following
A Mechanical Impact: A Simulation Study in 3D |
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| AUTHORS |
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Weihui Li,
Peter Kohl,
and
Natalia
Trayanova |
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| ABSTRACT |
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Commotio cordis has been reported with increasing frequency in young individuals
participating in sporting activities. Recently, the electrophysiological changes during
commotio cordis have been attributed to mechano-electric feedback, and particularly, to
the recruitment of stretch-activated ionic channels (SACs). However, the underlying
mechanisms by which a mechanical impact results in ventricular fibrillation remain
unknown. This study employs a 3D realistic model of rabbit ventricular geometry and
fiber orientation to elucidate the electrophysiological mechanisms involved in arrhythmia
induction following acute mechanical stimulation of the heart. Impact effects are modeled
through SAC activation in a 3D region of the ventricles representing the impact profile.
Both cation-nonselective and potassium-selective SACs are recruited upon mechanical
impact. The impact is administered at various coupling intervals following pacing at the
apex. To aid in the interpretation of the results, the effect of mechanical impact on the
single cell action potential is also examined. The results demonstrate that the region of
impact is characterized by different types of cellular responses, including generation of a
new action potential, shortening, or extending action potential duration. The impact
induces sustained reentry only when 1) a new activation is elicited by mechanical
stimulation, and 2) upon return to the original region of impact, this activation does not
encounter an extension of action potential duration.
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| FIGURES |
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< < Click on the image to enlarge!
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| MOVIES |
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© CCEL 2005
Johns Hopkins University |
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< < Click on the image to play the video!
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This movie displays an example of mechanical impact that didn't
induce reentry. Impact is administered at a coupling interval of 135ms after
pacing. At the time of impact, the tissue within and around the impact zone
was fairly refractroy. The impact didn't produce a new activation; it only
altered the repolarization of the cells within the force profile region. |
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w
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< < Click on the image to play the video!
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This movie represents an example of impact-induced reentry. Impact
is delivered at a coupling interval of 140ms, which is within the vulnerable window
found here. In the movie, an action potential was elicited in the lower portion of
the impact zone and propagated somewhat downwards and mostly to the right, thus circumnavigating the left ventricle. This wavefront encompassed both septum and left ventricle free wall. It propagated
simultaneously through the posterior site of the ventricles and through the
apex, forming a figure-of-eight circuit. When the wavefront arrived at the region
of impact, tissue there had already recovered sufficiently from the impact.
Consequently, the activation did not block within that region. Reentry was
induced. |
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