Key result
Including the response of action potential duration to recent activations in a model of excitable media demonstrated that spiral breakup can occur even when APD restitution slope is <1.
This computational model demonstrates that cardiac memory can drive spiral wave breakup and fibrillation during ischemia even when APD restitution curves are flat.
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Challenges steep APD restitution as sole fibrillation driver in ischemia; leaves open low-excitability breakup mechanisms for modeling.
The electrophysiology of cardiac tissue is altered during acute myocardial ischemia, making the tissue less excitable but, nonetheless, more susceptible to tachyarrythmias which frequently degenerate to fibrillation within several seconds. The transition from tachycardia to fibrillation is associated with the breakup of spiral waves into multiple offspring, and has been linked to steep restitution (slope>1) of action potential duration (APD). However, restitution curves become so flat during ischemia that this mechanism does not apply. We found that when the response of APD to recent activations is included in a model of excitable media, spiral breakup can occur even when the slope in APD restitutions is $<1$.
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Fenton et al. (1999) studied Acute myocardial ischemia. Model of excitable media including response of action potential duration to recent activations was evaluated on Spiral wave breakup. Including the response of action potential duration to recent activations in a model of excitable media demonstrated that spiral breakup can occur even when APD restitution slope is <1.
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