Key result
Mathematical modeling of interstitial potassium transport predicts that ischemia-induced depolarizing current peaks at the hypoxic border, suggesting ectopic activation likely occurs at the endocardium.
A mathematical model of potassium transport in myocardial ischemia suggests that ischemia-induced depolarizing currents are insufficient to cause ectopic activation at the lateral border, pointing to the endocardium as a more likely source.
Findings from this model should not guide clinical decisions; hypothesis-generating for endocardial ectopic triggers in myocardial ischemia.
Myocardial ischemia leads to an efflux of potassium ions from affected cells. The resulting depolarization of the resting membrane is one of the main features of ischemic myocardium. It has been shown experimentally that a part of the surplus interstitial potassium is transported out of the ischemic zone, even if no coronary blood flow is present in the affected area. We propose to model this transport mechanism mathematically with a diffusion equation. This model explains the measured spatial profiles of extracellular potential and potassium concentration. In addition, it allows a quantitative prediction of the transmembrane current that flows as a result of ischemia-induced depolarization. This current is thought to play a role in arrhythmogenicity, which is an important cause of mortality in acute myocardial infarction. Our model predicts that this current reaches its maximum exactly on the border of the hypoxic area. An important depolarizing current would be present just within the border, where hypoxia is accompanied by a resting membrane potential that is only slightly elevated, due to coupling with the adjacent normal tissue. Still, in the presence of potassium transport the predicted current density is not large enough to explain ectopic activation on the lateral border of the ischemia. This suggests that activation is more likely to occur at the endocardium, where the potassium gradient is steeper.
No takes yet. Share an insight, caveat, or question.
Potse et al. (2007) studied Myocardial ischemia. Mathematical modeling of interstitial potassium transport was evaluated on Spatial profiles of extracellular potential, potassium concentration, and transmembrane current. Mathematical modeling of interstitial potassium transport predicts that ischemia-induced depolarizing current peaks at the hypoxic border, suggesting ectopic activation likely occurs at the endocardium.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: