Change of short-term memory effect in acute ischemic ventricular myocardium: A computational study

The electrical restitution of the non-propagated cardiac ventricular action potential

“…Remembering, on the other hand, means storing information somewhere and, in the case of STM, we can think the information stored into the activation and inactivation kinetics of ionic channels and into their time, voltage, or intracellular ion concentration dependence. Unlike long-term cardiac memory, STM is removed as soon as the beating stops for few beats or, more physiologically, when it reaches a steady state, and can in fact be estimated by measuring the time taken for APD to reach steady-state value after an abrupt change of constant pacing CL [ 94 , 185 , 188 ]. STM, in other words, measures the difference between a sudden and a steady-state response to a pacing CL change between two different constant values and, as such, is not captured by ER S1-S2,DI nor by ER dyn,DI curves [ 5 ], but it can be measured from the angle between the two [ 42 , 94 ].…”

“…Finally, Fenton and colleagues have shown in a theoretical study how STM dependence of ER explains the pro-arrhythmic properties of ischemia-induced flattening of the ER S1-S2,DI curve [ 38 ]. Restitution portraits were also used to estimate STM under acute myocardial ischemia in a guinea pig ventricular AP model [ 94 ]. They showed that ischemia induced a significant decrease of STM, mainly due to the decrease in extracellular calcium rather than to changes in membrane currents.…”