A) Consequences of gain-of-function on the ventricular
action potential. Due to an increased net influx of Na+-ions, action
potential duration is increased (red trace), which can evoke arrhythmic events.
B) Different mechanisms that can be responsible for the
gain-of-function in INa, i.e. increased late current
(INa,L), increased peak INa, decreased rate of
inactivation and increased window current. Most commonly, an increase in
sustained current (INa,L) is observed. C) Shifts in
voltage dependence of (in)activation (dashed lines) that lead to an increased
window current, as illustrated by the red and blue areas under the curve.