thaler chapter 1

1   The Basics

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This vector is precisely what our EKG electrodes record when measuring the electrical flow within the heart. The vector’s angle of orientation represents the average direction of current flow, and its length represents the voltage ( amplitude ) attained. At any given moment, the electrical forces moving within the heart can be represented by a single vector. Furthermore, over any particular period of time during the cardiac cycle ( e.g. , atrial depolarization), these individual vectors can be summed into a kind of vector of vectors, which describes the average direction and magnitude of current flow during that time period ( e.g. , during atrial depolarization, corresponding, let us say, to all the goalie’s kicks over the first half of the game). Thus, a particular wave (in this case, the wave of atrial depolarization) can be described by a single vector of given direction and magnitude. You will see how this works and how it simplifies our understanding of the 12-lead EKG in the following section.