Heart dipole vector

The Einthoven triangle is an example of a recorded voltage u (the electrocardiogram signal) modeled as the dot product of the lead vector of a bipolar PU electrode pair and the bound heart dipole vector m (see Section 10.1). 

Einthoven (1913) proposed an equilateral triangle model with the center in the heart center. Figure 10.5. Each side of the triangle corresponded to each of the three bipolar leads I, II, and III. He proposed the heart modeled as a bound dipole vector (he did not use that expression), and that a lead voltage was the projection of the heart vector on a corresponding triangle side (actually a dot product). He proposed that his model could... 

Figure 6.15 illustrates a situation with a finite and inhomogeneous volume where m is the dipole source, symbolizing for instance the heart vector. Under such conditions, the dipole equations are not exact solutions, and a more realistic approach according to limited conductor volumes and inhomogeneous tissue must be found. To find the lead vector H under more realistic conditions, the concept of reciprocal excitation was introduced (McFee and Johnston, 1953). Reciprocal excitation is to let the PU electrodes be CC with... 

The most basic electrical model of the heart is a bound vector with the variable vector moment m = iLcc see Eq. 6.10. Plonsey (1966) showed that a model with more than one dipole is of no use because it will not be possible from surface measurements to determine the contribution from each source. The only refinement is to let the single bound dipole be extended to a multipole of higher terms (e.g., with a quadrupole). 

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