Optimal anisotropic lead scaling of multichannel ECG to reduce magnitude signal variability

A method for selecting the best functional to nonlinearly project multilead electrocardiogram (ECG) measurements into a specific type of single channel signal is presented. The functional is restricted to a family of timeinvariant quadratic functionals parameterized with lead-wise weights. This way, the projected signals are useful in multilead ECG delineation. The method determines the optimal weights in the sense of least beat-to-beat variability, eliminating much of the extra-cardiac influence, which in its turn results in a stable signal. According to the results obtained, the multilead approach is better than using any single lead alone as signal variability is reduced in 80 % of the cases even when using a suboptimal uniform weighting scheme. With the presented optimal lead scaling method, the variability is further reduced in all cases compared to individual leads, and in 92 % of cases, compared to the uniform weighting scheme. The results also show that there is no single set of weights suitable for all situations due to notable variation between the test cases.