document: Noninvasive myocardial activation time imaging : a novel inverse algorithm applied to clinical ECG mapping data Linear approaches like the minimum-norm least-square algorithm show insufficient performance when it comes to estimating the activation time map on the surface of the heart from electrocardiographic -LRB- ECG -RRB- mapping data . Additional regularization has to be considered leading to a nonlinear problem formulation . The Gauss-Newton approach is one of the standard mathematical tools capable of solving this kind of problem . To our experience , this algorithm has specific drawbacks which are caused by the applied regularization procedure . In particular , under clinical conditions the amount of regularization can not be determined clearly . For this reason , we have developed an iterative algorithm solving this nonlinear problem by a sequence of regularized linear problems . At each step of iteration , an individual L-curve is computed . Subsequent iteration steps are performed with the individual optimal regularization parameter . This novel approach is compared with the standard Gauss-Newton approach . Both methods are applied to simulated ECG mapping data as well as to single beat sinus rhythm data from two patients recorded in the catheter laboratory . The proposed approach shows excellent numerical and computational performance , even under clinical conditions at which the Gauss-Newton approach begins to break down
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