Spatial characteristics of atrial fibrillation using body surface and intra-atrial signals

This licentiate thesis is in the field of biomedical signal processing with main focus on processing of cardiac signals measured on the body surface or invasively from patients with atrial fibrillation (AF). The first part addresses spatial analysis of AF using VCG data synthesized from the 12-lead ECG. Two parameters each are extracted to characterize the spatial orientation as well as the spatial extent of the VCG data during AF. In addition, the relation of the parameters to AF organization, which is expressed in AF frequency, is evaluated. It is concluded that the quantification of AF organization based on AF frequency and spatial characteristics from the surface ECG is possible. The results suggest a relatively weak coupling between loop morphology and AF frequency when determined from the surface ECG. In the second part, a novel technique to quantify the propagation pattern of the electrical activation during AF along a one-dimensional catheter in the right atrium is presented. Taking intra-atrial signal organization aspects into account, the atrial activations are detected from the electrograms and combined into wavefronts. Parameters related to the consistency of the detected wavefronts over time and the activation order along the catheter are developed and their relationship to body surface measures such as AF frequency is investigated. While the degree of wavefront consistency is not reflected by the body surface measures, AF frequency is able to distinguish between recordings with different degrees of intra-atrial signal organization, supporting the role of AF frequency as an organization measure of AF