Abstract:

Ventricular premature beats (VPB) occur when a cardiac depolarization is initiated from a focus in the ventricle instead of the sinoatrial node. Because the ventricular electrical excitation is not started from the intraventriclular conduction system, the excitation propagation in the ventricles behaves in an abnormal manner. This results in an extra asynchronous contraction of the ventricles. In addition VPBs can trigger life-threatening heart arrhythmias. Applying catheter ablation can cure VPB. Therefore it is of importance to localize the origin of VPB using a non-invasive approach before interventional treatment. In this work the inverse problem of electrocardiography is deployed to reconstruct electrical sources in the ventricles, from which the origin of VPB can be identified. By using a spatiotemporal maximum a posteriori (MAP) based regularization the quality of reconstructions is improved. In this work forward calculations with various VPBs are employed to construct a statistical a priori information.

Abstract:

Solving the forward problem of electrocardiography provides a better understanding of electrical activities in the heart. The inverse problem of electrocardiography enables a direct view of cardiac sources without catheter interventions. Today the forward and inverse computation is most often performed in a static model, which doesn't take into account the heart motion and may result in considerable errors in both forward and inverse solutions. In this work a dynamic heart model is developed. With this model the effect of the heart motion on the forward and inverse solutions is investigated.

Abstract:

The treatment of ventricular arrhythmia often requires detailed information about the location of ectopic beats. A noninvasive procedure is adopted to achieve this purpose. The aim of this work is the reconstruction of ectopic foci by using the critical point theory introduced by Greensite and Huiskamp [1]. The reliability and adaptability of the obtained simulation results are evaluated with regard to the reconstruction error.The reconstruction of bioelectrical sources from measured body surface potentials is an ill-posed problem and requires regularization. The advantage of the presented method is to deal with a well-posed formulation of the problem. Locations of ectopic beats can be detected by the critical point theorem. Four simulated ectopic centers have been localized to evaluate the method. The influence of Gaussian noise is considered.The reconstruction depends on the effective rank of a singular value decomposition (SVD) of the multi-channel ECG matrix. Regarding lower ranks, many critical points presenting ectopic foci can be observed. For higher ranks, the detection leads more and more to a stable estimation of ectopic locations. The detected critical points are shown to be reliable approximations of the simulated ectopic foci.