M. Reumann

Comparison of the electrophysiologically based optimization methods with different pacing parameters in patient undergoing resynchronization treatment

Many studies conducted on patients suffering from congestive heart failure have shown the efficacy of cardiac resynchronization therapy (CRT). The presented research investigates an off-line optimization algorithm based on different electrode positioning and timing delays. A computer model of the heart was used to simulate left bundle branch block (LBBB), myocardial infarction (MI) and reduction of intraventricular conduction velocity in order to customize the patient symptom. The optimization method evaluates the error between the healthy heart and pathology with/without pacing in terms of activation time and QRS length. Additionally, a torso model of the patient is extracted to compute the body surface potential map (BSPM) and to simulate the ECG with Wilson leads to validate the results obtained by the electrophysiological heart model optimization.

Modelling and Imaging Electrophysiology and Contraction of the Heart

A computer model of the human heart is presented, that starts with the electrophysiology of single myocardial cells including all relevant ion channels, spans the de- and repolarization of the heart including the generation of the Electrocardiogram (ECG) and ends with the contraction of the heart that can be measured using 4D Magnetic Resonance Imaging (MRI). The model can be used to better understand physiology and pathophysiology of the heart, to improve diagnostics of infarction and arrhythmia and to enable quantitative therapy planning. It can also be used as a regularization tool to gain better solutions of the ill-posed inverse problem of ECG. Movies of the evolution of electrophysiology of the heart can be reconstructed from Body Surface Potential Maps (BSPM) and MRI, leading to a new non-invasive medical imaging technique.

Computer Based Optimization of Biventricular Pacing According to the Left Ventricular 17 Myocardial Segments

Cardiac resynchronization therapy (CRT) has shown to improve hemodynamics and clinical symptoms of congestive heart failure. The present article investigates an automated non-invasive strategy based on a computer model of the heart to optimize biventricular pacing as a CRT with respect to electrode positioning and timing delays. Accurate simulations of the electrical activities of the heart require suitable anatomical and electrophysiological models. The anatomical model used in this work, is based on segmented MR data of a patient in which a variety of tissue classes for left ventricle are considered based on AHA standard in accordance with fiber orientation. The excitation propagation is simulated with the ten Tusscher et al. electrophysiological cell model using an adaptive cellular automaton. The simulated activation times of different myocytes in the healthy and diseased heart model are compared in terms of root mean square error (ERMS). The results of our investigation demonstrate that the efficacy of biventricular pacing can greatly be improved by proper electrode positioning and optimized A-V and V-V delay.

Computer Assisted Optimization of Biventricular Pacing Assuming Ventricular Heterogeneity

Reduced cardiac output, dysfunction of the conduction system, atrio-ventricular block, bundle branch blocks and remodeling of the chambers are results of congestive heart failure (CHF). Biventricular pacing as Cardiac Resynchronization Therapy (CRT) is a recognized therapy for the treatment of heart failure. The present paper investigates an automated non-invasive strategy to optimize CRT with respect to electrode positioning and timing delays based on a complex threedimensional computer model of the human heart. The anatomical model chosen for this study was the segmented data set of the Visible Man and a set of patient data with dilated ventricles and left bundle branch block. The excitation propagation and intra-ventricular conduction were simulated with Ten Tusscher electrophysiological cell model and adaptive cellular automaton. The pathologies simulated were a total atrioventricular (AV) block and a left bundle branch block (LBBB) in conjunction with reduced interventricular conduction velocities. The simulated activation times of different myocytes in the healthy and diseased heart model are compared in terms of root mean square error. The outcomes of the investigation show that the positioning of the electrodes, with respect to proper timing delay influences the efficiency of the resynchronization therapy. The proposed method may assist the surgeon in therapy planning.