Evaluation of magnetic navigation in an in vitro model of uterine artery embolization.

Purpose: To compare steering of a novel magnetic guide wire with a standard 0.014-inch guide wire within a vascular phantom.

Materials And Methods: The magnetic guiding system (MGS) was composed of two permanent magnets on each long side of the fluoroscopy table generating a 0.

Vascular guide wire navigation with a magnetic guidance system: experimental results in a phantom.

Purpose: To investigate the efficacy of a second-generation prototype magnetic guidance system in complex vessel phantoms versus conventional navigation in simulated interventional radiology procedures and to analyze procedure and fluoroscopy times.

Materials And Methods: The magnetic guidance system consists of two focused-field permanent magnets on each side of the body that create a 0.1-T navigation field and is integrated with a modified C-arm single-planar digital angiography system.

Spatial features in body surface potential maps of patients with ventricular tachyarrhythmias with or without coronary artery disease.

Body surface potential maps (BSPM) from patients with coronary artery disease or no structural heart disease were analyzed with respect to their spatial features and QT/QTc dispersion in order to determine whether BSPM allows identification of patients with ventricular fibrillation. QRST integral maps and QT/QTc dispersion were acquired from simultaneous recordings of 62 ECG leads during sinus rhythm in patients with idiopathic ventricular fibrillation (n=13), ventricular fibrillation and coronary artery disease (n=22), coronary artery disease without ventricular fibrillation (n=21) and healthy controls (n=18). The Karhunen-Loeve transformation was applied to reduce the dimensionality of the data matrix of the QRST map to eight coefficients.

[Analysis of QRST integral and QT dispersion by body surface potential mapping in patients with malignant ventricular arrhythmias].

In a retrospective analysis in 74 patients with coronary artery disease or no obvious heart disease, the value of "body surface potential mapping" for the identification of repolarization abnormalities was investigated compared to the standard 12-lead ECG. In patients with idiopathic ventricular fibrillation the number of extrema in the QRST integral map was significantly higher than in the control group (3.15+/-0.

Localisation of myocardial ischaemia from the magnetocardiogram using current density reconstruction method: computer simulation study.

A computer simulation study is performed to investigate the method of current density reconstruction to localise myocardial ischaemia. A computer model of the entire human heart is used to simulate the excitation and repolarisation process in eight topographically different cases of myocardial ischaemia. The associated magnetocardiogram is calculated at 37 positions of the KRENIKON biomagnetic measurement equipment.

Biomagnetic localization of electrical current sources in the human heart with realistic volume conductors using the single-current-dipole model.

The boundary element method was applied in order to investigate the localization accuracy for focal sources measured from MCG data. Various homogeneous volume conductor models were composed: the individually shaped torso, a scaled standard torso, an unscaled standard torso, a scaled cuboid and a scaled ellipsoid. We implemented these models in single-dipole inverse solution techniques.

Magnetocardiography: three-dimensional localization of the origin of ventricular late fields in the signal averaged magnetocardiogram in patients with ventricular late potentials.

The purpose of this study was to detect ventricular late fields recorded by a biomagnetic multichannel system in patients with ventricular late potential and to determine the site of these ventricular late fields non-invasively in three dimensions. Biomagnetic signals of sinus beats during a 5-min acquisition period simultaneously recorded by a 37-channel system Krenikon were averaged in all channels. Ventricular late fields were determined in each channel according to the algorithm of Simson for ECG data.

Three-dimensional computer model of the entire human heart for simulation of reentry and tachycardia: gap phenomenon and Wolff-Parkinson-White syndrome.

A computer model of the entire human heart has been developed for simulation of the excitation and repolarization process. Spatial distribution of refractory periods and conduction velocities in the different cardiac tissues, the anisotropy of conduction in the ventricles, and the cycle length dependence of refractory periods and conduction velocities are taken into account. The algorithm calculating the activation process is based on a modified version of Huygen's principle for constructing wavefronts.

A computer model of human ventricular myocardium for simulation of ECG, MCG, and activation sequence including reentry rhythms.

A computer model is presented for simulation of the spread of activation and repolarization in ventricular myocardium. The program calculating the activation sequence is based on an algorithm similar to Huygen's principle of constructing wavefronts. Physiological parameters of the heart, such as areas of early activation on the endocardium, conduction velocity, anisotropy of propagation, duration of action potentials and refractory periods are taken into account.