Biomedical subjects

O Kittnar

Publications and source records attributed to O Kittnar.

9 recordsLinked to original sources

PubMed1996

Three-dimensional finite element computer model of the forward problem of electrocardiology.

This study analyses forward problem of electrocardiology. Premature beats originated from subepicardial layer of myocardium were simulated in order to analyse their shape dependence on the site of origin. The equation governing the propagation of the electrical wave through human thorax together with transition and boundary conditions is derived under the clearly stated simplifying assumptions. The weak formulation of the forward problem of electrocardiology is introduced, too. The Galerkin method as a convenient tool for looking for the numerical solution is mentioned and its practical implementation--finite element method--then used in order to obtain numerical results. The obtained results were presented in the form of isopotential maps and compared with actually measured body surface isopotential maps of the depolarization phase. The parameters of the model were then optimalized in accordance with the measured data. In spite of the lack of quantitative data the model has proved that the presented method was able to be used for the simulation studies of ventricular ectopic beats. It was shown that only a small difference between the site of beat origin can be well distinguished on the simulated body surface maps. (Fig. 3, Ref. 3.)

Computer Simulation↗

PubMed1993

Quantitative evaluation of body surface potential mapping of heart electrical field in ischaemic heart disease.

New possibilities of quantitative evaluation of body surface potential mapping were studied in 78 patients with ischaemic heart disease. Integral maps of the Q wave, QRS and ST-T intervals were plotted and isochronous maps of ventricular activation time and maps of asynchronous potential minima of the Q wave were determined. Minimum and maximum potential values and their time relations were evaluated in the maps. Left ventricular contraction abnormality detected by left ventricular angiography was determined by a point score and expressed as an index of asynergy. The number of coronary artery branches with significant narrowing was assessed and the extent of coronary artery damage was evaluated by an arbitrary defined index. Using quantitative parameters from the maps, multiple stepwise linear regression was performed. The relationship between map parameters and index of asynergy corresponded to multiple correlation coefficient r = 0.69 (p = 0.01) in the whole group of patients. In the group of patients with left ventricular contraction abnormality the relationship between these parameters was found to be r = 0.87 (p = 0.01). The relationship between map parameters and the number of coronary artery branches with significant stenosis was r = 0.60 (p = 0.01) in the group of patients with positive coronary angiography. In the same group of patients the relationship between map parameters and the index evaluating coronary artery damage was equal to r = 0.63 (p = 0.01). The data obtained from body surface integral maps enable to quantify cardiac ischaemic damage.

Coronary Angiography↗

PubMed1993

Repolarization pattern of body surface potential maps (BSPM) in coronary artery disease.

The aim of our study was to assess if repolarization BSPM were able to evaluate the site, size and severity of chronic ischaemic damages and if BSPM were in any way related to the regional attenuation of myocardial contractility or to the site of coronary artery occlusion. The BSPM were obtained from 69 patients suffering from coronary artery disease confirmed by coronarography, with at least 75% occlusion of at least one coronary artery. According to the site of single occlusion, or a combination of the sites of multiple occlusions, the patients were divided into 6 subgroups. According to the region of attenuated kinetics the same group of 69 patients was also divided into other 6 subgroups. As in the polarity distribution there was only a limited accordance in BSPM with coronarographic and echocardiographic findings, in the localization of extreme values there were very important specific changes in patients with normal kinetics as determined by both contrast ventriculography and two-dimensional echocardiography. The repolarization maps can distinguish patients with coronary artery disease and normal echocardiography from healthy persons with a sensitivity of 85% and a specificity of 65% in the case of the isoareal map from the ST segment (RIAM) and 90% and 85%, respectively, in the case of the isointegral map from the whole ST-T segments (RIIM).

Adult↗

PubMed1993