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I Ruttkay-Nedecký

Publications and source records attributed to I Ruttkay-Nedecký.

At least 19 recordsLinked to original sources
PubMed2004

Comparative dipolar electrocardiotopographic study of ventricular activation in Macaca mulatta monkeys and man.

Electrocardiographic correlates of ventricular activation sequence were studied in 22 Macaca mulatta monkeys, aged 1-18 years, and 145 human subjects, aged 11-72 years, using the corrected orthogonal lead system of McFee-Parungao and the dipolar electrocardiotopographic (DECARTO) data presentation, where the time series of instantaneous spatial vectors are converted into time series of areas of activation on a spherical image surface enveloping the heart. Macaques had shorter ventricular activation time (61+/-11 vs. 97+/-11 ms) that could not be explained exclusively by their higher heart rate. Their DECARTO image of the resultant activation front occurred 10 ms after QRS onset (septal activation) identically with humans, but it attained a more anteriorly oriented maximum earlier than in humans (20 vs. 40 ms). The time course of the extent of the resultant activation front in old macaques (15-18 years) resembled to that observed in humans. On the average, female macaques had smaller DECARTO images of activation fronts throughout the QRS complex than males. This finding is in agreement with the known smaller QRS amplitudes in women than in men.

Age Factors↗
PubMed2002

[Orthogonal electrocardiography].

The orthogonal electrocardiography was a further development of Einthovens conception of electrocardiography. It eliminates the redundancy of the 12-lead ECG and offers a more precise and illustrative image of the model of an equivalent dipole. It was the prerequisite of the development of vectorcardiography. It improves the diagnostic performance of electrocardiology, especially by decreasing the spread of parameters used to characterize normal cardiac electrogenesis. It may be assumed that clinical electrocardiography will not petrify its standard 12-lead system but will utilize the possibilities offered by the more rational lead systems of orthogonal electrocardiography, as well as its enrichment by vectorcardiographic presentation of the cardiac electric field.

Electrocardiography↗
PubMed1996

The role of anthropometry in the assessment of vectorcardiographic norms.

There is scarcity of quantitative studies on the relationship between somatometric characteristics of chest configuration and vectorcardiographic variables. The objective of this study was to give a quantitative description of these relations in order to improve the recognition of normal vectorcardiographic ranges and limits. The magnitude of the maximum vector of atrial depolarization is strongly influenced by chest configuration, but not by age, while declination values of atrial activation are under the influence of both factors. The same holds for vectors of ventricular depolarization, while, as regards ventricular repolarization, somatometric variables are only related to the spacial orientation of the vector. Both age and chest configuration also influence the magnitude of the spacial angle between QRS and T integral vectors. These results speak for the need to consider somatometric data for correct assessment of normal limits of VCG variables. (Tab. 6, Fig. 1, Ref. 17.)

Adolescent↗
PubMed1996

Modelling developmental changes of human cardiac electric field in early postnatal period.

In early postnatal life, human cardiac electric field undergoes dramatic changes resulting from the adaptation of the heart to new hemodynamic conditions. For the study of the effect of changes in ventricular geometry as well as in spatial orientation of the heart occurring in this period of life, on the resultant heart vectors, our computer model of propagated activation was used. This model allows to change both mentioned characteristics of ventricles so that they reflect the developmental changes in the human heart. The pattern of activation of the model of newborn heart, characterized by equal thicknesses of the left and right ventricular walls as well as by the planar shape of the septum, showed that the resulting electrical forces were oriented anteriorly, slightly to the right, with clockwise rotation of the cardiac vectorgram in the horizontal plane projection. The gradual increase of the left ventricular wall thickness shifted the cardiac vector loop gradually to the left and anteriorly. When the ratio of the left to right ventricular wall thickness was the same as in adult human heart, the cardiac vector loop was oriented posteriorly, to the left and inferiorly. The left orientation of the initial cardiac vectors, commonly observed in 50% of full-term babies until 24 hrs of life, could be achieved only by the rotation of the heart around its long axis and/or by change of the azimuth of this axis. The simulated cardiac vectorgrams followed the typical early postnatal evolution of the vectorcardiograms of human newborns. (Fig. 4, Ref. 9.)

Computer Simulation↗
PubMed1994

Computer simulation of propagated activation in different types of left ventricular enlargement.

An increase of the left ventricular mass does not always have an unambiguous effect on the electro- or vectorcardiographic image of ventricular activation. To analyse this phenomenon, three types of left ventricular enlargement were simulated by a computer model of propagated activation in cardiac ventricles. These were obtained from the reference (normal) left ventricle by an increase of its wall thickness either centripetally or centrifugally, as well as by increase of the ventricular cavity dimensions (dilatation). Two different degrees of mentioned changes, corresponding to an increase of the value of the respective parameters by 50% or 100% of reference left ventricular wall thickness, were analysed. In the case of a centrifugal increase of left ventricular wall thickness, the magnitude of instantaneous cardiac vectors increased only during the last two-thirds of ventricular activation time. A centripetal increase of the wall thickness resulted in a decrease of the resultant cardiac vector magnitudes during the first half of ventricular activation followed by their slight increase. In dilatation of the left ventricle the cardiac vectors were enhanced during the whole activation time.

Action Potentials↗
PubMed1994

Dipolar electrocardiotopographic evaluation of ventricular activation in patients with various degrees of coronary artery disease.

Dipolar electrocardiotopographic imaging of instantaneous vectorcardiographic QRS vectors represents the ventricular activation front as a bounded area on the spherical image surface. Fuzzy set treatment of the elements of this area allows for the recognition of five classes of ventricular activation: I, abnormal; II, abnormal with normal component; III, normal with abnormal component; IV, marginally normal; and V, normal. In a group of 71 patients with chest pain and various degrees of coronary artery stenosis classes II, III, and IV were most frequently observed in patients with one- or two-vessel disease. The frequency distributions of classes II and III throughout the QRS were bimodal with peaks at 20 and 60 ms after QRS onset, while the frequency distribution of class IV was unimodal with a peak at 30 ms after QRS onset. The advantage of this method is the smoothing of threshold values on a quantitative basis.

Adolescent↗
PubMed1994

Role of left ventricular geometry in the alteration of initial QRS vectors due to concentric ventricular hypertrophy.

The relation between serial magnitudes of instantaneous spatial vectors, obtained throughout ventricular depolarization, and echocardiographically estimated left ventricular (LV) mass was investigated in 64 patients with congenital aortic stenosis and in 16 patients with coarctation of the aorta. While the correlation was positive between LV mass and vector magnitudes at 50 and 60 ms after QRS onset (r = .530 and .557, P < .01), it was found to be negative with regard to the magnitude of the initial 10 and 20 ms vectors (r = -.285 and -.355, P < .01). Computer simulation of activation propagation in different models of LV enlargement has shown that the decrease of the spatial magnitude of initial vectors, as well as a marked decrease of the area of the anterior portion of the horizontal plane QRS loop and of the Q amplitude of the orthogonal z lead, are characteristic of concentric LV hypertrophy with decreased diastolic volume and were not observed with unchanged or dilated chamber size. Repeated assessment of the magnitude of initial QRS vectors may indicate changes of LV remodeling in patients with LV pressure overload.

Aortic Coarctation↗
PubMed1993

Problems and perspectives of mapping the cardiac electric field.

The cardiac electrical field is important not only because of its diagnostic significance, but also as a biological and biophysical phenomenon. As such, it has become a research target of biologists, biophysicists and biomathematicians. It has also been an impetus for constructing more and more sophisticated measuring devices. Criteria for the diagnostic evaluation of body surface potential maps have often been derived from clinical studies based on a restricted number of cases. Further clinical research is therefore a conditio sine qua non for the acceptance of mapping as a routine diagnostic procedure. In the future, body surface potential distributions will be used as the input for computer simulation of potential distribution and activation chronograms on the geometric surface closely encompassing the heart. In such a way, electrocardiographic signals will be interpreted in terms of activation and repolarization sequences on the cardiac surface.

Computer Simulation↗
PubMed1992

[Vectorcardiographic features of right ventricular dilatation].

Axial McFee-Parungao lead system vectorcardiograms were obtained in 55 patients with type atrial septal defect, aged 3-24 years, prior to and in average 3 years after surgical repair of the defect. Changes of the QRS loop observed after intervention led to the conclusion that the vectorcardiographic signs of right ventricular dilatation consist of a rightward shift of the posteriorly orientated horizontal plane vectors at 50-70 ms of QRS, decrease of the magnitude of vectors around the 40th ms, no changes in the magnitude and orientation of the initial (10-30 ms) QRS vectors as well abnormal departures of the spatial VCG loop from its preferential plane even in the absence of other signs of right ventricular conduction impairment. The above abnormalities vanished after normalization of hemodynamics.

Adolescent↗
PubMed1992

[Vectorcardiography of variations in localization of specific conduction systems in the left ventricle].

A realistic computer model of propagation of ventricular activation was used to study the effects of varying the position of specific conduction system terminations in the left ventricle and the septum, representing the sites of initial activation, on the resulting simulated spatial heart vectors. Three differently localized foci of initial activation, each of them represented by one model element, were considered: in the central part of the left septal surface, posteriorly at about one third of the distance from the apex to the base, and in the upper part of the anterior free wall. During the model experiments, the positions of the initial activation were shifted +/- 5 model units (ca 5 mm) in the vertical and lateral direction either separately or in different mutual combinations. Small variations of the initial activation site in the basal parts of the left ventricle led to significantly smaller changes of the vectorcardiographic loop than variations of the same extent with the initial activation site located more apically.

Computer Simulation↗
PubMed1991

[Reference values of dipolar electrocardiotopography of the QRS complex].

Reference values of dipolar electrocardiotopogram of ventricular depolarization are presented. The data for establishing reference values in the McFee-Parungao lead system were obtained by manual processing of 145 records of healthy subjects (64 women, 81 men) in the age range of 11-72 years, and for the Frank lead system by automatic processing of 123 records of healthy subjects (54 women, 69 men) aged from 9 to 72 years. The obtained values of the X, Y, Z coordinates of the end points of QRS instantaneous vectors recorded at 10 ms intervals were processed by means of a biomathematical model in the form of activation areas on the spherical image surface. Electrocardiotopograms were represented in the form of discrete spherical image surface in the shape of a rectangle (11 lines, 24 columns). For each point of this matrix the value of relative frequency (probability) of its occurrence in activated state in the healthy population is given.

Adult↗
PubMed1990

[Vectorcardiographic and chronotopocardiographic study of septal hypoperfusion].

The study has been carried out in 73 patients (63 men and 10 women), aged between 22 and 59 years, suffering from angina pectoris. The localization in space of the extremities of the initial QRS vectors (10 and 20 ms) is an indicator which is relatively very sensitive to the disturbance in the myocardial irrigation in the regions around the septum and the adjacent ventricular wall. A good relationship has been found namely with the data obtained with thallium scintigraphy after effort. The sensitivity of the vectocardiographic method, like that of dipolar chronotopocardiography, was clearly superior to that of scalar graphs.

Adult↗
PubMed1989

[Comparison of echocardiography, vectorcardiography, electrocardiography, coronarography and ventriculography in coronary heart disease].

Fifty patients (9 women, 41 men) with angina pectoris, aged from 22 to 59 years, were examined by means of one- and two-dimensional echocardiography (ECHO), vectorcardiography (VCG) using the McFee-Parungao system of leads, standard 12 lead electrocardiography (ECG), coronarography (CAG), and ventriculography (VG). I of isolated positivity of either of these methods ans considererl as patse positivity and presence or absence of positivity in combination of at least two methods (ECG exeluted) astme positivity, or true negativity then VCG was found to have the highest sensitivity (96%), negative predictive value (80%), as well as the highest overall predictivity (83%), while ECHO had the lowest values, i.e. 55%, 36%, 64%, respectively. On the other hand, ECHO was leading in specificity and positive predictive value with 100%, whereas VCG ranked lowest with 62% and 83% respectively. The combination of ECHO and VCG versus CAG and/or VG positivity exhibited and 80% specificity, 90% sensitivity, 90% positive predictive value and 86% overall predictivity when stenosis of over 50% was considered to be criterion. If obstruction was required the figures were to 75%, 94%, 83% and 86% respectively. ECHO and VCG are complementary noninvasive methods able to predict the results of CAG and VG and have a good predictive value when lowing for mere presence of focal myocardial injury.

Adult↗
PubMed1987

Chronotopocardiography: a new method for presentation of orthogonal electrocardiograms and vectorcardiograms.

A mathematical model was developed to express and visualize signals from 3 orthogonal ECG (vectorcardiographic (VCG) leads as areas of activation on a spherical surface approximating to the walls of the cardiac ventricles, called the image surface. A computer program was compiled for presentation of orthogonal ECGs in the form of a series of instantaneous maps of cardiac activation, as well as chronotopocardiograms displaying the topography and the duration of activation on the image surface on two summary maps.

Electrocardiography↗