Slovakia
online
Volume 97 / No. 9 / 1996
SCHUBERT E., UNBEHAUN A., MROWKA R., PATZAK A.
Heart beat and respiration are rhythmical phenomena with separate intrinsic
frequencies which necessarily have to be effectively tuned by a network
of interactive processes. Their linear and nonlinear components may ripen
in different ways during childhood thus leading to unstable transitions
or risk of dangerous events. This study investigates the development from
newborns to children mainly between sleep and wakefulness.
42 healthy untrained children underwent a 24 hours monitoring of ECG,
respiration, actogram, and EOG. Linear parameters such as respiratory rate,
heart period duration (HPD), total and high frequency spectral power (TP,
HFP), low/high frequency power quotient (LF/HF) and coherence were calculated
in wake state, REM- and non-REM sleep. The largest Lyapunov exponent (LLE)
was evaluated as nonlinear parameter and proved by the surrogate data method.
The childrendata were compared to newborndata at days 1 and 180.
In wake children, all values except TP differ from that in non-REM
and except LLE from that in REM. All linear parameters differ between REM
and non-REM. Similar differences exist for quiet to active sleep in newborns
at day 1. At day 180 only LF/HF and coherence differ. Development from
day 1 to 180 exists in quiet sleep for LF/HF and coherence, in active sleep
additionally for LLE and from day 180 to children except for LF/HF and
coherence.
The results show clear differences in the linear parameters of the
activity states. Wakefulness, REM- and non-REM sleep, therefore, follow
varied rhythmical controls. The behaviour of LF/HF points to changes in
the intensity of vagal participation and that of the coherence accentuates
the differing tightness of the coupling. The clearly existing nonlinear
components have a separate value only in wakefulness hinting at larger
complexity at that state. The development within the first 180 days indicates
an increase of vagal participation and tightness of coupling in quiet sleep,
in active sleep also an increase in complexity. From that day no further
development in vagal and coupling effects has been detected among children.
The complexity remains unchanged, only the power parameters expressing
heart rate variability increase. (Fig. 3, Tab. 3, Ref. 13.)
Key words: development, heart rate, respiratory rhythm, childhood.
Bratisl Lek Listy 1996; 97: 510–515
BAEVSKII R.M., MOSER M., TITOMIR L.I., IVANOV G.G., AIDU E.A.I., TRUNOV V.G., FUNTOVA I.I., ZHEVNOV V.N.
Long term observation of the heart state during specialized professional
activities plays an important part in preventive medicine. This study is
aimed at assessment of electrophysiological state of heart in astronauts
by common electrocardiography, vectorcardiography, and dipole electrocardiotopography
(DECARTO technique). The subjects observed were two astronauts performing
a long term flight at the Mir orbital station. DECARTO technique was used
to obtain an intelligible-pictorial representation of the data in the form
of so-called decartograms for visual and quantitative analysis. The observations
showed rather stable chronotopography of the heart depolarization process.
However, there was an increase of the maximal magnitude of the electric
heart vector and a decrease of the ventricular gradient vector in the middle
part of the flight. Just upon landing, a pronounced decrease of the ventricular
gradient magnitude, followed by a fast restoration of its value was observed
in both subjects. The DECARTO technique used in combination with vectorcardiography
facilitated the detailed visual analysis of the electrocardiographic data.
(Fig. 3, Ref. 3.)
Key words: vectorcardiography, electrocardiographic mapping, space
flight.
Bratisl Lek Listy 1996; 97: 516–520
DIEZ U., GIRLICH I., HAUSLER H.J., BIERBACH U., RIESKE K., SCHWARTZE H.
Cardiomyopathy is a severe complication of the tomour therapy with anthracyclines.
Since even minor disturbances of myocardial cell membranes could influence
the dipole moment of the heart the noninvasive measurements of this parameter
might be useful, particularly in the paediatric population.
17 children aged 215 years treated clinically for various malign blood
diseases were examined repeatedly with a modified Nelson lead-system up
to 3 years. The dipole moment was evaluated by visual comparison of the
calculated horizontal and frontal VCGs, evaluation of 3 distinctive vectors,
as well as of the magnitude curves and the velocity curves, all of them
compared with the normal age dependent percentiles of each respective child.
Conventional 12-lead ECGs were used to confirm rhythm disturbances and
alterations of P-, PQ-, QRS-, and QT-durations.
Our results show that damages of the heart are different during the
time of the drug administration, then consisting of acute toxic reactions
such as sudden dilatation and/or rhythm disturbances, and of long-term
disturbances leading to growth retardation of the heart with the danger
of chronic congestive heart failure months or years after the end of the
anthracycline treatment.
Morphological and biochemical damages of myofibrils caused by the toxicity
of anthracyclines precede functional restraints of the heart. A noninvasive
method for an early and reliable diagnosis of these damages is urgently
needed, particularly for children. Measurements of the dipole moment with
the Nelson-lead system seem to offer this diagnostic tool which aims possible
changes of the drug administration protocol. (Fig. 3, Ref. 15.)
Key words: dipole moment of the heart, Nelson-lead system, children,
malign blood diseases, anthracycline therapy, cardiomyopathy, cardiotoxic
side effect.
Bratisl Lek Listy 1996; 97: 521–525
RYABYKINA G.V., SOBOLEV A.V., PUSHINA E.A., LUTIKOVA L.N., ALEEVA M.K., SERGAKOVA L.M., USTINOVA S.E., ARABIDZE G.G.
Long-term heart rate variability (HRV) data were obtained from 38 patients
with arterial hypertension and 20 healthy persons. New method of HRV analysis
based on calculation and estimation of variations of short rhythmogram
intervals (SRV) was applied. This method showed that HRV level depends
on number of factors. The most significant of them are patient's age, arterial
hypertension form and duration, and left ventricular hypertrophy degree.
Patients with these risk factors may be highly predisposed to rate variability
decrease. (Tab. 8, Ref. 8.)
Key words: heart rate variability, arterial hypertension, left
ventricular hypertrophy.
Bratisl Lek Listy 1996; 97: 526–530
SOBOLEV A.V., SAKHNOVA T.A., KOZHEMYAKINA E.S., CHAZOVA I.E.
VCG data (McFee-Parungao system) were obtained from 12 patients with
primary pulmonary hypertension (PPH). During 2 years, VCG investigations
were repeated from 2 to 5 times. Various VCG-parameters were analyzed.
Space and horizontal QRS areas, projection of integral QRS vector to axis
y and the sum of Rz and Sx were diagnostically most significant. Their
values proved abnormal at the beginning of survey. In the course of observation,
states of the right heart chambers together with VCG-parameter dynamics
were investigated in every patient. States of the right cardiac chambers
improved in 4 patients. In all of them the parameter turned to normal values.
In two patients, during the monitoring time monotonous increase of parameters
was observed, with the state of the right heart chambers declining. In
6 patients, state of right heart chambers appeared relatively stable. In
these patients, values of all the parameters were either stable or insignificantly
changeable around some mean values. Thus, the dynamics of VCG-parameters
makes it possible to estimate adequately the states of the right cardiac
chambers in PPH patients. (Tab. 1, Fig. 4, Ref. 4.)
Key words: vectorcardiography, primary pulmonary hypertension,
right heart.
Bratisl Lek Listy 1996; 97: 531–535
TITOMIR L.I., SAKHNOVA T.A., CHAZOVA I.E., BARINOVA N.E., KOZHEMYAKINA E.S.
Techniques for noninvasive observation of heart states play an important
part in experimental and therapeutic cardiology. The objective of this
work is to describe a new method for intelligible pictorial representation
of data acquired by an orthogonal electrocardiographic lead system and
demonstration of possibilities of this method in estimating the results
of long term treatment for a cardiac disease. The method used, dipole electrocardiotopography
(DECARTO), provides a set of maps (decartograms) that depict in an explicit
form the instantaneous, as well as integral electrophysiological properties
of the heart during the excitation cycle. The observed group of patients
contained 10 females and 2 males with primary pulmonary hypertension. It
was found that in all but one cases tested, the features of the maps strongly
correlated with the results of the other diagnostical methods and clinical
findings. The trends to improvement (6 cases), stabilization (4 cases),
or deterioration (1 case) of the heart state were clearly indicated. In
one case, however, the interpretation of the decartograms was ambiguous.
The advantage of the DECARTO technique lays in clearness of data representation
for visual analysis and facilitation of electrophysiological and anatomical
interpretation of the data. (Fig. 6, Ref. 2.)
Key words: orthogonal electrocardiography, vectorcardiography,
electrocardiographic mapping, pulmonary hypertension.
Bratisl Lek Listy 1996; 97: 536–542
BERNADIC M., ZLATOS L.
The examintaions were carried out on 24 young rats divided in groups:
1st group: Controls (C), 2nd group: swimming rats (S), 3rd group: sympathectomized
rats (G) and the 4th group: sympathectomized swimming rats (GS). ECG, VCG
and BSPM were recorded on the 42nd day of their life in pentobarbital anaesthesy.
We used regular 23-leads system which covers the entire precordium of the
rat. The average body weight of the individual groups was (C) 212.4 g,
(S) 182.3 g, (G) 183.7 g and (GS) 200.1 g and the heart weight was (C)
695.4 mg, (S) 761.1 mg, (G) 669.7 mg and (GS) 783.8 mg. Heart rate in the
groups G, GS and S in comparison to the control group (C) was significantly
decreased. In all three experimental groups the voltage of R wave increased.
The duration of the QRS complex was unchanged. The heart axis was orientated
more downward especially in G and GS rats. In all groups the activation
of ventricles in BSPM starts from the upper left precordium and propagates
in a circle downward to the right, continuing back upwardly to the left
so as to cover the entire precordium. During the repolarization the entire
area of precordium is positive. In S group inhomogeneity of electric field
with islands of negativity appears and repolarization sequence is late.
In the groups G and GS is similar course of activation without inhomogeneities.
The potential max values in groups GS (1.76 mV) and S (1.54 mV) are significantly
higher than in the C (1.1 mV). We assumed that the observed changes of
cardioelectric field in experimental groups probably reflected an increase
of the number of cardiomyocytes (see groups G and GS), resp. enlargement
of its volume (S): thus the different enlarged area of electrical active
membranes of myocardium. (Tab. 3, Fig. 3, Ref. 30.)
Key words: heart hypertrophy, swimming rats, sympathectomy by guanethidine,
body surface ECG maps, electrocardiography, experimental electrocardiography.
Bratisl Lek Listy 1996; 97: 543–549
CABELKA S., KITTNAR O., NOVOTNY J., MARSIK F., SLAVICEK J.
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.)
Key words: computer model, body surface isopotential map, forward
problem, finite element method, ventricular activation.
Bratisl Lek Listy 1996; 97: 550–552
REGECOVA V., RUTTKAY-NEDECKY I.
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 configuraton, 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.)
Key words: anthropometry, vectorcardiography, normal limits.
Bratisl Lek Listy 1996; 97: 553–557
TINOVA M., HUISKAMP G.J., TURZOVA M., TYSLER M.
The Uniform Double Layer (UDL) model of the cardiac generator is often
used for forward simulation of body surface potentials (BSPs). The model
also proved to be very useful for the inverse computation of heart activation.
However, for the purposes of Myocardial Infarction (MI) modelling mostly
the Multiple Dipole (MD) models are used.
In our study, the ability of UDL model to represent the activation
of the heart with an old MI was examined. The finite element model of the
heart was used to simulate electrical activation of the heart with an old
MI. Different locations of endocardial MI were used. For each of them three
cases were considered according to the scale of the infarcted area: small
and medium endocardial and large transmural. For the further computation
of the electric field within the torso volume conductor two types of UDL
representation of the cardiac generator were used. For the first UDL model,
supposing the scared tissue to be unexcitable, an "infarcted"
surface (different from the "healthy" surface) of activated myocardium
was generated for each case of MI. Times when activation wavefront reached
particular nodes on the surface served as an input for the forward computation
of BSPs. To be able to understand the behaviour of the UDL, we also created
the second UDL model, where the "infarcted activation sequence"
was approximated on the original "healthy" heart surface.
The BSPs were computed for each case of MI using both UDL cardiac generators.
The boundary element method with the inhomogeneous volume conductor was
used for computations. The BSPs generated by both models for the same case
of MI were compared using the correlation coefficient.
The results show, that it is possible to find an approximation of the
"infarcted activation sequence" on the "healthy" heart
generator surface in a way that BSPs generated by both models have a correlation
coefficient higher than 0.96 for the entire period of depolarisation.
Visualisation of the epicardial isochrones might help to understand
the UDL model behaviour under the MI conditions. It would be useful for
the correct interpretation of the results when using the UDL model for
inverse solution. (Fig. 7, Ref. 5.)
Key words: cardiac electric field, ecg modelling, myocardial infarction
modelling, forward solution, UDL model.
Bratisl Lek Listy 1996; 97: 558–561
TURZOVA M., TYSLER M., SVEHLIKOVA J., TINOVA M.
Inverse solution techniques are expected to help in noninvasive localization
of ventricular preexcitation sites. The influence of selected extracardial
factors on the accuracy of the inverse localization of the initial activation
sites was studied on a model.
Each of 8 simulated activation sequences was initiated in a different
single starting point at the atrioventricular ring. Corresponding ecg potentials
on the surface of a realistic model of inhomogeneous torso were used for
the inverse localization procedure. A multiple dipole (MD) model of the
cardiac generator composed of 39 segmental dipoles was used in the inverse
computations.
As it was shown in a previous study, the method was able to localize
the 8 starting points even if a simplified torso model and a limited number
of leads was used. In this study, influence of another two factors was
evaluated: inaccuracy of location of the MD generator and presence of noise
in surface potentials.
Several shifts and rotations of the heart generator relative to its
exact position were modeled. When the mean deviation of starting points
was about 1 cm the mean localization error varied from 0.5 cm up to 1.0
cm for complete model data 198 surface potentials and a torso model including
lungs and ventricular cavities.
When a noise with uniform and Gaussian distribution was added to the
surface potentials, the use of averaged body surface potentials significantly
improved accuracy and stability of the inverse solution. For root mean
square value of noise sigma=14 microV the mean error of localization was
0.9 cm. For higher noise (sigma=30 microV) the results were substantially
deteriorated. The influence of a noise was studied on complete model data.
(Tab. 3, Fig. 5. Ref. 6.)
Key words: cardiac electric field, inverse solution, multiple dipole
model, localization of initial ventricle activation.
Bratisl Lek Listy 1996; 97: 562–566
SZATHMARY V., RUTTKAY-NEDECKY I., ANDRASYOVA D.
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.)
Key words: cardiac electric field, model of ventricular activation,
neonatal vectorcardiogram, developmental changes of ventricular geometry.
Bratisl Lek Listy 1996; 97: 567–570