[Features of vectorcardiograms in patients with hypertension complicated by chronic heart failure with reduced left ventricle ejection fraction].

AIM: To explore the features of vectorcardiograms (VCG) of patients with essential hypertension complicated by chronic heart failure with reduced left ventricular ejection fraction (CHFrLVEF). MATERIALS AND METHODS: We analyzed VCGs of 70 hypertensive patients with CHFrLVEF and 275 hypertensive patients without clinical signs of CHF and with LVEF50%. We assessed the presence of rhythm and conduction disturbances, and the parameters of the synthesized VCG, i.e., module of the maximum QRS vector, planarity index of the spatial QRS loop (P/S), and spatial angle between the integral QRS and T vectors (sQRS-Ta). RESULTS: In hypertensive patients with CHF, certain conditions were detected more often as compared with hypertensive patients without CHF, i.e., atrial fibrillation (AF) in 52.9% vs 5.1%; p0.0001, and left bundle branch block (LBBB) in 38.6% vs 0.4%; p0.0001. The module of the maximum QRS vector and sQRS-Ta were significantly greater and P/S was significantly less in VCGs of patients with CHF. ROC-analysis showed that the presence of AF and LBBB just as VCG parameters assessed in this study provide clear discrimination between hypertensive patients with or without CHF both in the group as a whole and in the subgroups (1) without LBBB, (2) with sinus rhythm, and (3) with AF. sQRS-Ta was the most informative parameter (threshold 137, sensitivity 91%, specificity 92%). The P/S indicator at the optimal threshold value 0.92 was characterized by lower specificity (68%) with rather high sensitivity (79%). CONCLUSION: AF, LBBB, increased module of the maximum QRS vector and sQRS-Ta, and decreased P/S index are present in hypertensive patients with CHFrLVEF as compared with patients without CHF.

New approaches to the diagnosis of left and right ventricular hypertrophy by means of dipolar electrocardiotopography.

OBJECTIVE: The aim of this work was to describe a new approach to noninvasive differential diagnosis of left and right ventricular hypertrophies (LVH and RVH) caused by the arterial or lung hypertensions. METHODS: The vectorcardiographic measurements were analyzed by means of dipolar electrocardiotopography (DECARTO) technique based upon a simplified spherical model of the heart. The characteristics of LVH and RVH are obtained from the decartograms of activation duration. The integral indices of hypertrophy for the left ventricle and right ventricle (ILVH and IRVH) are formulated on the basis of the surface integrals of activation duration calculated over the regions where left and right ventricles are projected. The diagnostic decision is made through the comparison of ILVH and IRVH with specified threshold values. For comparison, the sums of wave amplitudes used in the orthogonal vectorcardiography, Rx+Sz for LVH and Rz+Sx for RVH, were also considered. RESULTS: The study included 141 males and 191 females aged 45+/-15 years, with reliably verified state of the heart, in particular, 143 persons without hypertrophy, 129 persons with LVH, and 60 persons with RVH. The ROC curves for criteria under study were statistically analysed. As a result, the ILVH criterion is preferable to Rx+Sz with confidence level greater than 95%, and the IRVH criterion is preferable to Rz+Sx with confidence level close to 99%. CONCLUSION: The proposed DECARTO method, initially intended mainly for intelligible-pictorial visualization of vectorcardiographic data, provides also some increase of diagnostic accuracy in recognition of the left and right ventricular hypertrophies as compared to the standard electrocardiography and orthogonal vectorcardiography.

[Informative value of orthogonal electrocardiogram in the diagnosis of the left ventricular hypertrophy].

AIM: To estimate the informative value of orthogonal ECG parameters for the diagnosis of left ventricular hypertrophy (LVH). MATERIALS AND METHODS: The study comprised 142 apparently healthy individuals and 125 patients with arterial hypertension (AH) and LVH (left ventricular mass index more than 125 g/m2 for males and more than 110 g/m2 for females). Characteristic curves (ROC curves) were used to describe and compare the informative value of vectorcardiographic, demapping criteria for L VH with the informavalue of the Sokolov-Lyons criterion, the Cornelian index, and the Cornelian product. RESULTS: The informative indices of orthogonal ECG were Rx + Sz and IADIM: the area under the ROC curve was 0.89 +/- 0.02 and 0.88 +/- 0.02, respectively, which was significantly higher than with the Sokolov-Lyons criterion (0.64 +/- 0.04; p < 0.05) and similar to the Cornelian product (0.84 +/- 0.03). Of great informative value is the angle phi (area under the ROC curve was 0.88 +/- 0.04) in males and the area of QRS loop in the horizontal plane (area under the ROC curve was 0.89 +/- 0.03) in females. With 96% specificity, the male sensitivity of IADIM was 80%, Rx + Sz--73%, which was significantly higher than that of the Cornelian index (56%; p < 0.05) and the Sokolov-Lyons criterion (27%; p < 0.05). With 96% specificity, the female sensitivity of IADIM was 73%, Rx + Sz--84%, SQRSxz--70%, which was significantly higher than that of the Cornelian index (49%; p < 0.05), the Cornelian product (55%; p < 0.05), and the Sokolov-Lyons criterion (30%; p < 0.05). CONCLUSION: The threshold values of the most informative indices of orthogonal ECG are presented, which could provide the optimum sensitivity-specificity ratios. These values allow cardiac lesions to be detected in hypertensive patients with normal 12-lead ECG.

The effect of psychoemotional load on ventricular repolarization reflected in integral body surface potential maps.

The aim of the present study was to investigate the reflection of psychoemotional stress in the body surface potential distribution as documented by isointegral maps of cardiac activation and recovery. In 72 young men (18.3+/- 7.3 y.) with no cardiovascular history body surface potential maps (BSPMs) at rest and during the test of mental arithmetic were recorded. The digitalized data for each point of the QRS, STT and QRST integral maps, for each subject in both situations, were processed and evaluated by methods of univariate as well as spatial mathematical and statistical modeling. The results showed during MA a significant decrease of repolarization integral values over the sternum and right precordium, which contributed to analogically localized decrements also in the QRST BSM. The decrease occurred in more than 2/3 of lead points. The most pronounced changes were observed in the right precordial area, where potentials decreased in more than in 70 % of subjects. In conclusion, the discriminative power of the difference STT and QRST integral maps was strong enough to distinguish the mental arithmetic induced changes in the superficial cardiac electric field. These adrenergic transient alterations in ventricular recovery may be of importance in subjects at risk for ventricular arrhythmias.

[New approaches to diagnosis of left ventricular hypertrophy by dipolar electrocardiography].

AIM: To show possibilities of dipolar electrocardiography (DECG) in diagnosis of left ventricular hypertrophy (LVH). MATERIAL AND METHODS: We made DECG in 151 healthy subjects and 158 hypertensive patients. To characterize DECG quantitatively, we used the integral activation duration index (IADI) calculated as a weighted sum of the areas with different duration of activation, module of the maximal vector QRS, QRSxIADI (IADIM). RESULTS: In patients with left ventricular myocardial mass index (LVMMI) under 150 g/m2, sensitivity of DECG was 38-49%, in the index over 150 g/m2 sensitivity reached 38-75%, specificity 89-98% compared to healthy examinees and 72-82% compared to hypertensive patients without LVH. The IADIM parameter correlates directly (moderate correlation) with duration of QRS complex and LVMMI. CONCLUSION: Possibilities of using parameters IADI and IADIM for assessment of electrophysiological myocardial remodeling and their correlation with other methods need further investigations.

[A method for determining the heart moving electric center on surface distributed models of the cardioelectric generator]. / Issledovanie metoda opredeleniia podvizhnogo élektricheskogo tsentra serdtsa na poverkhnostno-raspredelennykh modeliakh kardioélektricheskogo generatora.

Using mathematical models of the bioelectric generators of the heart with surface distributed configurations, it was shown that the coordinates of the moving electric center of the heart can facilitate the recognition of the global spatial position of electrogenic zones in the myocardium. These coordinates were determined by the previously proposed method from the cardioelectric potential measured noninvasively with a multichannel lead system in the framework of electrocardiographic mapping.

Changes of decartograms under gravitational acceleration and microgravity.

The Decarto technique was used to study the orthogonal ECGs recorded in 23 subjects during parabolic flights (44 records). A parameter of the instantaneous decartograms, namely the activation area (AA), which is the total area of the depolarization front projection on the image sphere, was analyzed. We compared the values of AA during the periods of horizontal flight, upward parts of all parabolas, and the initial 10 s of microgravity of all parabolas. According to the characteristics of the vectorcardiograms and AA, all subjects were subdivided into 3 groups: with increased electric activity of the right ventricle (I), the left ventricle (II) and both ventricles (III). Changes of AA with change of gravitational levels in these groups showed some differences. In groups I and II, the AA of the initial part of the QRS complex increased during microgravity and decreased during hypergravity. In group III it decreased during microgravity and changed variously during hypergravity. The AA of the middle part of the QRS complex decreased during microgravity and increased during hypergravity, and these changes were more pronounced in group III. The changes of AA in groups I and II may be explained by the Brody effect. In group III, AA seems to be influenced by some additional factors, possibly by changes in the intramyocardial or intraventricular blood volume. The AA of the last part of the QRS complex increased during microgravity and decreased during hypergravity in all groups. This may be explained by an effect of mutual neutralization of depolarization fronts related to the changes of the QRS duration.(Fig. 3, Ref. 4)

[Mobile cardiac electrical center: a new concept and mathematical modeling]. / Podvizhnyi élektricheskii tsentr serdtsa: novaia kontseptsiia i matematicheskoe modelirovanie.

A method for determination of the cardiac electric center on the basis of noninvasive multichannel measurements and multipole description of the cardioelectric potential is proposed. The method provides a more accurate and stable spatial location of the cardioelectric generator as compared to other methods (in particular, those based on minimization of the quadrupole potential). The position of the electric center is a useful characteristic for topical diagnosis of the electrophysiological state and function of the heart. Using mathematical models, the dependence of the position of the electric center, determined by the method presented, on the configuration and spatial position of the cardiogenerator is illustrated.

Assessment of electrophysiological state of heart in astronauts in terms of decartographic and conventional electrocardiographic characteristics.

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.)