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.

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)