Russian Society of Cardiology (RSC). With the participation of Russian Scientific Society of Clinical Electrophysiology, Arrhythmology and Cardiac Pacing, Russian Association of Pediatric Cardiologists, Society for Holter Monitoring and Noninvasive Electrocardiology. Approved by the Scientific and Practical Council of the Russian Ministry of Health.

A clinical case report of late diagnosis (in relation to clinical manifestation) of the classic phenotype of Fabry disease in patient with cardiac involvement: phenocopy of hypertrophy cardiomyopathy, cardiac arrhythmias and conduction abnormalities.

A retrospective study involving 40 patients, based on the initial division of the patients into 2 groups: group I (N = 20) - high response to cardiac resynchronization therapy (CRT) and group II (N = 20) - lack of response to CRT. Criteria of CRT efficacy were: decrease in end-systolic left ventricular volume equal to or more than 15 %, relative increase in left ventricular ejection fraction equal to or greater than 10 %, decrease in functional class of chronic heart failure (NYHA) equal to 1 or greater. Low response of CRT was determined as the absence of criteria said above (the lack of positive dynamics in left ventricle diameters and volumes, ejection fraction, or it had a negative value in the form of further enlargement of the heart chambers and the reduction of its contractile capacity). The initial patient separation by the degree of response to cardiac resynchronization therapy suggests verification the hypothesis that a different response to CRT may be associated with the relative position of the ventricle electrodes and the parameters of ventricular myocardial dyssynchrony.

Objective. To study possibilities of non-invasive electrophysiological mapping (NEM) in assessment of dependence of cardiac resynchronization effect from the position of the left ventricular electrode (LVE). Design and methods. NEM was performed on 24 patients, utilizing the «Amycard 01C EP LAB». Position of the stimulation LVE pole was estimated on the segmental epicardial ventricular model; and the epicenter of the late activation area of the left ventricular (LV) with complete left bundle branch block (LBBB) was determined. Also the interventricular electrode distance was measured. Results. The epicenter of the late zone on LBBB most frequently was determined in the basal area on the border of the posterior and lateral walls of the LV - 42 % (n = 10). In patients with response to cardiac resynchronization therapy (CRT) the distance (LVE pole - the epicenter of the epicardial late activation area of the LV on LBBB) was not significantly greater than the width of the LV segment. The smallest interventricular electrode distance of 49 mm was found in patient without response to CRT. Conclusion. Using NEM, one may accurately measure the distance between the stimulating poles of ventricular electrodes and the distance from the stimulating LVE pole to the epicenter of the epicardial late activation area of the LV on LBBB. The CRT effect is clearer if the distance between LVE and late zone is not significantly greater than the width of one LV segment.

The aim of the study was to provide comparative analysis of the zones with maximum intraventricular myocardial dyssynchrony (IVD) and the localizations of ventricular electrodes in patients with differential responses to cardiac resynchronization therapy (CRT). Materials and Methods: Retrospective study comprised patients (n=40) who had sinus rhythm, complete left bundle branch block (LBBB), left ventricular (LV) ejection fraction (EF) 15%, relative increase of LV eF ≥10%), and group 2 (n=20) with insufficient response to CRT (the absence of dynamics in the sizes, volumes, and LV EF). For topical evaluation of the zone of stimulation with ventricular electrode, a vector analysis of ECG was performed in the beginning and the end of the follow up period (VL was divided in 12 segments, RV was divided in 3 segments). Intraventricular and interventricular dyssynchrony of the myocardium was detected by echocardiography with tissue Doppler sonography. Results: initially, the groups did not differ in regard to gender, age, and parameters of echocardiography with tissue Doppler sonography. The absence of initial IVD was observed in 7 patients of group 1 and in 8 patients of group 2, p = 0.503, cardiomyopathy of ischemic genesis significantly prevailed in group 2 (75%, n=15, р=0.014). Dislocation of the leads was not documented for the entire period of the study, displacement of LV electrodes within the vein of the coronary sinus occurred in three cases. The final sizes, volumes, and LV EF values differed between the groups (р < 0.001), mean LV EF was 44.9±5.9% in group 1 and 26.9±6.4% in group 2. Overlapping of maximum IVD zone with the site of LV electrode implantation was more significant in group 1, р = 0.028. Final values of IVD were within normal ranges in both groups, the absence of IVD was observed in 95% and 80% of patients in group 1 and group 2, respectively, р = 0.493. Conclusions: correspondence of the myocardial zone with maximum dyssynchrony to the site of the Lv lead implantation was associated with a high response to CRT in the long term. Insufficient response can be caused by a non-optimal positioning of the LV electrode, lack of agreement between implantation site and IVD zone, and by positions of the ventricular electrodes close to each other.

Electrocardiography (ECG) is one of the main methods of cardiovascular diagnosis, its principle consists of graphically reflected electrical signals from the myocardium. The currently used standard electrocardiogram leads reflect changes in the excitation processes of myocardium in both time and space - in the frontal and horizontal axes. Direction of the excitation wave can be conventionally represented as a total vector which reflects the running of electrical impulses in the heart. Cardiac resynchronization therapy (CRT) with biventricular pacing is aimed to synchronize the timing of right and left ventricle. Response to CRT depends on the site of ventricular leads implantation and their relative position, which can be determined by using ECG vector analysis. The aim of this study: to give a descriptive assessment of the ECG patterns in isolated left/right ventricular stimulation at various electrode positions using the standard X-ray projections in CRT patients.