Phenomenological Regularities of Assessment of Left Ventricle Function in Mitral Valve Insufficiency

Objective: to examine relationship between anatomical changes of the left ventricle (LV), dynamics of velocity of its volume modification, and blood flows in the LV in patients with mitral regurgitation (MR) before and after surgical treatment. Materials and methods. We included into this study 58 patients with severe 3-4 degree MR (38 men, 20 women aged 24-69 [mean age 51±9] years) in sinus rhythm (96%) or atrial fibrillation (4%). The control group included 86 healthy volunteers, mean age 39±7 years. Transthoracic echocardiographic studies were performed in both groups by standard technique at rest using a high-quality echocardiograph Vivid E9, equipped with a 3.5-4.6 MHz multi frequency transducer (in patients before and after surgical repair - mitral valve [MV] replacement and MV reconstruction with annuloplasty ring). The analysis of files recorded was performed off-line by vector analysis technique including estimation of myocardial deformation velocities and dynamics of LV volume modification, construction of “flow-volume” diagram, calculation of the expended kinetic energy, and registration of intraventricular blood flows. Results. End diastolic volume (EDV), end systolic volume (ESV) and total stroke volume (TSV) (effective + retrograde) were significantly increased in patients with severe LV volume overload before surgery in comparison with the control group (p<0.001). After MV replacement EDV decreased from 157 to 101 ml, which averaged 36% of the initial value. TSV before surgery was about 106 ml, after surgery it decreased 43% down to 61±12 ml. Vector analysis technique and diagram method showed that velocities of LV volume modification and sum of normal velocities both in systole and diastole were significantly higher in patients with MR before surgery compared with the control group; with this the velocity of modification of LV length (dL/dt[s]) in systole and diastole did not differ from values in the control group. The ratio of the velocity amount (Σ Vη) - diastole to systole ratio - differed from values in the control group by 13-15%. Kinetic energy loss (E_kin) in patients with MR before surgery was several times higher in diastole than in systole. After MV replacement E_kin in systole and diastole decreased becoming closer to normal values. MV replacement restored the pattern of LV filling from the left atrium, and the blood flow reached the LV apex virtually without energy loss. Conclusions. Thus, myocardial deformation velocities, LV blood flows allow to quantify cardiac function in patients with MV insufficiency and to assess the effectiveness of surgical treatment in the early and remote postoperative periods. Phenomenological patterns in evaluation of LV myocardial function and valve apparatus are based not only on anatomical changes of heart chambers, but also on the dynamics of myocardial deformation velocities, what allows to get closer to a assessment of global cardiac function, taking into consideration blood flow dynamics and turbulence in the ventricles, characterizing the cardiac performance and particularly the kinetic energy of the myocardium. Evaluation of stagnant areas in the LV based on the velocity of intracardiac blood flow, reconstructed from color Doppler mapping can be used as a method to identify topological structures with the assessment of qualitative and quantitative characteristics of the myocardium and valve apparatus.

митральная недостаточность, функция левого желудочка, векторный анализ, внутрисердечные потоки крови, mitral insufficiency, left ventricular function, vector analysis technique, intracardiac blood flows

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