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8
II. ХИРУРГИЯ
ATRIUM MECHANICAL FUNCTION IN PATIENTS WITH ISCHEMIC MITRAL REGURGITATION
МРНТИ 76.29.30
Musayev S.A., Abbasov F.E., Qurbanov E.F., Mahmudov R.M.
Sceintific center of surgery named after M.A. Topthubashov, Baku, Azerbaijan
Abstract
Aim. To assess the left atrium (LA) mechanical function in patients with ischemic mitral regurgitation (IMR) using technologies of vector analysis of endocardium movement rate.
Materials and methods. The study enrolled107patients aged 56 ± 7,5 among which 96 men (89,7 %). The entry criteria: I-III degree of ischemic mitral regurgitation on echocardiography, angiography reveling coronary artery disease requiring surgical revascularization, sinus rhythm with the heart rate ranging from 60 to 89 per minute, superior echocardiography visualization of LA endocardium. We hypothesize that atrial changes in deformation and deformation rate can be associated with severity of regurgitation.
Results. Values of left atrium mechanical function decline proportionally to IMR severity. Longitudinal deformation and LA deformation rate reflect link with IMR greater than conventional indices used for estimation of LA geometry.
Conclusions. Left atrium mechanical function values are associated with IMR and connected with mechanical remodeling of the left atrium.
Ишемиялык митральды регургитациясы бар наукастарда жYрекшелердщ механикалык функциясы
Мусаев С.А., Аббасов Ф.Е., Гурбанов Е.Ф., Махмудов Р.М.
М. А. Топчубашев атында?ы ?ылыми хирургия орталы^ы, Баку, Эзiрбайжан
Ацдатпа
Мацсаты. XYpeKriq ишемиялык ауруы (ЖИА) бар наукастардын сол жак журекшесшщ механикалык, кызметШ баталау Yшiн эндокард козталысы жылдамдытн векторлык талдау технологиялары пайдала-нылды.
Материалдар жэне эд'стер. Зерттеуге 56±7,5 жас аралы^ындаты 107 наукас катысты, онын шнде ер адамдардын саны - 96 (89,7%). Кртысу критерийлерi: эхокардиографиядаты I-IV дэрежел'! ишемиялык митральдi регургитация, хирургиялык реваскуляризацияны кажет ететн жYректiн ишемиялык ауруы ангиографиясы, жYректiн минутына 60-90 рет жиырылу житшщ синустык ритм'!, СЖ эндокардынын тамаша эхокардиографиялык визуализациянуы. Б'з щрекше деформациясынын жэне деформация жылдамдырыныц e3repyi регургитацияныц курделтше байланысты болуы mymkh деп тужырымдаймыз.
Нэтижелерi. Сол жак жYрекшенiн механикалык кызмелнщ мэн IMR ауырлырына пропорционал шамада твмендейдi. СЖ геометриясын баталау Yшiн пайдаланылатын дардылы индекстерге каратанда, Бойлык деформация мен СЖ деформациясынын жылдамдыт IMR-мен байланысты толытырак айкындайды.
Цорытынды. ЖИА бар наукастарда сол жак щрекше кызметщ взrеруi онын механикалык кайта курылуына байланысты.
ABOUT THEАUTHORS
Musayev S.A. - senior researcher of the Scientific Center of Surgery named M.A. Tothubashov
Abbasov F.E. - professor of the Scientific Center of Surgery named M.A. Tothubashov
Qurbanov E.F. - researcher of the Scientific Center of Surgery named M.A. Tothubashov
Mahmudov R.M. - researcher of the Scientific Center of Surgery named after M.A. Topchubashev
Keywords
Ischemic mitral regurgitation, left atrium, longitudinal deformation, deformation rate
АВТОРЛАР ТУРАЛЫ
Мусаев С.А. - М.А. Топчубашев ат. FХИ aFa FbrnbiMn nbßMerKepi
Аббасов Ф.Е. - М.А. Топчубашев ат. ЮИ профессоры
Гурбанов Е.Ф. - М.А. Топчубашев ат. ЮИ FbrnbiMn KbßMerKepi
Махмудов Р.М. - М.А. Топчубашев ат. ЮИ FbrnbiMn KbßMerKepi
Туйш сездер
Ишемиялнк миrрaльдi регургитация, сол жак журекше, бойльщ деформация, деформация жылдамдыгы.
Механическая функция предсердий у пациентов с ишемической митральной регургитацией
ОБ АВТОРАХ
Мусаев С.А. -
Старший научный сотрудник НЦХ им. М.А.
Топчубашева
Аббасов Ф.Е. -
Профессор НЦХ им. М.А. Топчубашева
Гурбанов Е.Ф. -
Научный сотрудник НЦХ им. М.А.
Топчубашева
Махмудов Р.М. -
Научный сотрудник НЦХ им. М.А.
Топчубашева
Ключевые слова
Ишемическая митральная регур-гитация, левое предсердие, продольная деформация, скорость деформации
Мусаев С.А., Аббасов Ф.Е., Гурбанов Е.Ф., Махмудов Р.М.
Научный центр хирургии им. М. А. Топчубашева, Баку, Азербайджан
Аннотация
Цель. Для оценки механической функции левого предсердия (ЛП) у пациентов с ишемической митральной регургитацией (ИМР) использованы технологии векторного анализа скорости движения эндокарда.
Материалы и методы. В исследование были включены 107 пациентов в возрасте 56±7,5 лет, среди которых 96 мужчин (89,7%). Критерии включения: ¡-IV степень ишемической митральной регур-гитации на эхокардиографии, ангиография с ишемической болезнью сердца, требующей хирургической реваскуляризации, синусовый ритм с частотой сердечных сокращений от 60 до 89 в минуту, превосходная эхокардиографическая визуализация эндокарда ЛП. Мы предполагаем, что предсердные изменения в деформации и скорости деформации могут быть связаны с серьезностью регургитации.
Результаты. Значения механической функции левого предсердия снижаются пропорционально тяжести ¡МЯ. Продольная деформация и скорость деформации ЛП отражают связь с ¡МЯ больше, чем обычные индексы, используемые для оценки геометрии ЛП.
Выводы. Изменение функции левого предсердия у пациентов ИБС связаны с механическим ее ремоделированием.
Introduction
The issues of ischemic mitral regurgitation (IMR) remains most relevant in the treatment of patients with coronary heart disease (CHD), since even a small degree of IMR is associated with an increased risk and poor prognosis [9]. Potentially, the assessment of the hemodynamic significance of varying degrees of insufficiency in a particular patient and the study of its influence on the remodeling of the heart can help in the choice of treatment approach. At the same time, heart chambers or hemodynamic characteristics, which change due to the direct impact of IMR, can be considered effectors of regurgitation [7]. One of the main effectors of chronic IMR is the left atrium (LA). It is known that an increase in the volume of LA is a powerful predictor of mortality, but it is unclear how its mechanical function changes, which depends on the overload with a regurgitating volume and thus may become an important component in assessing the effects of regurgitation [7]. In study by Y. Y. Liu et al. it has been shown that strain indicators and strain rate of LA are earlier and more sensitive indicators of volume overload than geometric changes in the atria [13]. There are number of studies regarding the changing strain in patients with arterial hypertension, CHD, and atrial fibrillation, while the contribution of mechanical LA function to the process of global heart remodeling in patients with IMR has not been practically evaluated.In the literature, there are few data on the mechanics of LA in patients with MR during the reservoir and systolic phase of the LA
[10]. Features of the strain indicators in the other phases of the atrium (absorption phase and conduit period) have notbeen evaluated. The features of the functional volumetric and mechanical parameters of the LA depending on the severity of MR in all phases of the LA activity are not yet described. We assume that atrial strain and strain rate may be associated with the severity of IMR. The aim of the study is to evaluate the mechanical function of the LA in patients with IMR using the vector analysis of the movement rate of the endocardium.
Materials and methods
The study included 107 patients aged 56 ± 7.5years old, of which 96 (89,7%) are men - hospitalized with coronary artery disease at our clinic in 2017. All participants signed informed consent, and the study was approved by ethical institution committee. Inclusion criteria: echocardiography showing I - III degree of MR, the presence of coronary artery diseaseshowed by angiography requiring surgical revascularization, sinus rhythm with the heart rate ranging from 60 to 89 per minute, superior echocardiography visualization of LA endocardium.
Exclusion criteria: the presence of acute coronary syndrome, a history of surgical revasculariza-tion, degenerative and other non-ischemic mitral valve lesions, pathology of aortic, tricuspid, and pulmonary valves of any etiology, documented supraventricular rhythm, constant use of diuret-icsand inotropic agents, presence of non-cardiac
Data Study group Control group P <
Heart rate (beats / min) 68,96±12,1 70,28±12,7 0.69
End diastolic volume (ml, Simpson) 116,3±26,2 90±12 0.0001
LVEF (%, Simpson) 43±11,2 60±5 0.0000
The average pressure in the pulmonary artery, mm Hg. 26,5±10,2 14,3±4,5 0.0002
Maximum volume of LA (ml) 78,5±26,5 47,6 ±10,2 0.0000
Minimum volume of LA (ml) 53,4±22,2 31,4 ±7,6 0.0000
P-volume LA (ml) 66,3±24,6 38,8±8,1 0.0000
The fraction of passive emptying of LA (%). 16,7±7,8 27,2±10,3 0.001
The fraction of active emptying of LA (%). 22,4±9,9 28,1±7,3 0.03
LA Expansion Index 0,8±0,5 2,46±0,7 0.0000
Table 1.
Basic echocardiographic characteristic of the examined patients.
diseases associated with pulmonary hypertension. The comparison group consisted of 20 healthy volunteers, of which men - 10 (50%), aged between 38 to 65 (52.6 ± 13,4) years old. The study group included 12 (11.2%) patients with functional class II angina pectoris, 69 (64.5%) patients with functional class III angina pectoris and 26 (24.3%) patients with functional class IV angina pectoris. The time from the onset of symptoms of IHD was 4.5 ± 3.3years. Patients who underwent a Q-wave myocardial infarction - 68 (63.6%), anterior with a Q-wave - 21 (19.6%), repeated myocardial infarction - 18 (16.8%). Symptoms of heart failure of II functional class were registered in 12 (11.2%) patients, III functional class in 64 (59.8%) patients and IV functional class in in 31(29.0%) patients.21 patients (19.6%) had concomitant diabetes mellitus type 2, and arterial hypertension was detected in 60 ( 56%) patients.
Patients received conservative therapy that complies with current guidelines for treatment of IHD such as aspirin, statins, beta-blockers, an-giotensin-converting enzyme inhibitors [3]. All patients underwent a complex of clinical, laboratory and instrumental examinations (ECG, general and biochemical blood tests, coagulation parameters, chest X-ray, 24-hour ECG monitoring, echocardiography, coronary angiography. All the patients underwent echocardiography examination usingAc-cuson S2000 (Siemens Medical Systems, Mountain View, CA, USA) equipped with a 4V1c probe. The severity of the IMR was assessed by several quantitative parameters, including the measurement of the width of the proximal regurgitation jet (vena contracta, VC, average 0.52 ± 0.21 cm for the group), the index of the area of the regurgitation flow (percentage of the jet relative to the area of the LA, the average MR value is 28.7 ± 11.5%) [8, 11].
The mean end-diastolic volume (EDV) in the study group was 116.3 ± 26.2 ml, the LV ejection fraction (EF) - 43.0 ± 11.2%, the maximum volume of LA - 78.5 ± 26.5 ml, the average pressure in the pulmonary artery - 26.5 ± 10.2 mmHg.
All the patients in comparison group had no MR as shown in echocardiography and all the echocar-diographic data corresponded to the norm [4]. For echocardiographic examination of the LAfollowing indicators were evaluated characterizing the geometry (volumes), the function (volume change), and the mechanics of the LA (longitudinal deformation and strain rate). To study the function of the LA, the fraction of passive emptying as a characteristic of the conductor function, the fraction of active emptying (as a characteristic of the pumping function), and also the expansion index of the LA as an indicator of the reservoir function were evaluated [2]. Vector analysis of the longitudinal strain (strain, S,%) and strain rate (SR, s - 1) of the LA was carried out on the basis of a dynamic assessment of a two-dimensional echocardiographic image using the patented Speckle Tracking Syngo VVI technology (Siemens Medical Systems, Mountain View , CA, USA).
SR and S were studied during the four phases of the LAactivity: 1) the reservoir phase or the accumulation period, characterizes the flow of blood from the pulmonary veins during LV systole, when the mitral cusps are still closed; data acquisition was performed from the opening of the aortic valve cusps to the opening of the cusps of the mitral valve synchronously with the ECG: from the beginning of the ST segment to the end of the T wave; 2) conduit phase or percolation period associated with the flow of blood from the LA to the LV during its early diastole, the values were recorded from the opening ofmitral valves until the end of the diasta-sis, synchronously with the ECG: from the end of the T wave to the beginning of the P wave;3) the contractile phase or the period of atrial systole, displays the active flow of blood from the LA to the late LV diastole, measurements were performed from the beginning of the P wave to the R wave on the ECG; 4) the absorption phase reflects the flow of blood from the pulmonary veins and the filling of the LA in the early LV systole, estimated from the closing of mitral cusps to the opening of the aortic
Table 2.
Echocardiography values of the mechanical function of the left atrium
Phase Study group(n=107) Control group (n = 20)
Mean (%) Index of 10ml LA Volume Mean Index of 10ml LA Volume
Contractile -3,6±2,3 -0,98±0,3 -12,4±1,8 -5,6±0,7
Suction -1,2±0,3 -0,9±0,1 -0,44±0,7 0,09±0,02
Reservoir 26.5±3.8 2.9±0,7 29.8±2.7 7.3±1.1
Conduit -0.1±0.17 -0.0012±0.01 -0.37±0.2 -0.08±0.01
Contractile -0.57±0.4 -0.1±0.002 -1.83±0,31 -0.64±0,003
Suction 0.1±0.07 0,08±0.004 0.43±0,08 0.16±0.001
Reservoir 1.3±0.7 0.15±0.03 2.3±0.6 0.6±0.01
Conduit -1.4±1,5 -0.22±0,1 -3.5±1.0 -0.8±0.3
valve cusps, which corresponds to the period from the peak of the R wave to the end of the S wave on the ECG [15].
Statistical analysis of the data was carried out using Statistica 8.0. For the description of quantitative data, the values of mean M and standard deviation SD were used. The evaluation of the statistical significance of differences p between the groups was carried out using parametric criteria with a normal distribution of the trait - the two-sample Student's t-test for comparisons of means (M ± SD). Differences in values were considered significantat level of p <0.05. Determination of the relationship between the studied quantitative values was carried out using the Spearman linear correlation coefficient Rs. The dependence of the variables and the verification of the significance of differences between the averages within the groups were determined using ANOVA.
Results and discussion
Maximum (78.5 ± 26.5 ml), minimum (53.4 ± 22.2 ml) and P-volumes of the left atrium (66.3 ± 24.6 ml) significantly differed in the patients of the study group and in the comparison group (47.6 ± 10.2 ml, 31.4 ± 8 ml, 38.8 ± 8.1 ml, respectively, p <0.05). Only a moderate direct correlation was found between the volumes of the LA and the MR area index of the flux (Rs = 0.46 for the MR and the maximum volume of the LA, Rs = 0.5 for the minimum, Rs = 0.45 for the P-volume of the LA). The fraction of passive emptying of the LAin the comparison group was significantly higher than in patients with MR, which indicates a decrease in atrial conduction function in patients with IMR (26.5 ± 10.3% versus 15.3 ± 8.2%, p <0.05 ).
A moderate inverse correlation was found between the index of the area of the flow of the MR and the fraction of passive emptying of the LA (Rs = -0.55). The larger id MR, the smaller the volume of fluid flowing through the LA into the LV during the conduit phase of the atria, thereby reducing the contribution of the atrium to the LV stroke volume, therefore, to the LV systolic function. A moderate
direct correlation was found between the fraction of passive emptying and LV EF (Rs = 0.46), which indicates a moderate associationbetween LV and LV dysfunction. The fraction of passive emptying which reflects pumping function of LA was significantly reduced in patients with MR compared with the control group (22.4 ± 9.9% versus 28.1 ± 7.3%, p <0.05). There was a mild inverse correlation between the fraction of active emptying of the LA and MR (Rs = -0.27). The LA expansion index characterizing the atrial reservoir function was significantly higher in the comparison group (patients with MR 0.8 ± 0.5 versus 2.47 ± 0.8 in the comparison group, p < 0.05). There was a strong inverse correlation between the LA expansion index and the index of the area of the flow of the MR (Rs = -0.76), which confirms the deterioration of the atrial reservoir function. When analyzing differences in the functional parameters of the LA depending on the degree of MR we found the absence of a significant difference in the fraction of passive emptying of LA between patients with moderate and severe MR (with second degree MR 13.9 ±8%, with third degree MR 14.8 ±7.2%, p =0.6).
However, when indexing the obtained data to the corresponding volume of the LA, significant differences were found (S in the group with MR -2.8 ± 0.7% / 10 ml of the maximum volume of the LA, in the comparison group - 7.5 ± 1.2% / 10 ml of the maximum volume of LA, (p = 0.001), which confirms the hemodynamic significance of chronic overload with regurgitating volume of blood of LA. Longitudinal systolic deformation of LA was significantly reduced in the contractile phase (in patients with MR -3.6 ± 2.3% versus -12.4 ± 1.8% in the comparison group,p<0.05) and in the absorption phase (in patients with MP -1.2 ± 0.3% versus -0.44 ± 0.7% in the comparison group, p <0.05). In the conduit phase, the deformation was minimal both in patients with MR and in the comparison group, but paradoxically larger values were recorded in patients with MR than normal (-0.37 ± 0.2 and -0.1 ± 0.17%, respectively, p <0.05). A pronounced direct correlation of S in the systolic phase of the LA and
Degree of MR SR S
systole phase suction phase reservoir phase conduit phase systole phase suction phase reservoir phase conduit phase
1 (n = 19) -1.8±0.07 0.4±0.02 2.4±0,1 -3.1±0.8 -12.3±2.8 -0.3±0.03 29.7±0.61 -0.4±0.01
II(n = 17) -1.1±0.04 0.17 ±0,02 1.8±0,2 -2,3±1,2 -6,5±1,4 -1,1±0,06 24,8±0,72 -0,2±0,02
111(11 = 46) -0,2±0,03 0,07±0,01 0,81±0,1 -0,3±0,17 -2,3±0,2 -1,5±0,08 27,6±0,5 -0,03±0,02
IV(n = 25) -0,2±0,04 0,08±0,02 0,72±0,1 -0,2±0,1 -1,9±0,23 -1,3±0,07 25,8±0,7 -0,01±0,02
MR (RS = 0.88), moderate S in the conduit phase and MR (RS = 0.5) and inverse correlation S in the phase of absorption and MR (RS = -0.58 ), S in the reservoir phase and MP (RS = -0.5). We analyzed indicators S of LA depending on MR (tab. 3).
The maximum differences were found in individuals without MR and in patients with minor MR during the systole of LA (-12.4 ± 1.8% vs. -6.5 ± 2.2%, p <0.05, respectively) and during the absorption phase ( -0.44 ± 0.7% vs. -1.1 ± 0.07%, p <0.05, respectively), as well as between patients with mild and moderate MR (S during the period of LA systole in patients with MR Grade I —12.3 ± 2.8% versus --6,5± 1,4 % with MR of Grade II, p <0.05); S during the absorption phase with MP of the I degree —1.8 ± 0.07% versus -1.4 ± 0.07, p<0.05). Similarly to the indicators of SR between patients with moderate and severe MR, no differences in S values were found in all phases (see Table 3).
The qualitative assessment of LA deformation and its practical value has been the subject of discussion in the last decade [6]. Stoylen et al showed that LA deformation is reciprocally associated with LV deformation, in other words, all mechanical processes in the atrium are only a mirror reflection of LV deformation and are more dependent on movement of the annular plane of LV systolic and diastolic functions [14]. However, further studies showed significant limitations of these data, demonstrating the significance of atrial contribution (systolic negative deformation) in the formation of an adequate preload of the LV and the contribution of reservoir phase (diastolic positive deformation of the LA) in the formation of the LV stroke volume [6]. In contrast to previous studies of mechanical function of LA, which evaluated only the peak positive longitudinal S and SR (as indicators of the accumulation period) and the peak negative S and SR (as indicators of the systolic phase of the LA), we attempt to give a comprehensive assessment of the atrial activity along with the contribution of the conduit and suction phase. Of course, the conduit period is difficult to evaluate, since it is biphasic: during the beginning of early filling of the LV, atrial deformity is minimal, but the deformation rate is highest, however in the second period, we witness the plateau, when both the deformation and the deformation rate are close to or equal to
0. In addition, the conduit function of LA depends on afterload, largely determined by the pressure in the receiving chamber which is LV, which increases as the diastolic stiffness and systolic dysfunction of the LV increases [15]. Thus, the deformation values obtained during the period of blood flow from the LA to the LV in the normal state more reflect LV function than the LA function. But, as demonstrated in our study, the presence of chronic nMR significantly changes the deformation rate of LA in the conduit period proportionally to the severity of regurgitation (which is confirmed by a direct cor-relationof MR and SR during this phase). Deformation in patients with minor MR in the conduit phase are minimal, and in patients with moderate and severe MR, they are close to zero during the entire phase. Consequently, the LA in the conduit period in patients with moderate and severe MR in terms of deformity functions as a "passport" with minimal S and SR values even during the early filling of the left ventricle. With inhibition of the deformity in the systolic phase of the LA, it becomes clear that themechanical contribution to the filling of the LV is significantly reduced, despite the increase in the maximum volume of the LA. Perhaps these changes are related to the processes of structural remodeling of the atrium and loss of elastic properties due to chronic overload with theregurgitated blood volume. S.S Kuppahally et al.,showed that a decrease in S and SR is an independent predictor of ultrastructure changes in LA, in particular interstitial fi-brosis [12]. Consequently, a decrease in deformity into the conduit phase of LA may be considered an effector of hemodynamic significance of MR. Several authors indicated the reduced SR and S in the atrial systole are associated with the severity of re-gurgitation[5]. The changes of the deformation we detected in the absorption phase were multidirectional in the control group, patients with minor regurgitation and patients with III - IV degree of MR. Deformation in this phase is close to zero, which is normal (in the control group S -0.44 ± 0.7). The presence of more negative results of deformation in patients with MR (-1.3 ± 0.07%) during this period remains unclear. In patients with III and IV degree of MR, the deformation values were even lower than in patients with mild MR. It is possible that due to atrial remodeling caused by MR, since the deformation
Table 3.
Phase analysis of deformity and deformation rate of the left atrium depending on the degree of mitral regurgitation (M±SD;-95 to +95%).
was recorded synchronously with the ECG (from the R-wave to S), from the view of electrical processes, this was already the phase of LA absorption, and from the point of view of mechanics, the end of the LA systole period. It is because of the complexity of differentiation of the onset of the phases most researchers prefer to ignore this phase and not to study its features. Our data regarding the reservoir period are dissonant with the results of A. N. Borg et al., who showed that the longitudinal deformation during the accumulation period was higher in patients with MR compared with the healthy group [7]. Normally, during the phase of the LA reservoir (towards the end of the LV systole), the maximum (among all LA phases) positive deformity is recorded, which is accompanied by the greatest increase in atrial volume. The reservoir period depends on the preload conditions and is fundamentally volume dependent. This means that the deviation of the mechanical characteristics from the normal range is related to the additional volume appearing in the atrium during this period (i.e., directly from the MR). The data obtained by us can be explained by taking into account the mechanical and functional changes along with the all phases of the LA. With a mild degree of MR, there was an increase in the active volume of the LA, due to which, in patients with stage I of MR, the fraction of active emptying remained within normal limits and compensated for the mechanical synergy. But with a moderate and pronounced degree of IMI, indicators charac-
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terizing contractilitywere decreased. Similarly to the classical Frank - Starling curve after a certain "threshold" volume of chambers further growth of contractility does not occur: it begins to decrease. In our study, this "threshold" was not the atrial volume, but the LA expansion index, which functionally characterizes the reservoir phase. A correlation was found between the expansion index and the fraction of active emptying of the LA (Rs = 0.70), the expansion index and the deformation rate of the LA in the reservoir phase (Rs = 0.63).
In this study, we demonstrated the importance of analyzing mechanical data (SR and S in patients with IMR) for complex assessment of the function of LA, along with traditional geometric parameters. Atrial activity can be interpreted not only from the standpoint of changes in atrial size and volume, but also on the basis of the evaluation of the mechanical properties of LA. Particularly noteworthy is the identification of a significant difference in SR inhibition between patients with mild and moderate MR and uncertain differences in SR indices in patients with moderate and severe MR. The results obtained probably indicate comparable ultrastructural changes in the atria that occur with chronic volume overload of MR from grade II and higher. Further detailed study of the dynamics of the mechanical function of the LA in patients with MR may be a promising and useful tool in assessing its hemodynamic significance and in the choice of surgical approach for additional intervention on mitral valve with IMR.
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