Deformation of the left ventricular myocardium in patients ischemic heart disease before and after revascularization

Introduction. In the domestic literature, this technology is defined by the term “visualization of the myocardial velocity vector” [5]. LV contractile function is the result of the interaction of longitudinal, radial and circular fibers. During systole, there is a shortening of longitudinal and circular fibers, as well as transverse thickening of the radial fibers [6]. Deformation (S) and strain rate (SR) are indicators reflecting the function of LV fibers [2]. It is known that in ischemic heart disease, the deformation indices of the longitudinal fibers primarily change, since the blood supply to the subendocardial layers suffers to a greater extent [7]. Dysfunction of radial and circular fibers is observed mainly in transmural lesions [6, 8, 9].

The study of the function of LV myocardial fibers using VVI technology began with an analysis of the average S and SR values of longitudinal, circular and radial LV fibers.

Analysis of longitudinal fiber function was performed in 450 LV segments before and after revascularization. Normal indicators S (-19.3 ± 1.19%) and SR (-1.01 ± 0.07 s - 1) were detected in 19 (4.2%) LV segments (group 1) and remained without significant changes after revascularization (S -16.25 ± 6.4% (p = 0.09); SR -1.08 ± 0.5 (p = 0.56)).

In group 2 (n = 211 (46.8%)) low indicators S (-9.7 ± 4.0%) and SR (-0.59 ± 0.2 s - 1) increased (S -12.4 ± 5.6 (p = 0.000001); SR -0.89 ± 0.4 s – 1 (p = 0.000001)), but did not reach the norm. High S (-25.4 ± 4.03%) and SR (-1.91 ± 0.8 s - 1) in group 3 (n = 56 (12.4%)) decreased in such a way that S reached the norm (S -17.6 ± 6.6 (p = 0.000001)), and SR remained high (-1.31 ± 0.7 (p = 0.0001)).

In groups 4 (n = 9 (2%)) and 5 (n = 37 (8.2%)), normal S values (-20.6 ± 3.0% and -19.5 ± 1.1%) were combined with a decrease (-0.81 ± 0.05 s – 1) and an increase (-1.44 ± 0.25 s – 1) SR. After revascularization, no significant changes were detected in group 4 (S -17.3 ± 8.0% (p = 0.28); SR -1.22 ± 0.58 s - 1), and in group 5, a decrease in S ( -15.8 ± 5.37 (p = 0.0002)) and normalization SR (-1.14 ± 0.4 s – 1 (p = 0.0006)). In groups 6 (n = 70 (15.5%)) and 7 (n = 39 (8.6%)) with low S (-12.8 ± 3.2% and -14.3 ± 3.1 %), normal (-

0.97 ± 0.25 s – 1) and increased (–1.42 ± 0.36 s – 1) SR values were observed. After operative treatment in group 6, S significantly increased (-14.5 ± 5.4 (p = 0.03)), but did not reach the norm, while the dynamics of SR (-1.03 ± 0.5 s - 1 (p = 0.4)) is not marked.

In group 7, the indicators remained without significant changes (S -15.2 ± 6.9% (p = 0.37); SR -1.2 ± 0.1 s – 1 (p = 0.14)). The S index in groups 8 (n = 7 (1.5%)) and 9 (n = 2 (0.8%)) was increased (-23.3 ± 1.3% and -22.1 ± 0.04 %, respectively), while SR in group 8 was within the normal range (-1.97 ± 0.06 s – 1), and in group 9 it was reduced (–0.82 ± 0.04 s – 1). After revascularization, there was no change in S and SR indices in groups 8 (S -17.21 ± 8.8%, p = 0.12; SR -1.24 ± 0.6 s - 1, p = 0.27) and 9 (S -14.18 ± 9.07%, p = 0.43; SR -0.89 ± 0.63 s - 1, p = 0.89). No segments with a change in the direction of movement (group 10) were found in the analysis of longitudinal fibers.

In group 6 (n = 47 (10.4%)) S remained unchanged (below normal) (S -13.8 ± 6.8% (p = 0.15)), SR significantly decreased from -1.54 ± 0.1 s – 1 to -1.20 ± 0.5 s – 1 (p = 0.0002). In group 7 (n = 15 (3.3%)), the SRc indicator normalized -2.34 ± 0.3 s – 1 to -1.33 ± 0.4 s – 1 (p = 0.000006), then there was no increase in S (S - 14.9 ± 5.9% (p = 0.86)). In group 10 (n = 10 (2.5%)) (S 18.5 ± 9.2%; SR 1.18 ± 7.02 s – 1) after revascularization, the correct nature of fiber movement is noted, although the deformation properties of the segments remain low (S -16.9 ± 7.8% (p = 0.000001); SR -1.21 ± 0.5 s – 1 (p = 0.000002)).

A detailed study of the postoperative segments showed a significant positive dynamics in the function of segments with low S and SR values of all LV fibers, as well as an increase in the number of segments with normal or increased SR values. Thus, a detailed analysis of the segments shows a positive effect of revascularization on LV fiber function in the early stages.

Conclusions: 1. The influence of coronary artery disease on LV segments is expressed not only in a combined decrease or compensatory increase in S and SR (groups 2, 3), but also characterized by various options associated with a change mainly in the indicator S or SR (groups 4–9). Along with this, there is a change in the direction of movement of LV myocardial fibers (group 10).

• 2.    Decrease in deformation indices (S and SR) in patients in response to coronary artery disease was noted in 211 (46.8%) longitudinal segments, in 232 (51.5%) circular and 116 (25.7%) radial LV fibers, then as 239 (53.2%) segments of longitudinal, 218 (48.5%) circular and 328 (72.8%) segments of radial fibers are represented by normal and increased values of S and SR, as well as different variants of changes in S or SR.

• 3.    The influence of surgical revascularization is carried out in the form of a significant positive dynamics of the deformation properties of longitudinal and circular LV fibers in the group with low S and SR values (group 2), as well as an increase in the number of segments with high or normal SR values.