Myocardial stress of the left ventricle during occupational vibration

Aim. Study of intramyocardial stress of the left ventricle (LV) in persons exposed to occupational vibration and patients with hand-arm vibration syndrome (HAVS).

Materials and methods. We examined 15 individuals exposed to vibration, 44 individuals with grade 1 HAVS, 10 individuals with grade 2. The control group consisted of 20 persons without cardiovascular pathology, who had not been exposed to hazardous occupational factors. The main occupational hazards in persons with HAVS were vibration, noise, physical exertion.

Echocardiography was carried out to determine the total volume of LV (Vtotal); the volume of myocardium (Vm); myocardial mass (LVMM); myocardial mass index (LVMMI); systolic intraventricular pressure; the intensity of the functioning of the LV structures; LV circumferential and meridional diastolic and systolic stresses (σcd, σcs and σmd, σms respectively); LV tension in the circumferential and meridional direction during systole and diastole (Tcs, Tcd and Tms, Tmd respectively).

Results. In persons exposed to vibration, in comparison with those who have not been exposed to occupational hazards, there is an increase in σmd by 2.5 times (p < 0.05) and σcd by 2.8 times (p < 0.05). The tension increases during systole and diastole both in the circumferential (Tcs by 17.35%, p < 0.05; Tms by 2.74 times, p < 0.05) and in the meridional (Tcd by 14.59%, p < 0.05; Tmd by 2.76 times, p < 0.05) directions. In persons with grade 1 HAVS, there is an increase during diastole σmd by 2.2 times (p < 0.05), σcd by 2.4 times (p < 0.05), and Tmd (p < 0.05) and Tms by 2.5 times (p < 0.05). In patients with grade 2 HAVS, in contrast to those with grade 1 and persons exposed to vibration, there is a change in the working conditions of LV. With the same values of Vtotal, Vm, LVMM and LVMMI, as in the described groups, in patients with grade 2 HAVS, there is a decrease by 12.3% (p < 0.05) in systolic intraventicular pressure against the background of an increase in σmd by 14.7% (p < 0.05), Tmd by 13.6% (p < 0.05), as well as σms by 2.25 times (p < 0.05) and Tcd by 1.97 times (p < 0.05).

Conclusion. In the group of persons exposed to vibration and patients with grade 1 HAVS, in contrast to those who are not exposed to occupational hazards, there is an increase in stress and tension, primarily in the circumferential direction during diastole, which indicates the activation of the heterometric type of autoregulation of activity of the heart. In patients with grade 2 HAVS, stress and tension increase in the meridional direction during systole, which indicates the levelling of LV hyperfunction by isotonic type.

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