Structural and functional characteristics of the myocardium according to the tissue Doppler imaging in patients with ischemic mitral regurgitation: focus on the myocardial viability
The aim of the study - to evaluate the possibilities of using tissue Doppler imaging (TDI) using the parameters of longitudinal Strain and Strain Rate of the myocardium to diagnose left ventricle (LV) myocardial viability and reversibility of ischemic mitral regurgitation (MR) after myocardial revascularization. Material and methods. The study included 74 patients with coronary artery disease and ischemic MR. Depending on the reversibility of ischemic MR according to the test with nitroglycerin and comparison with the dynamics of MR after myocardial revascularization, an analysis was carried out in two groups of patients: group 1 (36 patients) with a reversible ischemic MR, in which a decrease in MR to a slight degree was observed with a sample with nitroglycerin and after myocardial revascularization; group 2 (38 patients) - with the irreversible ischemic MR, in which there was no significant decrease in the degree of MR when tested with nitroglycerin. Results. Using the parameters of longitudinal Strain and Strain Rate of the left ventricle and papillary muscles of mitral valve allows to predict the nature of myocardial dysfunction (reversible / irreversible) and the dynamics of ischemic MR after revascularization. In patients with the irreversible ischemic MR, the Strain and Strain Rate parameters of the LV segments and papillary muscles are worse. This regularity was established both in the presence of asynergy of the analyzed segments, and with their visually normal contractility. In the first case, this indicates more severe myocardial dysfunction (mainly irreversible) in the asynergic segments under consideration, in the second case, significant global remodeling of the left ventricle. Pulse-wave mode TDI allows you to evaluate the severity of ischemic dysfunction of the myocardium of the left ventricle and papillary muscles. In patients with irreversible ischemic MR, lower myocardial velocities of the papillary muscles and adjacent LV segments are determined both in the presence of asynergy of the analyzed segments and their visually normal contractility. Based on the predictor analysis, the most significant TDI indicators were revealed, which make it possible to predict the irreversibility of ischemic MR: Strain of the LV segments less than -5%, Strain papillary muscle less than -3%, Strain Rate (s) of LV segments less than -0.3 s-1, Strain Rate (s) of papillary muscle less than -0.5 s-1. Conclusion. The use of TDI, and especially the longitudinal Strain and Strain Rate, can be an effective tool in assessing LV myocardial dysfunction and its reversibility. This will allow differentiating patients who need to perform a combined operation and those who will have optimal and effective only myocardial revascularization.