BackgroundSeveral studies have demonstrated that local ischemic preconditioning can reduce myocardial ischemia–reperfusion injury in cardiac surgery patients; however, preconditioning has not become a standard cardioprotective intervention, primarily because of the increased risk of atheroembolism during repetitive aortic cross-clamping. In the present study, we aimed to describe and validate a novel technique of preconditioning induction.MethodsPatients undergoing coronary artery bypass grafting (12 women and 78 men; mean age, 56 ± 11 years) were randomized into 3 groups: (1) Controls (n = 30), (2) Perfusion (n = 30), and (3) Preconditioning (n = 30). All patients were operated under cardiopulmonary bypass using normothermic blood cardioplegia. Preconditioning was induced by subjecting the hemodynamically unloaded heart to 2 cycles of 3 min of ischemia and 3 min of reperfusion with normokalemic blood prior to cardioplegia. In the Perfusion group, the heart perfusion remained unaffected for 12 min. Troponin I (TnI) levels were analyzed before surgery, and 12, 24, 48 h, and 7 days after surgery. The secondary endpoints included the cardiac index, plasma natriuretic peptide level, and postoperative use of inotropes.ResultsPreconditioning resulted in a significant reduction in the TnI level on the 7th postoperative day only (0.10 ± 0.05 and 0.33 ± 0.88 ng/ml in Preconditioning and Perfusion groups, respectively, P < 0.05). In addition, cardiac index was significantly higher in the Preconditioning group than in the Control and Perfusion groups just after weaning from cardiopulmonary bypass. The number of patients requiring inotropic support with ≥ 2 agents after surgery was significantly lower in the Preconditioning and Perfusion group than in the Control group (P < 0.05). No complications of the procedure were recorded in the Preconditioning group.ConclusionsThe preconditioning procedure described can be performed safely in cardiac surgery patients. The application of this technique of preconditioning was associated with certain benefits, including improved left ventricular function after weaning from cardiopulmonary bypass and a reduced need for inotropic support. However, the infarct-limiting effect of preconditioning in the early postoperative period was not evident. The procedure does not involve repetitive aortic cross-clamping, thus avoiding possible embolic complications.
The study analysed the level of troponin I (Tn) in the blood in patients with coronary artery disease after coronary artery bypass grafting in comparison with patients after aortic valve replacement surgery. The dynamics of troponin in the early postoperative period was studied, a parallelism was established between the occurrence of complications after surgery and the degree of myocardial damage. A new method has been developed for assessing the degree of intraoperative myocardial damage and the risk of complications using the «index of myocardial damage», the Tn level is determined twice after the operation, in the period up to 6 hours – Tn early and 12–24 hours later – Tn late, the index is calculated as the ratio of Tn late one to Tn early one. A correlation analysis of the «index» with other laboratory parameters was carried out, as a result of which no significant correlations were found, which indicates the absence of duplication and the significance of the developed indicator for assessing myocardial damage after cardiac surgery.
The study of dynamics of laboratory markers before and after heart surgery makes it possible to predict the risks of postoperative complications. Troponin I is ‘the gold standard’ for diagnosing acute myocardial infarction, but with an increase in the marker after heart surgery, the interpretation of the results can be difficult. Therefore, the search for new combinations of laboratory markers can help in assessing the degree of myocardial damage after surgery, as well as the risk of complications. Myeloperoxidase as a new laboratory indicator is of interest, since there are many studies on the prognostic value of an increase in this marker in patients with coronary heart disease in the development of cardiovascular complications. In the present study, the dynamics of myeloperoxidase, troponin I, and C-reactive protein in patients (n = 60) with a confirmed diagnosis of coronary heart disease before and after elective coronary artery bypass grafting under cardiopulmonary bypass was assessed. The following results were obtained: an increased level of myeloperoxidase in blood plasma in patients before surgery is an additional indicator in assessing the risk of postoperative complications, regardless of the concentration of C-reactive protein. A correlation was found between the concentration of troponin I and the level of myeloperoxidase in the blood, as well as between the duration of cardiopulmonary bypass and the level of MPO 24 hours after surgery.
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