[Metabolic effects of mexidole during cardiosurgical operations using extracorporeal circulation].

The effect of mexidole on the levels of glutathione, the activity of its metabolic enzymes, glutathione reductase (GR) and glutathione peroxidase (GP), and antioxidative enzymes, superoxide dismutase (SOD) and catalase (CAT) in the red blood cells under hypothermic perfusion was studied. A total of 96 patients were examined. The study was performed before perfusion, at the cooling and warming stages, an hour after perfusion, and in the morning of a following day. Mexidole was administered to 26 patients in the evening, before surgery, and at the cooling and warming stages (Group 1). The agent was not given to 70 patients (Group 2). In Group 2, there was an association of the level of glutathione and the activity of the enzymes under study with temperature. There were the least changes observed at 30-34 and 26-29 degrees C and a substantial decrease (by more than 30%) at the cooling stage as compared with pre-perfusion values. In the mexidole group, the content of glutathione increased under all temperature conditions at the study stages (by 30 to 58%) and the activity of all the test enzymes: GR and GP up to 33%, SOD up to 20-60%, CAT by 20-30%. The elevated level of all the parameters was also preserved on the following postoperative day. It may be suggested that mexidole activates the biosynthesis of glutathione and antioxidative enzymes, thus enhancing the antioxidative defense of cell membranes.

[Hypothermal perfusion: protection or damage?]. / Gipotermicheskaia perfuziia -- zashchita ili povrezhdenie?

Ninety six patients were examined during operations on the open heart and great vessels: 25 perfusions were performed at a temperature of 30-32 degrees C; 41 perfusions at 26-29 degrees C; 10 at 23-26 degrees C; 20 at 12-14 degrees C. It was found that with superficial hypothermia and moderate PaO2, blood myoglobin (MG) release was minimal and the count and activity of platelets were optimal. The degree of myoglobinemia increased as PaO2 rose. As the body's temperature lowered, the blood concentrations of MG, its differences smoothed in the subgroups with different PaO2 values. Critical myoglobinemia (over 30 times higher than the baseline values) was noted in a group with superdeep cooling to a temperature of 14 degrees C. By taking into account the fact that the myocardium contains large quantities of MG, loss of this heme-containing protein involves myocardial blood supply disorders and hence decreased myocardial contractility. A considerable platelet loss entails higher postoperative hemorrhagic diathesis and requires efforts in correcting coagulopathies.

[Temperature regimen of extracorporeal circulation during aortocoronary bypass surgery]. / K voprosu o temperaturnom rezhime iskusstvennogo krovoobrashcheniia pri operatsiiakh aortokoronarnogo shuntirovaniia.

The purpose of the study is to comparatively evaluate the impact of normo- and hypothermic perfusion on acid-base balance (ABB), gas blood composition, metabolic parameters, and hemostasis. Fifty patients undergone multiple aortocoronary bypass under extracorporeal circulation (EC) were examined. Twenty four patients and 26 (Groups 1 and 2, respectively) had been operated on under normo- and hypothermia. The groups did not differ in age, body weight, the duration of an operation, the number of shunts, the time of EC, and myocardial ischemia. ABB, gas blood composition, the concentrations of hemoglobin, lactate, fibrinogen, prothrombin time, thrombin time, activated partial thromboplastin time, activated coagulation time, blood coagulation time as described by Leigh-White, the count of platelets, and ADP-induced platelet aggregation in the early postperfusion and postoperative periods, following 24 and 48 hours after surgery. There were no significant differences in the values of ABB, gas blood composition, blood lactate levels in patients from both groups. However, metabolic acidosis, elevated blood lactate concentrations were more frequently encountered in Group 2 patients, which suggests that hypothermia prduces a more aggressive effect on systemic homeostasis. Impact of normo- and hypothermia on the coagulative link of homeostasis was not revealed. Nevertheless, hypothermic EC halved the functional activity of platelets, which has a substantial effect on the size of postoperative blood loss.

Platelet monoamine oxidase activity during surgical intervention under condition of hypothermic perfusion.

Platelet and plasma monoamine oxidase activity was determined at early stages of hypothermic perfusion and circulatory arrest. Monoamine oxidase activity decreased more drastically and restored more slowly against the background of deep (14 degrees C) compared to moderate hypothermia (26-29 degrees C). The decrease in platelet monoamine oxidase activity was accompanied by its increase in the plasma, which attests to mechanical (in tubes) and toxic damage to platelets. The latter is associated with increased partial O(2) pressure in the plasma during hypothermia, which promotes the formation of reactive oxygen species.

[Causes of myoglobinemia in surgery with artificial circulation]. / Prichiny mioglobinemii pri operatsiiakh s iskusstvennym krovoobrashcheniem.

Release of myoglobin (Mg) into the plasma and increase of its concentration during perfusion are a result of muscle cell injury during artificial circulation. High values of oxygen tension and hypothermia during cardiosurgery are sources of active oxygen forms damaging the biomembranes. We investigated release of Mg into the blood and relationship of this parameter with oxygen tension and depth of cooling. 95 patients were tested during open-heart surgery and operations on the main vessels: 25 perfusions at 30-32 degrees C, 41 at 26-29 degrees C, and 20 at 12-14 degrees C. The patients were divided into subgroups depending on arterial blood oxygen pressure. Myoglobin release into the blood was minimum under mild hypothermia and moderate PaO2. The degree of myoglobinemia increased with elevation in PaO2. As body temperature decreased, the concentration of Mg increased and differences between the groups with different PaO2 leveled. Critical myoglobinemia (30-fold vs. the initial value) was observed in the group with the deepest hypothermia (14 degrees C). Since the myocardium contains high amounts of Mg, it is clear that loss of this heme-containing protein impairs the feeding of the myocardium and, hence, decreases its contractility.

[The effect of the perfusion parameters on the functional characteristics of the thrombocytes]. / Vliianie nekotorykh parametrov perfuzii na funktsional'nye kharakteristiki trombotsitov.

Platelet and plasma monoamine oxidase (MAO) activity was evaluated in two groups of patients at different stages of surgery (before perfusion, at the depth of cooling, height of warming, and 1 h and 24 h after perfusion). Group 1 consisted of 26 patients with acquired heart diseases operated on under artificial circulation and hypothermia (26-29 degrees C), group 2 consisted of 13 patients subjected to reconstructive operations on the aorta under artificial circulation with deep hypothermia (14 degrees C) and circulatory arrest for 50 min. The activity of platelet MAO was decreased in group 1 (by more than 50% during cooling and by 68% during warming and 1 h after perfusion); 24 h after surgery MAO activity increased, but did not reach the initial value. In group 2 the decrease in MAO activity was more expressed, starting from the second switching of the artificial bypass device after circulatory arrest (by almost 50% during cooling, by almost 90% after second switching of artificial circulation, by 94% during warming, and by at least 70% 1 h after perfusion); 24 h after the intervention the platelet MAO activity increased negligibly. MAO activity in the plasma notably increased in both groups during surgery, more so in group 2, which indicates washing out of the enzyme from platelets during artificial circulation because of these cells' damage. These data suggest that platelet injury is a result of their mechanical injury in the bypass circulation and of excessive partial oxygen pressure (400 mm Hg and higher) during perfusion, due to increased oxygen solubility in the plasma at low temperature. This leads to production of excessive active oxygen forms which damage cell membranes and inhibit MAO activity.