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A series of hydroxynaphthazarins has been synthesized. Some of them were found in in vivo experiments to be protectors of myocardium under ischemia-reperfusion and to reduce the infarction zone by 50% without any adverse effect. All compounds exhibit a moderate or small toxicity and are active in low doses.

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The dynamics of signal-averaged ECG and late potentials was studied in 19 patients with coronary heart disease during spontaneous anginal episodes. Baseline late potentials were observed in 9 (45%) patients, they remaining in all during and after anginal episodes. The occurrence of new late potentials was recorded in none of them. There were no significant differences in some parameters of signal-averaged ECG before, during, and after an anginal episode, though the duration of low-amplitude signals tended to increase at the end of the QRS complex and the mean square amplitude of late 40 msec of QRS complex decreased during transient myocardial ischemia. The differences did not achieve their statistical significance. It was concluded that transient myocardial ischemia during spontaneous anginal episodes failed to lead to the appearance of a substrate for the occurrence of late potentials.

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The frequency of recording late potentials and their dynamics were studied in 25 patients with coronary heart disease before, during, and after transluminal angioplasty (TAP). Baseline late potentials were observed in 6 (20.7%) cases. During TAP, late potentials were recorded significantly more frequently (48.3%) than the baseline ones (p < 0.03), in 6 (20.7%) patients, late potentials appeared only in arterial dilatation and disappeared after TAP. There was a profound decrease in root-mean-square amplitude of late 40 msec in the QRS complex and an increase in the duration of low-amplitude (less than 40 microV) signals at the end of the QRS complex as compared to the baseline values. In ST-segment elevation, the parameters of the ECG signal-average become deteriorated to a greater degree than those in ST-segment depression.

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To study the dynamics of signal-averaged ECG and late potentials (LP) in the first month of myocardial infarction (MI) and the impact of coronary reperfusion on them, examinations were made of 98 patients with primary myocardial infarction, in 69 of whom coronary reperfusion was achieved. LP was found to be detectable just in the first hours of MI, their stabilization (steady-state appearance or cessation) mainly occurred at day 3 of the onset. LP detection at this time allowed them to be predicted before the patients' discharge (70% sensitivity and 95% specificity, 82% predictive value in the first 24 hours of MI, LPs are characterized by more instability than those in the subsequent period of the patients' hospitalization. Thrombolytic therapy and coronary artery patency have no impact on the frequency of LP recording and parameters of signal-averaged ECG. No significant difference was found in the frequency of recording LP in anterior and inferior MI before discharge. The frequency of LP recording does not depend on the sex and age of a patient, the maximum creatine phosphokinase levels, and the presence of postinfarction angina pectoris and heart failure.

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To examine the impact of exercise test (bicycle ergometry) and exercise-induced transient ischemic changes in ST segment on signal-averaged ECG parameters, the authors studied a homogeneous group including 65 patients (62 males and 3 females) with a 2-3-week history of primary myocardial infarction. The findings showed that induced myocardial ischemia caused no significant changes in signal-averaged ECG and late potentials, exercise might induce late potentials without clear-cut ECG signs of myocardial ischemia. It was also indicated that exercise-labile late potentials were significantly more frequently associated with the development of ventricular arrhythmias than steady late potentials.

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Echinochrom, a new antioxidant of the polyhydroxynaphthaquinone class, was tested for its cardioprotective activity in a model of occlusive reperfusion myocardial infarction (90-min occlusion and 4-hour reperfusion) in the acute experiments with open-chest dogs. The bolus intravenous injection of echinochrom in a dose of 1 mg/kg 5 min before reperfusion caused a significant (over 40%) reduction in the size of a necrotic focus. A supplementary administration of echinochrom 5 min after the onset of ischemia failed to contribute to a significant enhancement of its protective effect, suggesting that there is no substantial effect of the agent on ischemic lesion. The efficacy of echinochrom given after prolonged ischemia, low effective doses, and no adverse effects create prerequisites for using the drug in the clinical setting.

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An experimental mathematical model was proposed to assess the efficiency of experimental myocardial infarction (MI) size limitation. A canine model of occlusion-reperfusion myocardial lesion was used in an acute experiment with an open chest. 90-minute occlusion and 4-hour reperfusion were performed by carotid coronary bypass surgery. The necrotic zone and the risk area were visualized by double perfusion with tetrazolium staining. Retrograde coronary blood flow was used as a measure of collateral blood flow. The multiple linear regression equation with values of the risk zone and retrograde blood flow/risk area ratio used as independent variables enabled the size of myocardial infarction to be highly accurately predicted. Comparison of the true size of MI with the "expected" one provided methods for quantitative assessment of pharmacological limitation of MI sizes. Calculating an individual value for each animal made it possible to examine its relation to coronary circulation parameters and facilitated comparison of benefits from various agents.

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