PATHOLOGICAL PHYSIOLOGY OF CORONARY HEART DISEASE

Аннотация

Ischemic heart disease is a disease that develops as a result of absolute insufficiency of the coronary circulation and manifests itself by myocardial damage of varying degrees. Insufficiency of the coronary circulation is a pathological condition characterized by the inability of the coronary vessels to provide blood supply to the heart in accordance with its energy needs. In other words, there is a discrepancy between the energy needs of the heart and the delivery of oxygen and nutrients by the coronary vessels. Insufficiency of the coronary circulation can be relative and absolute. Keywords: ischemia, coronary arteries, heart failure, hypoxia, myocard. Introduction: Relative coronary insufficiency occurs in the case of a primary increase in the energy needs of the heart (an increase in the load on the heart during physical work, arterial hypertension). At the same time, the intensity of the coronary blood flow may increase, but this turns out to be insufficient to meet the increased needs of the heart. Absolute coronary insufficiency occurs in the case of a primary violation of the coronary circulation, as a result of which the delivery of oxygen and nutrients to the myocardium decreases both at rest and with an increase in the energy needs of the heart. Causes of myocardial ischemia: I. The obturation mechanism is a decrease in the lumen of the coronary arteries. Its causes may be: a) stenosing atherosclerosis (is the cause of myocardial ischemia in 90% of cases); b) thrombosis of the coronary arteries (most often a consequence of atherosclerosis); с) embolism of the coronary arteries; d) inflammatory processes in the wall of the heart vessels - coronariitis (with rheumatism, syphilis). For the development of clinical signs of myocardial ischemia, the value of "critical stenosis" is important. This is a minimal decrease in the lumen of the vessels, in which ischemia occurs. In humans, this indicator is 75%. II. Angiospastic mechanism - spasm of coronary vessels. Its causes may be: a) excitation of α-adrenoreceptors against the background of blockade of β- https://inlibrary.uz 8 0 45-son_2-to’plam_May -2025 ISSN:3030-3621 Ta'lim innovatsiyasi va integratsiyasi adrenoreceptors; b) vasopressin; c) angiotensin II; d) thromboxane A1; e) hypocapnia; e) endothelin is a biologically active substance of endothelial origin. A known clinical form of coronary angiospasm is Prinzmetal angina. III. Compression mechanism - compression of the coronary vessels. It may occur with tachycardia (the total duration of the period of compression of the coronary vessels during the systole of the heart increases). Sometimes it is caused by scars and tumors. Pathogenetic factors in coronary insufficiency: 1. Hypoxia. 2. Acidosis. It develops as a result of the accumulation of acidic metabolic products due to impaired blood outflow and activation of glycolysis. 3. An increase in the extracellular concentration of potassium ions in the ischemic area. It is noted from the very beginning of disorders of the coronary circulation (after a few minutes), when there is still no damage to cardiomyocytes. During this period, for reasons still unknown, there is a passive release of potassium ions from cells (the permeability of K+ channels may increase), and its extracellular concentration increases to 8 mmol/ l or more. After a few hours, the "outflow" of K+ ions from the cells may be due to a malfunction of the Na-K pumps (ATP deficiency) and an increase in the permeability of damaged membranes. Consequences of coronary circulatory insufficiency: 1. Violation of myocardial contractility with the development of heart failure. 2. The appearance of abnormal electrical activity – electrical instability of the heart, the development of arrhythmias. 3. Damage to cardiomyocytes caused by ischemia. 4. Reperfusion syndrome. The main clinical forms of ischemic heart disease: 1) angina pectoris - attacks of short-term (up to 20 minutes) acute coronary insufficiency, which are accompanied by pain syndrome, a sense of fear and related vegetative reactions. There are tension angina, rest angina and Prinzmetal angina (coronary artery spasm); 2) preinfarction condition (unstable angina, intermediate coronary syndrome, or acute focal myocardial dystrophy) - develops with a duration of myocardial ischemia from 20 to 40 minutes; 3) myocardial infarction - necrosis of the heart muscle caused by disorders of the coronary circulation. Occurs with reversible (transient) ischemia lasting over 40-60 minutes, or with irreversible disorders of coronary blood flow; 4) cardiosclerosis - sclerotic changes of the heart muscle. They can be diffuse (atherosclerotic cardiosclerosis) and focal (postinfarction cardiosclerosis). https://inlibrary.uz 8 1 45-son_2-to’plam_May -2025 ISSN:3030-3621 Ta'lim innovatsiyasi va integratsiyasi The main causes of myocardial infarction: 1. Atherosclerosis of the coronary arteries. Its development is accompanied by a violation of the suppl