Acute myocardial infarction – necrosis of the site of the heart muscle, caused by circulatory disorders. Infarct is one of the main causes of disability and mortality among the adult population.
Infarction can be considered an acute form of coronary heart disease or its complication.
Peculiarities of the heart – permanent contractions of the myocardium – cause a very high level of metabolic processes in its cells, a large consumption of oxygen and nutrients. This mode of operation requires an uninterrupted flow of highly oxygenated (oxygen rich) blood, which is provided by a branched network of cardiac vessels starting from the aorta in the form of coronary (coronary) arteries.
The reverse side of the effectiveness of the heart muscle is its high sensitivity to oxygen starvation buy meldonium online. When eating disorders in the myocardium develop pathological phenomena, very quickly becoming irreversible.
If the lack of blood flow is not critical, there is reversible ischemia (anemia) of the site of the heart muscle, which is manifested by stenocardic pain behind the sternum. With the complete cessation of blood flow to a specific site, a cascade of pathological processes develops-there is accumulation of toxic metabolic products that are not eliminated, transition to an anaerobic (anoxic) mode of operation using internal energy reserves of cells.
Own reserves of energy carriers (glucose and ATP) very quickly (approximately 20 minutes) are depleted, and the bloodless area of the heart muscle dies. This is myocardial infarction – necrosis, the size of which depends on the level of the closure of the vessel (large or small branch), the rate of onset of ischemia (with a gradual cessation of blood supply, partial adaptation is possible), the patient’s age and many other factors. For example, acute transmural myocardial infarction (with all necrosis of the heart muscle), which has a very severe course, develops with occlusion (overlap) of the large branch of the coronary vessel.
Among the causes of the violation of blood supply to the myocardium, the block of lumen of the vessel with an atherosclerotic plaque or thrombus is most often found (these phenomena can be combined). In addition, a sharp spasm of the coronary arteries under the influence of physical (cold) or chemical (poisons, drugs) factors is possible. Severe anemia, in which there is a sharp decrease in the content of hemoglobin in the blood, and consequently, its ability to transport oxygen, can also cause myocardial ischemia. The mismatch of blood supply to increased needs occurs with a sharp hypertrophy of the cardiac muscle – cardiomyopathy.
Symptomatic of myocardial infarction
In the development of the pathological process, several periods are distinguished, each of which has its duration and symptoms. Pre-infarction period can last from several minutes to months. It is characterized by an increase in angina attacks and intensification of their intensity. The sharpest period in which ischemia develops and necrosis of the heart muscle lasts up to several hours. Can have a typical and atypical version of the current.
A painful, or anginal variant, is typical (about 90% of all cases). Characterized by pain behind the sternum of high intensity of burning or pressing character, which can irradiate (give) to the left extremities, jaw, neck. There may appear fear of death, sweating, blushing or redness of the face, shortness of breath. Severity of pain depends on the size of the affected area – a large-focal heart attack causes more severe symptoms than a small-focal one. Pain is not stopped by taking nitroglycerin.
Atypical variants can proceed according to the asthmatic type (have symptoms of asthma attack), abdominal (with symptoms of an acute abdomen), arrhythmic (in the form of an attack of cardiac arrhythmia), cerebral (with impaired consciousness, dizziness, paralysis, vision disorder).
The acute period lasts about 10 days. The necrosis zone is finally formed and delimited, the absorption of the decay products begins and the scar is formed. Pain syndrome disappears or decreases. There may be fever, hypotension and heart failure.
Subacute period (about two months) – the stage of formation and consolidation of the scar. Pain syndrome is absent, the condition gradually improves. The state of health in this period is largely determined by the nature and amount of changes that occurred in the heart muscle.
The post-infarction period, or rehabilitation (up to half a year), is characterized by the absence of clinical and laboratory signs of a heart attack (changes remain on the ECG – they will remain for life), however, in this phase, the development of heart failure, stenocardia of tension and repeated infarction.