Causes of myocardial necrosis
Acute myocardial infarction contributes to the development of necrosis of the area of the heart muscle. This occurs as a result of acute coronary insufficiency caused by a sudden cessation of blood flow through the coronary artery or insufficient oxygen and nutrients consumed by the myocardium.
Myocardial infarction can provoke blockage of one of the vessels by a thrombus that forms in the area of atherosclerotic plaque. It is necessary to understand that in case of heart ailments, emergency assistance is always needed, at the first symptoms it is necessary to seek help from a doctor, because such an insidious disease progresses quickly.
When a blood clot blocks the vessel supplying the heart, the supply of oxygen is sufficient for 10 seconds. Then for another 30 minutes the heart muscle remains viable and in this short period it is still possible to save the heart with the help of intensive therapy. But if you do not provide help, then irreversible changes in the cells begin and after 3-6 hours from the beginning of the violation of the patency of the blood vessels, the heart muscle in this area dies.
Necrosis can affect the entire thickness of the myocardium (transmural) or captures a small area, depending on the size, the dead areas are called - large and small focal infarction. The clinical picture of myocardial infarction is complex and diverse, which makes it difficult to establish the correct diagnosis as soon as possible. Diagnosis is based on three characteristic indicators:
Typical pain syndrome
Changes in the electrocardiogram
Changes in the parameters of the biochemical blood test
Pain, the very first symptom of this disease, can vary in intensity and duration. A person may feel a prolonged squeezing, pressing pain behind the sternum in the region of the heart, radiating to the arm, neck, back area of the shoulder blades, but symptoms may manifest as discomfort and heart interruptions.
It also happens that there is no pain at all and only pallor of the skin, cold sweat and fainting are a signal of the disease. Difficult to diagnose cases, cord disease is manifested by shortness of breath with shortness of breath and abdominal pain. Every day, cardiologists of the admission departments of hospitals carry out diagnostics of patients who have applied with complaints of pain in the thoracic region.
If during the examination there are problems with the diagnosis, then it is necessary to determine in the blood markers of myocardial necrosis. Identification of the level of markers of myocardial necrosis helps to determine the severity of the condition and to choose the most favorable treatment.
Types of myocardial necrosis markers
There are criteria for the requirements for a biochemical marker:
· High specificity;
· High sensitivity to myocardial necrosis;
• reaching a significant level in a short time from the onset of symptoms and maintaining it for several days;
Unfortunately, there is no such single ideal marker that has all these criteria.
To diagnose myocardial infarction, use:
1. Early marker:
Myoglobin - a complex muscle protein that binds oxygen carried by hemoglobin to form oxymyoglobin, provides the working muscle with a supply of oxygen. This is the so-called respiratory pigment of human muscle tissue, its content in blood serum rises within 2 hours after the onset of heart attack symptoms. It is not used as an independent marker due to its low specificity.
· The cardiac form of creatine phosphokinase (CPK) - is also present in human muscle tissue; for the diagnosis of MI, the mass of this enzyme is determined, and not its activity, since it has a low specificity for myocardial necrosis. Appears in blood serum 3-4 hours after the onset of pathological processes.
· Cardiac form of protein that binds fatty acids - is sensitive in detecting myocardial necrosis;
2. The late marker has high specificity and shows a diagnostic result after 6-9 hours:
· Lactate dehydrogenase (LDH) - a cytosolic protein with five isoenzymes. Due to the late increase in serum concentration, the LDH marker is not used in the early diagnosis of myocardial infarction.
· Aspartate aminotransferase (AST) - is found in large quantities in the liver, has a low specificity in relation to myocardial necrosis. For diagnostics, it is used in combination with sensitive and specific markers.
· Cardiac troponins I and T - high specificity and sensitivity allows us to call this marker the “gold standard” in biochemical studies. This is currently the most compelling marker.
The duration of the marker detection helps to clarify the diagnosis of myocardial infarction at a later date. To accurately determine the timing of the disease, "short-lived" markers of necrosis are examined. Biomarkers of myocardial necrosis are measured in all patients with symptoms of acute coronary syndrome.
Article author: Mochalov Pavel Alexandrovich | d. m. n. therapist
Education: Moscow Medical Institute. IM Sechenov, specialty - "General Medicine" in 1991, in 1993 "Occupational Diseases", in 1996 "Therapy".
