Myocardial infarction: signs, diagnosis, treatment and emergency treatment for myocardial infarction
Improper nutrition, bad habits and constant stress are the three most important factors that can disrupt the work of the heart of even the healthiest person.Coronary heart disease is a disease that causes the death of most people worldwide every year( in 2012, 7.4 million), and myocardial infarction is the most severe complication of it.Contents: Causes of myocardial infarction The role of atherosclerosis in the development of heart attack symptoms and signs of heart attack diagnosis of myocardial infarction Treatment
Causes of myocardial infarction
Myocardial infarction develops as a result of complete clearance closing supplying the heart muscle arteries:
- atheroscleroticA plaque;
- thrombus( most common cause);
- embolus( fat or gas bubble);
- by spastic contraction of the muscular walls of blood vessels( usually due to drug or drug use),
and also due to:
- cardiac arrhythmias;
- congenital heart disease;
- diseases of bronchopulmonary system( bronchial asthma, pneumonia, obstructive diseases);
- anemia, etc.
It is also possible to develop an iatrogenic infarction due to erroneous bandaging or the intersection of the coronary artery during cardiac surgery.Infarction develops only when the vessel is clogged for a sufficiently long time.The lack of blood supply causes a lack of oxygen in the cells of the heart muscle, so they begin to die.If the cause of the blockage is eliminated before the onset of massive cell death, the infarction will be avoided.
The role of atherosclerosis in the development of infarction
Atherosclerosis is a disease in which the fat metabolism in the body is disrupted.The main substrate of pathology is atherosclerotic plaque, which arises in the artery wall, gradually increases in size and prevents normal blood flow.Under certain conditions, it can necrotize and become a kind of "foundation" for the formation of a thrombus.This is the most frequent mechanism of blockage of blood vessels. The second way in which the infarction occurs is the detachment of the plaque from the vessel wall and its movement with blood flow into the narrower branches of the arteries, which it clogs, causing necrosis.
Symptoms and the first signs of a heart attack
Not every case of myocardial ischemia( the so-called oxygen starvation of cardiac muscle cells in a scientific way) leads to its infarction. Specialists have developed an interim diagnosis of "acute coronary syndrome", which is exposed to any patient with coronary heart disease when certain objective and subjective symptoms appear:
- of chest pain that does not pass alone or after taking 3 nitroglycerin tablets for 20 minutes;
- is a characteristic irradiation of pain that can be given to the left arm, scapula, interscapular region, neck, lower jaw;
- pallor of the skin, cold sweat, weakness( these symptoms signal a threatening cardiogenic shock);
- fear of imminent death;
- dyspnea arising at rest;
- changes in blood pressure;
- appearance of all sorts of arrhythmias, etc.
The main symptom of acute coronary syndrome is still considered chest pain.Information on their nature and precise localization can provide an opportunity to either confirm or disprove the diagnosis of ACS at the first stage of diagnosis.However, modern medical rules do not allow the doctor only on the basis of this symptom to reject the likelihood of such a serious disease .That's why the expert fully examines the patient, finding out:
- Features of the current pain:
- for the first time whether it occurred;
- when exactly the pain began;
- did the patient take any medications and what was the effect.
- Whether the patient was previously examined, whether he had previously been diagnosed with a disease capable of causing myocardial ischemia.
- Does the patient have bad habits - smoking, drinking alcohol, excess fatty foods in the diet.
- What factors provoke or aggravate pain - physical activity, stress, taking certain medications.
- Did the patient suddenly lose consciousness in recent times, did not experience unexplained sudden attacks of severe weakness.
After a quick interview, the doctor should measure blood pressure, listen to heart tones( with myocardial ischemia, the rhythm of "gallop", III and IV tones).
A variety of clinical manifestations of the infarct, the existence of its painless or atypical( for example, abdominal, in which the disease manifests itself by abdominal pain, vomiting and stool disorders) makes laboratory and instrumental research particularly important.The simplest of them is electrocardiography, conducted at a minimum of 12 leads.This study can detect the very fact of ischemia, as well as identify a region that has undergone necrosis. The second study is a laboratory analysis of markers of myocardial damage.According to WHO recommendations, the level of cardiac troponins, creatine phosphokinase and( separately) its cardiac isoenzyme should be determined within the first 60 minutes from the onset of a pain attack.After 6 hours, a second analysis is performed.Elevation of the level of cardiac troponins under the condition of presence of chest pain is sufficient grounds for diagnosing myocardial infarction.In addition, studies of the brain natriuretic peptide( a marker that predicts the likelihood of severe disease), markers of inflammation, concentration and clearance of creatinine, the presence of alubumins in the urine can be conducted.A general and biochemical blood test is taken to clarify the diagnosis and identify possible co-morbidities that can affect the course of the infarction. Among the instrumental studies in addition to ECG, diagnostic value is possessed by:
- echocardiography, which allows to clarify the risk of heart failure;
- radiograph of the heart, produced for the same purpose( less informative than EchoCG);
- myocardial scintigraphy, with which you can precisely locate the area of damage to the heart muscle;
- coronary angiography - X-ray contrast test, which allows to detect the point of occlusion of the artery;This is the "gold standard" for diagnosing all forms of coronary heart disease.
All these studies are designed to give the most complete picture of the disease, knowing that the doctor can determine both the degree of risk to the life of the patient, and the tactics of his treatment.
Treatment of myocardial infarction
Myocardial infarction is perhaps the only disease where self-medication is not only permissible, but also vitally important.Statistics show that 80% of people who died from a heart attack could be saved if they started fighting the disease immediately.
In the author's practice, there was a case where the elderly man had chest pains for 7 hours, after which his spouse called an "ambulance".In the presence of the doctor, the patient had a cardiac arrest, which, despite all the efforts of the doctors, could not be started.It is possible that a man would have lived a few more years if he had not treated his condition negligently, but would immediately tell his wife about his deterioration.
Emergency care for myocardial infarction
So, treatment should begin in the very first minutes after the onset of pain. The patient should be laid on his back, provide him with complete physical and emotional peace, air access.Taking a dose of nitroglycerin( tablet, capsule or spray) often eliminates pain syndrome.Sometimes you need to re-take the medication( every five minutes, a maximum of three doses). Important: if after 15-20 minutes the pain does not disappear completely( it does not just weaken, it must completely go away!), You should immediately call an ambulance. ATTENTION! Nitroglycerin is not used if the patient is unconscious or his blood pressure is reduced( less than 90 mm Hg - systolic). The measures that can be taken by the visiting doctors are:
- oxygen therapy - the patient is allowed to breathe oxygen - this reduces the degree of oxygen starvation of the heart muscle;
- anesthesia - intravenously injected with morphine;
- decrease in blood viscosity - one of the anticoagulants( heparin, enoxaparin, fractiparin) is injected subcutaneously or intravenously;
- decrease in the ability of platelets to glue - antiplatelet therapy with aspirin, clopidogrel, ticagrelor;
- use of beta-blockers, reducing the need for cardiac muscle cells in oxygen and reducing the heart rate.
After this, the question of hospitalization in a medical institution that can conduct thrombolysis therapy is the best way to prevent necrosis of the myocardium.In large cities, this method of treatment can be used by ambulance doctors, specially trained and equipped with the necessary drugs and equipment.The essence of thrombolytic therapy is that the patient is injected intravenously with medications that destroy the formed thrombus - alteplase, tenecteplase, actilysis, etc. The earlier this process begins, the more chances for complete success( after 12 hours from the onset of the disease, thrombolysis ceases to be effective).
Surgical treatment of infarction
Serious alternative to thrombolysis therapy is transluminal coronary balloon angioplasty.This method consists in introducing into the coronary artery a special probe, by which the narrowed section of the artery widens and the thrombus or plaque is removed.Simultaneously, the second intervention is usually performed - stenting, in which a tube is inserted into the narrowing site, expanding the lumen of the vessel to an acceptable size. Aorto-coronary bypass is a full-fledged operation, in which a by-pass path for blood flow past the narrowed section of the artery is superimposed.This method can significantly prolong the life of a patient with coronary heart disease.In the acute period of myocardial infarction CABG is not used because of the excessive risk of complications. Surgical treatment of patients is exposed only after the acute effects of the infarct have completely subsided and the volume of necrosis is finally clear.
Complications of a heart attack
Even a small heart attack can lead to the development of quite serious complications.Much depends on the volume and location of the necrosis zone.So, for example, with myocardial infarction of the atria, it is possible to develop pulmonary edema-a life-threatening complication, in which blood plasma leaves the lungs due to a decrease in blood flow in the pulmonary artery system.A person "drowns" from within, and only professional medical help can save him.Unfortunately, mortality from this complication is extremely high - 80% of people die.Cardiogenic shock develops with a sharp drop in the contractility of the heart.It manifests itself with sudden loss of consciousness, pallor and cyanotic skin, profuse cold sticky sweat, violation of the blood filling of the capillary bed and, most importantly, a critical drop in blood pressure.This is the most dangerous complication of a heart attack after fatal arrhythmias.Mortality reaches 95% even with medical assistance in full.The cardiac arrest is a practically unavoidable complication of myocardial infarction in the "field" conditions.The only way to give a chance to a person for survival is immediate( within seconds!) The beginning of cardiopulmonary resuscitation.And even in this case the probability of salvation is very low, although it is not equal to zero. Cardiac arrhythmias usually lead to cardiac arrest:
- ventricular fibrillation( in 90% of all cases of cardiac arrest);
- asystole - complete absence of electrical activity of the heart;
- electromechanical dissociation, in which the existing electrical activity of the heart does not lead to its contraction;
- ventricular tachycardia without pulse - the heart contracted so often that it does not have time to fill up with blood, which means that it beats "idle".In addition to these disorders, it is possible to develop on such dangerous, but also very unpleasant arrhythmias and other changes - blockades, flickering and fluttering of the atria, tachy- and bradyarrhythmias( acceleration or slowing of the pulse), etc. All of them require close attention fromCardiologist and appointment of lifelong treatment.A rupture of the left ventricle is, perhaps, the most dangerous complication of a heart attack.The dead wall of the myocardium of this chamber of the heart, unable to bear the load, is torn and the blood is poured into the heart bag.The result is the inevitable death of the patient( mortality is 99-100%).Fortunately, a heart failure is relatively rare.Myocardial infarction is one of the most serious pathologies, but even after it, people survive and can lead a full life.The main thing is to start treatment as early as possible, and even better - to prevent neither heart attack nor coronary heart disease.And for this it is enough to just quit smoking, remove excess weight and do sports.
Bozbey Gennadiy, medical reviewer, ambulance doctor