Myocardial infarction

Myocardial infarction (MI) is closely related to the extinction (necrosis) of a larger or smaller portion of the heart muscle. At the heart of the pathology is a violation of the coronary circulation, which results in oxygen starvation in the background of the physical and emotional tension of the cells of the myocardium.

Men aged 35 to 50 years are more likely to suffer from myocardial infarction, and the risk of developing the disease increases markedly when women reach 50 years of age.

In the definition of MI, timely diagnosis is important, for which the first thing to be done is the correct interpretation of the clinical picture. In particular, information about the normal work of the heart and the first signs of myocardial infarction will be useful to everyone. In some cases, this can save somebody's life, because ambulance will be called in a timely manner.

Video: How does the human heart works - myocardial infarction first signs

Classification

Above the creation of the clinical classification of myocardial infarction, there were many specialists who were assembled in the working groups. In particular, the definition of the disease in 2007 was facilitated by the cardiology communities of Europe, America and the World Organization. As a result, the following clinical forms of myocardial infarction were identified:

• The first type (spontaneous MI) is a coronary circulatory disorder that develops on the background of a change in the structure of the atherosclerotic plaque due to its cracking, erosion or bundle.
• Second type (secondary MI) - lack of oxygen is associated with a violation of its intake or increased consumption, which is often observed with anemia, hypertension, hypotension, embolism, spasm of the coronary arteries.
• The third type (sudden coronary death) - may be due to the death of the patient or with an increased risk of sudden cardiac arrest. In the pathological process, the blockade of the left leg of the hyza bundle, the coronary thrombosis is often determined.
• Fourth type A (ChKV-associated MI) - ischemia develops against the background of percutaneous coronary intervention.
• Fourth type B (MI due to stent thrombosis) - the violation should be confirmed by autopsy or angiography.
• Fifth type (ACS-associated MI) - ischemia occurs as a result of coronary artery bypass grafting.

In some cases, the same patient has several types of MI. It should be noted that the term "myocardial infarction" and "necrosis of cardiomyocytes" are not the same. The latter pathological condition is mainly due to aortic-coronary bypass, which was carried out against a background of insufficiency of the kidneys or heart, electrical stimulation of cardiac activity, inflammation of the myocardium or electrophysiological ablation.

Common in clinical practice is the clinical classification of myocardial infarction:

• By periods of development: the sharpest (develops the first six hours from the onset of the attack), acute (up to 14 days), subacute (up to two months), scarring (two months and more).
• By volume of lesion: small-focal (not considered Q-heart attack) and large-focal (still known as transmural), in which the pathological tooth Q appears.
• Anatomically, the site of the lesions is subendocardial, subepicardial, intramural and transmural.
• By localization of the necrotic focus: IM of the right ventricle, septal MI (or interventricular septum), isolated MI (or upper extremities of the heart), MI of the left ventricle (may be on the anterior wall, posterior, lateral and lower).
• In the course of myocardial infarction, it is prolonged, monocyclic, recurrent and repeated.

Reasons

The heart muscle is supplied by the blood vessels of the coronary arteries, which feed on oxygen and nutrients. When clogging (obturation) of the lumen of the vessel, the larger or smaller portion of the myocardium ceases to supply the bloodstream, which leads first to ischemia, and then to dying (necrosis) of the tissue.

The main causes of coronary arteri obliteration:

• Up to 98% of cases are associated with atherosclerosis of the coronary vessels.
• Obliterization due to surgical intervention.
• Enclosure of the vessel embolus (fatty, thrombotic, and the like).
• Spasm of coronary vessels.

In some cases an anomaly of the development of coronary arteries is observed, then due to a similar malignancy, the myocardium also does not have enough blood supply.

Muscle tissue necrosis may occur in any other part of the body, but the heart is of vital importance, which is why the risk of death of the patient is high at his injury.

Developmental factors

Atherosclerosis is on the first place among the reasons for the development of myocardial infarction, so this factor of the appearance of pathology should be considered separately.

Under favorable circumstances, an atherosclerotic plaque begins to form on the inner surface of the coronary arteries.This formation has a fibrous tire, which can break, and then subendothelial connective tissue is in contact with blood cells and other shaped elements. In the future, platelets accumulate on the site of the damage, thrombin gradually forms, which leads to thrombosis of the vessel.

The process of occlusion of the vessel takes a certain amount of time, while it is dynamically changing, since occasional occlusion, stenosis and restoration of the local circulatory system alternately occur.

Thrombotic occlusion of the vessel may be formed against the background of undeveloped collateral arteries, as a result of which the MI with the uplift of the ST segment is diagnosed. If such a rise is absent, this does not mean at all that the affected area is smaller than with the presence of a similar ECG sign. Still, the MI with the rise of the ST segment is isolated separately, since in this form of pathology a special treatment tactic is implemented, most often with the use of thrombolysis and coronary angioplasty.

In the process of MI education, there are four stages:

1. Ischemia
2. Necrobiosis (damage)
3. Necrosis.
4. Scrubbing.

Ischemia can go on acutely and for a long time. This stage is conventionally called compensatory, as most of the lumen of the vessel is not completely covered. If the occlusion of the artery was 70% or more, then a rather rapid stage of damage occurs in which the metabolism is broken and the myocardium does not perform its function. The duration of the damage stage is approximately 4-7 hours.

During ischemia and damage it is still possible to turn the pathologist back to the original changes. At the onset of a necrosis stage, tissue repair is not possible.

Necrosis is susceptible to those areas of the myocardium that are most affected by a disturbed metabolism.Cardiomyocytes die and instead of them, the connective tissue begins to form. This occurs at the end of the second week after a heart attack. The whole process of scarring takes about 1-2 months.

Risk factors

The presented risk factors (FC) are closely related to those in coronary heart disease, which in turn are called with FC atherosclerosis. It is precisely the latter reason that most often results in the formation of atherosclerosis of coronary vessels, followed by IHD and MI.

The main risk factors include:

• age;
• floor;
• genetic predisposition;
• malnutrition;
• dyslipidemia;
• arterial hypertension;
• diabetes mellitus;
• hemostatic factors;
• increased body weight and obesity;
• hypodynamia;
• smoking and drinking alcohol.

Also, the formation of atherosclerosis, and with it the MI, may be associated with psychological factors and dental diseases.

The WHO bulletin, October 2017, states: "The application of extensive smoking legislation in Chile has led to a sharp, almost instantaneous decrease in the incidence of myocardial infarction."

It is important to point out that the more risk factors are determined in the patient, the higher the probability of developing a myocardial infarction with all the consequent consequences. Also, if the MI was considered to be the disease of 55-60 years old, now, after 35 years, every tenth American develops coronary heart disease.

The pathogenesis of the disease plays a significant role not so much the age as the sex. There is no doubt that there are men who are more likely to suffer from MI than they are 50 years of age. The highest incidence of atherosclerosis in men than in women is observed at the age of 30-39, since in the first case the rate of occurrence of the pathology is 5%, and in the second only 0.5%. Only by the age of 70 the incidence of atherosclerosis and coronary heart disease in both sexes is comparable.

There are signs that are regarded as the "first bouts" of a heart attack in the future. First of all, these are diseases associated with the cardiovascular system - arrhythmias, swelling of the legs and hands, shortness of breath that occurs after physical work. Also, the presence of prerequisites for the occurrence of MI testifies to bleeding of the gums, periodontal disease, frequent urination at night and frequent headaches, snoring and painful sensations in the left shoulder.

Species

Myocardial infarction is divided into forms according to the clinical picture. If signs characteristic of the disease are observed, then they are talking about a typical form of a heart attack. Otherwise, an atypical course of the disease is noted.

Typical form of MI

Anger pain is a characteristic symptom for this clinical form of MI. Characterized by high intensity, located behind the sternum. Pain often spreads nerve fibers to other parts of the body - the shoulder blade, throat, abdomen, arm. The pain does not pass quickly. Her duration can range from 15 minutes to an hour or more. In the face of severe pain, patients often experience fear of death, there is a sticky sweat.

Large-centered myocardial infarction in 30% of cases is accompanied by heart failure, therefore, shortness of breath and unproductive cough arise.

Prior to the development of myocardial infarction, there may be a hypertensive crisis, physical or emotional over-tension, and severe fatigue. In addition, the patient may notice interruptions in the work of the heart, which will indicate atrial fibrillation / ventricles or extrasystole.

Atypical forms of MI

Diagnosis of a heart attack will be difficult if clinical symptoms manifest themselves against the background of an atypical form. The following possible manifestations are distinguished:

• Abdominal syndrome - pathological manifestations are more about the gastrointestinal tract. Correspondingly, the pain is localized in the upper abdomen, in addition to the patients, it is disturbing the hiccup, the severity of the abdomen, swelling, nausea and vomiting may occur. These symptoms are most commonly thought up with the idea of acute pancreatitis.
• Asthmatic syndrome - severe dyspnea is gradually increasing, so at first glance, bronchial asthma, and not im.
• Cerebral syndrome - the symptoms of central nervous system are dominated by symptoms such as dizziness, disturbances of perception, etc.
• Arrhythmic syndrome - severely impaired heart rhythm by type of paroxysm.
• Collaptoid syndrome - the patient sharply decreases arterial pressure, there is a dizziness, cold sweat appears, darkening in eyes may be marked.

In some cases, patients note the localization of pain sensation in the throat, arms, spine, mandible, then speak of the peripheral form of the MI. Painless ischemia may also develop, when severe pain is observed instead of pain (similar to that of patients with diabetes mellitus). In some cases, in one patient, manifestations of several atypical forms occur, then the combined form of the MI is diagnosed.

Diagnostics

Depending on the stage of disease development, early and late diagnosis of MI is distinguished. The first group includes electrocardiography, echocardiography, laboratory tests. The second one is coronary angiography and scintigraphy of the heart muscle.

An important role in the definition of MI is electrocardiography. Depending on the stage of the pathological process, the following changes are distinguished:

• During the development of the MI on the ECG, a dome-shaped increase in the ST segment that merges with the T wave, an increase in the tooth R, and the appearance of a non-deep Q.

• The acute stage of the MI is characterized by the appearance of a negative T wave, a decrease in the height of the tooth R, the groove Q.

• The process of healing of the MI is determined on the ECG by the negative tone T and the segment ST that approaches the isoline.

• The healed IM is manifested on an electrocardiogram by a stable pathological Q-wave, which is supplemented by a lowered-amplitude waveform R. The segment ST and the tooth T correspond to the norm.

The course of myocardial infarction is in some cases similar to the clinic for other diseases. For example, ECG signs of MI are similar to pericarditis, myocarditis. Irradiation pain is often observed when the aortic laxative aneurysm is present, but often it appears not only with an MI, but also a thromboembolism of the pulmonary artery. Therefore, additional research methods are used to determine the exact diagnosis:

• Echocardiography - in the case of an MI, an ST segment increase of 1 mV or more is observed, this should be noted in at least two adjacent leads.
• Laboratory diagnostics (troponins, myoglobin, creatine phosphokinase).
• Coronography - narrowed or sharply interrupted vessels are visible.

Complications

The disease can give rise to severe complications, which do not always manifest immediately. Therefore, depending on the developmental time, early and late complications of myocardial infarction are determined.

• An early complication is thromboembolism, cardiogenic shock, heart rupture, cardiogenic shock and acute heart failure. Conduction disorders, allergic and hemorrhagic lesions may also develop.
• Late complications - develop after two or three weeks from the onset of MI. They can be expressed in thromboembolism, aneurysm of the heart, chronic heart failure and postinfarction syndrome.

CHD treatment

Assistance in myocardial infarction can be divided into two large groups: first aid and medication treatment. The tasks of specialists providing first aid include saving a patient's life. In the process of medical treatment, patients are helped to restore the work of the heart while simultaneously rehabilitating after the loss of some physical possibilities.

First aid

It starts to appear even at the pre-hospital stage, when the person only felt a lot of pain, but emergency medical care has not yet arrived.

Procedures for the First Aid:

1. The patient should be seated or laid, while trying to calm him down. The optimum position is sitting or halving.
2. If the patient has tight clothing, then it should be removed or unbuttoned.
3. The previously prescribed medicine should be given in the dosage indicated by the doctor. If you have nitroglycerin on hand, you can also give it to the patient. Although the drug does not completely relieve pain, it can weaken the attack somewhat.
4. Ambulance should be called if, after three minutes from the beginning of the MI, the condition of the patient did not improve or even deteriorated.
5. In some cases, the ambulance can not arrive quickly, then the patient should be taken to the hospital by passing transport. It is advisable to have a companion besides the driver in the car with the patient.
6. At the pre-hospital stage, aspirin is available in a dose of 300 mg, but at the same time the patient should not have a known allergic reaction.
7. With loss of consciousness and lack of cardiac activity, cardiopulmonary resuscitation is performed.

If before, only in the absence of pulse began to perform CPR, today, indications for its implementation is the lack of rhythmic breathing and loss of consciousness.

Video: Myocardial infarction. First Aid and Action Algorithm

Medicinal therapy

In hospital conditions, they work in a situation. If the patient was unconscious or had a cardiopulmonary resuscitation earlier, then CPR continues. With the preservation of consciousness in the patient, doctors adhere to the following treatment tactics:

• Elimination of pain, shortness of breath, excessive anxiety . Morphine hydrochloride is most often used for analgesia. In some cases, the drug may contribute to the early death of the patient, especially in the absence of a rise in the segment of ST. Sometimes the preference is given to neuroleptics (droperidol, fentanyl). With a high anxiety, a tranquilizer (mainly diazepam) is used.
• Oxygen therapy . Helps to cope with cardiogenic shock, pulmonary edema. For it, the patient wears a cannula on her face, through which oxygen inhalation is carried out.
• Reperfusion of the myocardium . It is carried out in the presence of a rise of segment ST and passage from the beginning of the attack no more than 12 hours. The greatest benefit from reperfusion is observed when it is performed in the first hours of the MI. As a reperfusion procedure, thrombolysis or angioplasty acts. The second option is considered to be more effective, because according to the research it is possible to reduce the risk of death with a MI by 22%. In the absence of contraindications to thrombolysis and the impossibility of conducting angioplasty, thrombolytic therapy is performed. But most often thrombolysis begins to be carried out without delay, and already after, if possible, perform coronary angioplasty.

Used in the treatment of myocardial infarction of the group of medicines:

• Anticoagulants are an extensive group including heparin without and with thrombolysis, as well as direct thrombin inhibitors.
• Beta-adrenoblockers - drugs are mandatory for all patients, especially in the presence of acute bronchospasm.
• ACE inhibitors are prescribed in tabular form, shown to all patients, especially with reduced systolic capacity of the left ventricle.
• Calcium antagonists are prescribed only in cases when the patient is diagnosed with supraventricular tachycardia and cocaine infarcts.

Preparations from groups of antiarrhythmic and inotropic drugs are prescribed only in extreme cases, since without obvious evidence they can increase the risk of death.

Rehabilitation after myocardial infarction

After the medical treatment of the MI and the appointment of the patient to the basic preparations for their reception at home, a rehabilitation of the patient should be organized. This will help:

• avoid disability;
• reduce the likelihood of developing repeated MI and sudden cardiac arrest;
• reduce blood pressure;
• reduce the sense of death;
• slow down the progression of atherosclerosis;
• to improve the condition of the cardiovascular system;
• improve emotional and psychological state;
• improve physical and motor activity.

The optimal conditions for the passage of rehabilitation are created on the basis of sanatoriums, which may take trips on 14-16 and 18-21 days.

During rehabilitation, the following treatments can be performed: metered walking, Scandinavia walking, therapeutic gymnastics, swimming, massage by type, manual, vacuum or underwater. It is also useful to perform pearl-coniferous and iodine-bromine baths, circular soul, external counterpulsation, psychotherapy. Be sure to comply with the dietary rules.

If necessary, the patient is given a consultation of a physiotherapist, doctor of exercise therapy, a nutritionist, a psychologist, a cardiologist. Rehabilitation in a sanatorium can not pass in the presence of cardiac insufficiency IIB-III stage, severe forms of extrasystoles, heart aneurysms with stage II and III CH, hypertonic pressure with severe complications, cerebrovascular disorders and diabetes mellitus with severe or decompensated flow.

Video: Rehab after myocardial infarction

Prevention

It is important to remember that the earlier the antithrombotic therapy was started, the lower the risk of re-development of myocardial infarction. For this, in the absence of indications, aspirin is used. If this drug can not be prescribed, then clopidogrel is taken.

Some patients have a high risk of re-infarction. For its prevention, a suitable drug from the group of beta-blockers is used. It may be carvedilol, metoprolol, bisoprolol.

Mortality among patients with myocardial infarction helps to reduce the use of statins.

Omega-3-polyunsaturated fatty acids, when administered in high doses, can significantly reduce the risk of developing complications against a background of developed MI.

In the primary unstable angina, the risk of myocardial infarction increases. Low molecular weight or non-fractional heparin is used to reduce it.

With a decrease in the fraction of left ventricular ejection to 40% and below, the risk of developing an MI is significantly increased. In order to improve the outlook for the disease, ACE inhibitors are prescribed.

Forecast

Myocardial infarction can be complicated by diseases of different degrees of severity, therefore at MI most often give a conditionally unfavorable prognosis. The worst effects are expected in the case of extensive heart attacks, when large parts of the heart muscle are affected. So-called micro-infractions can be transplanted on the legs, but this does not mean that it does not threaten the patient. Most likely, with time, arrhythmias may appear. Therefore, it is extremely important to carry out timely treatment of the MI, especially in the form of thrombolytic therapy, after which the outlook for the disease is significantly improved.

Video: What are the chances of survival after extensive myocardial infarction?

Myocardial infarction: statistics

• In 13% of cases it ends with death, and 50% of patients leads to disability.
• Only 50% of patients with acute myocardial infarction survive to the hospital in case of emergency delivery.
• Up to 35% of patients die in hospital conditions due to the occurrence of postinfarction complications.
• In 25% of patients diagnosed with myocardial infarction, a "dumb" form is determined, which is not manifested externally, therefore, the absence of symptomatology is not evidence of the absence of a heart attack.
• Myocardial infarction can occur already in 17-19 years and this risk is much higher among those people whose parents were ill with cardiovascular diseases up to 60 years.
• Approximately 41% of all cases of the disease come from the age of 50 to 59 years.
• In 95% of cases, myocardial infarction develops due to occlusion of the coronary vessel.
• Every year in the West 5% of patients die from the MI, and 30% in Ukraine.
• In Poland, the program of interventional cardiology began to be actively implemented, which allowed reducing mortality from MI from 35% to 4%.
• About every 25 seconds in the United States, someone dies of myocardial infarction.