Myocardial infarction

Myocardial infarction is a disease caused by necrosis of the site of the cardiac muscle due to acute ischemia, most often associated with the clotting of a branch of coronary arteries of the heart with a thrombus; Form of ischemic heart disease. In a number of cases, myocardial infarction develops as a result of spasm of the coronary artery, plugging it with an embolus, an atherosclerotic plaque with a hemorrhage to its base. The most common myocardial infarction is observed in patients with coronary artery atherosclerosis.

C lynichesky symptoms and flow. Acute myocardial infarction is usually preceded by angina of different duration of the flow, which, shortly before the development of the infarction, often acquires a progressive character: its attacks increase, their duration increases, they are poorly eliminated by nitroglycerin. In a number of cases, myocardial infarction develops suddenly in patients without clinically manifested heart disease. However, careful questioning often allows, and in such cases, to establish that a few days before the patient's health deteriorated: fast fatigue, weakness, decreased mood, there were indeterminate unpleasant sensations in the chest.

Typical manifestations of myocardial infarction are a feeling of severe compression or pain behind the sternum, or somewhat to the left of or to the right of it. The pain is most often constricting, pressing, tearing (feeling cola in the chest), sometimes burning. Stitching or cutting aching pain is not typical. Characterized by the irradiation of pain in the left shoulder, shoulder, arm, less often in the neck and lower jaw, sometimes in the right half of the shoulder girdle, in the interscapular space. Relatively rare (mainly with infarction of the posterior wall of the left ventricle), the pain is localized in the epigastric region - gastralgic variant of myocardial infarction. Unlike angina, pain with myocardial infarction lasts more than half an hour, usually several hours, and in case of pericarditis adherence - several days. Accepted nitroglycerin brings only a slight and short-term relief. Many patients note that chest pain restricts a deep breath, but the intensification of pain with deep breathing is not characteristic of myocardial infarction (if it is not complicated by pericarditis) and suggests another cause of pain. Sometimes the leading symptom may be shortness of breath with little or no pain. Regardless of how pronounced the pain, often marked by a sharp weakness and cold sweat. Often, in acute stage of myocardial infarction, patients experience nausea , vomiting , hiccups , bloating, having a reflex character. In some cases, myocardial infarction Myocardium is practically asymptomatic.

The face of the patient in the period of pain has a painful appearance, the skin is usually pale, sometimes with a cyanotic shade. Brushes, feet, and often the entire skin is cold and damp. Breathing is rapid and often superficial. BP at the time of the onset of pain may increase, but soon falls to an unusually low level for the patient. There is a soft and frequent (sometimes, on the contrary, very rare) pulse of weak filling. The heart's gonads are weakened, sometimes an additional third tone (diastolic rhythm of the gallop) is heard during diastole at the apex of the heart and in the fourth intercostal space to the left of the sternum. In most patients, it is possible to identify various cardiac arrhythmias. With uncomplicated myocardial infarction, the occurrence of cardiac murmurs is irregular; In some patients, a weak systolic murmur is determined above the apex of the heart. The sudden appearance of pronounced noise is characteristic of complicated myocardial infarction (aneurysm, septal rupture, infarction of papillary muscle, etc.). On the 2nd-5th day of the disease, about a quarter of patients above the anterior surface of the heart appear pericardial friction noise due to the development of fibrinous pericarditis. A few hours after the onset of the disease, body temperature rises (rarely exceeding 38.5 ° C), which usually normalizes during the next 5 days.

Myocardial infarction can begin or be combined with a picture of acute cerebral vascular accident, confusion, speech disorders (cerebral form). At the heart of cerebral symptoms lie disorders of cerebral circulation due to a decrease in cardiac output and spasm of cerebral vessels.

The clinical course of myocardial infarction is extremely diverse. Some patients carry it on their feet, in others it proceeds though with typical clinical symptoms, but without serious complications, in some cases - as a serious long-term disease with dangerous complications that can lead to death. In some patients, as a result of myocardial infarction, sudden death occurs.

Complications . The most formidable complications in the acute period of myocardial infarction are cardiogenic shock , acute heart failure , manifested as cardiac asthma , pulmonary edema, rupture of the necrotic wall of the ventricle of the heart.

Cardiogenic shock is caused by a decrease in the contractility of the myocardium and is manifested by a sharp drop in blood pressure (systolic - below 90 mm Hg) and symptoms of severe peripheral circulatory disorders. The appearance of the patient is characteristic: the skin is pale with a greyish-cyanotic hue, the facial features are pointed, the face is covered with cold sticky sweat, the subcutaneous veins fall off and can not be distinguished when viewed. His hands and feet are cold to the touch. Pulse is threadlike. The heart sounds are deaf, at the apex of the heart II is louder than the first. Urine is not separated or almost not separated. The patient is initially inhibited, later falls into an unconscious state.

Cardiac asthma and pulmonary edema are manifestations of acute left ventricular heart failure, which is also most often caused by a decrease in the contractile function of the myocardium of the affected left ventricle, and in some cases is associated with acute mitral insufficiency due to myocardial infarction. In a number of cases, especially in elderly patients, the pain syndrome is absent or not very pronounced, and the main manifestation of myocardial infarction is an asthmatic attack of asthma. Characteristic is the growing shortness of breath , which changes into choking, the patient is forced to take a lofty position, a cough appears (at first dry, then with an ever more abundant foamy, often pink sputum), moist rales are heard first over individual areas of the lungs (mostly small-bubbly), then, Pulmonary edema, they become abundant medium- and large-bubbly, audible at a distance. The patient tends to adopt a sitting position (orthopnea); In the respiratory act, not only the intercostal muscles and abdominal muscles begin to take part, but also the facial muscles of the face (the wings of the nose swell, the patient swallows the air with his mouth open). The border of the heart is widened to the left, the arterial hypertension is often increased (if suffocation is accompanied by collapse, - the forecast is unfavorable), tachycardia is determined . Heart sounds are deaf, can hear the rhythm of the canter. The rupture of the ventricular wall and the cardiac tamponade associated with it in the overwhelming majority of cases lead to death within a few minutes.

Violations of the rhythm and conductance of the heart with myocardial infarction are extremely diverse. More often there is ventricular extrasystole of various severity, which can be transferred to ventricular tachycardia and ventricular fibrillation. Less often, atrial disturbances of the rhythm are recorded: extrasystole, paroxysmal tachycardia , atrial fibrillation. Atrial arrhythmias, unlike ventricular arrhythmias, are usually not life-threatening. Among the conduction disorders associated with necrosis in the field of the conduction of the heart, the most dangerous is the atrioventricular blockade. With arrhythmic variant of myocardial infarction, rhythm disturbances are its only clinical manifestation.

A frequent complication of a large heart attack, especially localized in the anterior wall of the left ventricle, is an aneurysm of the heart, the development of which contributes to arrhythmias and heart failure.

Pristenochny thrombosis of the cavities of the heart can cause embolism of the arteries, supplying blood to internal organs (brain, kidneys, spleen, etc.) and limbs.

The diagnosis of myocardial infarction is based on the presence of at least two of the three main criteria: 1) a prolonged attack of pain in the chest; 2) changes in ECG, characteristic of ischemia or necrosis of the myocardium; 3) increased activity of blood enzymes.

Thus, in the vast majority of cases, a correct diagnosis can be made at the prehospital stage on the basis of a clinic and an ECG.

A special role in the diagnosis of myocardial infarction belongs to electrocardiography. By ECG changes, it is possible to determine the localization of the infarct, its vastness and depth - large-focal, small-focal, transmural (through) or intramural (lying in the thickness of the myocardium), sometimes also prescription (in the first weeks) and a number of other features. For transmural myocardial infarction in the acute period, the disappearance of the R wave, the appearance of the deep and broad QS wave, the rise of the ST segment above the isoelectric line, and the first 1 to 2 days, it merges with the positive T wave. In a large focal infarct, a pathologically wide and deep tooth O , The tooth R decreases, but does not disappear; The rise of the ST segment is less than in the transmural infarction; From the 5th day of acute myocardial infarction, the ST segment decreases steadily and the negative isosceles T wave is formed. Echocardiography and radionuclide research methods are used to clarify the magnitude and localization of myocardial infarction. Biochemical shifts in the blood appear on the 2nd -3rd day of the disease and can not serve as a basis for early diagnosis. Thus, the activity of cardiac fraction of creatine phosphokinase increases in 8-10 hours from the onset of myocardial infarction and returns to normal after 48 hours, the activity of lactate dehydrogenase increases by 3-5 days, aspartic aminotransferase - within 3 days.

Differential diagnosis with an atypical clinical picture of myocardial infarction is carried out with pulmonary artery thromboembolism, exfoliating aortic aneurysm, pleurisy, spontaneous pneumothorax. Differential diagnosis may be difficult for gastralgic variant of infarction, when often in patients mistakenly recognize the perforated stomach ulcer, acute cholecystitis , pancreatitis . Diagnostic difficulties are aggravated by the fact that in elderly people a number of acute diseases of the abdominal cavity can be combined with reflex angina. In such cases, a carefully collected history and a proper examination of the patient contribute to the diagnosis. With cholecystitis, there are indications of bouts of hepatic colic in the past, sometimes followed by mechanical jaundice, the pain is localized mainly in the upper right quadrant of the abdomen, radiating to the right scapula and the right shoulder. Acute pancreatitis is characterized by localization of pain in the epigastric region and to the left of the navel, their girdling character, abundant repeated vomiting . As with pancreatitis, and with acute cholecystitis, the disease often occurs after eating fatty foods. When perforating the ulcers of the stomach or duodenum, the starting points for the differential diagnosis are peptic ulcer disease , the relatively young age of patients, sudden daggerache in the abdomen, as well as the appearance of the patient and the pronounced muscle tension of the anterior abdominal wall. The significance of differential diagnosis is due to differences in management tactics and the nature of emergency care. If, in acute surgical diseases of the abdominal cavity, the use of narcotic analgesics before examination by a surgeon is unacceptable, then with the myocardial infarction taking place with pains in the epigastric region, the same therapy as for pain with chest retention is used.

With pericarditis intensive long pain in the upper half of the chest is often associated with respiratory movements and body position, combined with fever. In an objective study, pericardial friction noise can be heard. On the ECG in the initial period of the disease, ST segment elevation in all standard and thoracic leads is recorded, only after its reduction to the isoline negative teeth T begin to form (in myocardial infarction, negative T teeth occur long before the ST segment falls to the isoline). In addition, pericarditis is not characterized by a decrease in the amplitude of the R wave and the appearance in the dynamics of the pathological O.

Treatment . If repeated taking nitroglycerin does not reduce pain, add narcotic analgesics - promedol (1-2 ml of 2% solution), morphine (1-2 ml of 1% solution), omnopon (1-2 ml of 1% solution) with 0.5 ml of 0 , 1% solution of atropine subcutaneously, intramuscularly or intravenously, fentanyl (1-2 ml of 0.005% solution) with neuroleptic droperidol (1-2 ml 0.25% solution) in 20 ml of 5% glucose solution or the same amount of isotonic sodium chloride solution (Administered intravenously slowly).

When expressed asphyxia, the patient should be given a semi-sitting position with his legs down (at a low blood pressure, only slightly raise the head end of the bed), let him inhale oxygen through a gauze moistened with 70% ethyl alcohol. In addition, 10,000 units of heparin are injected intravenously at the prehospital stage and 300 mg of aspirin are given intravenously (the tablets should be chewed).

Regardless of whether the pain was completely or partially removed, all patients with myocardial infarction showed emergency hospitalization. The patient is transferred to the vehicle on stretchers. In houses with narrow staircases, you can transfer the patient on a sturdy stool, a few thrown back. In the hospital patient is transported in the prone position: in the presence of signs of left ventricular failure (choking, bubbling breath), the head end of the stretcher should be raised, letting the patient breathe in pairs of alcohol with oxygen.

Patients with acute myocardial infarction, if possible, are hospitalized in special intensive care units (units), equipped with equipment that allows monitoring monitoring - to constantly monitor the ECG and other circulatory parameters.

In the hospital, if no more than 6 hours have passed since the infarction, in the absence of contraindications, treatment aimed at dissolving the blood clot in the coronary artery (more often using streptokinase) or on preventing the progression of thrombosis (injected with heparin) is initiated.

To stop the spread of myocardial necrosis, drip intravenous nitroglycerin (reduces the burden on the heart), taking anaprilin and other agents that reduce the need for myocardium in oxygen.

Surgical treatment is indicated if, after dissolution of the thrombus on angiograms, stenosis of a large branch of the coronary artery is detected. The operation of widening the narrowed section of the artery with the help of a special catheter is used, at the end of which a balloon is strengthened, capable of straightening (but not stretching) when it is injected with liquid under pressure. In the acute period, sometimes aortocoronary or mammaro-coronary bypass surgery is performed (creating bypass prosthesis between the aorta or the internal artery of the breast and the coronary artery below the constriction site).

Of particular importance in preserving the patient's life is the timely and sufficiently vigorous treatment of complications of myocardial infarction. With cardiogenic shock, the patient is given a horizontal position. In the absence of a doctor, an average paramedic can slowly enter into the vein 0.5 ml of a 1% solution of mezaton in an isotonic solution of sodium chloride, while observing that the systolic pressure does not exceed 110 mm Hg. Art. According to the doctor's prescription, intravenously drip mezaton , norepinephrine or dopamine (dopamine), focusing on the same systolic pressure.

In the development of severe cardiac rhythm disturbances (ventricular extrasystoles of high degrees or ventricular tachycardia), 5-6 ml of a 2% solution of lidocaine is injected intravenously, after which the dropping is adjusted at a rate of 2-4 mg / min (if 200 mg of the solvent contains 10 ml 2% lidocaine solution, average injection rate of about 60 drops per minute). In the case of ventricular tachycardia, electropulse therapy can be shown, with progressive atrioventricular blockade - temporary endocardial electrical stimulation of the heart.

With cardiac asthma or pulmonary edema, raise the head end of the bed. Intravenously injected lasix (40-160 mg), narcotic analgesics (morphine, promedol , omnopon) or fentanyl with droperidol, intravenously drip-nitrate. Nitroglycerin (nitro Mac, perlignanite) is injected in an isotonic solution of sodium chloride, intravenously dripped at a rate of 10 mg / min, followed by an increase in the rate of 20 μg / min every 5 minutes under the constant control of blood pressure and heart rate. Usually, the effect is achieved at a rate of administration of 50-100 μg / min, the maximum rate of administration is 400 μg / min. In the absence of a dispenser, 4 ml of a 1% solution of nitroglycerin is diluted in 400 ml of isotonic sodium chloride solution and injected intravenously at a rate of 6 to 8 drops per minute. The rate of administration is increased if the pain syndrome persists with stable hemodynamics. With the help of special pumps, foamy sputum from large bronchi is evacuated. For the destruction of foam in small bronchi, inhalation of oxygen with ethyl alcohol vapor (50% when breathing through a mask and 70% using a nasal catheter) is used. Sometimes resort to artificial ventilation of the lungs under increased pressure, as well as to ultrafiltration of blood - the removal of a part of the water contained in the blood with electrolytes dissolved in it with the help of special apparatus.

The mode of the patient with myocardial infarction depends on the size of the focus or foci (if there are several of them) of the damage to the heart muscle and the time that has elapsed since the onset of the disease. With small-focal infarction, a non-strict bed rest is prescribed for 1 to 2 days. If the doctor is convinced that there is no tendency to expand or relapse the infarction, the patient is transferred to the ward, and a week later he is allowed to move within the department with a gradual further activation. With an uncomplicated transmural infarction, the patient is usually placed in bed with the help of a nurse or a therapeutist on the 7th day of the disease, and allowed to walk in the ward on the 14th day; Discharged from the hospital after approximately 28 to 30 days from the onset of the disease.

Nutrition of the patient in the first days of the disease includes easily digestible food (juices, kissels, soufflé, soft-boiled eggs, kefir). Products that cause increased gas formation in the intestine are excluded. From the 4th day of the disease, the diet is gradually expanded and by the end of the week they switch to diet No. 10.

In the rehabilitation system of patients, an important role belongs to therapeutic physical education. It promotes stimulation of auxiliary circulatory mechanisms facilitating the work of the heart, training the contractile function of the weakened cardiac muscle, and the apparatus for regulating systemic hemodynamics. Under the influence of exercise therapy, breathing moderately activates, the tone of the nervous system rises, the function of the gastrointestinal tract improves, which is especially important during the patient's stay on bed.

Care for a patient with acute myocardial infarction, especially in the early days of the disease, when the patient is on strict bed rest, should ensure the exclusion of physical and emotional overvoltages inadmissible for the patient. During this period, the patient should usually be fed by a nurse, although with the patient's persistent desire, with the permission of the doctor, he can eat independently, especially if the bed is equipped with a bedside table. In the first days of illness, a nurse daily washed the patient, later, when the patient is allowed to sit, helps him wash. If the patient's bed rest is delayed due to complications, it is necessary to turn the patient in bed every day, wipe the skin with camphor alcohol, toilet water or cologne. In the first 2-3 days of illness the patient is not allowed to shave himself.

It is important to regulate physiological items. Typically, patients in the early days develop constipation, for the elimination of which apply unsalted laxatives (buckthorn, Alexandrian leaf, vaseline or vegetable oil). It is often necessary to cleanse the intestines with an enema. With prolonged absence of stools, it may be necessary to fracture the rectum in the rectum of the stool. Sometimes the doctor allows patients who can not empty the intestine lying in bed, transplant with this purpose on the bedside, the stool already from the 2nd -3rd day of the illness (in cases when the patient's efforts spent on emptying the intestines in bed far exceed the effort required For transplantation to a toilet seat with the help of a nurse). It is necessary that the patient's chair should be at least once every 2 days. Stiffening during defecation can lead to recurrence of painful attacks and even sudden death of the patient.

If the patient has a delay in urine, the doctor determines its cause. If necessary, the bladder is emptied through the urinary catheter, in some cases the catheter is left in the urinary tract for 1 -2 days, after which the patient is allowed to empty the bladder on his own. If the patient empties the bladder while standing, the nurse must help him to get out of bed at the minimum load: first he needs to turn to his right side, ask him to bend his legs; Then they lower the legs of the lying patient, after which they help him to sit in bed, and after 2 to 3 minutes of rest - get up. During urination, the patient must be maintained.

Rehabilitation (rehabilitation therapy) of patients begins already in the hospital. It is aimed at restoring, if possible, a full-fledged general physical and mental state of the patient. Permission for the patient to eat and shave independently refers to the number of rehabilitation measures: the majority of patients, having received such permission, believe that they have already begun to recover. Rehabilitation measures include the timely expansion of the regime, the appointment of therapeutic physical education. By the end of stay in the hospital, the patient learns to walk for 1.5 - 2 km and 2 flights of stairs. It is psychologically useful to have a confidential conversation with a patient about other patients who have been hospitalized with the same disease, but now have a full-time working life and a normal family life.

The prognosis depends on the extent of the infarct, and also on the presence and nature of complications in acute and subsequent periods. With uncomplicated and not very extensive or small-focal myocardial infarction, the prognosis regarding life and recovery is usually favorable. It is significantly worse with extensive infarction (especially with acute left ventricular aneurysm), as well as with complications - severe cardiac rhythm and conduction, heart failure. Practically complete recovery is sometimes observed only with small-focal, less intramural and very rarely - with a small lesion in the transmural myocardial infarction that occurred without complications. In other cases, recovery for one reason or another is regarded as partial, since the presence of postinfarction scar predisposes to heart rhythm disturbances and gradual development of heart failure, especially if myocardial infarction is complicated by heart aneurysm.

Prevention is reduced to combating risk factors for the development of atherosclerosis, to medical or surgical treatment of coronary heart disease and diseases accompanied by increased blood pressure, to the timely hospitalization of patients with frequent, prolonged and resistant to the action of nitroglycerin attacks of angina pectoris.