Myocardial infarction refers to the defeat of the heart muscle due to a violation of its blood supply. In the part where oxygen starvation has developed, cells die, the first die after 20 minutes after the cessation of blood supply.
Infarction is one of the top diseases that cause mortality. Every year only in Europe for this reason, 4.3 million people die.
Stages of development and clinic of typical forms
Classification of myocardial infarction implies four stages of the development of the disease over time and a clinical picture - lesions, acute, subacute, cicatricial.
Damage period( initial)
Symptoms occur during the period from several hours to 3 days of .At this stage, transmural damage to the fibers is observed as a result of circulatory disorders. The longer the latent phase, the more serious the disease.
Recognize the disease allows the ECG.Potassium ions, beyond the dead cells, form damage currents. Then there is a pathological tooth Q , which is fixed for the second day.
If necrotic disturbances occur in the heart, the ST segment is much higher than the isoline, the convexity is directed upward, repeating the shape of the monophasic curve. At the same time, the merger of this segment with a positive T-tooth is recorded.
It is noteworthy that if there is no Q wave, then all the cells of the heart muscle are still alive .This tooth can appear even on the 6th day.
Acute
The duration of the second stage is from 1 day to 3 weeks .
Gradually, potassium ions are washed out of the damage zone, weakening the current. At the same time, the damaged zone decreases, as some fiber area dies, and the surviving part of tries to recover and turns into ischemia ( local blood circulation decrease).
The ST segment descends to the isoline, and the negative tooth T acquires an expressive contour. However, with myocardial left ventricular frontal myocardial infarction, the ST rise is likely to persist for some time period.
If there is an extensive transmural infarction, the growth of the ST segment lasts the longest, which indicates a severe clinical picture and a poor prognosis.
If there was no Q in the first stage of the tooth, then now it appears in the form of QS for transmural and QR with nontransmural type .
Subacute
The stage lasts for about 3 months, sometimes up to the year .
At this stage, deeply damaged fibers pass into the necrosis zone, which stabilizes. Other fibers are partially restored and form an ischemic zone. In this period the doctor determines the size of the lesion. In the future, the ischemia zone is shrinking, the fibers in it continue to recover.
Scarring( final)
Scarring of fibers lasts the whole life of the patient. In place of tissue necrosis of adjacent healthy areas, is connected. The process is accompanied by compensatory hypertrophy of the fibers, the lesion zones are reduced, the transmural type sometimes turns into not transmural.
In the final stage of the , the cardiogram does not always show the Q tooth of the , so the ECG does not report a transferred disease. There is no zone of damage, the segment ST coincides with the isoline( myocardial infarction proceeds without its rise).Due to the absence of an ischemic zone, the ECG shows a positive T wave, characterized by a smoother or lesser height.
Anatomical division of the lesion
The anatomy of the lesion distinguishes the disease:
- transmural;
- is intramural;
- subendocardial;
- subepicardial.
Transmural
With transmural infarction, is an ischemic lesion of the entire muscular layer of the organ. The disease has many symptoms that are typical of other diseases. This greatly complicates the treatment.
Symptoms of ailment resemble angina with the difference that in the latter case ischemia is a temporary phenomenon, and with an infarction it acquires the irreversible nature of .
Intramural
Lesions concentrated in the thickness of the wall of the left ventricle, does not affect the endocardium or epicardium .The size of the lesion may be different.
Subendocardial
This is the term infarct in the form of a narrow band in the endocardium of the left ventricle. Then the lesion area surrounds the subendocardial lesion of , resulting in the ST segment descending below the isoline.
In normal course of the disease, excitation rapidly passes subendocardial parts of the myocardium. Therefore, above the zone of the infarction, the abnormal tooth Q does not have time to appear. The main sign of the subendocardial form is that the ST segment below the electric line is shifted horizontally above the lesion area by more than 0.2 mV.
Subepicardial
The lesion occurs near the epicardium. On the cardiogram, the subepicardial form is expressed in a reduced amplitude of the R wave, in the leads above the infarction region , the abnormal Q tooth is seen, and the ST segment rises above the isoline. A negative T wave appears in the initial stage.
More details about the definition of the disease on the ECG, see the video:
The volume of the affected area
There are large-focal, or Q-myocardial infarction, and small-focal, which is also called non-Q-infarction.
Large-Scale
Causes a large-heart infarction of thrombosis or prolonged spasm of the coronary artery. As a rule, it is transmural.
The development of Q-infarction is indicated by the following symptoms:
- pain behind the breastbone, gives to the right upper part of the trunk, under the left scapula, to the lower jaw, to other parts of the body - the shoulder, the arm on the right side, the epigastrium;
- inefficiency of nitroglycerin;
- the duration of pain is different - a short or more than a day, perhaps several attacks;
- weakness;
- depression, fear;
- often - shortness of breath;
- lower blood pressure in patients with hypertension;
- pallor of the skin, cyanosis( cyanosis) of mucous membranes;
- profuse sweating;
- sometimes - a bradycardia, in some cases turning into a tachycardia;
- arrhythmia.
When examining the body, signs of atherosclerotic cardiosclerosis, the expansion of the heart in the width are revealed. Above the top and at the Botkin point, the 1st tone is weakened, sometimes split, dominates the 2nd tone, systolic noises are heard. Both heart tones become muffled by the .But if necrosis does not develop against the background of pathological changes in the organ, then the first tone prevails.
With a large focal infarction , the pericardial friction noise is heard, the heart rhythm becomes galloping, which indicates a weakened contraction of the heart muscle.
Laboratory tests show a high level of leukocytes in the body , an increase in ESR( after 2 days) , the effect of "scissors" is observed in the ratio between these two indices. The large-focal form is accompanied by other biochemical anomalies, the main of which is hyperfermentemia, which occurs in the first hours and days.
With the large-focal form , the hospitalization of is indicated. In the acute period, the patient is prescribed a bed rest, mental rest. Food - a fractional, limited calorie.
The purpose of drug therapy is to prevent and eliminate complications of - heart failure, cardiogenic shock, arrhythmias. To stop the pain, narcotic analgesics, neuroleptics and nitroglycerin( intravenously) are used. The patient is prescribed antispasmodic drugs, thrombolytics, antiarrhythmics, ß-adrenoblockers, calcium antagonists, magnesium, etc.
Small-focal
With this form, the patient develops small foci of involvement of the heart muscle. The disease is characterized by a lighter flow of in comparison with a large focal lesion.
The sonority of the tones remains the same , there is no galloping rhythm and pericardial friction noise. The temperature rises to 37.5 degrees, but not higher.
The level of leukocytes is about 10,000-12,000 , high ESR is not always detected, in most cases there is no eosinophilia and stab shift. Enzymes are activated briefly and insignificantly.
On the electrocardiogram , the RS-T segment is displaced, most often descends under the isoline. Pathological changes in the T wave are also observed: as a rule, it becomes negative, symmetrical and takes a pointed shape.
Small-focal infarction is also a reason for the hospitalization of the patient .Treatment is carried out using the same means and methods as with large-focal form.
The prognosis for this form is favorable, the lethality is low - 2-4 cases per 100 patients .Aneurysm, rupture of heart, heart failure, asystole, thromboembolism and other consequences of small-focal myocardial infarction are rare, but this focal form of the disease in 30% of patients develops into a large focal.
Localization of
Depending on the location, myocardial infarction can occur in the following clinical variants:
- left and right ventricle - the blood flow to the left ventricle stops more often, and several walls can be affected at once.
- partitions , when the interventricular septum suffers;
- apical - necrosis occurs in the apex of the heart;
- basal - damage to high sections of the posterior wall.
Atypical types of the disease and their clinical manifestations
In addition to the above, other forms of this disease are distinguished. Atypical forms develop, in particular, in the presence of chronic ailments. So, with osteochondrosis, the main pain syndrome is supplemented with a girdle in the chest, which is strengthened by the back deflection. Atypical forms make diagnosis difficult.
To atypical forms of myocardial infarction are:
- abdominal - in this form the symptoms resemble acute pancreatitis, the pains are localized in the upper abdomen and are accompanied by nausea, swelling, hiccough, sometimes vomiting;
- asthmatic - this form resembles the acute stage of bronchial asthma, dyspnea appears, the severity of the symptom increases;
- atypical pain syndrome - a man complains of pain in the lower jaw, ileal fossa, in the arm, shoulder;
- asymptomatic - this form is rare, and it affects mainly diabetics who, due to the characteristics of a chronic disease, are less sensitive;
- cerebral - there are neurological symptoms, complaints of dizziness, impaired consciousness.
Multiplicity
This feature distinguishes the following types of myocardial infarction:
- primary - occurs for the first time;
- recurrent - the lesion is fixed for two months after the previous one, and in the same zone;
- continued - same as recurrent, but the affected area is different;
- repeated - is diagnosed after two months and later, any zone is affected.
Therefore, when the first symptoms that may indicate a heart attack, should immediately seek medical help.
