How myocardial infarction manifests itself on the ECG: an overview
From the article you will learn about the role of ECG in myocardial infarction. When there are characteristic signs, what they mean. Cardiogram as an assistant in determining the degree of pathological changes in cardiac tissue and the localization of the process.
content of the article:
Temporary stage infarction on ECG
Types depending on the size of the hearth: ECG signs
ECG changes at a different location of myocardial infarcts
Atypical Electrocardiography in acute disorders of blood flow in the myocardium - the "gold standard" diagnostic. The informativity of the study increases during the first hours after the development of the infarct, when when recording the electrical activity of the heart, characteristic signs of the cessation of blood flow to the tissues of the heart appear. Click on the picture to enlarge
The film recorded during the development of pathology may reflect only the phenomena of initial disturbance of the blood flow, provided that they did not develop at the time of recording( ST segment change with respect to the isoline in different leads).This is due to the fact that for typical manifestations it is necessary:
violation of the excitation of myocardial tissue( develops after complete necrosis or necrosis of cells);
change in electrolyte composition( extensive yield of potassium from the destroyed tissue of the myocardium).
Both processes take time, therefore, signs of a heart attack appear at registration of electroactivity of the heart in 2-4 hours from the onset of an infarction.
ECG changes are associated with three processes that occur in the infarction zone, dividing it into areas:
Necrosis or tissue necrosis( there are only Q-infarcts).
Damage to cells( may subsequently go to necrosis).
Lack of blood supply or ischemia( fully restored in the future).
Symptoms of a developing infarction on the ECG:
Changes in the area of the formation of the infarction zone
Changes in the infarction-free area of the
The tooth R is absent or significantly reduced in height
The segment S-T lies below the isoline
There is a deep( pathological) tooth Q
Segment S-T raised above isoline
Tine T negative
It should be borne in mind that, depending on the size of the area with a violation of blood flow and its location relative to the cardiac envelopes on the cardiogrammay register only a part of these symptoms.
These signs allow:
To establish the presence of a heart attack.
Determine the area of the heart muscle where the pathology originated.
Solve the issue of the limitation period of the process.
Choose the appropriate treatment strategy.
Forecast the risk of complications, including lethal ones.
Assigns ECG to any medical professional( doctor, paramedic), who suspected a pathological process in the myocardium.
The research is carried out by
The investigation is carried out by
The tape is deciphered by
Emergency medical personnel in the prehospital phase of
emergency medical personnel Sisters of functional rooms and intensive care units in a hospital
Functional diagnostics physician, therapist or cardiologist at hospital care stage
Interim stages of ECG
ECGsigns of myocardial infarction are of a strict temporal nature, which is extremely important for the choice of tactics of medical measures. The most vividly displayed heart attacks with a large amount of tissue damage( large).
Stage name
Time interval
ECG symptoms
Acute
From the first hours to three days
High S-T position relative to the contour over the infarct area
Tip T thus not visible
Subacute
From the first days to three weeks
Slowreduction of the S-T segment to the line, when it reaches the end of the stage
Negative T
Scarring
From the first week to three months
Gradual return of the T wave to the contour may even become positiveIncreasing the height of the tooth
R
Reduction in the amount of pathological Q( in its original stock)
Click for zoom
Types, depending on the hearth size:
ECG signs of myocardial infarction on ECG has various displays that depend on the affected area. If it is located close to the external surface of the heart muscle or captures the entire wall, then a violation of blood flow originated in a large vessel. With small foci only the terminal branches of the arteries are affected.
Type
Variants
ECG signs
Large or Q-infarction
Transmural - zone captures the entire thickness of the heart wall
No tooth R
Deep, enlarged zQ
recorded Segment S-T high above the line merges with the T-wave over the infarction zone
SegmentS-T below the contour line - according to data from the opposite side infarction
Negative T in the subacute period
Subepicardial - the zone is located next to the outer shell of the
The R tooth is significantly reduced in size, but registering
There is an enlarged and expanded tooth Q
Smoothly passes into the high segment of the S-T over the infarction area of the
Segment S-T below the line in the other leads
The tine T becomes negative in the subacute stage of the
Small-focal or infarction without Q
Intramural -layer
No pathology of R and Q teeth
Segment S-T unchanged
Negative tooth T recorded, which persists for more than two weeks
Subendocardial - an area adjacent to the inner shell of the heart
Teeth R and Q without pathology
Segment S-T below the line more than 0.02 mV
Tine T smoothed or without pathology
Click on photo to enlarge
ECG changes in different location of infarction
Localization of myocardial infarction is determined by data,which are removed by different electrodes from all regions around the heart muscle.
For accurate diagnosis, all 12 electrodes must be applied:
three standard( I, II, III);
three reinforced: from the right and left hands, right legs( AVR, AVL, AVF);
six thoracic( V1-V6).
Click on photo to enlarge
If you suspect a violation of blood flow in the myocardium of an acute nature, it is absolutely unacceptable to use fewer electrodes!
Depending on the location of the affected area on the ECG, the infarction is displayed in the recordings from each of the sensors in its own way.
Anterior or anteroposterior Q-infarction
Leads
Type of changes
Standard 1, 2 and left hand
Abnormal deep tooth Q
Segment S-T above the contour, forms a single curve with a positive tooth T
Standard 3 and from the right leg
The segment S-T below the line passesin the negative tooth T
Thoracic 1-3( with the transition to the apex and 4 thoracic)
No tooth R, instead of it a wide complex QS
Segment S-T above the isoline more than 2-3 mm
From the right arm and pectoral 4-6
Flat tooth T
Slight offset withS-T down
Click on photo to enlarge
Lateral Q-infarction
Leads
Nature of changes
Standard 3, from left hand, right foot and thoracic 5-6
Deep, greatly expanded tooth Q
Increase segment S-T
Tine as a single line with segment S-T
Click on photo to enlarge
Anteroposterior or combined Q-infarction
Leads
Nature of changes
Standard 1, 3, from left hand and right foot, thoracic 3-6
Extensionand a deepening of the tooth Q
Significant elevation of the S-T segment above the
isolate. Tine T positive and merging with the S-T segment.
. Click on the photo to enlarge
. Back or diaphragmatic Q-infarction.
.
leads.
. Standard 2, 3 and from the right leg.
. Deep,wide tooth Q
Segment S-T above the contour, merges with T
Tine T positive
Standard 1
Segment S-T falls below the line
Chest 1-6( not always)
Segment S-T below the contour
The tooth T is deformed,is closer to the negative
Click on photo to enlarge
Q-infarction of interventricular septum
Leads
Nature of changes
Standard 1, left-handed, thoracic 1-2( front part of partition)
Digestion Q
Elevation of segment S-T
Positive tooth T
Thoracic 1-2( posterior part of septum)
Pathological enlargement of the tooth R
Segment of the S-T on the contour or slightly biased down
A-V blockade of any degree
Click on photo to enlarge
Anterior subendocardial not Q-infarction
Leads
Type of changes
Standard 1, left hand, pectoral 1-4
Positive T wave, above R
Standard 2, 3
Gradual reduction of segment S-T
T negative
Decrease in tooth height R
Breast 5-6
Tine T is half positive and the other part below the isoline
Click on photo for enlargement
Rear subendocardial not Q-infarction
Leads
Nature of changes
Standard 2, 3, from the right leg and thoracic 5-6( latter less often)
Decrease of the toothR
Positive T
Later - lowering the segment S-T
Click on the picture to enlarge
Any right ventricular infarction
Combined with anterior lesions of the left ventricle due to a common source of blood flow. According to the ECG, myocardial infarction in the right ventricle is extremely complicated in diagnosis, requires additional electrodes and even rarely is diagnosed in this case.
For its diagnosis, an ultrasonographic examination of cardiac tissue is indicated.
Atypical infarctions
This group includes:
Blood flow disturbances in the myocardium against the background of any forms of bundle bundle blockade.
Early recurrent infarctions.
Repeated abnormalities in the area of cicatrical changes in the heart muscle.
Click on the picture to enlarge
Such pathologies are extremely difficult to diagnose. The main role is played by the degree of doctor's experience, which deciphers the tape, and the presence of previous "pre-infarction" ECG films to isolate new changes.
Without following these requirements, all three types of acute pathology may not be diagnosed.
Click on the picture to enlarge 
Click for zoom 
Click on photo to enlarge 
Click on photo to enlarge 
Click on photo to enlarge 
Click on photo to enlarge 
. Click on the photo to enlarge 
Click on photo to enlarge 
Click on photo to enlarge 
Click on photo for enlargement 
Click on the picture to enlarge 
Click on the picture to enlarge 
