- What is it based on?
- Why is it important to identify signs of angina?
- What is myocardial ischemia?
- Pathogenesis of the disease on the ECG
- What changes on an ECG
- Physical examination
- Differential diagnostics
- The use of physical stress tests and ECG changes
- Localization of the site of ischemia on the ECG
- Severe tachycardia
- Signs of ischemia on an ECG depending on the type of disease
- Clinical recommendations for coronary heart disease
It is rather difficult to answer unequivocally what the ECG results will look like with coronary heart disease on film. When hypoxia of the heart muscle occurs, the movement of electrical potentials slightly slows down, potassium ions exit the cells, which negatively affects the resting potentials. At the same time, compensatory processes are started, the heart begins to overstrain, a pressing pain behind the sternum develops, the patient is disturbed by the unpleasant feeling of lack of air.
Characteristic signs of ECG in chronic coronary heart disease and oxygen starvation of heart tissue are:
- Sloping or horizontal ST segment depression.
- Decrease in the T wave, or its movement below the horizontal line.
- T wave expansion due to slower ventricular repolarization.
- The appearance of a pathological Q wave with the development of large focal necrosis.
- The dynamics of changes in the electrocardiogram, which is a sign of “freshness” of the pathological process.
ECG signs of coronary heart disease should not be ignored. Additionally, signs of arrhythmias and blockages that appear as a complication of ischemic processes may appear on the image. In most cases, with the development of cardiac muscle ischemia on an ECG, the QRS complex retains its normal form, since oxygen deficiency predominantly affects the restoration (repolarization) of the ventricles, which completes the cardiac cycle within normal limits.
Clinical recommendations for coronary heart disease will be given below.
The clinical symptoms of angina pectoris are fairly well known. 75% of patients have:
- paroxysmal pain behind the sternum lasting from a few seconds to 40 minutes;
- irradiation in the left half of the chest, shoulder, lower jaw;
- oppressive or compressive in nature;
- concomitant arrhythmias, dizziness, shortness of breath.
The effectiveness of Nitroglycerin for relieving pain is in favor of angina pectoris.
For a more accurate diagnosis, instrumental examination methods are used. One of the most affordable is electrocardiographic. An ECG for angina pectoris serves as objective evidence and a sign of an imbalance between the oxygen demand of myocardial cells and its intake. The equipment is equipped with ambulances, all outpatient clinics, and feldsher points. Doctors of any specialties are acquainted with possible changes on the ECG.
An electrocardiogram can be prescribed by a doctor of almost any specialization, but most often a cardiologist, therapist or gynecologist (for the diagnosis of pregnant women) gives a direction to the study. The procedure can be carried out as a preventive measure to detect hidden diseases; in the presence of complaints for diagnosis or to monitor the dynamics of treatment.
- the patient has complaints of pain or discomfort in the chest in the heart;
- high blood pressure;
- frequent fainting, dizziness;
- shortness of breath, which can occur not only after physical exertion, but also at rest;
- in the presence of certain diseases: diabetes, rheumatism, after a stroke or myocardial infarction;
- before surgery;
- pregnant women, since in this condition the load on the heart increases significantly, due to an increase in blood volume and a change in hormonal levels;
- people over the age of 40 for the timely detection of diseases that may be asymptomatic (coronary heart disease) or stroke “on the legs”.
The procedure is absolutely safe and has no contraindications, so if there are indications, it can be performed even for women in position or small children.
There are several types of ECG, which allow you to determine the work of the heart muscle in different conditions and under different conditions of the patient. Let’s consider each of them. Classical ECG.
The procedure is carried out in a special room, a patient with a naked torso and legs is laid on a couch.
Special electrodes are located on the chest, arms and legs, which for a certain time record the strength and direction of the electric current that occurs with each heart beat. All indicators are recorded on paper, after which the doctor decrypts them and makes a diagnosis.
ECG according to Holter. Such a study allows you to evaluate the work of the heart in different conditions, since the control is carried out throughout the day. Data is recorded on a special device that is constantly with a person and records indicators at rest, during sleep, during exercise and eating. After the study, the doctor decrypts the result using a computer and makes a “verdict”.
Stress ECG (electrocardiogram with load). During the procedure, the patient performs physical exercises (running on a treadmill or exercising on an exercise bike) and at this time, heart performance is recorded. At the end of the study, the data is decrypted and the data are compared with the results of the ECG at rest.
An ECG does not require special preparation. There are only a few requirements, the observance of which will help to obtain the most accurate results: the procedure must be carried out at least 2 hours after eating, before the study you should rest 10-15 minutes to restore the usual rhythm.
At the end of the study, the patient is given a leaflet with the results of a cardiogram, which must be consulted with a cardiologist for interpretation. When studying the data, special attention is paid to the following indicators:
- Heartbeat. With normal heart function, the gap between the RR teeth will be the same. If they are different, this is a rhythm disturbance and the patient needs additional examination.
- Heart rate (HR). This indicator depends on the age of the patient. So, in a healthy adult, heart rate is 60-90 beats per minute. In children, these data are much higher, for example, in a newborn 140-160 beats / min, in children from 1 to 2 years old – 120-125.
- Source of arousal. In a healthy person, this source is the sinus node, and so the normal rhythm is the sinus node. An increased rhythm indicates tachycardia, and a slower one indicates bradycardia. Pathology is an indication in the ECG results of atrial, ventricular, or atrioventricular rhythms.
- The electrical axis of the heart. Normally, this indicator varies from semi-horizontal to semi-vertical. If the EOS is shifted left or right, this may indicate impaired conduction or myocardial hypertrophy.
- Analysis of the T and P waves. The first shows the attenuation of the excitation of the ventricles and its positive indicator will be the norm. In the case of a negative indicator of the T wave, the development of myocardial infarction or coronary heart disease is possible. The P wave is a reflection of the appearance of an impulse in the cells and the positive data are the norm.
- QRS indicators provide an opportunity to track how an impulse is carried out in all parts of the heart. The norm is its duration up to 0,1 seconds. Changes in indicators indicate myocardial infarction, ventricular tachycardia or blockade of the legs of the bundle of His.
An electrocardiogram is a quick, simple and reliable study of the work of the heart muscle, which allows you to identify the slightest pathological changes. For the procedure, you do not need to prepare or follow strict rules for its implementation. Based on the interpretation of the results, the doctor makes a diagnosis and, if necessary, prescribes treatment or an additional examination.
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What is it based on?
ECG diagnostics is based on the recording of electrical impulses that occur in the heart. For this, an electrocardiograph is used, the principle of which is to register the difference in bioelectric potentials that occur in different parts of the body at the time of contractions and relaxation. Similar processes are recorded on heat-sensitive paper in the form of a graph, which consists of hemispherical or spiky teeth and horizontal lines in the form of gaps. An ECG for coronary heart disease and angina pectoris is prescribed very often.
In order to register the organ’s electrical activity, it is necessary to fix the electrocardiograph electrodes on the legs and arms, as well as on the anterolateral surface of the sternum on the left. This allows you to register all directions of the passage of electrical pulses.
Each of the leads indicates that they record the passage of an impulse through a specific area of the heart, so that doctors receive the following information:
- about the location of the heart in the chest;
- about the structure, thickness and nature of the blood circulation of the atria and ventricles;
- on the regularity of pulses in the sinus node;
- about obstacles in the way of impulses.
Why is it important to identify signs of angina?
At the initial stage of the development of coronary heart disease, pain in the heart occurs only during increased physical or emotional stress, smoking. This type of disease is called “angina pectoris.”
The method of electrocardiography records myocardial malnutrition also only against the background of the clinical manifestations of the attack. After its completion, the ECG has normal parameters, there are no deviations.
This means that typical changes can only be registered if:
- long-term monitoring of the patient with subsequent decoding of the results – the principle is used during Holter examination, when the ECG is recorded from the electrodes attached to the patient during the day;
- artificial provocation of an attack – tests with increased physical exertion, electrical stimulation of the atria, the introduction of special drugs, psychoemotional tests are used.
In ECG cabinets there is a structure of two steps 22,5 cm high for the simplest load test
Professional selection provides for the exclusion of admission of people with initial manifestations of coronary heart disease. Targeted programs to study the prevalence and causes of cardiac diseases need examination of people of different age groups and sex.
a) record before the attack; b) changes in angina are highlighted in red; c) after the attack, everything returned to normal
- Working under stress is a necessary requirement for the health of people in professions related to military service, police, emergency situations, air transportation, and driving. Therefore, when passing the medical commission, tests with physical activity are mandatory.
- In the treatment of angina pectoris, rehabilitation after myocardial infarction or heart surgery, a cardiologist may need to monitor the resistance of the body and heart muscle to physical activity.
- Mass studies of the population to identify early signs of coronary disease are carried out within specific programs and territories. Based on the results of such a survey, morbidity forecasts are built.
- The treatment of coronary heart disease should be started as early as possible, therefore, any means of detecting angina pectoris at the stage of absence of pain manifestations at rest is important.
- The insidiousness of angina pectoris is atypical symptomatology. Attacks can simulate cholecystitis or biliary colic, pancreatitis, gastritis, intercostal neuralgia. Some patients are convinced of a cold and sore throat. In a surgical hospital with an emergency admission of a patient with unclear abdominal pains, an ECG is not complete.
What is myocardial ischemia?
We learn what is ischemic heart disease (ICD-10 I20-I25), or coronary heart disease.
The heart is the most powerful muscle in the human body. It can pump up to 7000 liters of blood per day at a speed of 1,5 km / h, which can be compared with the operation of the pump. In addition, the heart is highly sensitive to oxygen starvation, which often leads to damage to cardiac tissue. The main method in the study of heart disease, including any form of coronary heart disease, is an ECG, which is a registration of electrical impulses performed in all leads, which helps to detect even long-standing symptoms of myocardial ischemia.
IHD (ICD-10 I20-I25) is a condition that occurs as a result of impaired arterial blood flow to the heart muscle due to occlusion of the coronary vessels or their spasm and proceeds in a chronic or acute form. When the necessary amount of oxygen does not enter the heart, portions of connective tissue are formed in the lumens of the muscle fibers, which have lost the ability to fully function.
What can be seen on the ECG with coronary heart disease is interesting to many.
Pathogenesis of the disease on the ECG
The pathogenesis of ischemic heart disease is as follows:
- Stable angina pectoris, which is characterized by pressing paroxysmal pain in the sternum, which occurs under the influence of physical exertion and gradually disappears when stress conditions are eliminated. Most often, ischemic heart disease with rhythm disturbance.
- Unstable angina pectoris, which is an intermediate period between stable ischemia of the heart muscle and the development of various complications. Its main clinical symptom is pain behind the sternum, which develops even in a calm state and can provoke damage to heart tissue cells.
- Small focal myocardial infarction, which is a rather insidious variant of coronary heart disease and is characterized by the absence of a pathological Q wave on the ECG, as well as microscopic foci of tissue death. Often, these violations go unnoticed, as they are disguised as an acute angina attack.
- Q myocardial infarction. The most dangerous complication of myocardial ischemia is large-focal infarction, which is distinguished by a transmural lesion of the heart muscle with elevation of the ST segment and the formation of an additional Q wave, which persists even after absolute replacement of necrotic areas with connective tissue.
Here is how informative an ECG can be with coronary heart disease.
What changes on an ECG
The main electrocardiographic diagnostic signs of angina are:
- ST interval offset;
- changes in the T wave (flattening, downward orientation, high and sharp in shape).
These changes appear on the background of an attack, rarely last from a few minutes to hours after the end of the pain.
If the reduced ST interval and negative T persist longer, we can assume an acute focal
or chronic coronary insufficiency.
The shape of the T wave indicates the depth of the ischemia site:
- with a subendocardial form – T is high in amplitude, the ST segment is simultaneously reduced;
- with subepicardial localization – in addition to T, the ST segment rises and takes the form of an arc.
Against the background of an attack, rhythm and conduction disturbances are often recorded. Cases of the appearance of a negative U wave.
If you suspect angina, the severity of the manifestations is assessed. This disease is characterized by the presence of such a clinical picture:
- soreness in the chest occurs in response to physical or emotional stress;
- sensations have a burning, oppressive and compressive character;
- localization of discomfort in the left side of the chest;
- symptoms spread to other parts of the body;
- an attack of pain lasts about a quarter of an hour;
- for relief, you need to rest or take Nitroglycerin.
Using an assessment of symptoms, the doctor can determine that this is an attack of angina pectoris, and not myocarditis, pleurisy, osteochondrosis and other pathologies. But this is not enough to fully confirm the diagnosis, therefore, other methods are also used.
Since the signs of ischemic processes in some subspecies of this disease coincide, a number of additional examinations have been established to determine a heart attack. Early markers of cardiac muscle necrosis include creatine phosphokinase and myoglobin. For the most accurate diagnosis after 7-9 hours, it is advisable to study the level of troponins, aspartate aminotransferase and lactate dehydrogenase.
The registered changes in the ST segment and T wave are characteristic not only for angina pectoris. They are observed with dystrophic myocardial disorders of various causes, myocarditis, electrolyte disorders.
Medical tests help to distinguish them:
- positive changes after taking Nitroglycerin indicate ischemia of the heart;
- Improving the ECG pattern after taking potassium-containing drugs is not typical for IHD, but confirms electrolyte changes;
- a positive result after taking Obzidan is more characteristic of myocardial dystrophy of neuroendocrine origin, but it is also possible with angina pectoris.
The use of physical stress tests and ECG changes
The use of dosed physical activity to detect hidden pathology, an early stage of the disease is widely used in cardiology. The use of samples is carried out in the presence of a doctor with a preliminary examination and ECG examination. Pulse rate, blood pressure, oxygen consumption are taken into account.
The most commonly used dynamic sample is the Master-Oppenheimer. They introduced the Harvard Step Test in 1929, standardized the study, and developed scorecards. In the modern version, the patient is invited to climb and go down the stairs for 1,5 minutes (simple option) or three minutes (double test). The method is cons >
A person on the track walks or runs on a horizontal surface, but you can lift it and simulate a climb uphill
Depending on the level of education of the patient, his physical activity, special tests can be used to establish the effect of the sympathetic nerve on the occurrence of an attack. For this, samples are required that require increased attention, nervous tension:
- mind count;
- memorizing a series of numbers;
- tasks on the computer.
Execution is limited by time. The initial and repeated ECG are compared.
Electrocardiography is not the only method for diagnosing angina pectoris. It is taken into account in combination with ultrasound. If necessary, transesophageal atrial stimulation, radioisotope scanning, and biochemical blood tests are performed in special centers. The most indicative is angiography of coronary vessels.
Localization of the site of ischemia on the ECG
The endocardium (inner layer) is most susceptible to oxygen deficiency, since blood flows into it much worse than into the epicardium, as a result of which it receives much higher blood pressure, which is filled with the ventricles.
ECG results can vary significantly depending on the volume and location of damaged cardiomyocytes. Changes in the ST segment are often indicative of oxygen starvation of the myocardium, for example, this may consist in depression with a depth of more than 0,5 mm in two or three adjacent leads. Such depression is horizontal and oblique.
ECG changes in coronary heart disease can be directly related to the site of ischemia. In this case, it is observed:
- damage to the anterior wall of the left ventricle in the endocardium, which is characterized by a high T wave and its sharp end, which is distinguished by apparent symmetry;
- hypoxia of the anterior part of the left ventricle with damage to the transmural form of myocardial tissue, which is one of the most dangerous variants of oxygen starvation, in which a smoothed, lowered T wave is observed;
- subendocardial ischemia, which is localized near the endocardium of the back of the left ventricle, on this ECG variant, the T wave will be almost flat and reduced;
- on subepicardial ischemic disturbances on an ECG at an anterior wall of the left ventricle is indicated by a negative T wave having a sharp apex;
- damage to the posterior part of the left ventricle of the transmural type is characterized by a high positive T wave with a sharp apex placed symmetrically.
When the oblique ST segment is observed in the image, this can be characterized by the presence of pronounced tachycardia in the patient. In this case, after eliminating the stress factor and tachycardia, the results of the electrocardiogram, as a rule, show the norm. If the patient was able to undergo an electrocardiographic examination during an acute infarction, then the image can be used to visualize the depression of the ST segment of the oblique type, turning into “coronary teeth” T, which are characterized by a significant amplitude.
Decryption of the ECG in coronary heart disease should be carried out by a qualified specialist.
Signs of ischemia on an ECG depending on the type of disease
The severity of oxygen starvation of the myocardium on an ECG depends largely on the severity and type of coronary heart disease. In cases of mild hypoxia of the heart muscle, this phenomenon can be detected exclusively during exercise, when the clinical symptoms are not significantly expressed.
Examples of ECG depending on the complexity of the pathological process:
- If the patient has mild ischemia, which manifests itself only during exercise, at rest, the result of the study will be normal. With the onset of an attack during training, lead D will experience depression of the ST segment, indicating true ischemia. Moreover, in leads A and I, the amplitude of the T wave can increase, which indicates the normal course of the repolarization process. At about 10 minutes of rest in lead D, ST depression persists and a T wave deepening is noted, which is a direct sign of myocardial hypoxia.
- With stable angina, bouts of pain can occur after a 15-minute walk. At rest, the ECG of such patients is normal in most situations. After mild physical exertion in certain pectoral leads (V4-V6), oblique depression of ST is noted, and the T wave in three standard leads will be negative. The heart of such a patient quickly responds to the load, and violations become noticeable almost immediately. What other forms of ischemic heart disease are?
- Unstable angina pectoris provokes a high risk of heart attack and, as a rule, is clearly visible on the cardiogram. The following changes develop for the presence of hypoxic disorders in ischemia in the anterolateral part of the left ventricle: oblique depression of the ST segment and negative T wave in aVL, I, V2-V6. Often on the ECG single extrasystoles are noted.
- Small focal infarction resembles angina pectoris and often goes unnoticed, and a specific troponin test and careful examination of ECG results help diagnose non-Q infarction. In this case, ST depression in leads V4-V5 and in V2-V6 indicate a negative T wave with amplitude in the fourth lead, which indicates necrotic lesions of the heart muscle.
It is clear that the results of ECG in coronary heart disease vary depending on the type of pathology.
Clinical recommendations for coronary heart disease
The basis of the conservative treatment of stable coronary heart disease is a modification of removable risk factors and complex drug therapy.
It is recommended that patients be informed of the disease, risk factors, and treatment strategies.
When overweight, it is strongly recommended to reduce it with the help of dosed physical activity and a low-calorie diet. If necessary, dietary corrections and / or selection of medication for obesity by a nutritionist.
All patients are advised to follow a special diet and regular monitoring of body weight.
The main goals of drug treatment:
- Elimination of the symptoms of the disease.
- Prevention of cardiovascular complications.
Optimal drug therapy – at least one drug for the elimination of angina pectoris / myocardial ischemia in combination with drugs for the prevention of MTR.
The effectiveness of treatment is evaluated shortly after initiation of therapy.
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