ECG for coronary heart disease: a transcript of the results. Signs of coronary heart disease on an ECG

What will the ECG show in CHD? This is a common question. We will understand it in more detail.

An ECG is one of the most informative and accessible methods for diagnosing cardiac pathologies, which is based on the registration of pulses passing in the heart and their graphic recordings in the form of teeth on a paper film.

Detailed description of the diagnostic method

Based on such data, conclusions can be drawn not only about the electrical activity of this organ, but also about the structure of the heart muscle. This means that with the help of ECG it is possible to diagnose various heart diseases.

The functioning and contractile activity of the heart is possible due to the fact that spontaneous impulses constantly arise in it. Within normal limits, their source is localized in the sinus node, which is located next to the right atrium. The purpose of these impulses is to pass through the conducting nerve fibers through all sections of the heart muscle, causing their contraction. When the impulse passes through the atria, and then through the ventricles, they alternately contract, called systole. In the period when impulses do not occur, the heart begins to relax and diastole occurs.

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.

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. Patients who previously had a lack of oxygen should be especially careful and undergo a medical examination regularly to prevent the recurrence of coronary artery spasms.

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. The process of damage to the heart muscle always occurs with the development of minor ischemia, which, without appropriate therapy, over time provokes the occurrence of a true heart attack.

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:

1. 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.
2. 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.
3. 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.
4. 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.

Additional examinations

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. Elevation of the ST segment is sometimes observed not only with the development of a heart attack, it is often found with unstable angina, which is why it is necessary to take into account all the visual changes in the teeth on the electrocardiogram.

Manifestations of ischemia on an electrocardiogram

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.

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.
  

Severe tachycardia

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 heart attack, then the image can be used to visualize the depression of the ST segment of the oblique type, which turns 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:

1. 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.
2. 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?
3. 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.
4. 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.

conclusions

In the case of heart muscle infarction, patients often turn to medical specialists for help, however, when it comes to the occurrence of angina pectoris, not all patients are able to adequately assess their condition. In order to prevent the transition of this pathological condition to the acute stage, with a history of ischemic disease, it is necessary to periodically conduct electrocardiography.

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:

1. Elimination of the symptoms of the disease.
2. 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.