Home Prevention Does the cardiogram show coronary heart disease? The effectiveness of the ECG procedure for ischemic heart disease: how accurate can the diagnosis be at rest, after an attack and with exercise? What is myocardial ischemia

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Does the cardiogram show coronary heart disease? The effectiveness of the ECG procedure for ischemic heart disease: how accurate can the diagnosis be at rest, after an attack and with exercise? What is myocardial ischemia

) lies stenosis of the coronary arteries, which develops as a result of their damage by atherosclerosis. With chronic, mildly expressed stenosis, patients at rest usually do not complain.

If stenosis reaches 50% of the artery lumen or more, symptoms of angina pectoris appear due to a discrepancy between the myocardial need for oxygen and its delivery with the coronary blood flow; At first, symptoms appear only during physical activity (stable angina), and later, as the stenosis progresses, also at rest (unstable angina).

As a result, when a coronary artery is blocked myocardial infarction develops(MI) and, possibly, sudden death (unstable angina and MI are combined into the concept of “acute coronary syndrome”).

IN pathogenesis of coronary stenosis An important role is played by damage to the endothelium of the coronary arteries under the influence of various cardiovascular risk factors. Macrophages, consuming lipid deposits in the intima of the artery, turn into foam cells, which participate in the formation of early atherosclerotic changes.

Further a fibrofatty plaque forms, and then a fibromuscular plaque, which narrows the lumen of the artery. As a result of intimal tears and rupture of the plaque, as well as hemorrhage into it and thrombus formation, partial or complete blockage of its lumen occurs. Clinically, plaque hemorrhage and coronary artery thrombosis manifest as ACS.

From cardiovascular risk factors that contribute to arterial stenosis, the following should be noted:
Age
AG
High low-density lipoprotein cholesterol and low high-density lipoprotein cholesterol
Elevated triglyceride levels
Smoking
Metabolic syndrome
Diabetes
Genetic predisposition
Physical inactivity
Psycho-emotional stress

Risk IHD increases if several risk factors are present simultaneously. The process of stenosis of the coronary arteries can be slowed or even stopped through lifestyle changes (for example, stopping smoking, correcting excess body weight), improving diet (limiting the intake of saturated fat), and prescribing drug therapy (for example, statins - drugs that block cholesterol synthesis) .

Under IHD Currently, a number of coronary syndromes are understood, differing in the severity of clinical manifestations. The vast field of cardiology deals with the treatment of patients with coronary artery disease. IHD is primarily divided into acute and chronic forms. Chronic ischemic heart disease, or ischemic heart disease in the narrow sense of the term, refers to stable angina. The acute form of IHD is designated as ACS.

Further articles on the site will discuss selected coronary syndromes and their characteristic ECG changes, and in some cases, depending on the coronary syndrome, the clinical picture is discussed in more detail.

Educational video ECG for angina and types of ST segment depression

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In the modern world, the number of people suffering from coronary heart disease (CHD) is increasing. This is due to the fact that people lead a sedentary lifestyle and are addicted to fried, fatty and sweet foods. If there is a suspicion that a person has coronary artery disease, then to diagnose this disease, an electrocardiographic study is required, in which an ECG or electrocardiogram is compiled. It records and displays the activity of the heart muscle. What does ischemia look like on an ECG? How to decipher the graphic forms of a cardiogram?

General concept of disease

Due to pathologies of blood flow in the myocardium, IHD develops. The dangerous thing about the development of coronary heart disease is its suddenness, which can lead to death. Since the main cause of ischemia is atherosclerosis, men are more susceptible to this disease. The female body produces a hormone that prevents the occurrence of atherosclerosis. But with the onset of menopause, women's hormonal levels change, so this disease occurs in women mainly in old age.

Using an ECG for coronary heart disease, the following forms of the disease can be identified:

the so-called silent form, when a person does not feel pain;
when the heart stops beating. In this case, the patient can be resuscitated or death occurs;
angina pectoris accompanied by pain;
when the supply of blood to all parts of the heart is stopped, a diagnosis is made of a dangerous disease caused by an acute disruption of the blood supply due to thrombosis (blockage) of one of the arteries of the heart with an atherosclerotic plaque - myocardial infarction;
with prolonged development of the disease, scars form on the heart, resulting in pathology in myocardial contraction.

All signs of ischemic heart disease can be easily diagnosed on an ECG.

Signs of myocardial ischemia can be seen using a cardiogram, thanks to which the disease is detected promptly and quickly.

This method is based on the high conductivity of body tissues and the ability to record electrical cardiac impulses. In the resulting cardiogram, different places are responsible for different manifestations of ischemia. Cardiologists believe that:

myocardial ischemia is determined by the T wave;
ischemic damage is determined by the ST segment;
myocardial necrosis is judged by the Q wave.

About the resting ECG procedure

Diagnosis using an ECG for ischemia is a safe and reliable method for identifying this disease, allowed to everyone without exception. Within 10 minutes, all necessary indicators of heart function will be taken without any consequences for the human body. For this:

it is necessary to free the chest and part of the leg from the knee to the foot from clothing;
the specialist will coat the necessary areas with gel and attach the electrodes;
through the electrodes, all necessary data will be transmitted to the sensor;
the device displays the transmitted information in the form of graphs on paper;
decoding of the results obtained in the form of a graph is done by a specialist.

You can conduct a study based on the ECG method at any time of the day. It can be used to identify the following ischemic disorders associated with ischemia:

pathologies in the cardiac cycle;
determine the signs of a person’s previous myocardial infarction;
changes in heart rhythm;
pathological changes in the myocardium.

About the ECG procedure at the time of manifestation of coronary artery disease

Using an ECG, the damaged area during ischemia is determined. It should be used if symptoms appear when an attack occurs and then disappear. Myocardial ischemia on the ECG looks like this:

the following violations from normal indicators are observed in the polarity of the T waves - they are negative, in amplitude - they can be above 6 mm, they are characterized by symmetry, since the muscles are relaxed due to oxygen starvation in the tissues;
if the T wave is characterized by symmetry, becomes non-negative and higher, then this is quite likely subepicardial ischemia;
When diagnosing a disease, the T wave may be smoothed, have two phases and a reduced appearance. The active electrode is placed in the peripheral area of coronary heart disease, in this case an indicator for diagnosing coronary artery disease can be detected;
even if symptoms of ischemic heart disease are detected, the ST segment does not change;
QRS in IHD does not deviate from the norm.

ECG monitoring

When monitoring an ECG, a sensor is installed on a person’s torso and information is collected for 24 hours, then an assessment is made of the obtained data on the work of the heart in everyday life and a conclusion is drawn about the prerequisites and symptoms of angina pectoris.

Load tests

If there is no attack of the disease and it is not detected in any way on the cardiogram, then stress ECG tests are used, the essence of which is to induce the development of an attack. Under these conditions, blood pressure and heart rate readings are taken. This examination is considered dangerous:

Using a treadmill or exercise bike, the specialist sets the load at which the indicators are recorded.
A drug is introduced into the body that artificially promotes an increase in blood pressure and increased cardiac activity.
A drug is administered that reduces blood flow in the myocardium and develops oxygen deficiency in it.
An electrode is inserted through the esophagus, through which impulses are passed, due to which the heart muscle is stimulated and its contraction frequency increases.

About decoding

Ischemic changes that are recorded on the ECG during coronary artery disease are varied, but in general they can be divided into:

electrocardiographic signs characteristic of the development of ischemia of the heart muscle;
emerging pathologies, the causes of which are ischemic heart disease;
due to necrosis.

We will describe in detail what will happen to the electrocardiogram:

As the disease develops, the following will be observed on the electrocardiogram: The T waves will change. Their height in the area of the chest leads indicates that the disease is developing. One can also assume the source of its occurrence. But if a person is young, then this indicator is the norm for some. Based on whether this indicator is negative or not and the presence of two phases, the diagnosis of the disease is more accurately made.
When the heart muscle receives various pathologies due to the fact that the patient has experienced ischemia, then on the electrocardiogram this will be expressed as a movement of the ST segment relative to the isoline. Depending on whether it rises on the cardiogram or is recorded as depression, the specialist more accurately determines the characteristics of IHD and the location of the pathologies.
When necrosis of the heart muscle occurs, this process will be visible on the electrocardiogram as an altered Q wave or QS complex. But in some cases, with a pathological Q wave, myocardial damage or acute ischemia is observed.
With angina, the T wave changes (it is symmetrical, pointed, negative, or can be biphasic, flattened, rounded) or the ST segment is displaced, but after an attack, changes in the electrocardiogram are normalized.
If a patient suffers from chronic ischemic heart disease, then his heart muscle may have scars, etc., which is reflected in various changes in the electrocardiogram. But they are all constant over a long period of time. In young people suffering from coronary artery disease, the resting electrocardiogram does not show any changes. For such cases, stress ECG tests are used.
If a myocardial infarction has occurred, then a specialist will also be able to see and determine this on an ECG. Myocardial infarction is a severe form of acute coronary insufficiency. The result is necrosis in the area of the heart muscle. On the ECG, the following stages of myocardial infarction are divided: ischemic, damage stage, acute, subacute and cicatricial. At the ischemic stage, lasting from 15 minutes to half an hour, a focus of ischemia is formed. The next stage of damage can last from a couple of hours to three days. The acute stage is also called the necrosis stage. Its duration is from two to three weeks. At the subacute stage, the electrocardiogram reflects changes associated with the necrosis zone and its resorption. The subacute stage is considered complete if there is no T wave dynamics on the ECG. During the scar stage, signs of ischemia disappear on the ECG, but scar changes remain.

When correctly determining the diagnosis, important importance is given to the readings of the electrocardiogram. Its interpretation during ischemia is studied in dynamics. Therefore, it is necessary to study ischemic changes from previous ECGs. Otherwise, a heart attack may be misdiagnosed.

It is also important to know that changes on the ECG are shown only an hour or two after the onset of the attack.

Currently, there are already ECG devices that analyze the depicted picture and make a preliminary diagnosis for the patient. But no one can replace an experienced doctor. Only a cardiologist will be able to correctly interpret the cardiogram and, based on it, correctly diagnose the disease.

Based on the signs of ischemia on the ECG, the characteristics of the disease can be determined. This type of examination is simple and accessible to everyone. But to fully understand the process of development of ischemia in humans, examination using ultrasound and other research techniques is desirable.

Department of Propaedeutics of Internal Medicine and Therapy Topic: ECG for coronary heart disease (angina pectoris and acute myocardial infarction) EchoCG. Lecture No. 9 for 3rd year students studying in specialty 060101 – General Medicine. Assoc. Ph.D. Ivanov A.G. Krasnoyarsk, 2014

Lecture outline:

Relevance of ECG, FCG, EchoCG for diagnosing heart diseases;
ECG for ischemic heart disease:
Principles of bioelectrical mechanisms of ECG measurement;
ECG for various manifestations of coronary artery disease;
3) FCG – general ideas and capabilities of the technique;
4) EchoCS - EchoCG - the essence of the method, diagnostic capabilities;
5) Conclusion.

Relevance of ECG, FCG, EchoCG.

When using these examination methods, the doctor receives important additional information about the functional and morphological state of the patient’s heart. This makes it possible to more accurately establish a diagnosis, prescribe and carry out adequate treatment, and make a more accurate prognosis.

ECG diagnosis of myocardial infarction. The importance of PCG in the diagnosis of heart defects. Basics of echocardiography

Focal myocardial lesion syndrome

Focal myocardial damage means a local circulatory disorder in a certain area of the heart muscle with disruption of the processes of depolarization and repolarization and the appearance of ischemia, damage and necrosis syndrome

Normal ECG

Sinus rhythm, heart rate = 66/min, EOS is not deviated

Myocardial ischemia

ECG during an attack of angina. In leads aVL, V2-V6, horizontal ST depression is up to 2 mm, which indicates subendocardial ischemia of the anteroseptal region of the left ventricle

Signs of myocardial infarction

Fociality
2) Discordance
3) Variability

Localization of myocardial infarction

ECG signs of MI at various stages

Acute stage – ST and T are merged into one wave (monophasic damage potential). Lasts from several hours to several days from the onset of a heart attack

Subacute stage – deep Q, small R, negative T begins to differentiate. Lasts 1-3 weeks from the onset of a heart attack

Recovery stage – deep Q, ST on the isoline, T negative (ischemic T). Duration – 2-6 weeks from the onset of a heart attack

Scarring stage – deep and wide Q, negative T. These changes can remain permanently

Anteroseptal MI.

Posterior MI in the acute stage in II-III, aVF, pathological Q waves, ST elevation similar to a monophasic curve are recorded. Discordant displacement of the ST segment in I, aVL, V1-V4

Dynamics of posterior myocardial infarction

Phonocardiography (PCG)

Phonocardiography is a method of graphically recording sound vibrations that occur during heart activity.

Location of standard points on the chest for recording a phonocardiogram

1 - above the apex of the heart; 2 - in the area of the projection of the mitral valve; 3 - in the area of projection of the tricuspid valve; 4 - above the aorta; 5 - above the pulmonary artery; 0 - zero point

Normal FCG

The value of the interval Q - I tone is 0.02 -0.06 s (less often - up to 0.07 s)
The beginning of the second tone corresponds to the end of the T wave of the ECG and normally can advance this position by no more than 0.02 s or lag behind it by no more than 0.04 s

Phonocardiogram of a healthy 29-year-old person (apex of the heart) The first sound consists of high-frequency oscillations of large amplitude and occurs 0.07 s after the onset of the ventricular ECG complex. The second tone appears 0.02 s after the end of the T wave of the ECG. 0.14 s after the start of the second tone, the third tone is recorded in the range of low and medium frequencies. Top of the wave. The jugular venogram coincides with the final oscillations

Phonocardiogram of patient B., 27 years old (apex of the heart). Severe mitral valve insufficiency. The amplitude of the I and II tones is increased. Immediately after the first sound, an increasing high-amplitude systolic murmur begins, merging with the second sound. 0.14 s after the onset of the 2nd tone, a pathological 3rd tone is recorded

Phonocardiogram of patient B., 35 years old (apex of the heart). Severe mitral stenosis. The amplitude of the first tone is increased. The interval Q - I tone is 0.10 s. Low amplitude systolic murmur. The interval II tone - OS is 0.08 s. The Wells index is 0.02. Pandiastolic murmur with high-amplitude oscillations in protodiastole and presystole

M-mode scanning example

Transesophageal echocardiographic study in the transverse plane: position of the long axis of the left ventricular outflow tract. LA - left atrium, LV - left ventricle, RV - right ventricle, RA - right atrium, LVOT - left ventricular outflow tract.

Parameters of normal echocardiography

Internal diameter of the aorta 2.0-3.6 cm Aortic valve: homogeneous structure Opening of the aortic valve leaflets 1.5-2.6 cm Blood flow velocity in the aorta 1.0-3.5 m/s Diameter of the left atrium 1.9-3.5 cm Thickness RVPW 0.45 Diameter RV 2.8 Thickness IVS 0.6-1.0 (diastole) 0.9-1.4 (systole) Diameter LV up to 5.5 (diastole) 2.2-4.0 (systole) Thickness LVPW 0.7-1.1 (diastole) to 1.6 (systole) Final LV volume (ml) 188-140 (diastole) 38-55 (systole) Contraction fraction 25% Ejection fraction 58-89% Myocardial mass (g) 140-170 Circulation speed fibers 0.0-1.4 Stroke volume (ml) 123-40 Minute volume (l/min) 8.9-3.7 Blood flow velocity through the mitral valve 0.6-1.3 m/s Blood flow velocity through the pulmonary valve 0.6-0.9 m/s Blood flow speed through the tricuspid valve 0.3-0.7 m/s

Conclusion:

That. ECG is one of the main methods for additional diagnosis of ischemic myocardial damage. It allows you to diagnose the location, stage, depth of the lesion

Coronary heart disease (CHD) is one of the most common diseases today. According to official statistics, 30% of deaths in our country are caused by this disease.

The development of coronary heart disease refers to the insufficient supply of oxygen to the heart, sent through the coronary arteries.

One of the dangers of the disease is that patients do not pay attention to the symptoms of IHD; in addition, it can sometimes manifest asymptomatically. ECG is a universal tool for detecting heart disease.

Purpose and procedure of the study

An ECG is aimed at diagnosing diseases and heart defects that can manifest themselves in myocardial infarction, angina, etc.

Deciphering the results will reveal the position of the heart, the size of the ventricles, their modifications, and the presence of inflammatory processes in the muscles of the heart and pericardium.

The procedure is not a complicated or lengthy process: the patient is fitted with special electrodes on each arm and leg, as well as on the chest. Then the device is turned on, recording the heart rate.

What determines the ECG readings?

The readings shown on the electrocardiogram depend on many factors. The main ones are:

duration of illness;
degree of damage;
place of spread of the disease;
reversibility of spread;
associated dysfunctions.

The main signs of IHD during the study

During the ECG procedure, doctors identify two main signs of coronary artery disease: highly probable and possible. The former are characterized by deformation of the ST segment and can be expressed in the forms of elevation and depression.

Elevation is an upward shift of the isoline on the cardiogram; it is a precursor to the appearance of the pre-scar phase on the heart.

Its slight change indicates tachycardia; ischemic heart disease is usually characterized by a more increased shift. The completion of the elevation phase is the appearance of high or negative T.

When conducting an ECG, in addition to elevation, specialists can also detect AV block, Q waves, and atrial fibrillation. In patients with ST elevation, in most cases, myocardial ischemia is detected, with coronary artery occlusion.

The depression phase is typical, usually characterized by vasoconstriction or partial compensation of blood flow.

The depression isoline is located at the bottom of the cardiogram, taking on a negative value.

The main reasons for this phenomenon may be: hyperventilation, the use of certain medications, various heart diseases, hypokalemia, etc.

The remaining deformations of the QRS complex are called possible. Most often, they are expressed by a negative T wave. They, as a rule, do not allow the doctor to diagnose the patient.

Signs of cardiac dysfunction include:

Forms of the disease detected using a cardiogram

Ischemia refers to a decrease in blood supply to certain organs, tissues, or areas of the body due to a decrease or cessation of arterial blood supply. The main forms of IHD are:

Medical institutions performing this procedure