The electrical axis of the heart (EOS) is one ofbasic parameters of the electrocardiogram. This term is actively used both in cardiology and in functional diagnostics, reflecting the processes occurring in the most important organ of the human body.
The position of the electrical axis of the heart showsspecialist what exactly happens in the heart muscle every minute. This parameter is the sum of all bioelectric changes observed in the organ. When removing the ECG, each electrode of the system registers the excitation passing at a strictly defined point. If you transfer these values to the conventional three-dimensional coordinate system, you can understand how the electrical axis of the heart is located and calculate its angle with respect to the organ itself.
How is an electrocardiogram taken?
ECG recording is performed in a special room.maximum shielded from various electrical noise. The patient sits comfortably on the couch, putting a pillow under his head. To remove the ECG electrodes are superimposed (4 on the limbs and 6 on the chest). Electrocardiogram recording is performed with quiet breathing. At the same time, the frequency and regularity of heart contractions, the position of the electrical axis of the heart and some other parameters are recorded. This simple method allows you to determine if there are any abnormalities in the work of the organ and, if necessary, refer the patient for a consultation to a cardiologist.
What affects the location of EOS?
Before talking about the direction of electricalaxis, you need to understand what is the conductive system of the heart. This structure is responsible for the passage of the pulse through the myocardium. The conductive system of the heart is atypical muscle fibers connecting different parts of the body. It begins with the sinus node located between the mouths of the hollow veins. Next, the impulse is transmitted to the atrioventricular node, localized in the lower part of the right atrium. The next baton is the bundle of His, which quickly diverges into two legs - left and right. In the ventricle of the bundle of His, they immediately pass into the Purkinje fibers, penetrating the entire cardiac muscle.
The impulse that came to the heart cannot be avoided.myocardial conduction system. This is a complex structure with fine settings, responsive to the slightest changes in the body. For any irregularities in the conducting system, the electrical axis of the heart is able to change its position, which will immediately be recorded on the electrocardiogram.
EOS Location Options
As is known, the human heart consists of twoatria and two ventricles. Two circles of blood circulation (large and small) ensure the normal functioning of all organs and systems. Normally, the myocardium of the left ventricle is slightly larger than the right. At the same time, it turns out that all the impulses passing through the left ventricle will be somewhat stronger, and the electrical axis of the heart will be oriented towards it.
If you mentally transfer the position of the organ tothree-dimensional coordinate system, it will be seen that the EOS will be located at an angle from +30 to +70 degrees. Most often, these values are recorded on the ECG. The electrical axis of the heart can also be in the range of 0 to +90 degrees, and this, according to cardiologists, is also the norm. Why are there such differences?
The normal location of the electrical axis of the heart
There are three main provisions of the EOS.The normal range is from +30 to + 70 °. This option is found in the overwhelming majority of patients who have come to see a cardiologist. The vertical axis of the heart is found in thin, asthenic people. In this case, the angle values will range from +70 to + 90 °. The electrical axis of the heart is horizontal and is found in low, densely folded patients. In their card, the doctor will mark the angle of EOS from 0 to + 30 °. Each of these options is the norm and does not require any correction.
Pathological location of the electrical axis of the heart
The condition in which the electrical axis of the heartrejected by itself is not a diagnosis. However, such changes on the electrocardiogram may indicate various disruptions in the work of the most important organ. The following diseases lead to serious changes in the functioning of the conducting system:
• coronary heart disease;
• chronic heart failure;
• cardiomyopathy of different origin;
• congenital malformations.
Knowing about these pathologies, a cardiologist will be able totime to notice the problem and refer the patient to inpatient treatment. In some cases, when registering the EOS deviation, the patient requires emergency assistance in resuscitation.
Deviation of the electrical axis of the heart to the left
Most often, such changes on the ECG are noted.with an increase in the left ventricle. This usually occurs with the progression of heart failure, when the body simply cannot fully perform its function. It is not excluded the development of this state and with arterial hypertension, accompanied by pathology of large vessels and increased blood viscosity. In all these conditions, the left ventricle is forced to work for wear. Its walls thicken, leading to the inevitable disruption of the passage of the pulse through the myocardium.
Отклонение электрической оси сердца влево also happens when the aorta is narrowing. In this case, a stenosis of the lumen of the valve located at the exit from the left ventricle occurs. This condition is accompanied by a violation of normal blood flow. A part of it lingers in the cavity of the left ventricle, causing it to stretch, and, as a result, to seal its walls. All this causes a natural change in EOS as a result of improper impulse conduction along the myocardium.
Deviation of the electrical axis of the heart to the right
This condition clearly indicates hypertrophy.right ventricle. Such changes develop in some diseases of the respiratory system (for example, in case of bronchial asthma or chronic obstructive pulmonary disease). Some congenital heart defects can also cause an enlarged right ventricle. First of all, it is worth noting the stenosis of the pulmonary artery. In some situations, failure of the tricuspid valve can also lead to the occurrence of a similar pathology.
What is dangerous about changing EOS?
The most common deviations of the electrical axis of the heartassociated with hypertrophy of a ventricle. This condition is a sign of a long-standing chronic process and, as a rule, does not require the emergency help of a cardiologist. The real danger is the change in the electrical axis due to the blockade of the His bundle. In this case, the impulse conduction along the myocardium is disturbed, which means that there is a risk of a sudden cessation of cardiac activity. This situation requires urgent intervention of a cardiologist and treatment in a specialized inpatient setting.
При развитии этой патологии ЭОС может быть rejected both left and right, depending on the localization process. The cause of the blockade may be myocardial infarction, infection of the heart muscle, as well as taking certain medications. The usual electrocardiogram allows you to quickly make a diagnosis, and therefore, allow the doctor to prescribe treatment, taking into account all the important factors. In severe cases, it may be necessary to install a pacemaker (pacemaker), which will send impulses directly to the heart muscle and thus ensure the normal functioning of the organ.
What if the EOS is changed?
First of all, it is worth considering that in itselfthe deviation of the axis of the heart is not the basis for making a diagnosis. The position of EOS can only give impetus to a closer examination of the patient. With any changes on the electrocardiogram, it is impossible to do without consulting a cardiologist. An experienced doctor will be able to recognize the norm and pathology, and also, if necessary, prescribe an additional examination. This may be an echocardioscopy for the aiming study of the state of the atria and ventricles, blood pressure monitoring and other techniques. In some cases, consultation of related specialists is required to decide on the further management of the patient.
Summing up, we should highlight a few important points:
• The normal value of EOS is the interval from +30 to + 70 °.
• The horizontal (from 0 to + 30 °) and vertical (from +70 to + 90 °) positions of the axis of the heart are permissible values and do not indicate the development of any pathology.
• Deviations of EOS to the left or to the right may indicate various irregularities in the cardiac conduction system and require expert advice.
• The change in EOS detected on a cardiogram cannot be used as a diagnosis, but is a reason to visit a cardiologist.
The heart is an amazing organ that providesthe functioning of all systems of the human body. Any changes occurring in it, inevitably affect the work of the whole organism. Regular examinations of the therapist and the passage of the ECG will allow time to identify the emergence of serious diseases and to avoid the development of any complications in this area.
