The electrical axis of the heart( EOS) is a clinical parameter that is used in cardiology and is reflected in an electrocardiogram. Allows you to evaluate the electrical processes that drive the heart muscle and are responsible for its correct operation.
From the point of view of cardiologists, the thorax is a three-dimensional coordinate system in which the heart is enclosed. Each reduction is accompanied by a number of bioelectric changes, which determine the direction of the cardiac axis.
Normal values and causes of the violation
The direction of this indicator dependsfrom various physiological and anatomical factors. The average norm is the position of +590.But variants of the normogram fall into a wide range from +200 to +1000 .
In the state of health, the electric axis is shifted to the left under the following conditions :
- at the time of deep exhalation;
- when the body's position changes to horizontal - the internal organs pressurize the diaphragm;
- with a high diaphragm - observed in hypersthenics( low sturdy people).
Right shift in the absence of pathology is observed in such situations :
- at the end of a deep inspiration;
- when the position of the body in the vertical;
- in asthenics( tall lean people) the norm is the vertical position of EOS.
Diagnosis on the ECG
An electrocardiogram is the main tool for determining EOS.To detect changes in the location of the axis, uses two equivalent methods of .The first method is more often used by doctors-diagnosticians, the second method is more common among cardiologists and therapists.
Detecting angle offset alpha.
The value of the alpha angle directly shows the displacement of the EOS in one direction or another. To calculate this angle, find the algebraic sum of the Q, R, and S dents in the first and third standard leads of the .To do this, measure the height of the teeth in millimeters, and when adding a positive or negative value, the specific tooth has a positive or negative value.
Then use a special table - according to Diedu .Substituting the obtained values into it, calculate the exact value of the alpha angle or the displacement of the electric axis.
The value of the sum of the teeth from the first lead is found on the horizontal axis, and from the third - on the vertical axis. The intersection of the lines obtained determines the angle α.
Visual definition of
A simpler and more visual way to determine the EOS - is to compare the R and S teeth in the first and third standard leads of the .If the absolute value of the R wave within one lead is greater than the magnitude of the S-wave, then the R-type ventricle complex is spoken. If on the contrary, the ventricular complex is referred to as the S-type.
When the EOS deviates to the left, the RI-SIII pattern is observed, which means the R-type ventricular complex in the first lead and the S-type in the third. If the EOS is deflected to the right, SI-RIII is determined on the electrocardiogram.
Diagnosis of
What does this mean if the electrical axis of the heart is turned to the left? Displacement of EOS is not an independent disease. This is a sign of changes in the heart muscle or its conduction system, which lead to the development of the disease. Deviation of the electric axis to the left indicates such violations:
- increase in the size of the left ventricle - hypertrophy( LVH);
- malfunction in the operation of the left ventricular valves, which causes the ventricle to overload the blood volume;
- cardiac blockades, for example, blockade of the left leg of the bundle Guiss( on an ECG, it looks appropriately, which you can learn from another article);
- violation of electrical conductivity inside the left ventricle.
Diseases that are accompanied by the
levogram If the patient has a deviation in EOS, may be due to diseases such as:
- ischemic heart disease( CHD);
- of cardiopathy of various genesis;
- chronic heart failure( CHF) in the left ventricular type;
- congenital heart disease;
- myocardial infarction;
- infectious myocardial infarction.
In addition to diseases, the blockade of the conduction system of the heart can lead to the taking of certain medications.
Additional studies
Detection on the cardiogram of the deviation of EOS in the left side is not in itself the basis for the final conclusion of the physician. In order to determine what specific changes occur in the heart muscle, additional instrumental studies are required.
- Bicycle ergometry ( electrocardiogram while walking on a treadmill or on a stationary bike).A test to detect cardiac muscle ischemia.
- US .With the help of ultrasound, the degree of ventricular hypertrophy and the violation of their contractile function are estimated.
- Daily monitoring of ECG by Holter. The cardiogram is removed within 24 hours. Assign in cases of abnormal rhythm, which is accompanied by a deviation of EOS.
- X-ray examination of the of the thorax. With a significant hypertrophy of the myocardium tissues, an increase in the cardiac shadow in the image is observed.
- Angiography of the coronary arteries( CAG) .It allows to determine the degree of coronary artery damage in a diagnosed ischemic disease.
- Echocardioscopy .Allows you to purposefully determine the condition of the patient's ventricles and atria.
Treatment of
Deviation of the electrical axis of the heart to the left of the normal position is not a disease in itself. This is a sign determined by means of instrumental research, which allows to reveal violations in the work of the heart muscle.
Ischemia, heart failure and some cardiopathies are treated with medications. Additional compliance with the diet and healthy lifestyle leads to the normalization of the patient's condition.
In severe cases, surgical intervention of is required, for example, in congenital or acquired heart diseases. If the conductive system is severely disturbed, a pacemaker transplant may be necessary, which will send signals directly to the myocardium and cause its contraction.
The most common deviation is not a threatening symptom. But if the axis changes its position sharply , reaches values of more than 900, then this may indicate the blockade of the legs of the beam of Guiss and threatens to stop the heart. Such a patient requires urgent hospitalization in the intensive care unit. A sharp and pronounced deviation of the electrical axis of the heart to the left looks like this:
Detection of the displacement of the electric axis of the heart is not a cause for concern. But , when identifying this symptom, should immediately consult a doctor for further examination of and identify the cause of this condition. Annual routine electrocardiography allows timely detection of heart abnormalities and immediate therapy.