Electrocardiogram: interpretation of the results and indications for fulfillment
Electrocardiography is one of the most common and most informative methods for diagnosing a huge number of diseases.ECG involves a graphic display of electrical potentials that are formed in a working heart.Removal of indicators and their display is carried out by means of special devices - electrocardiographs, which are constantly being improved.Table of contents:
ECG: results and capabilities of the
procedure As a rule, five teeth are fixed in the study: P, Q, R, S, T. At some moments, it is possible to fix a small wave U.
ElectrocardiographyAllows to identify the following indicators, as well as variants of deviations from reference values:
- Heart rate( pulse) and regularity of myocardial contractions( you can identify arrhythmias and extrasystoles);
- Disturbances in the heart muscle of an acute or chronic nature( in particular, with ischemia or infarction);
- metabolic disturbances of basic compounds with electrolytic activity( K, Ca, Mg);
- intracardiac conduction disorders;
- hypertrophy of the heart( atria and ventricles).
Please note: When used in parallel with a cardiophone, the allows the electrocardiograph to remotely identify certain acute heart conditions( presence of ischemia or infarction).
ECG is the most important screening technique for the detection of IHD.Valuable information is provided by electrocardiography with the so-called."Stress tests".
Isolated or in combination with other diagnostic techniques ECG is often used in the study of cognitive( mental) processes.
Important: electrocardiogram must be removed during the prophylactic medical examination, regardless of the age and general condition of the patient.We recommend reading:
ECG: indications for
There are a number of pathologies of the cardiovascular system and other organs and systems in which an electrocardiographic study is prescribed.These include:
- myocardial infarction;
- reactive arthritis;
- peri-and myocarditis;
- nodular periarteritis;
- acute renal failure;
- diabetic nephropathy;
Hypertension of the heart departments
With hypertrophy of the right ventricle, the amplitude of the S-wave in the leads V1-V3 increases, which may be an indicator of symmetric pathology from the left ventricle.
With hypertrophy of the left ventricle, the R tooth in the left thoracic leads is clearly pronounced and its depth in the leads V1-V2 is increased.The electric axis is either horizontal or it is deflected to the left, but it can often correspond to the norm.For the QRS complex in the V6 lead, the form qR or R is characteristic.
Note: of this pathology is often accompanied by secondary changes in the cardiac muscle( dystrophy).
For hypertrophy of the left atrium is characterized by a fairly significant increase in the P wave( up to the indices of 0.11-0.14 s).He acquires "two-humped" outlines in the left thoracic leads and leads I and II.In rare clinical cases, some flattening of the tooth is noted, and the duration of the internal deflection P exceeds 0.06 s in the leads I, II, V6.Among the most prognostically reliable evidence of this pathology is an increase in the negative phase of the P wave in the V1 lead.
For hypertrophy of the right atrium, an increase in the amplitude of the P wave( more than 1.8-2.5 mm) in the leads II, III, aVF is typical.This tooth acquires a characteristic pointed shape, and the electric axis P is mounted vertically or has some displacement to the right.
Combined atrial hypertrophy is characterized by a parallel extension of the P wave and an increase in its amplitude.In some clinical cases, such changes as the sharpness of P in the leads II, III, aVF and the splitting of the vertex in I, V5, V6 are noted.In lead V1, an increase in both phases of the tooth is occasionally recorded.
For heart defects formed during intrauterine development, a greater increase in the amplitude of the P wave in the leads V1-V3 is more typical.
Patients with a severe form of chronic pulmonary heart with emphysematous pulmonary involvement are usually identified by the S-type ECG.
Important: The combined hypertrophy of two ventricles is not often determined in electrocardiography, especially if the hypertrophy is uniform.In this case, the pathological features tend to mutually compensate.
Pathological changes in the conductivity of
With the "premature ventricular excitation syndrome" on ECG, the width of the QRS complex increases and the P-R interval becomes shorter.The delta wave, which affects the increase in the QRS complex, is formed as a result of an early increase in the activity of the ventricular heart muscle sections.
Blockades are caused by the termination of an electric impulse in one of the sections.
Impulse conduction impairments are manifested on the ECG by a change in shape and an increase in the size of the P wave, and with intraventricular blockade, an increase in QRS.The atrioventricular blockade can be characterized by loss of individual complexes, an increase in the P-Q interval, and in the most severe cases, a complete absence of a connection between the QRS and P.
Important: The sinoatrial blockade manifests itself on the ECG with a rather vivid picture;It is characterized by the complete absence of the PQRST complex.
For cardiac rhythm disturbances, evaluation of electrocardiography data is performed on the basis of analysis and comparison of intervals( between and intra-cycle) for 10-20 seconds or even longer.
An important diagnostic value in the diagnosis of arrhythmias is the direction and shape of the P wave, as well as the QRS complex.
Dystrophy of the myocardium
This pathology is visible only in some leads.It is manifested by changes in the T wave. As a rule, its pronounced inversion is observed.In a number of cases, a significant deviation from the normal RST line is recorded.The pronounced dystrophy of the cardiac muscle is often manifested by a pronounced decrease in the amplitude of the QRS and P wave.
If the patient develops an attack of angina, then an electrocardiogram shows a marked decrease( depression) of the RST, and in some cases - an inversion of T. DataChanges on the ECG reflect ischemic processes in the intramural and subendocardial layers of the left ventricular heart muscle.These areas are the most demanding for blood supply.
Note: The short rise of the RST segment is a characteristic feature of the pathology known as Prinzmetall's angina pectoris.
Approximately 50% of patients in the intervals between angina attacks do not have ECG changes at all.
In this life-threatening condition, the electrocardiogram provides information on the extent of the lesion, its exact location and depth.In addition, the ECG allows you to track the pathological process in dynamics.
It is morphologically accepted to distinguish three zones:
- central( zone of necrotic changes in myocardial tissue);
- surrounding hearth zone of pronounced cardiac muscle dystrophy;
- peripheral zone of severe ischemic changes.
All changes that affect the ECG dynamically change according to the stage of development of myocardial infarction.
Dyshormonal myocardial dystrophy
Myocardial dystrophy due to a sharp change in the patient's hormonal background is usually manifested by a change in the direction( inversions) of the T wave. Significantly, depressive changes in the RST complex are noted.
Important: The degree of expression of changes over time can vary.The pathological changes recorded on the ECG are rarely associated with clinical symptoms such as pain in the thoracic region.
To distinguish the manifestations of IHD from myocardial dystrophy on the background of hormonal imbalance, cardiologists practice samples using such pharmacological agents as β-adrenoreceptor blockers and potassium-containing drugs.
Changes in the electrocardiogram index against the background of the patient's admission of certain drugs
Changes in the ECG pattern may give the following medicines:
- preparations from the group of diuretics;
- means for cardiac glycosides;
In particular, if the patient takes digitalis preparations( glycosides) at the recommended doses, then tachycardia( rapid heartbeat) and the Q-T interval decrease are determined.The "smoothing" of the RST segment and the shortening of T are also possible. Overdosage with glycosides is manifested by such serious changes as arrhythmia( ventricular extrasystoles), AV blockade and even life-threatening condition - ventricular fibrillation( requires immediate resuscitation).
Thromboembolism of pulmonary arteries
Pathology causes an excessive increase in the load on the right ventricle, and leads to its oxygen starvation and rapidly increasing changes of a dystrophic nature.In such situations, the patient is diagnosed with an "acute pulmonary heart".In the presence of thromboembolism of the pulmonary arteries, blockages of branches of the bundle are not uncommon.
On the ECG, the rise of the RST segment is recorded in parallel in leads III( sometimes in aVF and V1,2).The inversion of T in the leads III, aVF, V1-V3 is noted.
Negative dynamics is increasing rapidly( in a matter of minutes), and progression is noted within 24 hours.With positive dynamics characteristic symptoms gradually dock within 1-2 weeks.
Early repolarization of the cardiac ventricles
For this deviation, the displacement of the RST complex upward from the so-called.Isolines.Another characteristic feature is the presence of a specific transition wave on the R or S teeth. These changes on the electrocardiogram are not associated with any pathology of the myocardium, therefore they are considered a physiological norm.
Acute inflammation of the pericardium is manifested by significant unidirectional elevation of the RST segment in any leads.In some clinical cases, the displacement may be discordant in nature.
Inflammation of the cardiac muscle is noticeable on the ECG by deviations from the T wave. They can range from reducing the voltage to inversion.If in parallel the cardiologist samples with potassium-containing agents or β-adrenoblockers are performed, the T wave retains a negative position.
In the absence of pathologies on the electrocardiogram, a clear rhythm is sinusoidal, and the heart rate per minute varies from 60 to 90. The location of the electric axis corresponds to the physiological norm.
More detailed information on the principles of the electrocardiograph operation and the basic rules for decoding ECG results can be obtained by viewing the video review:
Plisov Vladimir, medical reviewer