Under normal conditions, the human heart beats smoothly and regularly. The heart rate per minute ranges from 60 to 90 beats. This rhythm is set by the sinus node, which is also called the pacemaker. It contains pacemaker cells, from which excitation is transmitted further to other parts of the heart, namely to the atrioventricular node, and to the His bundle directly in the tissue of the ventricles.
This anatomical and functional division is important from the point of view of the type of a particular disorder, because a block in the conduction of impulses or acceleration of impulses can occur in any of these areas.
Disturbances in heart rhythm and conduction are called arrhythmias and are conditions when the heart rate becomes less than normal (less than 60 per minute) or more than normal (more than 90 per minute). Arrhythmia is also a condition when the rhythm is irregular (irregular, or non-sinus), that is, it comes from any part of the conduction system, but not from the sinus node.
Classification
All rhythm and conduction disorders are classified as follows:
- Heart rhythm disturbances.
- Conduction disorders in the heart.
In the first case, as a rule, there is an acceleration of the heart rate and/or irregular contraction of the heart muscle. In the second, the presence of blockades of varying degrees with or without slowing of the rhythm is noted.
In general, the first group includes disorders of the formation and conduction of impulses:
- In the sinus node, manifested by sinus tachycardia, sinus bradycardia and sinus arrhythmia - tachyarrhythmia or bradyarrhythmia.
- According to the tissue of the atria, manifested by atrial extrasystole and paroxysmal atrial tachycardia.
- At the atrioventricular junction (AV node), manifested by atrioventricular extrasystole and paroxysmal tachycardia.
- Along the fibers of the ventricles of the heart, manifested by ventricular extrasystole and paroxysmal ventricular tachycardia.
- In the sinus node and along the tissue of the atria or ventricles, manifested by flutter and fibrillation (fibrillation) of the atria and ventricles.
The second group of conduction disorders includes blockades in the path of impulses, manifested by sinoatrial block, intraatrial block, atrioventricular block of 1, 2 and 3 degrees and bundle branch block.
How to make an appointment with a cardiologist
- It is advisable to undergo an ECG with interpretation and get advice from a qualified doctor by visiting a diagnostic and treatment center. Regular customers note the following benefits of service:
- Modern diagnostic equipment, which makes it possible to obtain an accurate diagnosis and speed up the examination.
- Patients are advised and accompanied by specialists with scientific degrees, doctors of the highest category with many years of practice.
- Carrying out an ECG in the clinic or at home, issuing the result immediately after the study.
- Completion of the study on the day of treatment or any convenient time.
To make an appointment with a cardiologist, just use the feedback button on the Loritom clinic website.
Causes of cardiac arrhythmia
The causes of arrhythmia (the occurrence of heart rhythm disturbances) are so diverse that listing absolutely everything is a very difficult task. However, in many cases, the safety of the arrhythmia for the patient’s life and further treatment tactics depend on the cause of the arrhythmia.
Many different classifications of the causes of arrhythmia have been proposed, but none of them is currently generally accepted. We consider the following classification to be the most acceptable for the patient. It is based on the presence or absence of primary heart disease in the patient. If there is heart disease, the arrhythmia is called organic, and if there is no heart disease, it is called inorganic. Inorganic arrhythmias are also commonly called functional.
Organic arrhythmias
Organic arrhythmias include:
- Arrhythmias arising from coronary heart disease (myocardial infarction, angina). Arrhythmia is caused by damage to the heart muscle. It makes it difficult for electrical impulses to propagate correctly through the conduction system of the heart. Sometimes damage can even affect the cells of the main pacemaker - the sinus node. In place of the dead cells, a scar of connective tissue (cardiosclerosis) is formed, which is not able to perform the functions of a healthy myocardium. This, in turn, leads to the formation of arrhythmogenic foci and the appearance of rhythm and conduction disturbances.
- Rhythm disturbances that occur after an inflammatory process in the heart muscle - myocarditis. As a consequence, after suffering from inflammation, the myocardium is also replaced by connective tissue (cardiosclerosis).
- Arrhythmias observed in cardiomyopathies. For an unknown reason, myocardial cells are damaged, the pumping function of the heart is disrupted, and heart failure develops. In addition, various rhythm disturbances are very often associated.
- Arrhythmias that appear with various heart defects (congenital and acquired during life). It should be noted that there are congenital primary diseases of the conduction system of the heart itself.
Functional arrhythmias
This is also a fairly large group, including:
- Rhythm disturbances of neurogenic origin It is known that the heart is under the influence of the autonomic nervous system, which controls the activity of all internal organs. It consists of sympathetic and parasympathetic nerves. Their effect on the heart is opposite. An increase in the tone of the vagus nerve (this is a parasympathetic nerve) inhibits the work of the heart, and an increase in the tone of the sympathetic nervous system, on the contrary, stimulates its activity. Usually the influence of the vagus nerve and the sympathetic nerves are in a state of balance. However, during the day the activity of the sympathetic division of the autonomic nervous system prevails, and at night - the parasympathetic one. Excessive activation of sympathetic tone is promoted by stress, strong emotions, intense mental or physical work, smoking, drinking alcohol, strong tea and coffee, and spicy foods. The arrhythmias that arise at these moments are called sympathodependent. Often such rhythm disturbances occur in patients with neuroses. Activation of sympathetic tone also occurs in diseases of the thyroid gland, intoxication, feverish conditions, and blood diseases.
- Another group consists of vagus-dependent arrhythmias (from the Latin nervus vagus - vagus nerve). In such patients, interruptions in heart function occur at night. Diseases of the gastrointestinal tract: intestines, gallbladder, peptic ulcer of the stomach and duodenum, and diseases of the bladder can lead to an increase in the parasympathetic effect on the heart and, accordingly, to the appearance of gastrointestinal rhythm disturbances. Reflexes are formed in diseased organs, as a result of which the activity of the vagus nerve increases.
Do cardiac arrhythmias manifest themselves in the same way?
All rhythm and conduction disorders clinically manifest themselves differently in different patients. Some patients do not feel any symptoms and learn about the pathology only after a scheduled ECG. This proportion of patients is insignificant, since in most cases patients note obvious symptoms.
Thus, rhythm disturbances accompanied by rapid heartbeat (from 100 to 200 beats per minute), especially paroxysmal forms, are characterized by a sharp sudden onset and interruptions in the heart, lack of air, pain in the sternum.
Some conduction disorders, such as fascicular blocks, do not show any signs and are recognized only on an ECG. Sinoatrial and atrioventricular blockades of the first degree occur with a slight decrease in heart rate (50-55 per minute), which is why clinically they can manifest only slight weakness and increased fatigue.
Blockades of the 2nd and 3rd degrees are manifested by severe bradycardia (less than 30-40 per minute) and are characterized by short-term attacks of loss of consciousness.
In addition, any of the listed conditions may be accompanied by a general severe condition with cold sweat, intense pain in the left half of the chest, decreased blood pressure, general weakness and loss of consciousness. These symptoms are caused by impaired cardiac hemodynamics and require close attention from a doctor.
How to make a diagnosis?
When and who needs to undergo heart diagnostics?
The doctor prescribes this diagnostic test in the following cases:
- high blood pressure;
- chest pain, shortness of breath;
- dizziness or fainting;
- heart murmurs;
- heart rhythm is disturbed;
- rheumatism;
- diabetes.
An electrocardiogram is also prescribed in case of overdose of certain medications. An ECG is part of the examination during medical examination, prof. examination, pregnancy, preparation for operations.
This is not an exhaustive list of cases when an ECG is necessary. In addition, it is performed without a doctor’s referral.
Types of arrhythmias
Most people by arrhythmia mean erratic contractions of the heart muscle (“the heart beats as it wants”). However, this is not quite true. The doctor uses this term for any disturbance of cardiac activity (decreased or increased heart rate), so the types of arrhythmias can be presented as follows:
- Sinus arrhythmia, which may be associated with cycles of respiratory activity (increased rhythm during inhalation and slower rate during exhalation) or occur independently of breathing, but indicate some kind of cardiovascular pathology (coronary artery disease in old age) or be a consequence of autonomic dysfunction, for example, in teenagers. This type of arrhythmia is harmless and does not require special treatment measures. The ECG shows a difference between cardiac cycles (> 0.05 s).
- Sinus tachycardia is diagnosed if the heart rate exceeds 90 beats/min, of course, for no apparent reason (running, exercise, excitement). Typically, with such tachycardia, the heart rate does not exceed 160 beats per minute under calm conditions, and only during intense exercise can it reach up to 200 beats. It is caused by many factors associated with pathological processes in the body, therefore the treatment of such tachycardia is aimed at the underlying disease.
- Sinus bradycardia is characterized by a regular but slow sinus rhythm (less than 60 beats/min), associated with a decrease in the automaticity of the sinus node and resulting from excessive physical exertion (in professional athletes), pathological changes (not necessarily cardiovascular, for example, peptic ulcer). ), taking certain medications (digitalis, antiarrhythmic and antihypertensive drugs). Therapy is also aimed at eliminating the cause that caused bradycardia, that is, the underlying disease.
- Extrasystoles that occur with premature excitation and contraction of one part of the heart or all of them at once, therefore, depending on where and in what place the impulse was formed that disrupted the normal sequence of heart contractions, extrasystoles are divided into atrial, ventricular and those coming from the atrioventricular node. Extrasystolic arrhythmia is dangerous if it is group, early and frequent, since it poses a threat to hemodynamics, and as a result can “develop” into ventricular tachycardia or ventricular fibrillation, which will have serious consequences. During myocardial infarction, extrasystolic arrhythmia is recorded in 100% of cases.
- Paroxysmal supraventricular (supraventricular) tachycardia, which develops suddenly and also suddenly stops, is characterized by a regular, strict rhythm, although the contraction frequency can reach 250 beats/min. Such tachycardias include: atrial tachycardia, AV nodal tachycardia and tachycardia with WPW syndrome.
- Arrhythmias associated with conduction disturbances (blockades) are usually well recorded on the ECG, are a companion and symptom of various pathologies and are treated by influencing the underlying disease. Blockades that quite often produce (sinoauricular and atrioventricular) bradycardia (40 beats per minute and below) are considered life-threatening and require the installation of a pacemaker that compensates for cardiac activity.
- Atrial fibrillation, in terms of frequency of occurrence, follows immediately after extrasystole and holds 2nd place in prevalence. It is characterized by the formation of excitation and contraction only in certain areas (fibers) of the atrium, when these processes are absent as a whole. Such chaotic and disorderly excitation of individual fibers prevents the passage of impulses into the atrioventricular node, as well as into the ventricles, to which single impulses nevertheless reach, causing excitation there that responds with random contractions.
Based on heart rate, there are 3 forms of atrial fibrillation:
- Heart rate less than 60 beats/min – bradysystolic;
- 60-100 beats/min – normosystolic;
- Heart rate exceeds 100 beats/min – tachysystolic.
On an ECG with AF, the P wave is not recorded because there is no excitation of the atria, and only atrial f waves are detected (frequency 350-700 per minute), which are characterized by irregularity, differences in shape and amplitude, which gives the electrocardiogram a unique appearance.
The cause of MA may be:
- Organic damage to the heart muscle;
- Age-related changes (coronary heart disease, often in combination with arterial hypertension);
- In young people: rheumatism, valve defects (mitral valve stenosis, aortic valve disease);
- Thyroid dysfunction;
- Congenital pathology (heart defects);
- Acute and chronic heart failure;
- Myocardial infarction;
- Acute cor pulmonale;
- Myocarditis, pericarditis;
- Cardiomyopathy.
The incidence of atrial flutter (AF) is 20-30 times lower than AF. It is also characterized by contractions of individual fibers, but a lower frequency of atrial waves (280-300 per minute). On the ECG, atrial waves have a greater amplitude than in AF.
It is interesting that on one ECG you can see the transition of flicker to flutter and vice versa.
The causes of atrial flutter are similar to the causes of fibrillation.
Symptoms of flickering and fluttering are often absent altogether, but sometimes there are some clinical manifestations caused by erratic activity of the heart or symptoms of the underlying disease. In general, such a pathology does not give a clear clinical picture.
ECG results - sinus rhythm
If all the parameters reflected on the cardiogram correspond to sinus rhythm, this means that the innervation impulses correctly follow from top to bottom. Otherwise, the impulses come from secondary parts of the heart.
What does a vertical position mean when there is sinus rhythm on an ECG? This is the normal location of the heart in the thoracic region on the line of the conventional location of the central axis. The location of the organ is permissible at different angles of inclination and in different planes, both vertical and horizontal, as well as in intermediate ones. This is not a pathology, but only indicates the distinctive characteristics of the structure of the patient’s body and is detected as a result of an ECG examination.
