Sinus bradycardia
The content of the article:
- Kinds
- Causes
- Signs
- Diagnostics
- Features of sinus bradycardia in children
- Sinus bradycardia treatment
- Consequences and complications
- Prevention
Sinus bradycardia is one of the types of arrhythmia, which leads to the development of a violation of the ability of the sinus-atrial node to generate electrical impulses with a frequency of more than 60 per minute.
Sinus bradycardia on ECG
The clinical manifestations of this type of arrhythmia depend on the heart rate. Moderate sinus bradycardia is not accompanied by hemodynamic disturbances. If the heart rate drops to 40 beats per minute or less, the patient may develop a Morgagni-Adams-Stokes attack (fainting triggered by cerebral ischemia), heart failure.
Kinds
Sinus bradycardia is physiological and pathological.
Low heart rate without signs of any pathology is observed in people actively involved in sports. In addition, approximately 25% of men under the age of 30 have a normal heart rate of 50-60 beats per minute. During deep sleep, all people experience a decrease in heart rate by about 30% from baseline. The listed types belong to physiological sinus bradycardia.
Physiological bradycardia is often observed in sportsmen
Pathological sinus bradycardia is one of the manifestations of diseases of the cardiovascular, nervous system or intoxication. In turn, pathological sinus bradycardia is divided into acute (the heart rhythm is restored after the cure of the underlying disease) and chronic.
Depending on the reasons underlying the heart rhythm disturbance, the following types of sinus bradycardia are distinguished:
- organic;
- neurogenic (extracardiac);
- medicinal;
- toxic.
In cases where the cause of a low heart rate remains unknown, they speak of an idiopathic form of sinus bradycardia.
Causes
Different types of sinus bradycardia are caused by different reasons:
- neurogenic, or extracardiac. It is caused by an increase in intracranial pressure (as a result of cerebral edema, subarachnoid hemorrhage, brain contusion, meningitis), Ashner reflex (pressure on the eyeballs), massage of the carotid sinus, Meniere's syndrome, gastric ulcer and duodenal ulcer, gross intubation, myxedema;
- organic. Develops against the background of myocarditis, myocardial infarction, atherosclerosis of the coronary vessels, as well as fibrous and degenerative changes in the sinus node;
- medicinal. It is a complication of drug therapy with cardiac glycosides (Digoxin, Strofantin, Korglucon), calcium channel blockers (Nifedipine, Verapamil), sympatholytic drugs (Reserpine), β-blockers (Anaprilin), narcotic analgesics (Morphine).
- toxic. It can be caused by intoxication with organophosphorus compounds, as well as uremia, jaundice, sepsis, typhoid fever, severe hyperkalemia, hypercalcemia;
- sinus bradycardia of athletes. In people engaged in heavy physical labor or professionally involved in sports, neurovegetative regulation of cardiac output gradually changes, as a result of which the heart rate decreases to 40–55 beats per minute, even during wakefulness. At the same time, no signs of hemodynamic disturbance are found.
Signs
Moderate sinus bradycardia is not accompanied by the development of clinical symptoms, since it causes significant circulatory disorders.
The main symptom of sinus bradycardia is a decrease in heart rate.
Typically, signs of sinus bradycardia appear when the heart rate drops below 40 per minute. These include:
- dizziness;
- fainting or fainting;
- severe general weakness, severe fatigue;
- chest pain;
- feeling short of breath;
- unstable blood pressure;
- impairment of memory and ability to concentrate;
- transient disorders of cerebral circulation;
- transient disturbances of visual function.
Diagnostics
Diagnosis of sinus bradycardia is carried out according to the characteristic complaints of the patient and the data of an objective examination, during which a rare pulse with the correct rhythm, normal sonority of heart sounds, as well as signs of respiratory arrhythmia are determined.
Electrocardiography results confirm the presence of sinus bradycardia:
- decrease in heart rate to 60 per minute or less;
- each P wave corresponds to a QRS complex.
If during the usual recording of an electrocardiogram an attack of bradycardia was not recorded, daily ECG monitoring may be prescribed.
If an organic form of sinus bradycardia is suspected, an ultrasound scan of the heart is recommended, which allows you to accurately determine the size of the heart and its chambers, features of the contractile function, and identify possible areas of degenerative and sclerotic changes in the thickness of the myocardium.
The main method for diagnosing sinus bradycardia is daily ECG monitoring
In some cases, it is advisable to take a chest x-ray, which allows you to identify venous congestion in the lungs.
Exercise bicycle ergometry helps to study the peculiarities of changes in the rhythm of heart contractions under the influence of dosed physical activity.
Sinus bradycardia requires differential diagnosis with the following conditions:
- rhythm from the atrioventricular node;
- atrioventricular block (violation of the passage of an electrical impulse from the sinus node along the pathways of the heart) of the II or III degree;
- sinatrial blockade II degree.
Features of sinus bradycardia in children
Sinus bradycardia in children is considered a violation of the heart rhythm, in which the heart rate is less than the lower limit of the age norm. Thus, in newborns, it is possible to talk about the development of sinus bradycardia when the pulse rate does not exceed 100 beats per minute, and in preschoolers - 70-80 beats per minute.
In childhood, sinus bradycardia, both congenital and acquired, is a frequent pathology, ranking first in the overall structure of all arrhythmias.
The reasons for the development of sinus bradycardia in children are:
- congenital diseases of the cardiovascular system;
- endocrine system diseases (myxedema, obesity);
- diseases of the nervous system (neuroses, meningitis, volumetric formations of the brain, leading to an increase in intracranial pressure);
- overdose of certain drugs, such as cardiac glycosides;
- acute or chronic intoxication of the body (poisoning with nicotine, heavy metal salts);
- a state of convalescence after influenza or scarlet fever.
During the neonatal period, sinus bradycardia develops under the influence of cerebral hypoxia or a low concentration of thyroid hormones.
In adolescents, sinus bradycardia often occurs against the background of increased growth of internal organs, including the heart. Another reason for the development of arrhythmia at this age is hormonal changes in the body and metabolic disorders associated with it, neuroses, etc.
In children, sinus bradycardia may indicate low levels of thyroid hormones.
Moderate sinus bradycardia in children usually occurs without any clinical signs, and is detected by chance during a routine examination. With a more severe course of the pathology, the child complains of dizziness, weakness, chest pain, deterioration of the general condition after physical exertion. In some cases, fainting may occur. Severe sinus bradycardia is accompanied by a decrease in cardiac output, which leads to a deterioration in the blood supply to the brain. As a result, the child's memory deteriorates, concentration of attention decreases.
Sinus bradycardia treatment
Moderate sinus bradycardia, which is not accompanied by the appearance of any clinical symptoms, as well as the physiological form of this condition, does not require therapy.
With the dosage form of sinus bradycardia, it is necessary to revise the ongoing therapy (withdrawal of the drug that caused the violation of the heart rhythm, changing its dose or frequency of administration).
With an extracardiac, organic or toxic form of sinus bradycardia, treatment is aimed at the underlying pathology that caused the heart rhythm disturbance.
In cases where moderate sinus bradycardia is accompanied by dizziness and / or general weakness, belladonna preparations (Bellaspon, Bellataminal, Zelenin drops), caffeine, ephedrine, eleutherococcus extract or tincture of ginseng root are recommended.
If sinus bradycardia is accompanied by dizziness, the patient is shown belladonna drugs
The combination of sinus bradycardia with angina pectoris, ventricular arrhythmia, heart failure, arterial hypotension and syncope is an indication for active therapy (intravenous administration of atropine or izadrin). With its ineffectiveness, as well as the repeated appearance of attacks of Morgagni - Adams - Stokes in the patient, the issue of temporary or permanent cardiac stimulation is decided, that is, the implantation of an artificial pacemaker (pacemaker). Once inserted, the pacemaker takes over the sinus function and generates electrical impulses at a specified frequency. As a result, the heart rate is adjusted to physiological parameters, and the patient's condition is significantly improved.
Consequences and complications
With severe sinus bradycardia, a decrease in cardiac output occurs, which, in turn, reduces the blood supply to organs and tissues, the delivery of oxygen and nutrients to them. The most sensitive to such circulatory disorders are brain cells. Insufficiency of their blood supply leads to the development of hypoxic changes and provokes the development of attacks of Morgagni - Adams - Stokes, the main signs of which are loss of consciousness and generalized convulsive seizure, lasting from several seconds to several minutes. Against the background of an attack, the patient may stop breathing and cardiac activity.
The combination of sinus bradycardia with ectopic arrhythmias, the development of which is due to the presence of additional excitation foci in the thickness of the myocardium, each of which functions independently of the others, significantly increases the patient's risk of thromboembolic complications.
Persistent pronounced sinus bradycardia can cause disability in patients.
Prevention
Prevention of sinus bradycardia consists of the following measures:
- timely detection and elimination of extracardiac pathology and organic heart diseases;
- prevention of poisoning and intoxication that can have a toxic effect on the myocardium;
- carrying out drug therapy with drugs that affect the contractile activity of the myocardium only as directed and under the supervision of a physician.
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Elena Minkina Doctor anesthesiologist-resuscitator About the author
Education: graduated from the Tashkent State Medical Institute, specializing in general medicine in 1991. Repeatedly passed refresher courses.
Work experience: anesthesiologist-resuscitator of the city maternity complex, resuscitator of the hemodialysis department.
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
