Bradycardia (from the Greek. Βραδυ - slow and καρδιά - heart ) is a type of sinus rhythm disturbance that is controlled by the sinus node (this is the so-called first-order pacemaker ). It is located at the mouth of the upper and lower vena cava, that is, at the place where they flow into the right atrium.
| Bradycardia | |
|---|---|
 ECG sinus bradycardia | |
| ICD-10 | R 00.1 |
| ICD-9 | 427.81 , 659.7 , 785.9 , 779.81 |
| Mesh | D001919 |
Sinus bradycardia is understood as such a change in heart rate, in which there is a decrease in heart rate to 30-50 beats per minute, due to a decrease in the automation of the sinus node .
The causes of this condition are varied:
- sclerotic changes in the myocardium affecting the sinus node ;
- exposure to cold;
- increased tone of the parasympathetic nervous system ;
- increased intracranial pressure (with cerebral edema, tumor, meningitis, cerebral hemorrhage);
- the effect of drugs (digitalis, quinidine);
- lead poisoning , nicotine ;
- hypothyroidism (decreased thyroid function);
- starvation , typhoid fever , jaundice , etc.
Well-trained athletes and certain young healthy people can have a low heart rate (for example, the cyclist Miguel Indurein had a pulse of 28 beats / min at rest [1] ) This is normal in the absence of other pathological symptoms, such as fatigue, weakness, dizziness, fainting, chest discomfort or shortness of breath.
Minor disturbances of the sinus rhythm may not cause any subjective sensations in humans. If a significant decrease in heart rate (less than 40 beats per minute) is observed, then a person may complain of weakness , dizziness , cold sweat, fainting due to brain hypoxia (oxygen starvation), since adequate blood supply does not occur. In any case, it will be useful to conduct an examination with a cardiologist .
Content
ECG signs
This type of arrhythmia can be detected not only by the clinical picture, but also on the electrocardiogram .
- A decrease in heart rate to 59-40 per minute.
- Maintaining the correct sinus rhythm .
- Positive P wave in leads I, II, aVF, V4-V6.
Sinus bradycardia of extracardiac origin, which developed as a result of vagotonia, is characterized by an increase in heart rate during exercise and the administration of atropine and a frequent combination with sinus respiratory arrhythmia. With organic sinus bradycardia (intracardial form), respiratory arrhythmia is absent, after the administration of atropine, the rhythm does not increase, and with physical exertion, heart rate increases slightly.
Danger to the body
If the decrease in heart rate is insignificant, then this does not pose a direct danger to human life. But such changes can serve as the first signal of the beginning of some pathological process in the body from other organs and systems (for example, a change in the function of the thyroid gland ). If the violation of the sinus rhythm is expressed significantly, fainting conditions become very dangerous, since during these periods the risk of sudden cardiac arrest increases. For severe life-threatening illnesses, a pacemaker is recommended.
See also
- Tachycardia
- Sports heart
Notes
- ↑ L'Équipe, France, 2 July 2004
Literature
- Bradycardia // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.