Bradycardia - Causes, symptoms and treatment. MF.
Jun 08, 2018
Causes of bradycardia
Symptoms and Diagnosis
Complications and prognosis
The key to good blood supply to the internal organs are right, rhythmic heartbeats with a frequency of at least 60 and not more than 90 beats per minute. These characteristics of the heart rhythm are supported by the balanced influence of the autonomic nervous system on the contractile activity of the heart muscle. The immediate contraction of the myocardium depends on the speed of the electric pulse on the conduction system of the heart - the faster the impulses are carried out, the more often the heart beats, and vice versa. The path of the pulse in the norm follows in one direction - from the sinus node in the atrium to the atrioventricular( atrioventricular) node, then along the bundle of the Gis between the ventricles to the Purkinje fibers in the walls of the ventricles.
Sometimes in the body as a result of any diseases there are violations of the balance between the influence of the sympathetic and parasympathetic parts of the autonomic nervous system, or in the heart tissues processes that interfere with the normal occurrence and spread of the impulse develop. This can lead to the fact that pulses occur more often or less frequently, sometimes not in those parts of the conducting system, are conducted in the opposite direction or are not conducted through the blocked by the rumen, for example, the site in general. Such conditions are called disturbances of rhythm and conduction, and one of them is a bradycardia.
Bradycardia is a symptom that accompanies many cardiac and some non-cardiac diseases and is characterized by a decrease in heart rate of less than 60 per minute. It can occur both in diseases( pathological bradycardia), and against a background of complete health( physiological).The danger of pathological bradycardia is that with a contraction of the heart with a frequency of less than 40 per minute, blood supply to the brain and other organs is impaired, which can lead to death.
. Depending on which part of the conductive system is affected and interferes with the normal conduct of the pulse, the following are distinguished:
1. Sinus bradycardia occurs when the impulse formation in the sinus node( sinus node weakness syndrome) is violated
2. Bradycardia with heart block.
- with sinoatrial blockade
- with intracardiac blockade
- with atrioventricular blockade
- with blockade of the bundle of Gis
The following types of bradycardia are distinguished by severity:
- mild degree of manifestation( Heart rate 50-60 per min)
- moderately expressed( 40 -50 in min.)
- pronounced bradycardia( less than 40 beats per minute)
Causes of bradycardia
In healthy people, physiological bradycardia is often recorded. For example, the slowing of the rhythm during sleep to 30-40 per minute is considered normal, and is due not only to the prevailing influence of the vagus nerve on the internal organs at night, but also to the onset of an atrioventricular blockade of 1 st. This is often observed in children, adolescents and adults up to 40 years.
Another type of physiological bradycardia is respiratory( sinus) arrhythmia, characterized by an increase in the frequency of heart contractions on inspiration and slowing down on exhalation. It is caused by normal fluctuations of pressure in the chest during inspiration and exhalation, as well as by the peculiarities of the progress of blood through the chambers of the heart, which are conjugated with the respiratory phases.
Also, functional slowing of the rhythm occurs in athletes and persons with well-trained muscles. In an ordinary person, under load, the need for oxygen consumption by the tissues of the body increases, for this the heart should contract more often than usual, that is, tachycardia develops. The athlete is trained not only skeletal, but also heart muscle, which allows the heart to effortlessly provide the body with oxygen.
In the absence of any disease, the listed types of bradycardia have no significant clinical significance. But, like other rhythm disturbances, a bradycardia can develop not only in healthy people, but also in cases of reflex influence on the heart from the side of the nervous system or other organs, or with direct organic damage to the heart tissue.
The main diseases that can cause bradycardia are:
1. Cardiac diseases
- acute myocardial infarction and scarring( cardiosclerosis)
- chronic heart failure
- rheumatic heart disease
- bacterial endocarditis
- arterial hypertension
- heart defects
- atherosclerosis of the aorta and coronaryarteries
- heart injuries
2. Diseases of the nervous system
- trauma and brain tumors
- increased intracranial pressure
- brain disordersblood circulation
- neurotic states
3. Endocrine diseases
- hypothyroidism - thyroid function deficiency
- Adrenal insufficiency( Adison's disease)
4. Internal organs diseases
- terminal stage of renal and hepatic insufficiency
- peptic ulcer and 12-of the digestive tract
5. Overdose of drugs
- beta blockers( bisoprolol, carvedilol, etc.)
- antiarrhythmic drugs
-Calcium channel locators( verapamil, diltiazem)
- cardiac glycosides( digoxin, korglikon)
6. Pathological processes in the body
- chronic alcohol abuse
- infectious diseases( typhoid, hepatitis, meningococcal infection)
- electrolyte disturbances due to dehydration,fever( violation of the balance of potassium, calcium and sodium in the blood)
- shock of various origins( cardiogenic, arrhythmogenic, traumatic, etc.)
Clinical symptoms of bradycardia
Awilo, physiological and easy bradycardia, patients do not feel subjectively. Symptoms of pathological bradycardia are determined by the underlying disease that caused a slowing of the heart rate. From the side of the heart there are complaints of pain in the chest, dyspnea, swelling of the extremities. There is drowsiness, fatigue, noise in the ears, persistent dizziness, pale skin.
If the heart rate is 50 beats per minute or less, the patient may be disturbed by loss of consciousness. These are very dangerous situations, called Morganya-Edessa-Stokes attacks( MES attacks).Due to acute cerebral hypoxia, since cardiac output of arterial blood can not adequately provide brain cells with oxygen. A patient against a background of complete well-being or previous subjective discomfort pales, loses consciousness and falls. Loss of consciousness may be accompanied by convulsions due to transient ischemia of the brain, but, unlike epilepsy, there is no aura characteristic of an epileptic attack before an MES attack. Loss of consciousness with bradycardia lasts no more than 1 - 2 minutes, after which the patient comes to, and the skin turns pink. Seizures can occur with varying frequency - from one throughout life to several during the day. If a patient develops an episode of unconsciousness at least once, accompanied by a bradycardia of the ECG, he should necessarily go through the necessary research and treatment prescribed by the doctor.
Diagnosis of the disease
A bradycardia that does not appear clinically is detected, as a rule, during the passage of the planned ECG.
In the presence of characteristic complaints, the diagnosis of bradycardia can be suspected even during a survey and examination of the patient, and to specify its type and the cause that caused the slowing of the rhythm, the following diagnostic methods are prescribed:
1. ECG.Signs of bradycardia on the ECG - a reduction in the heart rate less than 60 per minute, combined with a syndrome of weakness of the sinus node or conduction disorders( blockades).
Sinus bradycardia - heart rate 40-60 per minute, rhythm sinus, correct.
Syndrome of sinus node weakness, depicted in the figure - persistent sinus bradycardia, sinoatrial blockade, against a background of a rare rhythm of atrial fibrillation or ectopic tachycardia
Symptoms of bradycardia can be combined with myocardial ischemia, atrial or ventricular hypertrophy.
2. Daily monitoring of the ECG must be prescribed to the patient with complaints of heart failure, regardless of whether episodes of bradycardia were recorded on a single ECG or were not. Allows you to assess the presence of bradycardia throughout the day, as well as to establish their relationship with physical activity and household activity of the patient.
3. The ultrasound of the heart allows evaluating the contractile function of the myocardium and revealing the structural changes in the cardiac tissues that caused rhythm disturbances.
4. Samples with physical activity allow to identify the adaptive capabilities of the body in relation to physical activity. Used tredmil test or veloergometriya.
5. EFI - is more often prescribed a transesophageal electrophysiological study of the heart than endocardial. It allows provoking a bradycardia if it was not possible to register with ECG and daily monitoring, and the patient makes specific complaints.
6. Coronarography is assigned to confirm or exclude the coronarogenic nature of arrhythmias. It allows to visualize coronary arteries and to assess their patency or degree of lesion with atherosclerosis.
7. MRI of the heart can be appointed according to the indications for detecting organic heart damage and clarifying its localization.
Treatment of bradycardia
Therapy with asymptomatic forms of bradycardia and in the absence of the underlying disease is not indicated.
With moderate and severe bradycardia, accompanied by clinical manifestations, and even more bouts of MES, treatment of the underlying disease is prescribed. With successful elimination of the causative factor, the bradycardia disappears.
Emergency care for bradycardia accompanied by manifestations of the disease( dizziness, general weakness, drowsiness, pre-patency) - the patient can take half of the tongue or an entire tablet of idazrin 0.005, or one fourth or half of the tablet of the theophedrine.
Emergency care for MES is as follows:
- to lay the patient with raised legs to ensure blood flow to the brain and to the heart
- measure blood pressure and count the pulse on the carotid( neck) or arm( ASUS) wrist
-immediately call an ambulance
- in the absence of consciousness for more than two minutes, accompanied by a lack of heartbeat and breathing, begin cardiopulmonary resuscitation according to the scheme of 15 strokes on the sternum through two injections of air into the lungs by the method of rom in the mouth before the occurrence of self-breathing or the arrival of the resuscitation team, but no more than within 30 minutes
The ambulance will perform the following measures:
- temporary cardiostimulation with the help of the defibrillator
- atropine 0.1% - 1 ml intravenously strontaneously( up to 4ml per day)
- dopamine 200 mg per 200 ml saline intravenously drip
- adrenaline 1% - 1 ml per 200 ml saline intravenously drip
- eufillin 2.4% - 5 to 10 ml intravenously stripped
- prednisolone 50 mg intravenously stripped
Bthe caseae of mild or moderate bradycardia, not accompanied by signs of a heart attack, stroke, acute heart failure, the patient after a cupping bouts of bradycardia can be left at home under the supervision of a district doctor from a polyclinic.
Severe bradycardia, especially accompanied by an attack of MES, signs of a heart attack, pulmonary edema or other impending complications, is an indication for inpatient arrhythmology or cardiology.
In the absence of effect from the treatment of the underlying disease, in the presence of atrioventricular blockade of 2 to 3 degree, complete blockade of the bundle of the Guiss, especially against the background of acute myocardial infarction, and also in combination with ventricular tachyarrhythmias( frequent ventricular extrasystole, paroxysmal ventricular tachycardia), the patient may bethe implantation of the pacemaker is shown according to the indications determined by the arrhythmologist and cardiac surgeon.
The figure shows an artificial pacemaker, sewn under the skin above the chest with the electrodes in the heart.
Lifestyle with bradycardia
Light and moderate bradycardia does not require a radical change in the usual physical activity or daily activity. It is enough to observe the principles of a healthy lifestyle, the basis of rational nutrition and to develop an adequate mode of work and rest.
In severe bradycardia with MES attacks, the patient should avoid excessive psychotraumatic situations, significant physical exertion.
It is useful for both categories of patients to know that with bradycardia it is desirable to eat foods such as walnuts, a mixture of honey, lemon and garlic, as well as a yarrow broth, as these products have a beneficial effect on the contractile ability of the heart muscle. All people with diseases of the cardiovascular system need to get rid of bad habits, observe a diet with the consumption of low-calorie foods and often rest in the fresh air.
If bradycardia develops in a pregnant woman, the ability to endure a child depends on the underlying disease. As a rule, mild and moderate bradycardia does not affect the supply of oxygen to the fetus. If the future mother takes any medications, she should agree on the possibility of their admission with the attending obstetrician.
Complications of bradycardia
Physiological, mild and moderate bradycardia, as a rule, do not lead to complications.
The main complication of severe bradycardia and MES attacks is asystole( cardiac arrest) and clinical death due to cerebral ischemia. In addition, there is a high probability of thromboembolic complications - thromboembolism of pulmonary arteries, ischemic stroke or myocardial infarction. Due to impaired conduction of the pulse, bradycardia may develop frequent ventricular extrasystole or paroxysmal ventricular tachycardia, which is fraught with the onset of ventricular fibrillation and death.
The prognosis for the physiological and mild forms of bradycardia is favorable. If the patient suffers from a disease leading to the development of moderate and severe bradycardia, the prognosis is determined by the stage of the cardiac disease or by the character of the non-cardiac disease that caused the bradycardia. For example, if the patient has hypothyroidism, but with the hormone replacement therapy in the body, an adequate level of thyroid hormones is maintained, then the prognosis from the heart is favorable. If the cause is chronic heart failure in the terminal( final) stage, the prognosis will be unfavorable, especially since it is unlikely that such a patient will be prone to interference with the pacemaker installation due to general exhaustion of the body and the presence of contraindications for the operation.
Doctor therapist Sazykina O.Yu.