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Causes of arrhythmias
Causes of arrhythmias are very diverse, but all of them can be divided into two major groups: disorders of the conduction system of the heart and primary diseases that contribute to arrhythmias. Therefore, we will look at the causes of arrhythmias in the context of these sets of factors.
Disturbances of cardiac conduction system. Normal heart rhythm ensures proper blood circulation in the body, thereby allowing work properly all organs and systems. This rate provides the conduction system of the heart, which is formed from a network of specialized units. Each unit consists of a cluster of highly specialized cells that generate and conduct electrical impulses to certain beams and fibers. It is these impulses cause the muscles of the atria to contract, specifying the desired frequency, synchronicity and regularity of their work.
The head node conduction system of the heart is located in the upper part of the right atrium. It is called the sinus node or Keys node-flick . It monitors the heart rate, depending on the activity of the person, the time of day, it nerve excitation. Pulses originating in the sinus node pass through the atrial contraction causing them to atrioventricular node. This node is called atrioventricular node and is located at the border of the atria and ventricles. He also, if necessary, can generate pulses, but during normal operation of the conduction system of the node slows impulses is reduced atrium, overtaking the blood into the ventricles. And then transmits them by conducting tissues, called bundle branch block next to the ventricles, causing them to reduce. Bundle of His divides into two branches made up of Purkinje fibers each leading to its ventricle, providing synchronization of their operation. After the contraction of the heart is resting and then the cycle repeats.
The rhythm in the range of 60-80 beats per minute is called sinus rhythm and this is the normal functioning of the heart and the conduction system. Any other rhythm different from the normal number of strokes are called - arrhythmia. This can occur in violation of pulses in one of the nodes or conduction disturbance in any section. Heart failure is observed in 17% of arrhythmias, but more often the protective function of the conduction system and the heart asks another node.
Diseases promote arrhythmias. Most arrhythmias are caused by disturbances in the human body or disease provoking these violations. Increase in blood levels of epinephrine, a hormone the pancreas or fall in blood sugar levels may contribute to heart rhythm disturbances. Violations of water-salt metabolism, in which changes in the blood levels of potassium, sodium, calcium and magnesium, acid-base balance when changing levels of oxygen and carbon dioxide in the blood, and provoke the disease.
Arrhythmias occur in diseases of the cardiovascular system - atherosclerosis, heart failure, heart defects. The contribution to cardiac arrhythmias as making and lifestyle. Arrhythmia becomes a consequence of intoxication alcohol abuse, smoking, drug use, and often meaningless medication. The last factor is often seen in people self-medicate, and the more self-diagnosis of diseases.
Varieties and symptoms of arrhythmias
Arrhythmias can be two types of slowing - bradycardia And more frequent - tachycardia . In the first case there are symptoms of arrhythmia as a weakness, dizziness . breathlessness , Darkening of the eyes, fatigue, state close to unconsciousness, or brief loss of consciousness. If tachycardia is felt heart palpitations, shortness of breath, weakness, fatigue. Some types of tachycardias lead to clinical death, so you need to be very careful with the manifestation of symptoms.
Sinus tachycardia - Increase in heart rate from 90do 150-180 beats per minute. Due to the acceleration of the increase of automaticity of sinus node at which pulses occur with greater frequency. In healthy people, this is often associated with physical activity, emotional stress, some medications, caffeine, alcohol, nicotine. Normal it is considered a temporary acceleration in anemia, fever, hypotension, and other diseases. In the case of a persistent increase in heart rate above 100 beats per minute, regardless of the state of wakefulness and rest for three months he regarded as a disease. At diagnostics ECG only observed an increase in the rhythm, and no other abnormalities.
Most often, the disease occurs in young women. It is believed that the disease contributes to improving the tone of the sympathetic nervous system. Treatment of arrhythmia in this case primarily aimed at eliminating the cause tachycardia. If it is associated with soldier's heart Appointed sedatives, beta-blockers. In the case of cardiac insufficiency, cardiac glycosides used.
Sinus bradycardia - Slowing of the heart rate below 60 beats per minute. By its nature, this slowing is not a pathology, is often found in healthy people, especially well trained physically. But if these symptoms occur arrhythmia as dizziness, shortness of breath, blackouts, loss of consciousness it regarded as a disease.
The occurrence of bradycardia may be due to myocardial infarction , Increased intracranial pressure, hypothyroidism , Viral diseases. The main reason is considered to be the primary lesion of the sinus node due to increased tone of the parasympathetic nervous system. Treatment of arrhythmias in this case is carried out with medication, appointment atropine , Izoprotenola and spend pacing. In the absence of clinical manifestations of slowing heart rate does not require treatment.
Sinus arrhythmia - Heart rate at which alternating periods of increased frequency and deceleration. More common respiratory arrhythmia in which the frequency is increased inspiratory and expiratory decreases. The disease is caused by the uneven appearance of the pulse that is associated with fluctuations in vagal tone, as well as changes in blood filling the heart with breathing. Often it occurs as a concomitant disease in neurocirculatory dystonia, and various infectious diseases.
At diagnostics ECG recorded only periodic shortening and lengthening of the intervals RR, the frequency of which is associated with the phases of respiration. All other indicators are normal since the passage of the pulse in the wire system is not broken.
Sick sinus syndrome is caused by a weakening or discontinuance of the sinus node. It may be due to ischemic area of the node, cardiosclerosis, myocarditis, cardiomyopathy, infiltrative myocardial damage. In some cases, the syndrome may be an innate feature of the conduction system.
In the event of termination of the sinus node is activated protective function of the conduction system, and delivers pulses of the atrioventricular node. In this work the conduction system of the heart rhythm slows down, but the sinus node becomes inoperative is very rare, usually it works with long intervals. During activation, the master node, the AV node does not stop feeding pulses and there is a significant acceleration of the rhythm of the heart. A characteristic feature of the disease is short-term sinking of the heart that many patients are not accompanied by unpleasant sensations, sinus block, which has the same features, is a form of this syndrome. In this work of the heart may show signs of insufficient blood supply to the brain, heart failure.
When the disease is often combined with sinus bradycardia paroxysms tahisistolicheskoy and ectopic arrhythmias . It may manifest itself flickering arrhythmia When the atrioventricular node. In some cases, patients do not need treatment. Pacing is performed only when the signs of blood disorders are important to the life of bodies. Patients contraindicated drugs used to tachycardia and bradycardia, since frequent changes of rhythm, they can enhance the components of the syndrome. The main treatment is directed at eliminating the causes of disease.
Beats can be viewed as a syndrome in mild, focal forms of myocarditis. Distinguish Atrial . atrioventricular . ventricular beats, depending on the pulse causes a reduction. Sources pulse may be several or one so distinguished monotopnye politopnye and arrhythmia. As the frequency of individual share to 5 beats per minute, multiple - more than 5 per minute, pair and group. Treatment of arrhythmias with organic lesions of the heart do not spend antiarrhythmic drugs, as after the termination of their admission syndrome returns. This was an increase in mortality is almost three times. Beta-blockers in the treatment also cause life-threatening complications, and does not bring any results. Treatment should be directed at eliminating the disease caused arrythmia.
Paroxysmal tachycardia - A sharp attack of palpitations with a frequency rate of 130 to 200 beats per minute. Attacks can last from a few seconds to several days. There is a disease due to the appearance of focus of excitation, which can be any of the departments of the conduction system, its cells generate pulses with a high frequency.
Distinguish atrial and ventricular paroxysmal tachycardia, depending on the location of the focus of generating pulses. Atrial paroxysmal tachycardia is caused by transient oxygen starvation of the heart, endocrine disorders, the amount of electrolytes in the blood. The source of the pulse becomes the atrioventricular node. Symptoms of arrhythmias in this case are as frequent palpitations, chest discomfort, which may become short of breath and pain in the heart. In some cases, an attack may be caused by disruption of the autonomic nervous system. This results in increased blood pressure, fever, feeling short of breath, a lump in the throat, and excessive frequent urination after the attack. On a normal ECG, such attacks are virtually invisible, because of its short duration.
Ventricular paroxysmal tachycardia is caused by acute and chronic forms of coronary heart disease, a little less cardiomyopathy, valvular heart disease, inflammatory disease of the heart muscle. 2% of patients arises from an overdose or prolonged use of cardiac glycosides. The pulses occur in the ventricles and the interventricular septum. The disease can be dangerous, as goes into ventricular fibrillation. This reduces the ventricular muscle is not all, but only the individual fibers in a chaotic rhythm. With this rhythm of the heart is unable to perform its function, because there are no phases of systole and diastole.
Treatment of paroxysmal tachycardia ventricular shape conducted drug lipokainom . Appointed him intramuscularly and intravenously, in a case where the effect is not achieved it is replaced novokainamid ohm . ritmilenom . kordaron . If the attack was the first time a patient is selected arrhythmic medication under the supervision of Holter monitoring. When atrial form of treatment depends on the disease causing the arrhythmia.
Conduction disorders. The increase in the conductivity of impulses called Wolff-Parkinson-White Or WPW syndrome. It is characterized by sudden-onset tachycardia due to the presence in the muscles of the heart accessory pathways. The most common syndrome is a congenital heart defect. When seizures in patients lowers blood pressure, there are dizziness, weakness, possible loss of consciousness.
Treatment WPW syndrome is performed by endovascular X-ray surgery . By means of special equipment additional pathways destroyed, leading to a full recovery of the patient. Hospitalization after such a relatively short-term intervention only 3 days. But the treatment depends on the quality of equipment and professional staff of such institutions a little.
Sinoauricular block - Violation of the impulse from the sinus node to the atria, which occurs when cardiac pause. The disease is rare, it occurs due to increased vagal tone or defeat sinuauricular atrial area. It can be observed in patients with organic changes in the atrial myocardium, but sometimes found in healthy people. There are three degrees of the disease. The first degree is slowing the momentum of transition from the node to the atria, the second - the blocking of some pulses, and third-degree full blocking pulse.
Reasons sinuauricular blockade can be diseases such as atherosclerosis, right coronary artery, inflammatory and sclerotic changes in the right atrium, myocarditis. If these deviations may occur proximate causes of the blockade, when the impulse is not generated in the sinus node, or a lack of strength to the depolarization of the atria, the impulse is blocked.
Symptoms of arrhythmias occur when the blockade of the second degree is a sense of disruption of the heart, feeling short of breath, weakness, dizziness. When third-degree block or when there are several consecutive deposition rate, there is a replacement rate.
Sinuauricular blockade is one of the most dangerous forms of sinus. It can lead to ischemia of the brain Morgan syndrome-Eden-Stokes . If there is persistent bradycardia injections of atropine subcutaneously kordiamina, ephedrine , Izadrina, novodrina, steroid hormones.
Intraatrial block - Violation of the pulse on the atrium, occurs for the same reasons that sinuauricular. Also, there are three degrees: the first is characterized by a slowdown of the second - periodically arising blocking impulse conduction to the left atrium, and the third is different completely blocked atrial impulse and dissociation.
Atrioventricular block - The atrioventricular node conduction disturbances, in which the delayed impulse from the atria to the ventricles. There are three degrees of the blockade, and the section of the second degree in the two subtypes. Separately considered artificial AV block. At the first degree the passage of the pulse slows down, as well as at other blockades of the first degree. At the second degree is slowing down the momentum of a partial blockage, which is characterized by loss heart rate. AV blockade of type I Mobittsa observed in athletes, when receiving cardiac glycosides, adrenergic blockers, calcium channel blockers, clonidine, propafenone, with rheumatism At myocarditis. AV block type II Mobittsa observed on the background of organic heart disease. Symptoms of arrhythmia characterized by bouts of Morgan-Adams-Stokes equations, and the same symptoms as sinus bradycardia. At the third level there is a full block of pulses in which the atria and ventricles independently.
Bundle-branch block
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