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In work of cardiovascular system arrhythmias are considered as the most frequent disturbances. They arise owing to many other disturbances in an organism. Failures in beat of heart, namely also call it arrhythmia, are often observed also at quite healthy people, at the same time they are almost imperceptible, but, nevertheless, lead to some complications.
Origins of arrhythmias
The reasons of arrhythmias are very various, but everything them can be divided into two big groups: disturbances of the carrying-out system of heart and primary diseases which promote emergence of arrhythmia. Therefore we will consider the reasons of arrhythmias in a section of these groups of factors.
Disturbances of the carrying-out system of heart. The normal heart rhythm provides the correct blood circulation in an organism, thereby giving the chance to work correctly with everything to bodies and systems. This rhythm is provided by the carrying-out system of heart which is formed of a network of specialized nodes. Each such node consists of accumulation of highly specialized cells which create and carry out electric impulses on certain bunches and fibers. These impulses force muscles of auricles to be reduced, setting necessary frequency, synchronism and uniformity of their work.
The main node of the carrying-out system of heart is located in upper part of the right auricle. It is called a sinus node or the Kis-Flyaka node. It controls cordial reductions depending on activity of the person, time of day, its nervous excitement. The impulses arising in a sinus node pass through auricles, causing their reduction to an atrioventricular node. This node carries the name of an atrioventricular node and is located on border of auricles and ventricles. He also if necessary can create impulses, but during the normal work of the carrying-out system this node slows down impulses until auricles are reduced, having overtaken blood in ventricles. Then transfers them on the carrying-out fabrics called by a ventriculonector is farther in ventricles, causing their reductions. The ventriculonector is divided into two branches of the leaders consisting of Purkinye's fibers everyone to the ventricle, providing synchronism of their work. After reduction heart has a rest and again the cycle is repeated.
The rhythm within 60-80 beats per minute is called a sinoatrial rate and it is normal cardiac performance and the carrying-out system. Any other rhythm different from normal quantity of blows, call — arrhythmia. It can occur at disturbance of impulses in one of nodes or disturbance of conductivity on any site. The cardiac standstill is observed in 17% of disturbances of a rhythm, but protective function of the carrying-out system works more often and cardiac performance is set by other node.
The diseases promoting arrhythmias. Often arrhythmias arise owing to disturbances in a human body or diseases provocative these disturbances. Increase in blood of level of adrenaline, hormone of a pancreas or falling of level of sugar in blood can promote disturbances of a heart rhythm. Disturbances of a water salt metabolism at which in blood the level of potassium, sodium, calcium and magnesium, acid-base balance when the level of oxygen and carbon dioxide in blood changes changes also provoke a disease.
Arrhythmias arise at diseases of cardiovascular system – atherosclerosis, heart failure, heart diseases. The contribution to disturbances of a heart rhythm is also made also by way of life. Arrhythmia becomes intoxication effect at an alcohol abuse, smoking, the use of drugs, frequent and senseless drug intake. The last factor is often observed at the people self-medicating and the more so self-diagnostics of diseases.
Versions and symptoms of arrhythmias
Today the medicine distinguishes several tens arrhythmias, all of them are followed by almost identical manifestations. But practically always symptoms of arrhythmia is an urezheniye or increase of a rhythm of cordial reductions, their irregularity. Distinguish several groups of arrhythmias depending on disturbances of cardiac performance. It disturbances of automatism, disturbance of excitability, conductivity and the mixed group.
Disturbances of a rhythm can be two types an urezheniye – bradycardia, and increase – tachycardia. At the first case there are such symptoms of arrhythmia as the general weakness, dizziness, an asthma, blackout, fast fatigue, a state close to a loss of consciousness, or a short-term loss of consciousness. At tachycardia a cardiopalmus, an asthma, the general weakness, fast fatigue is felt. Some types of tachycardias conduct to clinical death therefore it is necessary to be extremely attentive at manifestation of such symptoms.
Sinus tachycardia – increase in frequency of a cordial rhythm from 90do 150-180 beats per minute. Increase is caused by increase of automatism of a sinus node at which impulses arise with a bigger frequency. At healthy people it is often connected with an exercise stress, an emotional pressure, reception of some drugs, caffeine, alcohol, nicotine. Temporary increase at anemia, temperature increase, arterial hypotension and other diseases is considered normal. In case of permanent increase in frequency of a cordial rhythm 100 beats per minute are higher, irrespective of a condition of wakefulness and rest within three months regard it as a disease. At diagnosis of an ECG only increase in a rhythm is observed, and there are no other deviations.
Most often the disease occurs at young women. It is considered that the disease is promoted by increase of a tone of a sympathetic nervous system. Treatment of arrhythmia in this case first of all is directed to elimination of the reason of tachycardia. If it is connected with neurocircular dystonia, sedative drugs, beta adrenoblockers are appointed. In case of heart failure apply cardiac glycosides.
The sinus bradycardia – urezheny frequencies of a cordial rhythm is lower than 60 blows in a minute. By the nature such urezheniye is not pathology, often occurs at the healthy people who are especially well trained physically. But if such symptoms of arrhythmia are shown as dizziness, short wind, blackout, a loss of consciousness regard it as a disease.
Developing of bradycardia can be connected with a myocardial infarction, increase of intracranial pressure, a hypothyroidism, viral diseases. A basic reason primary defeat of a sinus node owing to the raised tone of a parasympathetic nervous system is considered. Treatment of arrhythmia is carried out in this case medicamentally, purpose of atropine, an izoprotenol, and carry out electrocardiostimulation. In the absence of clinical manifestations the urezheniye of a rhythm of heartbeat does not demand treatment.
Sinus arrhythmia – a rhythm of heartbeat at which the periods of increase and an urezheniye alternate. The respiratory arrhythmia at which frequency increases on a breath and decreases on an exhalation meets more often. The disease is caused by uneven emergence of an impulse that is connected with fluctuations of a tone of a vagus nerve, and also changes of a krovenapolneniye of heart at breath. Often arises as an associated disease at neurocirculatory dystonia and various infectious diseases.
At diagnosis on an ECG only periodic shortening and lengthening of intervals of R-R which frequency is connected with breath phases are noted. All other indicators are normal as passing of an impulse in wire system is not broken.
The sick sinus syndrome is caused by easing or termination of work of a sinus node. Can arise owing to ischemia of area of a node, a cardiosclerosis, myocarditis, a cardiomyopathy, infiltrative damage of a myocardium. In certain cases the syndrome can be inborn feature of the carrying-out system.
In case of termination of work of a sinus node protective function of the carrying-out system joins, and impulses are given by an atrioventricular node. During such work of the carrying-out system the heart rhythm is slowed down, but a sinus node non-working becomes very rare, more often it works with long breaks. During activation of the main node, the AV-node does not stop giving impulses and there is a considerable increase of a heart rhythm. Characteristic of a disease is the short-term sinking heart that at many patients is not followed by unpleasant feelings, the sinoauricular block having the same signs is one of forms of this syndrome. At such cardiac performance signs of insufficient blood supply of a brain, heart failure can appear.
At this disease often the sinus bradycardia is combined with paroxysms of takhisistolichesky and ectopic arrhythmias. Flickering arrhythmia can be shown, during the work of an atrioventricular node. In certain cases patients do not need treatment. Electrocardiostimulation is carried out only at signs of disturbance of blood supply of bodies, important for life. The drugs which are applied at tachycardia and bradycardia as at frequent change of a rhythm they can strengthen syndrome components are contraindicated to patients. The main treatment goes for elimination of causes of illness.
Excitability disturbances. One of the most frequent types of arrhythmia is the ekstrasistoliya. This premature reduction of heart at emergence of an impulse out of a sinus node. Extrasystoles, or premature reductions can arise both at patients, and at healthy people. Norm emergence to 200 over ventricular and 200 ventricular extrasystoles in days is considered. Most often arises under the influence of a stress, overfatigue, the use of caffeine, alcohol and tobacco. In fact such reductions are absolutely safe. But at patients with organic injuries of heart they can lead to complications.
Ekstrasistoliya can be considered as a syndrome at easy, focal forms of myocarditis. Distinguish atrial, atrioventricular, ventricular extrasystoles depending on the impulses causing reductions. Sources of an impulse can be a little or one is so distinguished by monotopny and polytopic ekstrasistoliya. On frequency divide single ekstrasistoliya to 5 in a minute, multiple – more than 5 in a minute, pair and group. Treatment of an ekstrasistoliya at organic lesions of heart is not carried out by antiarrhytmic drugs as after the termination of their reception the syndrome returns. At the same time increase in mortality is noted almost three times. Beta-blockers at treatment also cause life-threatening complications, and do not bring result. Treatment should be directed on elimination of the disease which caused an ekstrasistoliya.
The Bouveret's disease is a sharp attack of tachycardia with a frequency of rhythm from 130 to 200 beats per minute. Attacks can last of several seconds, about several days. There is a disease owing to emergence of the center of excitement which can become any of departments of the carrying-out system, its cells generate impulses with a big frequency.
Distinguish an atrial and ventricular Bouveret's disease depending on an arrangement of the center generating impulses. The atrial Bouveret's disease arises owing to passing air hunger of heart, endocrine disturbances, disturbance of amount of electrolytes in blood. The atrioventricular node becomes a source of impulses. Arrhythmia symptoms in this case consist in frequent heartbeat, unpleasant feelings in a breast which can pass into short wind and heartaches. In certain cases the attack can be caused by disturbance of work of a vegetative nervous system. At the same time there is an increase of arterial pressure, a fever, feeling of shortage of air, a lump in a throat, a plentiful and frequent urination after an attack. On the usual cardiogram such attacks happen almost imperceptible, because of the short duration.
The ventricular Bouveret's disease arises owing to an acute and chronic form of coronary heart disease, is a little more rare than a cardiomyopathy, heart disease, inflammatory diseases of a cardiac muscle. At 2% of patients arises from overdose or long reception of cardiac glycosides. Impulses arise in ventricles or an interventricular partition. The disease can be dangerous as turns into fibrillation of ventricles. At the same time not all muscle of a ventricle but only separate fibers in a chaotic rhythm is reduced. At such rhythm heart cannot carry out the function as there are no phases of a systole and a diastole.
Treatment of a Bouveret's disease of a ventricular form is carried out by drug lipocainum. Appointing it intramusculary and intravenously, in a case when the effect is not reached it replace novokainamidy, Rhytmilenum, kordaron. If the attack happened for the first time to the patient select arhythmic drug under control of holterovsky monitoring. At an atrial form treatment depends on the disease which caused arrhythmia.
Conductivity disturbances. Increase in conductivity of impulses is called by Wolf-Parkinson-Vayta's syndrome, or WPW syndrome. It is characterized by suddenly arising tachycardias owing to existence in muscles of heart of additional conduction paths. Most often the syndrome is inborn heart disease. At attacks at the patient arterial pressure sharply decreases, there are dizziness, weakness, the loss of consciousness is possible.
Treatment at a syndrome of WPW is carried out by means of endovascular X-ray surgery. By means of a special equipment additional conduction paths collapses that conducts to an absolute recovery of the patient. Hospitalization after such intervention quite short-term only 3 days. But treatment depends on quality of the equipment and professionalism of personnel, it is a little such establishments.
Sinoauricular block – disturbance of carrying out an impulse from a sinus node to auricles at which there is a cordial pause. The disease meets seldom, it arises owing to the raised tone of a vagus nerve or defeat of sinoaurikulyarny area of auricles. It can be observed at patients with organic changes of a myocardium of auricles, but sometimes it is found also in healthy people. Distinguish three degrees of a disease. The first degree is a delay of transition of an impulse from a node to auricles, the second – blocking of some impulses, and the third degree full blocking of impulses.
Such diseases as atherosclerosis of the right coronary artery, inflammatory and sclerous changes in the right auricle, myocarditis can be the reasons of a sinoauricular block. At these deviations there can be proximate causes of blockade when the impulse is not developed in a sinus node, or its force insufficient for depolarization of auricles, the impulse is blocked.
Symptoms of arrhythmia are shown at blockade of the second degree it feelings of interruptions in cardiac performance, feeling of shortage of air, weakness, dizziness. At the third extent of blockade or when there are several losses of a rhythm in a row, there is a substituting rhythm.
The sinoauricular block is one of dangerous forms of weakness of a sinus node. Can lead to brain ischemia with a syndrome of Morganye-Edema-Stoksa. In the presence of persistent bradycardia the atropine injection subcutaneously, Cordiaminum, ephedrine, Isadrinum, Novodrinum, steroid hormones is appointed.
Intra atrial blockade – disturbance of passing of an impulse on an auricle, arises for the same reasons as sinoaurikulyarny. Also distinguish three degrees: the first is characterized by carrying out delay, the second – periodically arising blocking of conductivity of an impulse to the left auricle, the third differs in full blocking of an impulse and atrial dissociation.
Atrioventricular block – disturbance of conductivity of an atrioventricular node at which the impulse from auricles in ventricles is late. Distinguish three extents of blockade, at the same time dividing the second degree into two subtypes. Separately artificial AV blockade is considered. At the first degree passing of an impulse is slowed down, also as well as at other blockade of the first degree. At the second degree there is a delay of carrying out an impulse to partial blocking that is characterized by loss of a rhythm of cordial reductions. AV blockade like Mobitts I observe at athletes, at reception of cardiac glycosides, adrenoblockers, antagonists of calcium, a clonidine, Propafenon, at rheumatism, at myocardites. AV observe blockade like Mobitts II against organic lesion of heart. Symptoms of arrhythmia are characterized by attacks Morganye-Adams-Stokes, and also the same symptoms, as well as a sinus bradycardia. At the third degree there is a total block of impulses at which auricles and ventricles are reduced independently from each other.
The only treatment of arrhythmia at atrioventricular blocks surgical. Carry out implantation of a constant electrocardiostimulator which recovers a normal rhythm of cordial reductions. Displays of bradycardia – short wind, dizziness, faints, and also pauses in cardiac performance, or heartbeat frequency less than 40 beats per minute become indications to operation.
Blockade of legs of a ventriculonector this disturbance of carrying out supraventricular impulses on one or both from legs, is localized both in legs, and in their branchings. At a total or partial block of one of legs the impulse of excitement influences both ventricles, through the unimpaired leg. At the same time bifurcation of cardiac sounds is observed. The total block of both legs leads to a heart block.
The disease caused by fibrous processes which are connected by a coronarosclerosis, limited myocarditis which is in turn connected with focal infection. Blockade of the left leg meets at aortal defects and an arterial hypertension, and right – at inborn and mitral heart diseases.
The mixed group of arrhythmias. Refer disturbances of a rhythm which have symptoms and clinical manifestations of other disturbances to this group of arrhythmias.
The most common form of supraventricular arrhythmia – fibrillation of auricles. Such disturbance is more often carries the name — a ciliary arrhythmia. Chaotic reduction of auricles with a frequency of 400-600 a minute, without coordination with ventricles is characteristic. As the AV-node is capable to pass only 140-200 impulses a minute, there is an irregular reduction of ventricles similar to blinking. The sinus node loses the ability to control the frequency and synchronism of impulses.
Disturbance increases risk of formation of blood clots which in turn can be the stroke reasons. Transition of a paroxysmal form of arrhythmia to a constant form leads to development of heart failure. The ciliary arrhythmia is shown by sharp increase of heartbeat, feeling of interruptions in heart, the general weakness, shortage of air, stethalgias and panic sensation of fear. Attacks can independently pass without drug intake and within several seconds or minutes, but often they can last long enough and demand medical care.
Disturbance at electric and structural changes in auricles develops that often occurs with age. Development of arrhythmia is provoked by organic heart diseases, the undergone open heart operations, diseases of a thyroid gland, an arterial hypertension, and also an alcohol abuse.
Disturbance can have character of attacks or to be constant. Attacks stop by means of medicines or electric methods of regulation of a rhythm. At a constant form of an illness continuous reception of medicamentous drugs is required. Except medicamentous therapy also radical treatment is applied. It consists in radio-frequency isolation of pulmonary veins. Efficiency of this method of 50-70%, but considering its complexity and high cost, operations are performed extremely seldom. Also the artificial atrioventricular block of thirds of degree after which the constant electrocardiostimulator is implanted can be carried out. Such method does not eliminate disturbance, but does it imperceptible for the person.
Diagnosis of arrhythmia
The very first diagnosis of disturbances of a cordial rhythm are their clinical manifestations. Symptoms of arrhythmia are not similar to displays of other diseases, at their emergence it is necessary to make the electrocardiogram. But the diagnosis can be confirmed at registration of the cardiogram only if arrhythmia has constant or steady character. In case of suspicion on arrhythmia of paroxysmal character carry out the round-the-clock registration of the electrocardiogram. This diagnostic method is called Holterovsky monitoring. It consists in continuous registration of a cordial rhythm by means of the sensors attached to the compact device. Sometimes in the daily mode it is not possible to record disturbance.
If not the ECG, holterovsky monitoring does not fix a disease, more difficult diagnosis of arrhythmia at which the factors causing its emergence are defined is carried out. It gives the chance to define the mechanism of its emergence. Carry transesophageal cardiac activation to such researches. The method is used at suspicion on a sick sinus syndrome, for specification of the diagnosis and purpose of the correct preventive treatment, at suspicion on WPW syndrome, the hidden coronary insufficiency, at impossibility of diagnosis of coronary heart disease by other methods. Research consists in imposing of a rhythm through a specialized electrode which is entered like a usual probe and is fixed in a gullet.
Also for detection of arrhythmias carry out tilt – the test. It allows to establish the reason of unconscious states. At test of the patient from horizontal position bring in vertical, with a different force of intensity. The test provokes an unconscious state, and the control of a cordial rhythm and level of arterial pressure which is carried out to inspection time gives the chance to define the reason of a loss of consciousness.
Endocardiac (invasive) electrophysiologic research is considered the most informative research of electrophysiologic properties of heart and the carrying-out system. Such diagnosis of arrhythmia is applied at specification of localization of an atrioventricular block, character of tachycardias and other deviations. Very important is this research at the choice of surgical treatment and the implanted electrocardiostimulators. In certain cases endocardiac electrophysiologic research is used for stopping of heavy arrhythmias.
Examination is conducted only in specially equipped laboratories as this method rather risky. For its carrying out punktirut the main vein of a shoulder, or a femoral vein. Under x-ray control enter electrodes catheters into the right departments of heart, and conduct research.
Complications at arrhythmia
Some types of arrhythmias are followed by acute or chronic heart failure at which there is a sharp falling arterial pressure, a fluid lungs. These are ventricular tachycardias, flickering arrhythmia, an atrial flutter. Full AV blockade and fibrillation of ventricles lead to a cardiac standstill and clinical death.
Sudden cardiac death — natural death owing to heart pathology. It is preceded by acute symptomatology of a heart disease, a loss of consciousness within an hour. But at the same time time of occurrence of death unexpected.
In 83% of cases of a sudden cardiac death are connected with coronary heart disease and a myocardial infarction. Influence development of complications and further fibrillation of ventricles, ventricular tachycardia, diseases of coronary vessels lead to a lethal outcome.
Prevention and treatment of arrhythmia
For prevention of a sudden cardiac death treatment or stopping of arrhythmias is directed. Therapy by antiarrhytmic drugs is for this purpose appointed, ablation of conduction paths of heart, implantation of pacemakers is carried out. Practically any treatment of arrhythmia goes for prevention of its repeated emergence and elimination of associated diseases which most often and are the reasons of arrhythmia. Today there is only one reliable way of elimination of life-threatening arrhythmias. It is therapy by means of the implanted cardioverters-defibrilyatorov, efficiency of this method makes 99% that reduces coronary heart disease mortality rate and after a myocardial infarction. Besides such therapy gives the chance to patients to lead full-fledged life, without limiting their physical capacities.