Cardiac arrhythmias - Causes, Symptoms and Treatment .MF .
cardiac arrhythmia - is any abnormal heart rhythms characterized by a change in frequency, regularity and consistency of cardiac contractions as a result of violations of the basic functions of the heart: automatism, excitability and conductivity.
Causes of cardiac arrhythmias
Arrhythmias are identified at an organic lesion of the heart: myocardial infarction, heart disease, etc., in violation of the functions of the autonomic nervous system, changing the water-salt balance, intoxications.Arrhythmias can occur even in otherwise healthy people on the background of pronounced fatigue, colds, after taking alcoholic drinks.
Many heart rhythm disturbances can not be felt by the patient, and do not lead to any consequences (sinus tachycardia, atrial premature beats), and more evidence of any extracardiac pathology (eg, increased thyroid function).The most dangerous is ventricular tachycardia, which may be the direct cause of sudden cardiac death (83%).No less dangerous for life and can be bradycardia, esp
What makes a normal heart rhythm Normal rhythm
provides cardiac conduction system.It is a consistent network of "power" (knots) - clusters of highly specialized cells able to create and execute on certain bundles of fibers and electrical impulses, which in turn causes excitation and contraction of the heart muscle (myocardium).
Although all elements of the conducting system capable of generating electrical pulses, the main power plant is the sinus node, located in the upper part of the right atrium.It sets the desired frequency of the heart (in the rest of 60-80 beats per minute during exercise - more during sleep - less).Pulses, "born" in the sinus node, spread out in all directions, as the sun's rays.Part of the pulse causes the excitation and contraction of the atria and the other - on special paths of the conduction system is sent to the atrioventricular node (AV increasingly talking point) - the next "power."The AV node slows down the momentum going (atria should have time to cut and overtake the blood into the ventricles).Further pulses are distributed to the bundle branch block, which, in turn, is divided into two legs.The right leg of the beam via the Purkinje fiber conducts impulses to the right ventricle of the heart, the left, respectively, to the left ventricle, causing their excitation and contraction.It is thus ensured rhythmic work of the heart.
in the cardiac conduction system may have two problems:
- violation education pulse in one of the "power".
- violation of the pulse in one of the sections of the system described.
In both cases, the primary function of the pacemaker takes over following the chain of "power."However, the heart rate is intermittently while less.
Thus, the cardiac conduction system is multi-layered protection from sudden cardiac arrest.But violations in its work possible.That is they give rise to arrhythmias.
Arrhythmias - a heart rhythm disorders that are accompanied by:
- deceleration (less than 60 beats per minute).
- quickening (more than 100 per minute).
- or irregular heart rate.
slowing of the heart rate is called bradycardia (bradi - rare), increased - tachycardia (Tahi - part).
There are dozens of types of arrhythmias.Here, we will give you an idea of the mechanisms of the most common and widespread of them.These include:
1. basic types of bradycardia:
- sick sinus syndrome.
- atrioventricular block (most say AV block).
2. irregular rhythm:
3. main types of tachycardia:
- Supraventricular (supraventricular) tachycardia.
- Atrial fibrillation (atrial fibrillation).
- Ventricular tachycardia.
Depending on the location of "home", supraventricular tachycardia are divided into, or supraventricular (for its location in the atria or the AV node region), and ventricular.
Depending on the duration, tachycardia divided into paroxysmal and persistent.Paroxysmal tachycardia - a sudden sharp acceleration of heart rate, lasting from a few seconds to several days, which is stopped as suddenly as it begins (often without interference).Permanent tachycardia - a long (more than 6 months) acceleration of the heart rate, resistance to drugs and electrotherapy (electrical cardioversion).
syndrome sick sinus uzlaobuslovlen violation impulse formation in the sinus node, or violation of the pulse "output" of the sinus node in contact with atrial tissue.This pathology can be accompanied by a stable bradycardia or recurring pauses in the work of the heart, caused by the so-called sinoatrial blockade.
Sinus bradycardia may occur in healthy, well-trained people, or be a sign of a pathological condition.For example, hypothyroidism (low thyroid function), increased intracranial pressure, some infectious diseases (typhoid fever), asthenia common during prolonged starvation.
atrioventricular block is a violation of the "bandwidth" of the AV node.When AV block first degree of impulse conduction through the AV node slows down when the second - to the ventricles applies only every second or third impulse came from the sinus node, with third degree (complete transverse blockade) - holding by ABfully-node locked.In this case cardiac arrest does not occur because, "comes into play" bundle of His, or the underlying structure of the conducting system of the heart, but it is accompanied by a rare heart rhythm, about 20-40 beats per minute.
Extrasystoles - is premature contraction of the heart (extra - over).We already know that all the structural units of the cardiac conduction system is able to generate electrical pulses.Normally, the main "power station" is the sinus node, since he is able to generate pulses with the greatest frequency.However, under the influence of various factors (arteriosclerosis, and other toxic) may appear abnormal (increased) activity of one of the structures of the cardiac conduction system, which leads to extraordinary heartbeat, which may follow after a compensatory pause.This is one of the most common types of arrhythmias.Depending on the appearance of the place, beats are divided into supraventricular (supraventricular) and ventricular.Single beats (up to 5 per minute) is not life-threatening, while frequent, pair and group ventricular is an unfavorable sign.
Supraventricular (supraventricular) tachycardia. For this type of tachycardia is characterized by increased heart rate to 140-180 beats per minute, due to the individual characteristics of the structure of the AV node or abnormal (increased) activity of one of the links in the cardiac conduction system at the level of the atria.To this species belongs tachycardias and Wolff-Parkinson-White syndrome (WPW syndrome), caused by the presence of additional congenital way of.In this pathology of atrial impulse through the AV node to the ventricles propagates, but after excitation, instantly, on a further way back to the atria, causing them to re-excitation and over again through the AV node to the ventricles is conducted.pulse movement can also occur in the opposite direction (downward in the ventricles - through an alternate path, up to the atria through the AV node).Such a pulse circulation can occur indefinitely and be accompanied by a high heart rate (over 200 beats per minute).
Atrial fibrillation (atrial fibrillation) - the most common form of supraventricular arrhythmia, which is characterized by chaotic atrial contraction of individual muscle fibers with a frequency of 400-600 per minute.It is important to note that the AV node in the heart not only performs the function of "power" and "conductor", but also the role of the filter frequency pulses conducted to the ventricles (normal AV node is able to undertake 140-200 cpm).Therefore, in atrial fibrillation only part of these impulses reach the ventricles, and their reduction is fairly chaotic, resembling flicker (hence the name of atrial fibrillation).Sinus node at the same time loses its function pacemaker.
Ventricular tachycardia - severe rhythm disturbance, manifested ventricular contraction with a frequency of 150-200 per minute.The "home" field is located directly in one of the ventricles of the heart.At a young age, this arrhythmia is most often caused by structural changes in the right ventricle, in old age - more common after myocardial infarction.Risk of cardiac arrhythmias determined by the high probability of its transition to fibrillation (flickering) of the ventricles, which, without the provision of emergency medical care, can lead to sudden death of the patient.The severity of these types of arrhythmias due to the lack of full contraction of the ventricles of the heart and, as a consequence, the lack of adequate blood supply to vital organs (especially the brain).
What is atrioventricular block?
atrioventricular block - is a violation of the "bandwidth" of the AV node - which is the "connecting link" between the atria and ventricles.When AV block first degree of impulse conduction through the AV node slows down when the second - to the ventricles is conducted only every second or third impulse came from the sinus node, with AV block 3rd degree (complete transverse blockade) -pulse conducting from the atria to the ventricles completely stops.In this case cardiac arrest does not occur because, as the main "power" comes in a bundle branch block or other structure of the cardiac conduction system.This is accompanied by a rare heart rhythm, about 20-40 beats per minute.
What are the clinical manifestations of atrioventricular block?
With this type of cardiac conduction are usually concerned:
- general weakness;
- shortness of breath;
If bradycardia appears:
- episodes of blackout;
- state close to unconsciousness ( "I want to grab hold of something, not to fall").
WARNING!The extreme manifestations of bradycardia are short-term bouts of unconsciousness (seconds) - "walked-walked - he came to himself lying on the floor."This may be preceded by a feeling of "hot flushes in the head."
Prolonged unconsciousness (5-10 minutes or more) is not characteristic of bradycardia.
What are the methods of diagnosis of atrioventricular block?
primary diagnosis can serve as the presence of clinical manifestations brdikardii.
The next step is to record the electrocardiogram.
is often necessary to conduct Hour ECG (Holter monitoring) in the normal mode of life of the patient.It is possible that during the daily monitoring of arrhythmia and will not be registered. In this case, a tilt - test.
What are the treatments for atrioventricular block?
implantation of a permanent pacemaker - the only treatment for bradycardia.This device restores normal heart rate.At the same time the volume of blood flowing to the organs, normalize, and bradycardia symptoms are eliminated.
main indications for implantation of a permanent pacemaker with atrioventricular block are:
- symptomatic bradycardia (shortness of breath, dizziness, fainting);
- break in the heart of more than 3 seconds.
Sudden cardiac death
What is sudden cardiac death?
Under sudden cardiac death, death due to understand the natural heart disease, which was preceded by a sudden loss of consciousness within one hour after the onset of acute symptoms that can be aware of prior heart disease, but the time and manner of death are unexpected occurrence.
Cardiovascular diseases remain the leading cause of death.After myocardial infarction, sudden cardiac death (SCD) is the second most common cause of cardiovascular mortality.Approximately 83% of SCD is related to coronary heart disease is not diagnosed at the time of death.
What are the risk factors for sudden cardiac death?
well known SCD risk factors: a history of SCD episode of ventricular tachycardia, myocardial infarction, coronary artery disease, cases of BCC, or sudden unexplained death in the family, reduced left ventricular function, hypertrophic cardiomyopathy, congestive heart failure, Brugada syndrome and elongated syndromeQT and others.
patients with sudden when ECG cardiovascular collapse have shown that ventricular fibrillation and ventricular tachycardia are observed in 75-80% of cases, whereas bradyarrhythmias, apparently, make a minor contribution to the development of the WBU.Approximately 5-10% of BCC occurs without the presence of coronary heart disease or congestive heart failure.
incidence of SCD, according to the Western countries, about the same and varies from 0.36 to 1.28 per 1000 population per year.
What are the methods of prevention of sudden cardiac death?
Treatment of patients with ventricular arrhythmias is aimed at the prevention or relief of arrhythmia.The treatment options to date include:
- therapy with antiarrhythmic drugs (AAP) III class;
- radiofrequency ablation of cardiac conduction pathways;
- implantation of implantable cardioverter-defibrillators (ICDs).
role of amiodarone and other antiarrhythmic drugs class III is the prevention of arrhythmias.However, if epizodzheludochkovoy tahikardiiilifibrillyatsii zheludochkovrazvilsya while taking AARP, the drug is not in a position to stop the arrhythmia.Tolkoimplantirovanny cardioverter defibrillator or defibrillator impolzovanienaruzhnogo doctors resuscitation can kupirovatzhizneugrozhayuschuyu tachycardia.
Thus, the only treatment capable of preventing sudden cardiac death with life-threatening arrhythmias, is therapy with implantable cardioverter-defibrillators.It is shown that the ICD 99% effective in the termination of life-threatening arrhythmias and, thus, preventing sudden cardiac death.
been shown that ICDs reduce overall mortality (all causes) by 31% among patients with myocardial infarction and with ejection fraction & lt;thirty%.Moreover, increased quality of life for patients, the functional status and physical capabilities.
WARNING!If your eyes man suddenly lost consciousness, with no spontaneous breathing and pulsation of the great arteries (in the neck, groin) is not defined, immediately proceed to resuscitation:
properly routed resuscitated by ensuring airway patency.To do this:
- patient should be put on a firm, level surface and maximum throw back his head.
- to improve the airway from the mouth need to remove dentures or other foreign bodies.If vomiting occurs, turn the patient's head to one side, and the contents of the mouth and throat using a swab to remove (or improvised).
Check for spontaneous breathing.
If no spontaneous breathing, start artificial respiration.