Paroxysmal tachycardia is a dangerous symptom, which in some cases leads to death.
In this article we will consider paroxysmal tachycardia from all sides - its symptoms, treatment, causes, whether it is dangerous and in what cases.
Distinguishing features
paroxysmal tachycardia - a abnormal heart rhythm with a frequency of 150-300 beats per minute .The focus of excitation arises in any part of the conducting system of the heart and causes high-frequency electrical impulses.
The reasons for the appearance of such foci have not yet been fully explored. For this form of the tachycardia, the sudden onset and end of the attack, which lasts from several minutes to several days, are characteristic.
With paroxysmal tachycardia, diastolic pauses are shortened as much as possible, therefore, the time for restorative processes is minimized, why changes occur.
also causes cardiac dysfunction of , due to Venkebach's "blockage of the atria."Then the blood accumulated in the atria is thrown back into the hollow and pulmonary veins, as a result of which pulse waves form in the jugular veins. The blockage makes it even more difficult to fill the ventricles with blood and provokes stagnant phenomena in a large circle.
Paroxysmal tachycardia is usually accompanied by mitral stenosis and coronary atherosclerosis.
How the disease develops
The rhythm is disrupted because an electrical signal, following the heart, meets obstacles or finds additional ways. As a result, the patches over the obstacle are reduced, and then the impulse returns repeatedly, forming an ectopic focus of excitation.
Sites that receive a pulse from additional beams are stimulated at a higher frequency. As a result, the recovery period of the cardiac muscle is shortened, the mechanism of ejection of blood into the aorta is disturbed.
According to the development mechanism, distinguishes three types of paroxysmal tachycardia - reciprocal, as well as focal and multifocal, or ectopic and multifocus.
The recurring mechanism of is the most frequent, when a pulse is regenerated in the sinus node, or a circulation of excitation is observed. Less often paroxysm generates an ectopic focus of abnormal automatism or post-depolarization trigger activity.
Regardless of which mechanism is involved, the always has an extrasystole before the attack. This is the name of the phenomenon of untimely depolarization and contraction of the heart or its individual chambers.
Basic classification, differences of species by localization
Depending on the current, is distinguished by acute, constant recurrent( chronic) and continuously recurring forms of .Especially dangerous is the last type of flow, as it causes circulatory insufficiency and arrhythmogenic dilated cardiomyopathy.
There are such forms of paroxysmal tachycardia :
- ventricular - resistant( from 30 seconds), unstable( up to 30 seconds);
- supraventricular( supraventricular) - atrial, atrioventricular.
Supraventricular
The atrial form is most common. The source of increased production of impulses is the atrioventricular node. Short-term attacks of are often not diagnosed on the electrocardiogram .
The antrioventricular form is characterized by what appears in the atrioventricular junction.
Ventricular
A foci of excitation with the ventricular form is located in the ventricles - bundle of His, his legs, in the fibers of Purkin .The ventricular form often develops against a background of cardiac glycoside poisoning( approximately 2% of cases).This is a dangerous condition, which sometimes develops into ventricular fibrillation.
The heart rate does not usually "accelerate" more than 180 beats per minute .Samples with awakening of the vagus nerve show a negative result.
Causes and risk factors
Supraventricular form causes high activity of the sympathetic nervous system .
An important cause of the atrioventricular form is the , the presence of additional pathways, which are congenital abnormalities. Such deviations include a bundle of Kent, located between the atria and ventricles, the Maheima fibers between the atrioventricular node and the ventricles.
For the gastric form, the cardiac muscle is characterized by necrotic, dystrophic, sclerotic, inflammatory anomalies. This form is more common for men in old age .They are diagnosed with hypertension, ischemic heart disease, myocardial infarction, and malformations.
Children are characterized by idiopathic paroxysmal tachycardia, or essential. Its causes are not reliably established.
There are extracardiac( non-cardiac) and intracardial( cardiac) risk factors.
Extracardial
So, in people with a healthy heart attack paroxysmal tachycardia develops after stress, a heavy load - physical or mental, as a result of smoking, drinking alcohol .
Also provoke an attack of spicy food, coffee and tea.
This includes diseases:
- of the thyroid gland;
- of the kidney;
- of the lung;
- of the gastrointestinal system.
Intracardial
By intracardial factors we mean cardiac pathologies - myocarditis, defects, mitral valve prolapse.
Symptoms
The clinical picture of paroxysmal angina is so expressive that it is enough for the doctor to talk with the patient. The disease is characterized by such symptoms:
- sudden shock in the heart area and the subsequent increase in the heart rate;
- pulmonary edema is possible in patients with heart failure;
- weakness, general malaise, chills, trembling in the body( tremor);
- headache;
- sensation of a coma in the throat;
- change in blood pressure indicators;
- in severe cases - loss of consciousness.
If paroxysmal tachycardia does not cause heart failure, a frequent attack is sharp polyuria - copious discharge of light urine with low specific gravity.
Symptoms are also complemented by manifestations that are characteristic of the disease that triggered tachycardia. For example, if the thyroid gland is broken, the patient loses weight, his hair deteriorates, gastrointestinal tract pains the stomach, torments nausea, heartburn, etc.
Between the attacks the patient may not complain about the state of health.
Diagnosis and signs on the ECG
When conducting diagnostic activities, the doctor conducts a survey of the patient on the nature of the sensations and the circumstances under which the attack began, refining the medical history.
The main hardware method of investigation is an electrocardiogram. But at rest they do not always record deviations. Then studies with loads are shown to provoke an attack.
ECG makes it possible to distinguish the forms of paroxysmal tachycardia .So, with the atrial location of the focus, the tooth P is in front of the QRS complex. At the atrioventricular junction, the tooth P takes a negative value, and merges or is behind the QRS.
The ventricular form is determined by deformed and expanded QRS, while the P tooth is unchanged.
If paroxysm is not recorded, daily ECG monitoring is indicated, showing short episodes of paroxysm, not noticed by the patient.
In some cases, of the endocardial ECG with intracardiac introduction of electrodes is performed to clarify the diagnosis.
Also perform an ultrasound scan, an MRI or MSCT organ.
First aid for attacks and therapy tactics
The first help in paroxysmal tachycardia is as follows:
- Soothe the patient, with dizziness and severe weakness - they are sated or put.
- Provide airflow, release from tight clothing, unbutton collars.
- Conduct vagal samples.
- In case of severe deterioration of the condition, an ambulance is called for.
In ventricular paroxysmal tachycardia in most cases, hospitalization is carried out, with the exception of idiopathies with benign course. The patient is immediately injected with a universal anti-arrhythmic drug - novocaineamide, isoptin, quinidine, etc. If the medicamental effect does not work, they resort to the electropulse method.
If ventricular tachycardia attacks occur more than 2 times per month , planned hospitalization is indicated. Patients with a diagnosis of "paroxysmal tachycardia" are observed outpatiently with a cardiologist.
Drugs for treatment are taken under ECG control .To prevent the transition of the ventricular form into ventricular fibrillation, β-adrenoblockers are prescribed, which are most effective in combination with antiarrhythmic agents.
How to treat paroxysmal tachycardia in severe cases? Doctors resort to surgical treatment of .It consists in the destruction of additional ways of impulse or foci of automatism, radiofrequency ablation, implantation of stimulants or defibrillators.
Prognosis, complications, possible consequences
To possible complications of prolonged paroxysms with a frequency above 180 beats per minute are:
- ventricular fibrillation is one of the causes of sudden cardiac death;
- acute heart failure with cardiogenic shock and pulmonary edema;
- angina, myocardial infarction;
- progression of chronic heart failure.
Whether paroxysmal tachycardia leads to heart failure depends largely on the condition of the heart muscle and the presence of other changes in the circulatory system.
The first sign of developing heart failure is tension in the neck, that occurs due to blood veins overflow, dyspnea, fatigue, heaviness and pain in the liver region of .
Prevention of relapse and prevention
The main preventive measure - healthy lifestyle , which assumes:
- healthy food, with enough vitamins, minerals, reduction in the diet of fatty, sweet, spicy foods;
- exception from the ration of spirits, caffeine-containing beverages, especially soluble coffee;
- quitting.
With emotional excitement, sedatives are prescribed.
To prevent attacks, the may prescribe drug therapy :
- for ventricular paroxysms - anaprilin, difenine, novocainamide, isoptin preventive courses;
- with supraventricular paroxysms - digoxin, quinidine, mercazolil.
Medications are prescribed if seizures are observed more than twice a month and require the help of a doctor.
