Author Ольга Кияница
Polymorphic tachycardia is also known as catecholaminergic polymorphic ventricular tachycardia (CPR). Relates to violations of the ventricular rhythm and is characterized by the appearance of ECG changes in ventricular complexes of the type "pyruvate". Additionally, a combination of phases of opposite polarities with the participation of minimal amplitude complexes is observed.
During a polymorphic tachycardia, a heart rate of about 150-280 beats per minute is observed, while the course of the illness may be complicated by syncope (fainting).
There is a pathology in both adults and children. It is more commonly defined in patients with a slow heart rhythm (bradycardia). It is important to know how dangerous is polymorphic tachycardia. First of all, the disease increases the risk of sudden death, so when diagnosing it, it is necessary to adhere to timely treatment.
Video Polymorphic Extrasystole
Description of polymorphic tachycardia
Pathology refers to kanalopathies, which are a group of hereditary or acquired diseases of the neuromuscular system, characterized by the disorder of the structure and function of the ion channels located in the cells of the nerve fibers or muscle cells.
Polymorphic ventricular tachycardia develops against the background of changes in the activity of the heart cells (cardiomyocytes) acting in the form of a reverse direction of increasing the activity of the ventricular wall. Ion channels are directly involved in this process. Changing the potency of the action promotes the appearance of polymorphic tachycardia in the type of reentry.
The disease is difficult to diagnose, as it can only detect a rhythm disorder during an attack. Between paroxysms suspect the presence of a pathology can be due to the presence of a slowed rhythm (bradycardia).
Symptoms of polymorphic tachycardia
Catecholaminergic polymorphic ventricular tachycardia is a syndrome that includes a number of characteristic symptoms:
- the first signs of a pathology appear in 7-9 years, in rare cases - after 40 years;
- is more often defined in men;
- the heart muscle is not amazed;
- Tachycardia is caused by emotional or physical overvoltage, in particular swimming;
- Hysteria or epilepsy could be defined earlier.
Syncope states with CKD are developing in 30-50% of cases. Very often, half of the patients aged 20-30 years develop sudden death. Also, pathology is characterized by heredity, which is confirmed by the presence of awkward conditions in close relatives or sudden death of up to 40 years.
In one third of patients during seizures there are convulsions, which far does not always allow correctly and at the early stage of the development of pathology to diagnose. A similar situation often contributes to the patient's standing on the account of the neuroscientist and for a long time to receive anticonvulsant treatment.
The early expression of a clinical picture is the first sign of a high risk of sudden cardiac death.
Causes of polymorphic tachycardia
The disease develops against the background of rare genetic mutations that contribute to the development of dysfunction of the ion channels located in the heart cells.
The ion channels are molecular structures that are included in the lipid layer of the cell membrane. The dimensions of the channels are very small and their main objective is the exchange of substances with the environment. With their help, excitation and inhibition of muscle fibers and nerve cells are carried out.
To date, research has confirmed that the development of a typical clinic of polymorphic tachycardia is associated with mutations determined by at least three genes. At the same time, it is not clear until the end whether the localization of the defect in one or another component gene is capable of influencing the clinical picture of the disease. For example, the slowing of the rhythm, determined between attacks, does not depend on the location of the mutation. Therefore, in the definition of similar details, research continues.
Risk factors associated with polymorphic tachycardia:
- previously diagnosed fibrillation of the ventricles;
- death of relatives from sudden cardiac arrest;
- determination of signs of illness in childhood;
- excessive physical activity.
Types / photos of polymorphic tachycardia
According to the genotypes, KPZHT is divided into several types.
The first genotype is a link to the gene of the so-called RyR2 Ryanthin Receptors. Their mutation became known in 2000, when the Italians and Finns almost simultaneously determined their influence on the calcium channels. Under the influence of these receptors, cardiomyocytes begin to contract more often, therefore, in the presence of defects in this gene, in 55% of cases, a polymorphic tachycardia develops.
The second genotype is the result of a defect in the gene of calciferin-2. Its main role is to bind calcium in the heart cells.In this case, it is directly related to the rianoindin receptor. If mutations occur in this gene, then the process of liberating calcium ions from the depot of cardiomyocytes is broken, which results in tachycardia.
The study of the main components in the process of formation of polymorphic tachycardia continues, since approximately 30-40% of patients fail to find the association of the disease with mutations in the above genes.
Diagnosis of polymorphic tachycardia
Directed for a thorough study of anamnesis not only the patient, but also his closest relatives. In the future, electrocardiography and echocardiography are performed.
During an attack of a polymorphic tachycardia, the ECG determines:
- ventricular complexes are more than three consecutive;
- The tachycardia volley has two or more different morphologies (bidirectional and polymorphic);
- the heart rate rises 25% above the age norm;
- Atrioventricular dissociation is determined in the tachycardia volley.
The key to diagnosing a disease is a stress test. In most cases in patients, the reaction is determined in a high level of reproducibility. Also, during the course of the disease, it is possible to observe the progression of signs of rhythm disturbance, which begins with monomorphic extrasystole of the ventricles, myalgia and ending with polymorphic tachycardia.
Treatment and prevention of polymorphic tachycardia
Most often, the therapy of polymorphic tachycardia is based on the administration of beta-blockers. According to the results of various studies, the high effectiveness of such a drug as nadolol is determined. There is also a positive dynamics in the treatment of patients taking propranolol. At the same time, it is recommended to prescribe the maximum dosages that the patient can take.
In some cases, beta-blockers are ineffective, then they are prescribed together with flekainidum, which, in addition to blocking the sodium channels, suppresses the activity of the rianoindin receptors. The latter drug is effective even in the case of patients without a genetic basis for tachycardia.
All patients with polymorphic tachycardia are strictly forbidden to engage in sports and other physical activity.
Surgical treatment is used in the case of ineffectiveness of the drug. Implantation of the cardioverter defibrillator is used, as well as selective sympathetic destruction of nerve fibers.
Prevention is mainly aimed at preventing the development of recurrent attacks and, in particular, sudden cardiac death.For this, in the presence of immediate relatives of sudden deaths, genetic testing is required.