Arrhythmogenic right ventricular cardiomyopathy is a disease of presumably genetic nature characterized by structural changes in the right ventricle and the development of arrhythmia. The course options range from asymptomatic forms to forms with pronounced tachyarrhythmia, extrasystole, cardialgia and heart failure. Diagnosis is carried out using echocardiographic, electrocardiographic, magnetic resonance imaging, as well as myocardial biopsy. There is no specific treatment, therapy is reduced to the elimination of arrhythmia and congestive heart failure. In the absence of the effect of drug therapy, implantation of a cardioverter defibrillator is used.
ICD 10
I42.8 Other cardiomyopathies
General information
Arrhythmogenic right ventricular cardiomyopathy (arrhythmogenic dysplasia of the right ventricle, arrhythmogenic disease of the right ventricle, ARV CMP) is a disease affecting the wall of the right ventricle, in which pathological foci of fatty and fibrinous infiltration form in the thickness of the myocardium, sometimes with the addition of inflammation (myocarditis). The pathology was described under the name “arrhythmogenic dysplasia of the right ventricle” in 1977 by G. Fontaine, after which the research was continued by F. I. Marcus, who in 1982 gave the disease its modern name.
The occurrence in various regions ranges from 1-6:10,000 inhabitants; among the detected patients, the vast majority are men under 40 years of age, the sexual distribution is 4:1. It tends to hereditary transmission, therefore, most forms of ARV CMP are currently defined as an autosomal dominant disease with incomplete penetrance. Interest in the disease has increased dramatically due to the identification of its role in the development of sudden cardiac death. Thus, histological studies of the myocardium in children and adolescents under 20 years of age, the cause of death of which was cardiovascular pathology, showed that changes associated with ARV CMP were detected in 26% of cases.
Causes
At the moment, there is no generally accepted point of view on the causes of the development of ARV CMP due to the heterogeneity of the manifestations of the disease. It is possible that AP KMP combines several pathologies similar in manifestations with different etiologies. But the only documented theory to date is hereditary, explaining the occurrence of arrhythmogenic right ventricular cardiomyopathy by a genetic mutation.
Gene abnormalities in chromosomes 12, 14, 17 and 18 were revealed during the study of the genome of patients with ARV CMP – these genes encode such myocardial proteins as alpha-actin, desmoplakin, plakoglobin, plakophylline and others. Violations of the structure of these proteins lead to a decrease in the resistance of cardiomyocytes to damaging factors, which eventually leads to fat infiltration. However, the main role in the development of arrhythmia in ARV CMP is played by a violation of the functions of the desmosome protein, as a result of which the spread of excitation through the myocardium changes.
In some cases, instead of focal fatty infiltration of the walls of the right ventricle, fibrinous is observed, which has an inflammatory character and generally resembles the picture with viral myocarditis caused by the Coxsackie virus, etc. This form tends to spread to the left ventricle and is characterized by a severe course, often leading to the death of the patient. From the point of view of the hereditary theory of the development of ARV CMP, it is believed that gene mutations increase the predisposition of the myocardium to be affected by viruses.
Most mutations are inherited by autosomal dominant type with a penetrance of 30-50%. One extremely rare form of arrhythmogenic right ventricular cardiomyopathy (Naxos disease – only 25 cases have been described) has an autosomal recessive character and high penetrance – more than 90%. Homozygotes of the mutant gene suffer from malignant ventricular arrhythmia and often die in childhood or adolescence.
Classification
Due to the pronounced heterogeneity of the clinical forms of ARV CMP, attempts have been repeatedly made to systematize and classify the types of this disease. Currently , the following types of arrhythmogenic right ventricular cardiomyopathy are distinguished:
- Pure, or reference, form.
- Naxos disease, characterized by autosomal recessive inheritance and malignant ventricular arrhythmias.
- Venetian cardiomyopathy – often spreads to the wall of the left ventricle, has a pronounced hereditary character (penetrance of about 50%), patients can die in childhood.
- Smoking disease, a form of ARV CMP detected in Japan, is the cause of sudden cardiac death of adolescents.
- Tachycardia caused by a focus of excitation in the right ventricle without extrasystoles or manifestations of heart failure.
- Rare ventricular extrasystoles, the source of which is a focus of excitation in the wall of the right ventricle associated with the site of inflammation. This form of ARV CMP can be complicated by myocarditis with a fatal outcome.
- Ula anomaly is a rare form of ARV CMP characterized by an increase in heart failure and death. Histological examination of the heart reveals complete replacement of cardiomyocytes with adipose and fibrinous tissue.
- Non–arrhythmogenic form – in most cases does not manifest itself in any way, it is associated with asymptomatic cases of sudden cardiac death.
Symptoms
Clinical forms of APCMP are divided into four main groups. With an asymptomatic form, the pathology does not manifest itself in any way during the patient’s life, including during electrocardiographic studies. The arrhythmic form is characterized by the development of tachyarrhythmia, ventricular extrasystole and the appearance of other electrocardiographic signs. Subjective symptoms are usually absent. With the development of a pronounced clinical form against the background of tachyarrhythmias, cardialgia, palpitations, dizziness occur. The most severe type of clinical manifestations of APCMP is the development of right ventricular heart failure with a characteristic symptom complex – venous congestion, edema, ascites. At the same time, heart failure can occur both against the background of a violation of the heart rhythm, and without it.
In some cases, these groups reflect the stage of development of disorders caused by arrhythmogenic right ventricular cardiomyopathy. However, in some patients, the development of pathology can last for years, while in others it may take less than a month from an asymptomatic form to heart failure. In addition, with any of the forms or any stage of ARV CMP, a fatal outcome is possible due to ventricular fibrillation, Ula anomaly or lightning-fast viral myocarditis.
Diagnostics
The whole range of modern methods of heart function research is used in practical cardiology for the diagnosis of APCMP:
- Ultrasound of the heart. The final diastolic size (CDR) and the final systolic size (CSR) of the ventricles are determined on EchoCG, after which these data are compared with each other. If the ratio of the CDR of the right ventricle to the CDR of the left is 0.5 or more, this indicates in favor of the presence of ARV CMP.
- ECG. ECG signs of arrhythmogenic right ventricular cardiomyopathy include an elongation of the ventricular complex over 110 ms on the V1 lead, an epsilon wave on the ST segment in the V1-V3 leads, an inversion of the T wave in the thoracic leads due to a slowdown in the depolarization of the right ventricle, as well as the presence of tachyarrhythmia and ventricular extrasystoles.
- X-ray. On radiopaque ventriculography, dilatation of the right ventricle can be determined, and in some cases, protrusion (aneurysm) in the area of the focus of fibrolipous myocardial dysplasia is directly visualized. In recent years, magnetic resonance imaging with gadolinium contrast has been used for the specific diagnosis of AP CMR, which allows not only to obtain a three-dimensional image of the heart, but also to differentiate fatty and fibrinous foci from unchanged myocardium.
- Myocardial biopsy. To clarify the diagnosis, a myocardial biopsy is practiced, followed by histological examination of tissues – with ARV CMP, fat infiltration, discoloration and shape of desmosomes, as well as a decrease in their number, will be observed.
An important sign is the familial nature of the symptoms or the presence of relatives in the patient who died from sudden cardiac death or ventricular fibrillation. In this case, the diagnosis is confirmed by gene diagnostics. Differential diagnosis is performed with idiopathic forms of ventricular tachyarrhythmias.
Treatment
Medical treatment of ARV CMP includes antiarrhythmic drugs. Reducing the severity of tachyarrhythmias plays an important role in preserving the patient’s life, the cardiologist monitors the effectiveness of drugs using Holter monitoring. In cases where drug therapy is ineffective, implantation of a cardioverter defibrillator or pacemaker is resorted to. With the development of heart failure, ACE inhibitors, beta-blockers are used.
Techniques of surgical treatment of arrhythmogenic right ventricular cardiomyopathy (ventriculotomy) are being developed, which are reduced to the removal of pathological foci with myocardial suturing. The first results of such operations are optimistic, but relapses occur in 30-40% of cases. In severe heart failure, heart transplantation will be an effective method of treatment.
Prognosis and prevention
The prognosis is uncertain due to the high variability of the manifestations of ARV CMP. Ventricular fibrillation with a fatal outcome can develop at any time, especially in the absence of treatment. With regular antiarrhythmic therapy, the risk of death is reduced by about a third. The best results are shown by a combination of pacemakers and drug therapy, which reduces the risk of lethal fibrillation to almost zero. With the development of heart failure, the prognosis is usually unfavorable.
