Arrhythmogenic right ventricular cardiomyopathy

Introduction to arrhythmogenic right ventricular cardiomyopathy Arrhythmogenic right ventricular cardiomyopathy (ARVC) is arrhythmogenic right ventricular dysplasia (ARVD), now expressed as ARVD/C, characterized by right ventricular myocardium replaced by progressive fibrous adipose tissue. Clinical manifestations of right ventricular enlargement, arrhythmia and sudden death. basic knowledge The proportion of sickness: 0.01% Susceptible people: no specific population Mode of infection: non-infectious Complications: arrhythmia, syncope, sudden death

Causes of arrhythmogenic right ventricular cardiomyopathy

(1) Causes of the disease

The cause is currently poorly understood and may be related to the following factors:

1. Genetic factors The occurrence of this disease has a certain relationship with genetic factors, often due to autosomal dominant mutations accompanied by decreased penetrance.

2. The theory of ontogeny abnormalities This theory suggests that right ventricular lesions are caused by congenital dysplasia of the right ventricle. Morphologically, the right ventricular wall is extremely thin, similar to the appearance of the Uh1 malformation, and the myocardial fibers are absent or disappeared. According to the fatty fiber tissue, it is more common in children or young adults. According to this, the disease should be a congenital gross cardiac structural abnormality. Most patients have no family history. Those who support this view call ARVD/C the right ventricle. Dysplasia.

3. Degeneration or degeneration theory The theory suggests that right ventricular myocardial defects are the result of degeneration and necrosis of progressive cardiomyocytes due to certain metabolic or ultrastructural defects, myocardial atrophy disappears with Duchenne muscular dystrophy and Becker chronic progressive muscular nutrition. Poor skeletal muscle atrophy is similar, and muscle atrophy characterized by progressive degeneration of skeletal muscle can be considered as a corresponding disease of the disease.

4. Inflammatory theory that the replacement of myocardium by adipose tissue is the result of the evolution of acquired damage (inflammation, necrosis) and repair process caused by chronic myocarditis. Animal experiments have confirmed that Coxsackie B3 virus and papaya virus can change in the same way.

(two) pathogenesis

Pathogenesis

(1) Genetic factors: A survey of some familial morbidities shows that the occurrence of this disease has a certain relationship with genetic factors, often due to autosomal dominant mutations accompanied by decreased penetrance, and through familial linkage. The analysis identified 7 independent ARVD/C, namely ARVD/C1, 14q23-q24; ARVD/C2, 1q42-q43; ARVD/C3, 14q12-q22; ARVD/C4, 2q32; ARVD/C5, 3p23; ARVD/ C6,10cpl2-p14;ARVD/C7,10q22; but the existence of a wider range of other genetic heterogeneity can not be completely ruled out. The current research on ARVD/C2 gene mutation has been successful, and its chromosomal range limitation and gene mapping are basically clear. hRYR2 (a cardiomygic receptor), one of the largest human genes (105 exons), encoding a 565-KDa monomer, interacting with four 12-KDa FK506 binding proteins (FKBPl2.6) It plays a central role in intracellular calcium ion stabilization and excitatory contraction coupling. The functional features of the RYR2 mutant have also been revealed and used to monitor human RYR2 gene mutations, helping to diagnose ARVD/C, catecholaminergic ventricular tachycardia and Familial tachycardia, different mutations in hRYR2 improve some clinical The susceptibility of the body to malignant arrhythmia in the case of fatigue, stress, etc., but there is no evidence that it is meaningful for a single clinical phenotype. It is currently considered that the above three clinical phenotypes are part of the clinical manifestations of the individual, and Affected by other genetic or environmental factors.

The molecular and cellular pathogenesis of ARVD/C is not well understood. Although apoptosis has been shown to be the key to its molecular pathogenesis, it is unclear how many ARVD/C related gene mutations are associated with cardiomyocyte apoptosis. Or it is susceptible to apoptosis, and the mechanism and pathway of apoptosis are also unclear. It has been reported that -adrenalin can stimulate and induce cardiomyocyte dystrophies, and then apoptosis occurs. Some people think that apoptosis is The response of the myocardium to biochemical stress emphasizes that protein kinase messenger pathways, particularly pressure-activated protein kinases, may play an important role.

(2) Metabolic abnormalities: Although studies have suggested that the disease is a hereditary disease, but many patients do not have a family history, so some people think that the disease is a metabolic disease, the right ventricular cardiomyocytes are progressively fiber Replacement of adipose tissue, muscular atrophy characterized by progressive degeneration of skeletal muscle can be regarded as the corresponding disease of the disease, such as a patient with a family of 2 cases of skeletal muscle atrophy, echocardiogram at 11 years old There were no abnormalities, but characteristic echocardiographic changes of ARVD/C occurred in both cases after 4 years.

(3) Myocarditis: It has been reported that the pathological changes of myocardium in a small number of patients with ARVD/C resemble myocarditis, which may be due to the fact that the characteristics of inflammatory lesions of the previous myocardium have completely or completely subsided over time, and eventually the myocardium is replaced by fibrous adipose tissue.

(4) Ventricular arrhythmia and exercise: Some people used echocardiography to measure the diameter of the left and right ventricles of 41 healthy athletes before and after exercise, and found that the right ventricular diameter increased significantly after exercise, and analyzed that this may be exercise to make right ventricular afterload. Increased, right ventricular wall extension and increased secretion of catecholamines may explain that patients with this disease often induce left bundle branch block ventricular tachycardia during exercise.

2. Pathology

The lesions of ARVD/C are mainly right ventricular free wall, but not completely limited to the right ventricle. The left ventricle can also be affected to varying degrees. The weight of the heart usually only increases to moderate to moderate, and there are many right ventricular hypertrophy with localization or generality. Sexual expansion, dilated part of the myocardium thinning, severe bulging to form a right ventricular aneurysm, the latter common in the funnel, right ventricular apex and posterior basal, that is, the triangle of dysplasia.

The typical pathological changes under light microscopy are that the right ventricle is replaced by fibrous adipose tissue or simple adipose tissue, and the trabeculae are flattened; the endocardium is also fibrotic, and local mononuclear cells or inflammatory cells infiltrate; Less involved, but visible focal interstitial fibrosis, some scholars according to histological performance, the disease is divided into fat replacement and fibrosis replacement type, but some scholars believe that these two types may represent myocardium In two consecutive stages of the pathological process, it is speculated that myocardial fibrosis can occur with the addition of myocarditis and myocardial damage on the basis of simple fat infiltration, and the simple fat replacement type can be converted into a fibrous fat replacement type. There are scattered lymphocytes, mononuclear cell infiltration with a small number of cardiomyocytes degeneration and necrosis, and myocardial necrosis is not obvious, so some people speculate that the cause of progressive cardiomyocyte reduction may be caused by cardiomyocyte apoptosis.

Arrhythmogenic right ventricular cardiomyopathy prevention

Strengthen publicity and education, improve the level of understanding of patients with this disease, actively eliminate the cause, avoid complications, improve living standards, should not be tired, and prevent infection.

Arrhythmogenic right ventricular cardiomyopathy Complications, arrhythmia, syncope

Common complications of this disease are arrhythmia, syncope, sudden death and so on.

1. Arrhythmia Ventricular arrhythmia is the most common manifestation of the disease. It is characterized by recurrent and non-sustained ventricular tachycardia. Dizziness, palpitations, syncope and even ventricular fibrillation can occur when ventricular tachycardia occurs, and emotions or fatigue Etc. can induce the occurrence of ventricular tachycardia.

2. Syncope due to the disease often complicated by severe ventricular arrhythmia (ventricular tachycardia) or ventricular fibrillation affecting hemodynamics.

3. Sudden death is more common in young people 35 years old. In emotional or strenuous exercise, sudden death can be induced. A few people have a family history of sudden death.

Symptoms of arrhythmogenic right ventricular cardiomyopathy Common symptoms Right heart failure Arrhythmia Circulatory congestion Coughing syncope Tachycardia Myocardial hibernation Heart sound abnormal Sudden syncope Bipolar syndrome

1. Patients often see symptomatic arrhythmia, especially ventricular tachycardia (left bundle branch block), some patients can find ventricular premature contraction in routine ECG, the latter often originated from right ventricular free Wall, and left bundle branch block pattern; some patients coexist with multiple types of arrhythmia.

2. A small number of patients can be asymptomatic, only due to the increase of right ventricular enlargement due to routine chest X-ray examination. Some children and young patients have first symptoms of syncope and sudden death, which often occur during physical activity.

3. The main signs of right ventricular enlargement, relative tricuspid regurgitation systolic murmur and pulmonary heart auscultation area second heart sound fixed division, a few may have third or fourth heart sound, right ventricular lesions can occur right Heart failure, a variety of clinical manifestations of systemic congestion.

Examination of arrhythmogenic right ventricular cardiomyopathy

1. The chest X-ray heart is normal or enlarged, the contour is spherical, the pulmonary artery outflow tract is dilated, and the left margin is bulging. In most patients, the cardiothoracic ratio is 0.5.

2. ECG common ECG chart is available:

(1) The time limit of the V1 lead QRS complex is usually greater than the time limit of the I lead and V6 lead QRS complex, reflecting the right ventricular activation delay. According to statistical analysis, the V1 lead QRS complex time limit > 110 ms, for the diagnosis of this disease The specificity is up to 100% and the sensitivity is 55%.

(2) There may be complete or incomplete right bundle branch block.

(3) Some patients can see the standing sharp wave (epsilon wave) in the terminal part of the QRS complex (common in the V1 lead), which is caused by a part of the right ventricle with a delay in activation, and the sensitivity of the electrocardiogram recording is increased by 2 times. 3 times easy to find the wave.

(4) Half of the patients had a T-wave inversion in the right chest lead, and the T-wave inversion of the chest lead was proportional to the degree of right ventricular enlargement.

(5) Patients with ventricular tachycardia often have positive ventricular late potential.

(6) At the onset of palpitations or syncope, ventricular tachycardia or ventricular fibrillation with a left bundle branch block pattern can be found.

3. Echocardiography and radionuclide ventriculography are the two most important non-invasive methods for diagnosing this disease. The former can be seen in the right ventricular end-diastolic diameter, the right ventricular general or localized activity is reduced, and the right ventricular wall is present. Segmental bulging; the ratio of end-diastolic diameter of the right ventricle to the left ventricle is >0.5 (specificity 93%, sensitivity 86%, positive predictive value 86%, negative predictive value 93%); the latter for diagnosis of right ventricular systolic abnormalities The specificity and positive predictive value were both 100%, but the sensitivity was only 80%. If both of the above results showed that the right ventricle and left ventricular end-systolic volume ratio was >1.8, or the right ventricular ejection fraction was <0.50 during exercise. , or the right ventricular wall motion score >1 during exercise, almost certainly the diagnosis of this disease.

4. Cardiovascular angiography showed that the right ventricle was enlarged, the right ventricular wall was abnormal, and there was no abnormality in coronary angiography.

5. Magnetic resonance imaging (MRI) is of great value in the discovery of intraventricular ventricular intraventricular fat accumulation. For example, a film magnetic resonance imaging technique that can accurately measure right ventricular volume can show an increase in right ventricular volume.

6. Endocardial myocardial biopsy can be diagnosed if the cardiomyocytes are replaced by fibrous fat, but the endocardial myocardial biopsy is mostly from the interventricular septum, and most patients have lower right ventricular lesions, ventricular septum. Generally not affected, so the biopsy results are negative and can not rule out the disease. At the same time, because normal human right ventricular myocardial cells often have small island-like adipose tissue, the clinical evaluation of this pathological change should be cautious.

7. Electrophysiological examination The endocardial mapping technique can be used to find that the conduction through the right ventricle, especially the lesion, is slow. This test can also determine the origin of ventricular tachycardia and contribute to ablation.

Diagnosis and differentiation of arrhythmogenic right ventricular cardiomyopathy

The clinical manifestations of this disease are diverse, especially in early diagnosis. In 1994, the European Heart Association developed the diagnostic criteria for this disease.

According to the above criteria, anyone who has 2 main indicators, or 1 main indicator plus 2 secondary indicators, or 4 secondary indicators, can be diagnosed as ARVD/C.

1. Uh1 malformation identification points.

2. Patients with ARVD/C with dilated cardiomyopathy may have left ventricular involvement, but the degree is mild, and there is no progressive left heart failure, while dilated cardiomyopathy often has left ventricular systolic dysfunction, and is often progressive. Aggravated.

3. Idiopathic right ventricular ventricular tachycardia is an unexplained benign ventricular tachycardia, characterized by ventricular tachycardia is not easy to induce, and late potential is negative, all cardiac examination of the right ventricle without abnormalities, the disease sometimes and atypical ARVD/C is not easy to identify.

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