ventricular myocardium noncompaction
Introduction
Introduction to ventricular myocardium densification Non-compaction of ventricular myocardium (NVM) is the morphological occurrence of endocardial myocardium in embryonic early stage, which makes the development of trabecular muscles unable to densify and lead to ventricular hypoplasia. It is a rare congenital cardiomyopathy. The disease is more common in children, and the incidence of adults is higher than expected. The lesions involve the left ventricle, and can also affect the right ventricle, leading to ventricular systolic and diastolic dysfunction, progressive progressive heart failure. The main pathological change of this disease is that the loose musculature constitutes the innermost layer of the ventricular muscle structure, and part of the ventricular cavity is divided into a plurality of small communicating cavities. The main clinical manifestations are heart failure, arrhythmia and endocardium. Thrombosis with embolism. No special treatment. basic knowledge Sickness ratio: 0.0004% Susceptible people: seen in young children Mode of infection: non-infectious Complications: heart failure, arrhythmia
Cause
Ventricular dysfunction
Causes
Myocardial congenital hypoplasia (45%):
Due to myocardial insufficiency caused by myocardial congenital hypoplasia, the disease can exist alone (called isolated ventricular muscle densification) or other congenital heart disease, such as aortic stenosis, the left coronary artery originates from the pulmonary artery. Pulmonary atresia, right heart, etc., the cause is not clear, but any teratogenic factors can lead to abnormal cardiac structure, can also lead to myocardial development stagnation, and endocardial myocardial ischemia may be one of the reasons, there are scholars Proof: The genetic abnormality of this disease is similar to Bath syndrome (X-linked abnormalities have dilated cardiomyopathy, skeletal muscle abnormalities, neutropenia and mitochondrial abnormalities).
Pathogenesis
It is not clear that it may be related to the following two types of factors:
Genetic factors (29%):
Sexual genetic linkage analysis suggested that the disease-related genes may be located on the Xq28 segment of the X chromosome. The G4.5 gene mutation is the origin of NVM. Bleyl et al reported a group of familial male INVM cases and found that the related genes are located on the X chromosome. In the Xq28 segment, this location is adjacent to genes associated with systemic myopathy (Emery-Dreifuss muscle atrophy, myotube myopathy, Barth syndrome), suggesting that NVM may be part of systemic myopathy, and some NVM children may coexist Other genetic diseases.
Secondary cause (21%):
On the basis of other congenital heart diseases, accompanied by NVM, persistent sinusoids are commonly used to describe complicated complicated cyanotic heart disease, left ventricular or right ventricular obstructive lesions and congenital malformations of the coronary arteries. In these "secondary" NVM patients, due to ventricular pressure overload and myocardial ischemia, the closure of the normal embryonic myocardial sinusoids is prevented, which hinders the formation of the endocardium, that is, the endocardium is absent. Causes the blood in the heart chamber to directly exert a high-pressure mechanical effect on the trabecular bone, so that the sinusoidal space persists without regressing.
Prevention
Ventricular muscle densification prevention
Strengthen publicity and education, promote prenatal and postnatal care, guide reasonable pregnancy, strengthen pregnancy care, and avoid the occurrence of fetal congenital malformations.
Complication
Ventricular dysfunction Complications heart failure arrhythmia
Heart failure, arrhythmia, embolism and other complications may occur.
Symptom
Ventricular muscle densification symptoms common symptoms heart failure right heart failure tachycardia cardiac hypertrophy
Clinical manifestation
Symptoms appear different in the morning and evening, different in severity, and their performance can range from asymptomatic to severe cardiac insufficiency, even heart transplantation, or sudden death; however, there are reports of morbidity over 60 years old, the difference may be related to the degree of NVM and The extent of the lesion is related to the main clinical manifestations:
1. Heart failure: mainly left heart failure, but also combined with right heart failure, the mechanism is:
1 The gap between the trabecular myocardium and the trabecular muscle affects the blood supply to the myocardium, especially the subendocardial myocardium, causing a decrease in subendocardial fibrosis and left ventricular systolic function, and a similar manifestation of dilated cardiomyopathy;
2 trabecular myocardium can limit ventricular diastole, producing symptoms and signs similar to restrictive cardiomyopathy.
2. Arrhythmia: Rapid ventricular arrhythmia is common, including ventricular tachycardia that can lead to sudden cardiac death; left bundle branch block is also more common; there are also reports of pre-excitation syndrome in children, ventricular The cause of arrhythmia is still unclear. It is speculated that in the myocardial segment with incomplete densification, the trabecular bone is connected in an irregular branch, and the pressure in the wall of the isovolumic systolic period increases, causing damage to the blood supply to the local coronary artery, thereby causing the heart. Electrical conduction delay, induced arrhythmia.
3. Endocardial thrombosis with systemic embolism: mainly for systemic embolism, associated with atrial arrhythmia or lesions in the heart cavity thrombosis and shedding.
4. Others: Some children may have specific facial features such as forehead protrusion, strabismus, nystagmus, low earlobe, face, cleft palate, upper arch, high genital area, etc.
Examine
Examination of ventricular myocardium insufficiency
Auxiliary inspection
1. Echocardiographic diagnosis NVM is mainly based on two conditions:
1 excessively protruding myocardial trabeculae, that is, in the left ventricle or right ventricular cavity, from the central part of the interventricular septum to the apical part of the ventricle, can be found in numerous intricately enlarged trabecular trabecular alignment; the affected heart chamber increases, The movement is significantly weakened;
2 color Doppler blood flow imaging, there are numerous trabecular space gaps with different sizes of ventricular cavity traffic, and there is blood flow in the heart cavity.
Chin et al. used echocardiography to calculate the ratio of the distance from the base of the trabecular bone to the epicardium (X) to the distance from the apex of the trabecular bone to the epicardium (Y) at different levels of left ventricular NVM, and found that NVM patients were The left ventricular mitral valve level, the papillary muscle level and the apical level X/Y ratio decreased progressively, 0.92 ± 0.07, 0.59 ± 0.05 and 0.20 ± 0.04, respectively, but the normal control group did not see this phenomenon, considered X / Y Ratio abnormalities contribute to the diagnosis of NVM.
UFCT can show the apex of the left ventricle, the front side wall is obviously thickened, the density of the outer layer of the ventricular wall is increased, and the density of the inner layer is low. UFCT enhanced contrast shows contrast agent filling between the trabecular crypts, and the magnetic resonance shows the apex. There are too many anterior sidewalls of the left ventricle, and the thick trabeculae protrude into the ventricular cavity. The deep trabecular space can be seen between them, and the inner layer of myocardial tissue is loose and "grid-like".
2. ECG
1T wave inversion and ST segment down;
2 conduction block: such as right bundle branch block (even left bundle branch block) and atrioventricular block;
3 cardiac hypertrophy: such as left ventricular hypertrophy, right ventricular hypertrophy, double chamber hypertrophy, left axis of the electric axis;
4 arrhythmia: ventricular premature contraction, paroxysmal supraventricular tachycardia, atrial fibrillation, sinus slow.
Diagnosis
Diagnosis and differentiation of ventricular myocardium
It relies mainly on the abnormal myocardial structural features of NVM for diagnosis.
Clinical manifestations and electrocardiogram are not helpful for the diagnosis of NVM. Ventricular angiography, ultra-high-speed CT (UFCT), magnetic resonance is helpful for diagnosis, and echocardiography is the most commonly used. Echocardiography can not only directly display abnormal myocardial structural features of NVM, but also Other cardiac malformations that can be clearly coexisted.
Ventricular dysfunction is mainly identified by the following diseases:
1. Hypertrophic cardiomyopathy: Ventricular trabeculae can be similar to NVM trabecular changes, but there is no typical trabecular space in NVM.
2. Dilated cardiomyopathy: There may be more protruding trabeculae, but the number is far from NVM, and there is a lack of deep trabecular space; the wall thickness is uniform and thin, different from NVM Uneven thickness.
3. Left ventricular apical thrombosis: The apex of the apex can sometimes be misdiagnosed as NVM, but the uneven density of thrombus echo helps to identify.
