Dilated cardiomyopathy in children

Introduction to children with dilated cardiomyopathy Dilated cardiomyopathy (DCM), also known as congestive cardiomyopathy (CCM), is the most common cardiomyopathy, with enlarged heart, systolic dysfunction, heart failure, etc., which is caused by primary myocardial disease. One or both sides of the unexplained cardiomyopathy. basic knowledge The proportion of illness: the probability of illness in infants and young children is 0.064% Susceptible people: children Mode of infection: non-infectious Complications: heart failure, arrhythmia, pulmonary edema, cerebral embolism

Causes of dilated cardiomyopathy in children

Viral myocarditis (30%):

1 virus continuous infection: 17% to 62% of myocardial tissue in DCM patients can detect enterovirus mRNA, continuous infection of the virus can dissolve myocardial fibers, myocardial hypertrophy, interstitial fibrosis.

2 virus-mediated immune damage: autoimmune reaction to form myocardial tissue damage under the induction of virus, DCM patients have been found to have humoral and cellular immune abnormalities, including cytotoxic T cells, inhibitory T lymphocytes and natural killer cells Various T cell abnormalities, many studies have shown that anti-myocardial antibodies corresponding to various antigens (including ADP/ATP vectors, 1-AR, M2 muscarinic receptors and myosin heavy chain) have been detected, some These autoantibodies (such as anti-ADP/ATP carrier antibodies) have important effects on myocardial pathological changes and myocardial function, and interfere with the normal regulatory function of the receptor. The study found that HLA-B27, HLA-A2 was found in myocardial tissue examination of DCM patients. Increased expression of HLA-DR4, HLA-DQ4 and HLA-DQ8 suggests that these immunological abnormalities (humoral immunity, cellular immunity and autoimmunity) may be caused by previously occurring viral myocarditis.

Genetic (familial) factors (25%):

A familial linkage analysis of DCM, about 20% of patients with first-degree relatives also showed evidence of DCM, most familial cases were autosomal dominant, a few were autosomal recessive and X-linked (female carrying family) Sexual DCM-related genes, but not easy to onset, patients are mainly male).

Linkage analysis of autosomal dominant families, targeting pathogenic genes on chromosomes 1q32, 2q14, 2q31, 3p22, 6q12, 6q23, 6q24, 9q13 and 10q23, the pathogenic genes are unknown, Olsen et al. (1998) reported a family and confirmed The myocardial -actin gene (CACT) located on chromosome 15q14 is a disease-causing gene, and the laminin A/C gene (LMNA) and desmin gene are found later. Mutations such as (DES) and delta-glycan gene (SAGD) have been shown to cause DCM.

Kamisago et al. (2000) reported that DCM pedigrees demonstrated mutations in the HCM pathogenic genes MYH7 and TNNT2, and Olson et al (2001) found TCM1 mutant DCM patients.

The DCM of the autosomal recessive family has reports of mutations in the CPT2 and DSP genes.

The onset of X-linked DCM is caused by a mutation in the dystrophin gene (DMD) located on chromosome X-p21.2, DMD is its causative gene, and Barth syndrome (DCM with neutropenia) , skeletal muscle disease) is caused by a mutation in the Tafazzin protein gene (G4.5), and mutations in mitochondrial DNA have also been reported.

Pathological changes (25%):

The pathology is mainly dilated by the heart chamber, and the left ventricular cavity is particularly prominent. There may be a wall thrombus, which is histologically non-specific, with cardiomyocyte hypertrophy, degeneration, fibrous tissue hyperplasia, due to myocardial lesions and fibrous tissue hyperplasia. The myocardial contractility is weakened, the cardiac output is reduced, the residual blood is increased during the diastolic phase, and the end-systolic end-stage pressure is increased, causing pulmonary circulation and systemic congestion. Myocardial fibrosis involves the pacemaker and conduction system, and various arrhythmias can be produced.

Pediatric dilated cardiomyopathy prevention

At present, there are no definite preventive measures, but active prevention and treatment of viral myocarditis; balanced diet, strengthening nutrition, especially prevention of selenium deficiency, lack of linoleic acid, lack of potassium and magnesium, etc., can cause myocardial damage. Drink plenty of water to keep the mucous membranes in the nose and mouth moist.

Pediatric dilated cardiomyopathy complications Complications heart failure arrhythmia pulmonary edema cerebral embolism

Can be complicated by chronic or acute heart failure, arrhythmia, mitral regurgitation, pulmonary edema, cerebral embolism.

1. Acute heart failure (AHF): refers to the insufficiency of tissue and organ perfusion and acute congestion syndrome caused by acute cardiac disease caused by acute cardiac output.

2, arrhythmia (cardiac arrhythmia): refers to the frequency, rhythm, origin, conduction velocity or agitation order of cardiac electrical activity, according to its principle of occurrence into impulse formation abnormalities and impulse conduction abnormalities.

3, cerebral embolism: refers to various emboli in the blood (such as the wall of the wall thrombus, atherosclerotic plaque, fat, tumor cells, fibrocartilage or air, etc.) with the blood into the cerebral artery and blocked Blood vessels, when the collateral circulation can not be compensated, cause ischemic necrosis of brain tissue in the blood supply area of the artery, and focal neurological deficit occurs.

Symptoms of dilated cardiomyopathy in children Common symptoms Irritability, edema, fatigue, systolic murmur, arrhythmia, anorexia, abdominal pain, heart enlargement, jugular vein engorgement

Children of all ages can be affected, most of the onset is slow, mainly manifested as chronic congestive heart failure, occasionally with sudden onset of acute heart failure or arrhythmia, older children appear as fatigue, anorexia, do not love activities Abdominal pain, dyspnea after exercise and obvious tachycardia, oliguria, edema, difficulty in feeding, low weight, difficulty breathing during sweating, excessive sweating, irritability, reduced food intake, about 10% of children with syncope or The symptoms of syncope, the patient's face is pale, the breathing and heart rate are accelerated, the pulse is weak, the blood pressure is normal or low, the anterior region is bulging, the apex beats to the left and the left, the heart is widened to the left, the first heart sound is weakened, and there is often galloping. Due to the enlargement of the heart chamber, functional mitral regurgitation occurs, and the apical part of the apex appears to have a mild to moderate systolic murmur. The left atrium enlarges the left main bronchus to cause left lower lung atelectasis, so the lower left back breath sound is reduced, and There may be voices, liver pain, lower extremity edema, larger children can see jugular vein engorgement, in addition, there may be cerebral embolism.

Examination of children with dilated cardiomyopathy

1. routine inspection

2. Endomyocardial biopsy: no specific pathological changes, limited value, can be used as a reference for the differential diagnosis of specific cardiomyopathy, histology can be seen myocardial cell hypertrophy, degeneration, interstitial fibrosis, myocardial cells in myocardial biopsy of DCM patients Different degrees of hypertrophy, fibrosis, and no obvious lymphocytic infiltration, can be ruled out by histological or PCR methods to exclude myocarditis, hereditary metabolic cardiomyopathy and mitochondrial disease, myocardial biopsy is mostly used for the evaluation of heart transplantation.

3. Molecular genetics examination: can be diagnosed with familial DCM gene abnormalities and mitochondrial hereditary cardiomyopathy.

4. Chest X-ray examination: Chest X-ray showed a moderate to severe increase in heart shadow, with left ventricular enlargement being more obvious, and heartbeat weakened. Under fluoroscopy, the heart beat was weakened, and pulmonary congestion was seen in heart failure. Pulmonary edema, sometimes visible pleural effusion and left lower lung atelectasis.

5. Electrocardiogram examination: Electrocardiogram showed myocardial damage, arrhythmia and ventricular hypertrophy as the main changes, sinus tachycardia, left ventricular hypertrophy and ST-T changes were the most common, and may have atrial hypertrophy, right ventricular hypertrophy and abnormal Q wave Arrhythmia with first degree atrioventricular block, bundle branch block and ventricular premature contraction more common, dynamic electrocardiogram monitoring about half of patients with ventricular and supraventricular arrhythmia.

(1) ST-T change: the ST segment decreases mostly horizontally, and the T wave is inverted or low.

(2) ectopic beats and ectopic rhythm: ventricular or atrial premature contraction is the most common, can be frequent, polymorphic, multi-source ventricular premature contraction, can develop into ventricular tachycardia or Ventricular fibrillation.

(3) conduction disorder: in some cases, atrioventricular block (one to three degrees), indoor, bundle branch and branch block.

(4) ventricular hypertrophy: some cases have different degrees of left ventricular hypertrophy, right ventricular hypertrophy or bilateral ventricular hypertrophy is rare.

6. Echocardiography: Each ventricular cavity is significantly enlarged, mainly left ventricle; ventricular septum and left ventricular posterior wall motion amplitude is reduced, anterior and posterior mitral valve opening amplitude is small; left ventricular systolic dysfunction (ejection fraction and short The axial shortening rate decreased), the left ventricular posterior wall and ventricular septal motion decreased, the ejection fraction and shortening score decreased significantly, and Doppler examination suggested mitral regurgitation.

7. Radionuclide imaging: Visible myocardial hypertrophy, ventricular cavity enlargement, wall motion is weakened, ejection fraction often citrate 67Ga scan and 111In anti-myoglobulin antibody development can detect acute inflammation of the myocardium.

8. Cardiac tomography: Single-photon tomography (SPECT) and positron emission tomography (PET), which can measure the ejection fraction of the left ventricle, right ventricular partition, and the peak ejection rate of the left ventricle and right ventricle; SPECT and PET can measure left ventricular, right ventricular peak filling rate and early detection of diastolic function damage.

9. Cardiac catheter and cardiovascular angiography: Echocardiography can assist in the diagnosis of DCM. Cardiac catheterization has been rarely used. Cardiac catheterization, cardiovascular angiography and endomyocardial biopsy can be used to monitor hemodynamics. Changes, coronary artery disease and myocardial histology, left ventricular end-diastolic pressure, left atrial pressure and pulmonary capillary wedge compression, cardiac output and stroke volume decreased, ejection fraction decreased, left ventricular angiography visible The left ventricular cavity is enlarged and the left ventricular wall is weakened.

Diagnosis and identification of dilated cardiomyopathy in children

diagnosis

Family history should be asked in detail, and if necessary, the first generation of relatives should be subjected to echocardiography in order to find familial DCM. At present, the disease lacks specific diagnostic indicators, and is still an exclusion diagnosis, clinically showing heart enlargement, congestive heart failure. In children with arrhythmia, echocardiography shows a significant increase in ventricular cavity, ventricular septum and posterior wall motion of the left ventricle are reduced, and no other causes should be considered. DCM is mainly characterized by heart failure and left ventricular systolic function. Obstacle, through clinical observation and echocardiography, can generally be diagnosed, but detailed medical history and family history should be asked to identify cardiomyopathy caused by familial DCM and other causes.

Differential diagnosis

The disease should be differentiated from rheumatic heart disease, viral myocarditis, pericardial effusion and restrictive cardiomyopathy.

1. Rheumatic heart disease: Rheumatic fever and valvular murmur, echocardiography, pericardial effusion can be seen in the pericardial opaque area, no ventricular enlargement, DCM can have mitral or tricuspid regurgitation The murmur and enlargement of the left atrium are easily confused with rheumatic heart disease. DCM has no history of rheumatic fever, heart murmur is louder in heart failure, and noise is reduced or disappeared after heart failure is improved. Rhythm is obviously obvious after heart failure control. There are often mitral and/or aortic valve diastolic murmurs. Echocardiography is mostly left atrial enlargement, and the mitral and/or aortic valves are often malformed. The valve is generally free of deformities.

2. Restricted cardiomyopathy: The atrium is obviously enlarged, the ventricular cavity is not large, there may be deformation, ventricular diastolic dysfunction and contractile function are mostly normal.

3. Viral myocarditis: history of precursor virus infection, multiple acute onset, serum myocardial enzyme (CK-MB quality) and cardiac troponin (cTnT, cTnI) increased, ECG changes with ST-T, QRS wave low voltage and Arrhythmia is more common, radionuclide myocardial imaging can show inflammation or necrosis, but sometimes still need to be diagnosed by myocardial biopsy.

4. Infant DCM should be differentiated from left coronary artery origin malformation, primary endocardial fibroelastosis and type II glycogen storage disease. The age of primary endocardial fibroelastosis is less than 1 year old. ECG shows left ventricular hypertrophy with ST-T changes, echocardiography in addition to the left atrium, left ventricular enlargement, endocardial echo enhancement, endocardial myocardial biopsy is helpful for diagnosis.

5. Arrhythmia: Sustained arrhythmia and chronic atrial tachycardia, patients with tachycardia are more common, patients with left ventricular enlargement, decreased systolic function, clinical symptoms of heart failure And signs can be misdiagnosed as DCM, patients with rapid tachycardia cardiomyopathy once arrhythmia control, heart retraction, heart function returned to normal.

6. Pericardial effusion: When a large amount of pericardial effusion, the shape of the heart is enlarged, similar to the generalized heart of dilated cardiomyopathy, DCM apex beats to the left, in the left outer edge of the heart sounding boundary, mitral valve, tricuspid auscultation area It can be audible and squeaky; the apex beat is not obvious when the pericardial effusion is located, or it is located on the inner side of the left outer edge of the heart sounding boundary, the heart sound is far away, the mitral valve, the tricuspid auscultation area has no systolic murmur, and the DCM heart failure can also be A small amount of pericardial effusion appears, and echocardiography can confirm the diagnosis.

7. Congenital heart disease (congenital heart disease): Some congenital heart disease can have obvious heart failure, the first heart sound is weakened, the third or fourth heart sound appears, the X-ray shows the heart spherical enlargement, should be differentiated from DCM, congenital heart disease There are obvious signs of heart in young children, often with obvious murmurs, some children have obvious cyanosis, echocardiography and cardiac catheterization are not difficult to rule out, some children with DCM and congenital heart disease can coexist, or after congenital heart disease surgery Appeared, at this time the diagnosis often has certain difficulties, the clinical needs attention.

8. Pulmonary heart disease: Children with pulmonary heart disease have a clear history of respiratory diseases, with the right ventricle and right atrium expanding. The pulmonary valve area can be heard and the relative pulmonary regurgitation is closed. Period murmur, pulmonary hypertension increased, related examination showed obvious lung lesions, and identification with DCM is not difficult.

9. Keshan disease: The clinical manifestations of Keshan disease are difficult to distinguish from DCM, but Keshan disease has certain epidemic areas, arrhythmia is severe and common, acute phase serum creatine phosphokinase, aspartate aminotransferase and lactate dehydrogenase often Significantly elevated, this is different from DCM.

10. Secondary cardiomyopathy excludes secondary cardiomyopathy caused by systemic lupus erythematosus, scleroderma and amyloidosis.

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