First, viral myocarditis
Viral myocarditis is quite common. It is a kind of primary myocardial inflammation caused by cardiophilic virus, which often involves pericardium and causes pericarditis. In fact, the so-called idiopathic myocarditis is most likely caused by virus infection.
Etiology and pathogenesis
There are many kinds of viruses that can cause myocarditis, among which Coxsackie virus, echovirus (human enterovirus), rubella virus, influenza virus and mumps virus are the most common. Coxsackie virus and rubella virus occupy a particularly important position, because they can cause fetal congenital heart malformation when infected in the first three months of pregnancy. Coxsackie virus B infection is the most common myocarditis in human beings. Generally speaking, cardiotropic virus can directly destroy myocardial cells, but it can also indirectly destroy myocardial cells through T cell-mediated immune response. Because the molecular structure of glycoprotein in the capsid of this virus is similar to that in the myocardial cell membrane, the antibodies produced by the body after infection (antibodies to activate complement and antibodies to neutralize virus) are aimed at both the virus and myocardial cells. Therefore, when cytotoxic T cells are sensitized, they can destroy myocardial cells infected by virus.
pathological change
The pathological changes of this disease vary with the patient's age. When the fetus in the first three months of pregnancy is infected with rubella virus, it can cause unresponsive myocardial cell necrosis in subendocardial myocardium. In the third trimester of pregnancy, when the fetus is infected with Coxsackie virus, it can cause panmyocarditis, which is often accompanied by the proliferation of cardiac periosteal fibrous elastic tissue. Neonatal viral myocarditis shows myocardial cell necrosis and granulocyte infiltration. Subsequently, macrophages, lymphocytes and plasma cells infiltrated and granulation tissue formed. Adults often involve the posterior atrial wall, interventricular septum and apical area, and sometimes the conduction system. The main pathological change under microscope is necrotizing myocarditis. There is obvious myocardial interstitial fibrosis in the late stage, accompanied by compensatory myocardial hypertrophy and cardiac cavity dilatation (congestive cardiomyopathy).
Second, bacterial myocarditis
Bacterial myocarditis can be caused by direct bacterial infection, or the effect of toxins produced by bacteria on myocardium, or allergic reactions caused by bacterial products.
1. Myocardial abscess is often caused by purulent bacteria, such as staphylococcus, streptococcus, pneumococcus, meningococcus, etc. Suppurative bacteria come from metastatic colonies of septic septicemia or suppurative thromboembolism of bacterial endocarditis. Visually, there are many small yellow abscesses on the surface and section of the heart, and there are blood bands around them. Microscopically, myocardial cells in the abscess are necrotic and liquefied, and there are a large number of pus cells and bacterial colonies in the abscess cavity. There are different degrees of degeneration and necrosis in the myocardium around the abscess, and neutrophils and monocytes infiltrate in the stroma.
2. Diphtheria myocarditis Bacillus diphtheriae can produce exotoxin, which on the one hand blocks the protein synthesis of nucleosomes in myocardial cells, and on the other hand blocks the transport of long-chain fatty acids to mitochondria mediated by carnitine, resulting in fatty degeneration and necrosis of myocardial cells. Microscopically, focal myocardial degeneration and necrosis were observed, and myocardial cells showed eosinophilic degeneration, sarcoplasmic coagulation, steatosis and sarcoplasmic lysis. Lymphocytes, monocytes and a few neutrophils can be seen in the lesion. Lesions are more common in the right ventricular wall, and tiny reticular scars are formed after healing. In some cases, diffuse myocardial necrosis may lead to sudden cardiac death.
3. Non-specific myocarditis Acute non-rheumatic myocarditis can be complicated by streptococcal infection (acute angina pectoris and tonsillitis) and scarlet fever in the upper respiratory tract. Its pathogenesis is not clear, and it may be caused by streptotoxin. The lesion is interstitial myocarditis. Microscopically, lymphocytes and monocytes infiltrated around myocardial interstitial connective tissue and small blood vessels, and myocardial cells degenerated and died to varying degrees.
Third, parasitic myocarditis
Parasitic myocarditis has the following two common types:
1. Toxoplasma myocarditis This type of myocarditis is caused by Toxoplasma gondii infection in rats. Humans are mainly infected by eating undercooked meat containing capsules. After Toxoplasma enters the human body, it reaches the mononuclear phagocyte system and various tissues through blood flow, and reproduces in the cells. Toxoplasma gondii proliferates rapidly after invading myocardial cells, forming aggregates, also known as pseudocysts. Cardiac muscle cells soon burst and pathogens entered the surrounding tissues. Lymphocytes and monocytes infiltrated around the damaged myocardial cells. After healing, a scar is formed. About half of the patients died of heart failure.
2. Chagas Myocarditis This kind of myocarditis is caused by Trypanosoma cruzi infection and is prevalent in Latin American countries. The illness is serious and the mortality rate is high. Can cause focal or diffuse myocardial necrosis, surrounded by lymphocytes and monocytes infiltration. The heart cavity is enlarged and the ventricular wall (mainly in the apical area) is thinned, which often forms ventricular aneurysm and is accompanied by thrombosis in the heart cavity.
Four. Immune reactive myocarditis
This kind of myocarditis is found in some allergic diseases, such as rheumatism, rheumatoid arthritis, systemic lupus erythematosus, polyarteritis nodosa and so on. Among them, rheumatic myocarditis is the most common, and typical rheumatic granuloma can be seen in myocardial interstitial connective tissue (see section VI of this chapter for details).
In addition, some drugs can cause allergic myocarditis, such as sulfonamides, antibiotics (penicillin, tetracycline, streptomycin, chlortetracycline, etc. ), anti-inflammatory drugs (phenylbutazone and indomethacin), antidepressants (amitriptyline) and antiepileptic drugs (phenytoin). The lesions mainly involved the left ventricle and interventricular septum. Interstitial myocarditis is often seen under the microscope. It can cause necrosis and dissolution of myocardial cells and infiltration of lymphocytes, plasma cells and significant eosinophils.
Verb (abbreviation of verb) solitary myocarditis
Isolated myocarditis, also known as idiopathic myocarditis, is still unknown. Because it was first described by Fidler (1899), it is also called Fidler myocarditis. More common in young adults aged 20 ~ 50. Acute type often leads to cardiac dilatation, which can lead to sudden death of heart failure.
pathological change
According to histological changes, it can be divided into two types:
1. Diffuse interstitial myocarditis Microscopically, a large number of lymphocytes, plasma cells and macrophages infiltrated around the myocardial interstitium and small blood vessels. Sometimes eosinophils and a few neutrophils can also be seen. There is less degeneration and necrosis of myocardial cells.
2. Idiopathic giant cell myocarditis is characterized by focal necrosis and granuloma formation (Figure 8-43). In the center of the lesion, there is red stained non-structural necrosis, surrounded by lymphocytes, plasma cells, monocytes and eosinophils, mixed with many multinucleated giant cells. Giant cells vary in shape and size, and can be foreign body type or Langans type multinucleated giant cells (Figure 8-44).
Figure 8-43 Idiopathic giant cell myocarditis
This is an inflammatory and necrotic focus (gray-white area of different sizes) of the left ventricular myocardium. Male, aged 37.
Figure 8-44 Idiopathic giant cell myocarditis
Most mononuclear cells and multinucleated giant cells ×200 are found in myocardium.
Myocarditis refers to localized or diffuse inflammatory lesions of myocardium, especially viral myocarditis. General viral infection, malnutrition, fatigue, high fever, colds, drinking and other pathogenic conditions can induce viral myocarditis. Most of its clinical manifestations can appear fever, sore throat and other symptoms similar to upper respiratory tract infection within 1 ~ 2 weeks, followed by chest tightness, palpitation, fatigue, precordial pain, shortness of breath and other symptoms, and severe cases can be complicated with heart failure. But some of them were found to be myocarditis sequela's from the beginning.
Health guide:
1. Prevention of infection: Viral myocarditis is caused by viral infection. It is very important to prevent the invasion of viruses. Especially to prevent respiratory tract infection and intestinal infection. People who are prone to colds should pay attention to nutrition, avoid overwork and choose appropriate physical activities to enhance their physique. Avoid going out unnecessarily. When you have to go out, you should pay attention to keep warm and eat healthily. Wear a mask during the cold epidemic and avoid going to crowded public places.
2. Combination of work and rest: physical fatigue caused by sudden emotional excitement or excessive physical activity should be avoided, which will reduce the body's immunity and disease resistance.
3. Appropriate rest: generally, you should stay in bed for 2-4 weeks during the acute attack, and you should still rest for 2-3 months after the acute attack. Severe myocarditis with enlarged cardiac boundary should be rested for 6 to 12 months until the symptoms disappear and the cardiac boundary returns to normal. Myocarditis sequela people can live and work as normal as possible, but don't read, work or even stay up late for a long time.
4. Diet adjustment: The diet should be high in protein, calories and vitamins. Eat more glucose, vegetables and fruits. Avoid overeating and avoid spicy, smoked and fried products. When smoking, nicotine in tobacco can promote coronary artery spasm and contraction, affect myocardial blood supply, and drinking alcohol can cause vascular dysfunction, so we should quit smoking and drinking alcohol. You can take chrysanthemum porridge, ginseng porridge and so on in your diet. And you can take sun-dried ginseng and American ginseng according to the doctor's advice, which is beneficial to the recovery of myocarditis.
5. Physical exercise: In the recovery period, if you take proper exercise according to your physical strength, such as walking, aerobics, qigong, etc., you can recover as soon as possible to avoid sequelae. As long as myocarditis sequela has no serious arrhythmia, he can take part in general physical exercises, such as jogging, dancing, Hexiangzhuang Qigong and Tai Ji Chuan. Persistence is definitely good for the recovery of the disease.
Why does myocarditis cause arrhythmia?
Myocarditis is mostly caused by infection, but it can also be caused by non-infectious diseases. No matter what the reason, myocardial degeneration is always accompanied by different degrees of inflammation. Lesions are usually eventually replaced by scar tissue, so local fibrosis always occurs after focal degeneration. Due to the inflammatory reaction of myocardium, the injury of myocardial small blood vessels and the emergence of immune mechanism, coronary arteriopathy, cardiac neuropathy and excessive contraction of the heart may occur. For example, the blockage of arterioles in the ventricle will lead to insufficient blood supply to the myocardium, loss of contractility, reduction of cardiac output, enlargement of the heart and failure. When the arterioles of the conduction system are blocked, which affects the cardiac repolarization, conduction disorder and arrhythmia may occur, thus various arrhythmias may occur.
Young people have arrhythmia. Must be myocarditis?
Some young people often have chest tightness, shortness of breath, rapid heartbeat and palpitation after work stress, fatigue and shock. Check the electrocardiogram for arrhythmia. People often think that myocarditis is not necessarily caused by myocarditis. The arrhythmia caused by the above symptoms is mostly functional, that is, it causes heart and nerve dysfunction. So it is more common in people with mental stimulation and excessive brain tension. Due to the dysfunction of autonomic nervous system, the excitation and inhibition process of cerebral cortex is damaged, which affects the normal function of cardiovascular system and causes arrhythmia.
Therefore, in the above situation, first of all, don't be nervous, let go of mental burden, listen to relaxing music, adjust your mood and check and treat yourself under the guidance of a doctor, and rule out other diseases. Better curative effect can be obtained by conditioning with traditional Chinese medicine or applying sedative drugs for a short time.
In addition to the above reasons, arrhythmia in a few young people is an infection caused by myocarditis or congenital heart disease and genetically related heart disease.
How to judge whether arrhythmia is caused by viral myocarditis?
Judging whether arrhythmia is caused by viral myocarditis mainly includes the following points:
(1) infection often occurs first, especially upper respiratory tract infection, which often causes symptoms such as fever, joint pain and general burnout. A few patients have digestive tract symptoms such as nausea and vomiting.
(2) Subsequently, symptoms of myocarditis such as palpitation, chest tightness, dull pain in precordial area, dizziness and dyspnea occurred.
(3) Physical examination can find tachycardia or other arrhythmia that is not parallel to the degree of fever. Some patients have enlarged hearts and changed heart sounds, and the third heart sound or the first heart sound is weakened or the fourth heart sound is rushing.
(4) Laboratory examination: The white blood cell count may or may not increase, for example, the erythrocyte sedimentation rate may increase in acute phase, and serum enzymes include aspartate aminotransferase, lactate dehydrogenase and creatine phosphokinase. Can ECG show ST? T change, R wave decrease, pathological Q wave, about 1 /3 patients can have I to II degree atrioventricular block.
(5) Etiological examination: The virus can be isolated from throat swabs or feces, and the specific antibodies (neutralization, hemagglutination mechanism and complement fixation test) in serum are increased, and the IgM titer is increased. If a myocardial biopsy is done, the virus can be isolated from the myocardium.
Therefore, whether arrhythmia is caused by myocarditis in clinic must be judged by combining medical history, clinical manifestations and auxiliary examination.
In addition, myocarditis can also be caused by "bacterial" infection, such as rheumatic fever caused by streptococcus infection, and it can also cause rheumatic myocarditis. According to the hemogram, ESR, anti-O and medical history, it is not difficult to distinguish it from viral myocarditis.
Under what circumstances is the arrhythmia of myocarditis easy to appear?
Recently, some young people have myocarditis, the most common is viral myocarditis, and some are bacterial (diphtheria, etc. ) fungi and protozoa. These viruses and bacteria directly invade the myocardium, as well as the damage of small blood vessels in the myocardium, myocardial damage caused by immune mechanism and myocardial damage caused by toxins, leading to myocardial cell lysis, interstitial edema and monocyte infiltration. If pathological sections are examined, microscopic examination shows that there may be histiocyte, lymph, eosinophil or neutrophil infiltration and interstitial edema in the connective tissue between myocardial fibers and around blood vessels, and myocardial fibers may be fatty, granular or glassy, or myocardial dissolution or necrosis.
If the pathological changes of myocarditis affect the pacing conduction system of the heart, such as sinoatrial node, atrioventricular node, atrioventricular bundle, Purkinje fiber, etc., arrhythmia is easy to occur.
In addition, patients with myocarditis should have a full rest in the acute phase, and should prevent excessive fatigue, emotional excitement, full meal, overeating spicy and greasy, and excessive atrioventricular. Otherwise, under the above circumstances, it is easy to aggravate the burden of myocardium, aggravate the condition and lead to arrhythmia.