Signs, treatment and classification of acute myocarditis

Causes of occurrence

According to the classification proposed by the working group on myocarditis and pericarditis of the European Society of Cardiology in 2013, there are three mechanisms for the development of the inflammatory process of myocardial tissues - infectious, immune-mediated, toxic. In most cases, an autoimmune-mediated effect on heart cells occurs, although the direct cytotoxic effects of the etiological factor also play a role in the development of the disease. The following mechanisms of damage are distinguished:

• Direct toxic effect of the etiological agent on heart tissue.
• Secondary damage to myocardial cells caused by the body's immune response to the introduction of the pathogen.
• Expression of cytokines - activation of enzyme systems and release of active biological substances in the myocardium.
• Aberrant induction of apoptosis - abnormal processes of destruction of healthy cardiomyocytes are triggered.

The etiology of myocarditis is presented in table 1:

Tab. one

Classification of myocarditis

In half of the cases, it is not possible to establish the exact etiology. Cardiologists call such myocarditis idiopathic. Scientists have also discovered an interesting "geographical" phenomenon - on the European continent parvovirus B19 and human herpes virus type 6 are more often detected in cardiobiopsy, in Japan - hepatitis C virus, in North America - adenovirus. In addition, a change in the leading etiological agent was observed over time - until the 1990s, myocarditis was caused in most cases by the Coxsackie virus type B, from 1995 to 2000. - adenoviruses, and since 2001 - parvovirus B19.

Symptoms and Signs

The clinical picture usually occurs several weeks after the infection. It is important to exclude other heart diseases and non-cardiological pathology occurring against the background of angina pectoris, hypertension. The patient may complain about:

• hyperthermia - a sharp increase in temperature;
• muscle pain due to concomitant inflammation of the skeletal muscles.
• interruptions in the work of the heart;
• shortness of breath, which "lies in wait" for a person at rest or with minimal physical activity;
• chest pain in which taking Nitroglycerin does not bring relief;
• general weakness and sweating;
• cough, sometimes with hemoptysis - this indicates a complication of myocarditis, pulmonary embolism, pulmonary infarction and peri-infarction pneumonia.

Myocarditis can cause circulatory failure - acute (develops within two weeks) or chronic (the phenomenon is increasing gradually, more than 3 months). With damage to the myocardium of the left ventricle (left ventricular failure), the patient shows signs of stagnation in the pulmonary circulation:

• moist wheezing in the lungs on auscultation;
• shortness of breath at rest;
• suffocation attacks.

With a deterioration in the function of the right ventricle (right ventricular failure), swelling of the cervical veins, edema of the extremities, and enlargement of the liver appear. The clinical picture depends on the degree of damage, the activity of the inflammatory process, the leading symptom.

Sometimes, sudden death due to ventricular fibrillation may be the first and only manifestation.

Features in children

Pediatricians distinguish congenital and acquired myocarditis. Clinical manifestations in children depend on age. They are often mistakenly interpreted as symptoms of other diseases - pneumonia, obstructive bronchitis, gastroenterocolitis.

During the neonatal period, myocarditis is characterized by a severe course. Can be observed:

• rejection of the breast;
• shortness of breath when sucking;
• vomiting and regurgitation syndrome;
• pallor;
• swelling of the eyelids;
• apnea attacks;
• tachycardia;
• cough;
• noisy exhalation;
• retraction of the intercostal spaces on inspiration;
• wheezing in the lungs on auscultation.

In preschoolers and younger schoolchildren, myocarditis can manifest itself as vomiting, abdominal pain, hepatomegaly. In high school students - excessive weakness, rapid breathing, fainting.

Changes in the muscle structure of the heart with myocarditis

Classification and special types of disease

Several variants of the classification of this disease have been proposed. Most of them take into account the etiology, pathogenesis, morphology, course, clinic, stage of the disease. One of the most fully reflecting the symptoms of myocarditis in adults is presented in table. 2.

Tab. 2 Clinical and morphological classification of myocarditis E.B. Lieberman et al. (1991)

There are also the Dallas criteria that divide myocarditis into:

• active, arising against the background of inflammatory infiltration (necrosis, degenerative changes);
• borderline - a small amount of infiltrates or no signs of cell destruction.

Let's talk in more detail about the individual forms of myocarditis.

Autoimmune myocarditis

The cause of development is the reaction of antibody production to external allergens (drugs, toxins).They also appear in systemic diseases, when the body begins to synthesize antigens (systemic lupus erythematosus, celiac disease).

One of the variants of autoimmune myocarditis is the rejection of the transplanted heart due to the production of allogens.

Toxic myocarditis

When examining such a heart under a microscope, there are practically no eosinophils (leukocytes characteristic of allergies), foci of necrosis are revealed with subsequent compaction. Cocaine intoxication causes acute myocarditis, which is accompanied by pulmonary edema.

In the case of taking anthracycline antibiotics, dystrophy develops, followed by cardiosclerosis, often accompanied by pericarditis. In case of poisoning with some compounds, manifestations can only be expressed by changes in the electrocardiogram.

Diphtheria myocarditis

Diphtheria in ¼ cases is accompanied by myocardial dystrophy. In this case, the pathways that are responsible for the transport of the electrical signal are often affected. Complications usually occur in the second week of the illness. Heart enlargement and heart failure are characteristic.

Eosinophilic myocarditis

It occurs more often in people who use drugs or toxic substances, often accompanied by itchy spotty rashes. Under the microscope - foci of necrosis and eosinophilic infiltration.

Giant cell

Differs in persistent ventricular tachycardia and progressive heart failure. Less common are conduction disturbances.

Abramov-Fiedler's idiopathic myocarditis

A rare disease characterized by malignant progression and the development of right ventricular failure. Arrhythmias and thromboembolic events appear. In a chronic course, it can proceed latently, ending in sudden death.

Abramov-Fiedler idiopathic myocarditis under a microscope (source: beregi-serdce.com)

Diffuse myocarditis

It is manifested by extensive damage to the muscle layer. Since children and young people suffer more often, some authors call it a "young" disease. Often it is infectious myocarditis, accompanied by fever, heart rhythm disturbances, distension of the heart.

Rheumatic myocarditis

In acute rheumatic fever, 50 - 90% of the heart suffers, which is manifested by endomyocarditis. Symptoms include joint pain, subcutaneous granulomatous nodules, and convulsions.

Focal myocarditis often affects the posterior wall of the left atrium and affects the posterior left papillary muscle.

One of the forms of myocarditis, scientists consider peripartum cardiomyopathy - a pathology that occurs in late pregnancy or after childbirth, characterized by left ventricular failure.

Diagnostic criteria

Most cases of myocarditis are not clinically apparent. Endomyocardial biopsy is considered the basis of diagnosis. But given the invasiveness of the technique, in 2013 European criteria were proposed, according to which a doctor can suspect the pathology in question and determine the need for mini-surgery. These include:

• symptomatic: pain syndrome, breathing disorders, loss of consciousness, arrhythmias, cardiogenic shock (a sharp drop in pressure) of unknown origin;
• data from laboratory and instrumental examinations.

Analyzes

Laboratory diagnostics of myocarditis includes: general and biochemical blood tests, rheumatological screening, immunological methods. Pay special attention to:

• markers of inflammation (increased ESR, C-reactive protein, an increase in the number of eosinophils);
• increased levels of cardiac troponins, creatine kinase;
• an increase in the titers of viral antibodies and the determination of those to the cells of the heart.

The above changes cannot accurately confirm or deny myocarditis in the patient, since many of them (ESR, C-reactive protein) are not specific, and the detection of antibodies to a certain type of virus does not indicate the presence of myocarditis.

Echocardiographic signs

Echocardiography allows you to assess the size of the chambers, the thickness of the walls of the ventricles and indicators reflecting the function of the myocardium. Thanks to it, other causes of heart failure can be excluded. An examination is prescribed to assess the effectiveness of therapy and before the endomyocardial biopsy.

ECG

The result of decoding the electrocardiogram is not a reliable conclusion. EKG abnormalities indicate the involvement of the myocardium in the pathological process. Some changes can serve as a marker of a poor prognosis of the disease.

Scintigraphy, tomography and other methods

Given the high toxicity to the body of radionuclide methods, scintigraphy is performed only for the purpose of diagnosing sarcoidosis.

The most optimal non-invasive examination method is magnetic resonance imaging. It gives the doctor an idea of ​​the existing pathological processes in the myocardium. But the information content decreases with a long chronic course of the disease. Also, MRI cannot be performed in patients with life-threatening conditions.

Coronary angiography will exclude ischemia as a cause of circulatory failure. Chest x-rays will reveal heart enlargement, signs of pulmonary hypertension, and pleural effusion.

Treatment

Treatment for myocarditis is aimed at eliminating the cause, congestion and improving blood circulation in the body. There are two types of therapy:

1. Etiological - the appointment of antibiotics and antiviral agents for infectious myocarditis, immunosuppressants - in case of systemic diseases, sarcoidosis, glucocorticoids (Prednisolone) - in case of allergic disorders, drug withdrawal - if myocardial damage is associated with the toxic effects of the drug.
2. Symptomatic - it is recommended to limit physical activity, the use of salt, exclusion of alcoholic beverages, the fight against rhythm and conduction disturbances, circulatory failure, prevention of life-threatening conditions.

From medications, vasodilators are prescribed (dilate blood vessels), angiotensin-converting enzyme inhibitors, beta-blockers, diuretics. Anticoagulants can be recommended as prevention of thromboembolic events, although there is no reliable evidence on the appropriateness of their use. Precaution requires the appointment of antiarrhythmic drugs, since in some cases they can aggravate the course of heart failure.

Digoxin is contraindicated in acute circulatory disorders in patients with viral myocarditis.

In some cases, myocarditis requires surgical intervention:

• urgent (temporary) transvenous cardiac stimulation - as an emergency therapy for complete atrioventricular block;
• the use of a heart-lung machine or extracorporeal membrane oxygenation.

Indications for hospitalization

Patients with symptoms of acute myocarditis must be hospitalized. In the chronic course of the disease, hospitalization is necessary in case of deterioration of the condition and in case of hemodynamic disorders. In a medical institution, you can provide:

• hemodynamic and cardiological monitoring;
• oxygen therapy;
• adequate fluid therapy.

Individuals with life-threatening conditions require treatment and care in intensive care units.

Exercise therapy and rehabilitation after myocarditis

After suffering myocarditis, patients need rehabilitation measures. Supportive therapy at home and in a sanatorium is recommended, as well as regular monitoring by a cardiologist, the duration of which depends on the outcome of the disease, on average - at least one year.Sports are possible no earlier than 6 months after the normalization of myocardial function.

The consequences of myocarditis

The outcomes of myocarditis can be recovery and complete restoration of the functions of the heart muscle, the development of circulatory failure, as well as residual effects in the form of arrhythmias. Patients need prevention in the form of:

• remediation of foci of infections;
• prevention of purulent complications with cuts;
• preventive vaccinations;
• compliance with basic hygiene rules.

Patients should be informed about the mechanisms of development, the importance of diagnostic procedures, adherence to treatment, the consequences of myocarditis.

Forecast

In acute and fulminant forms of myocarditis, in most cases, complete recovery occurs. Subacute and chronic course significantly worsen the prognosis. The development of NYHA grade III and IV heart failure, as well as foci of late enhancement on MRI, has adverse consequences.