Heart Muscle Inflammation (Myocarditis): Causes

Pathogenesis (development of disease)

In myocarditis, inflammation causes edema (swelling of tissue due to fluid retention) and secondary necrosis (cell death) of myocytes (muscle fiber cells). Structural dilatation can also be demonstrated. According to histology (microscopic examination of tissue), the following forms of myocarditis can be distinguished:

  • Parenchymal myocarditis – the myocardium (heart muscle) is directly affected; necrosis (cell death) of individual fibers or groups of muscle fibers is seen
  • Interstitial myocarditis – in this case, there is an interstitial mononuclear inflammation (affected is the tissue that lies between the actual function-bearing tissues, the parenchyma, i.e. the myocardium) accompanied by myocyte necrosis (cell death of muscle cells). Subsequently, the myocardial necrosis often leads to dilated cardiomyopathy. As a result, left and/or right ventricular dysfunction (dysfunction of the left and/or right ventricle) occurs.

Causes are infectious agents, autoimmune diseases and drugs or toxic substances. In North America and Europe, viral infections (see below) are the most common cause of myocarditis.

Etiology (Causes)

Behavioral causes

  • Pleasure food consumption
    • Alcohol
  • Drug use
    • Cocaine

Causes related to disease

  • Viral infections, especially with parvovirus B19, enteroviruses (Coxsackie A/B, Echo) or adenoviruses, play the most important role in Germany: of the further: Arboviruses, cytomegalovirus, erythroviruses, Epstein-Barr virus, herpes viruses (Epstein-Barr virus, human herpesvirus 6 as well as human cytomegalovirus), influenza A/B, HIV, hepatitis virus C (HVC), human immunodeficiency virus (HIV), poliovirus, varicella-zoster.
  • Bacterial infections, especially in septic diseases – Borrelia burgdorferi, Chlamydia, Corynebacterium diphtheriae, Legionella, Mycobacterium tuberculosis, Mycoplasma, Rickettsia, Salmonella (Salmonella enterica), Staphylococcus aureus, β-hemolytic streptococci.
  • Other pathogens such as:
    • Parasites (larva migrans, schistosomiasis, trypanosoma (Trypanosoma cruzi)).
    • Fungi (Aspergillus, Candida, Crytococcus, Histoplasmodia).
    • Protozoa (Toxoplasma gondii, trichinae, echinococci).
  • (Auto-)immune activation
    • Inflammatory bowel disease
    • Influenza vaccination
    • Post-infectious
    • Collagenoses – series of autoimmunological diseases such as:
      • Systemic lupus erythematosus (SLE) – autoimmune disease in which there is formation of autoantibodies.
      • Scleroderma – diseases associated with hardening of connective tissue of the skin alone or the skin and internal organs (especially digestive tract, lungs, heart and kidneys).
      • Sjögren’s syndrome (group of sicca syndromes) – autoimmune disease from the group of collagenoses leading to a chronic inflammatory disease of the exocrine glands, most commonly the salivary and lacrimal glands; typical sequelae or complications of sicca syndrome are:
        • Keratoconjunctivitis sicca (dry eye syndrome) due to lack of wetting of the cornea and conjunctiva with tear fluid.
        • Increased susceptibility to caries due to xerostomia (dry mouth) due to reduced salivary secretion.
        • Rhinitis sicca (dry nasal mucous membranes), hoarseness and chronic cough irritation and impaired sexual function due to disruption of mucous gland production of the respiratory tract and genital organs.
    • Rheumatoid arthritis
    • Sarcoidosis (synonyms: Boeck’s disease or Schaumann-Besnier’s disease) – systemic disease of connective tissue with granuloma formation.
    • Vasculitides – diseases in which autoimmunological processes lead to inflammation of arteries, arterioles, capillaries, venules and veins, which also damages the supplied organ such as:
      • Eosinophilic granulomatosis with polyangiitis (EGPA; formerly Churg-Strauss syndrome (CCS)) – granulomatous (roughly: “granule-forming”) inflammation of the small to medium-sized blood vessels, in which the affected tissue is infiltrated (“walked through”) by eosinophilic granulocytes (inflammatory cells)
      • Takayasu arteritis (granulomatous vasculitis of the aortic arch and outgoing great vessels; almost exclusively in young women)

Medication*

  • Anthracyclines* * (e.g. doxorubicin).
  • Antibiotics
    • Cephalosporins
    • Tetracyclines
  • Antirheumatic drugs (rheumatism drugs)* .
  • Cephalosporins*
  • Checkpoint inhibitors – combined therapy with ipilimumab and nivolumab may lead to fuminant myocarditis
  • Chemotherapeutic agents* *
  • Clozapine* (neuroleptic) – so-called hypersensitivity myocarditis.
  • Catecholamines* *
  • Penicillin*
  • Tricyclic antidepressants*
  • Sulfonamides*
  • Cytokines* *

* Allergic/hypersensitive * * Toxins X-rays.

Environmental pollution – intoxications (poisoning).

  • Arsenic
  • Lead
  • Copper
  • Lithium
  • Zinc