What is the Medical Term for Heart Muscle Disease and Its Causes

Understanding Myocarditis

Myocarditis, a term that originates from the Greek words myo (muscle) and carde (heart), is the inflammation of the myocardium, the muscle tissue that comprises the heart walls. This condition, an inflammatory cardiomyopathy, has a vast array of causes and clinical presentations, ranging from subtle to life-threatening.

Myocarditis is frequently caused by a diverse range of infectious agents, autoimmune disorders, exogenous agents, genetic factors, and environmental predispositions. It often manifests in individuals who are otherwise healthy, and may lead to rapidly progressive heart failure or cardiac arrhythmias. This inflammation can be classified into different types: fulminant myocarditis, acute myocarditis, chronic active myocarditis, and chronic persistent myocarditis.

Etiology: A Multitude of Agents

Viral Myocarditis

Viral myocarditis can be triggered by various viruses, including Coxsackievirus types A9 and B3, parovirus, influenza, cytomegalovirus, Epstein-Barr virus, and SARS-CoV-2 (responsible for COVID-19). Among these, Coxsackievirus A9 is often self-limiting, while that caused by B3 has a high mortality rate. Viral myocarditis can present flu-like symptoms, joint pain, and upper respiratory issues.

Bacterial Myocarditis

Bacterial myocarditis may result from pathogens such as diphtheria, tuberculosis, streptococci, meningococci, brucellosis, clostridia, staphylococci, Mycoplasma, psittacosis, rickettsia, and Spirochaetae. Diseases like Rocky Mountain spotted fever, Q fever, syphilis, leptospirosis, Lyme disease, candidiasis, aspergillosis, cryptococcosis, histoplasmosis, and toxoplasmosis can also cause myocarditis.

Helminthic Myocarditis

Helminthic myocarditis can be caused by parasitic infections such as Trichinosis, echinococcosis, schistosomiasis, cysticercosis, filariasis, and more.

Myocarditis from Bites or Stings

Myocarditis can also be caused by venom from scorpion, snake, black widow, wasp, tick paralysis, and more.

Myocarditis Induced by Drugs

Myocarditis triggered by drugs, usually as a result of hypersensitivity reactions, affects patients with reactions to medications like penicillin, chloramphenicol, sulfonamides, streptomycin, doxorubicin, cyclophosphamide, and anthracyclines.

Myocarditis Induced by Chemicals

Chemical-induced myocarditis can arise from exposure to various substances, including hydrocarbons, carbon monoxide, arsenic, lead, phosphorus, mercury, and cobalt.

Physical Agents Causing Myocarditis

Physical agents such as radiation, heatstroke, hypothermia, or systemic inflammatory diseases can also lead to myocarditis. Conditions like sarcoidosis, Kawasaki disease, chronic ulcerative colitis, systemic lupus erythematosus, hyperthyroidism, rheumatoid arthritis, and scleroderma have been linked to myocarditis.

Peripartum Cardiomyopathy and Posttransplant Cellular Rejection

Myocarditis can also occur as a result of peripartum cardiomyopathy or posttransplant cellular rejection.

Idiopathic Myocarditis

In some cases, the underlying cause of myocarditis may remain idiopathic. Although viral etiology is often suspected, it is not always confirmed. Approximately 50% of myocarditis cases might fall under this category.

Clinical Manifestations of Myocarditis

Patients with myocarditis may present with a range of symptoms, including chest pain, bother caused by concurrent pericarditis, fever, sweating, chills, shortness of breath, and dyspnea. Viral myocarditis may also exhibit flu-like symptoms such as joint pains, malaise, pharyngitis, and tonsillitis.

Some adults may experience few symptoms, while others may face severe symptoms resulting from sudden and diffuse cardiac inflammation. In cases of fulminant myocarditis, unrecognized and untreated conditions may lead to cardiogenic shock, ventricular arrhythmias, or multiorgan system failure. Chronic heart failure may also develop years after an initial myocarditis event.