Myocarditis diagnosis: From light microscope to molecular analysis and cardiac magnetic resonance

Telling story of myocarditis is characterized by discoveries and inventions. The invention of the microscope opened new avenues in medicine, with the observation of myocardial inflammation by Carl Ludwig Alfred Fiedler. Rudolph Virchow discovered that cells are the elementary units. Karl Albert Ludwig Aschoff first reported rheumatic pancarditis. Gilbert Dallford found enterovirus in the faeces of children, who died suddenly in the village of Coxsackie. Werner Forssmann entered in his own right ventricle with a urologic catheter via the left radial vein. Endomyocardial biopsy, via the femoral or jugular veins, made possible to take away myocardial samples <i>in vivo</i>, for diagnosis of myocarditis or cardiac rejection of transplanted heart. The invention of polymerase chain reaction by Kary Mullis allowed to achieve diagnosis of concealed infections and genetically determined cardiomyopathies. Myocarditis, a significant cause of sudden death, was found to be frequently ascribed to viruses. Cytotoxicity of Coxsackievirus B was proved to consist on released protease 2, encoded by virus genome and cleaving dystrophin. RNA (Coxsackie) and DNA (adenovirus) viruses share a common receptor. Cardiac magnetic resonance revealed to be sensitive and specific in the diagnosis of myocarditis by detecting myocardial oedema. However, it is unable to establish the histotype. The onset of myocarditis may be fulminant; however, extracorporeal membrane oxygenation, invented by Robert Bartlett, allows heart rest, while replacing cardiac contractility. High rates of survival have been achieved, probably because of mild myocardial damage.