Myocarditis, or an inflammation of the heart muscle or myocardium is characterized by a number of infectious or non-infectious etiologies, but most commonly is the result of viral infections that include Chagas’ disease, a tropical parasite, enterovirus such as D68, a fast spreading virus related to hand-foot-mouth disease, adenovirus, commonly infecting the eyes, lungs, intestines and urinary tract, and parvovirus, another infectious intestinal virus. Other viruses have been implicated, such as hepatitis C, herpes simplex and cytomagalo virus. Bacterial and fungal infections are also possible causes.
The exact incidence of myocarditis is not clearly known since the clinical presentation varies considerably and the diagnosis can be difficult, but post mortem studies indicate that up to one in eight cases of sudden death in children are due to myocarditis.
Myocarditis is not an easy diagnosis to make, since it mimics many other conditions. Patients may be asymptomatic, they may only present transient ECG abnormalities or they may present cariogenic shock, cardiovascular collapse and even sudden death. ECG changes include T wave inversion, low QRS voltage, and non-specific ST segment changes. For the echocardiographer, look for pulmonary hypertension, reduced ejection fraction, reduced cardiac performance, wall motion abnormalities, cardiomegaly and particularly, pericardial effusion. Also important is to look for diastolic dysfunction, both left and right ventricular. Blood testing and radiology exams are not that helpful in this diagnosis.
Treatment involves afterload (the amount of force required by the myocardium in order to eject blood out of the ventricle) reduction, diuretics and vasodilators in order to reduce demand on the heart muscle.
Ken Heiden