Infectious myocarditis

Overview

Infectious myocarditis: Inflammation of the muscle of the heart (myocardium) due to an infection. It often occurs as a complication of various bacterial, viral or parasitic infections such as rubella, polio and rheumatic fever.

Symptoms

The list of signs and symptoms mentioned in various sources for Infectious myocarditis includes the 7 symptoms listed below: * Fever * Chest pain * Heart palpitations * Fatigue * Shortness of breath * Rapid heartbeat

Causes

  • bacterial infections — diphtheria; tuberculosis; typhoid fever; tetanus; and staphylococcal, pneumococcal, and gonococcal infections 
  • chemical poisons — such as chronic alcoholism 
  • helminthic infections — such as trichinosis 
  • hypersensitive immune reactions — acute rheumatic fever and postcardiotomy syndrome 
  • parasitic infections — especially South American trypanosomiasis (Chagas’ disease) in infants and immunosuppressed adults; also toxoplasmosis 
  • radiation therapy — large doses of radiation to the chest in treating lung or breast cancer 
  • viral infections (most common cause in the United States and western Europe) — coxsackievirus A and B strains and, possibly, poliomyelitis, influenza, rubeola, rubella, and adenoviruses and echoviruses. Myocarditis occurs in 1 to 10 of every 100,000 people in the United States. The median age for this disorder is 42, and incidence is equal between males and females. Children, especially neonates, and persons who are immunocompromised or pregnant (especially pregnant black women) are at higher risk for developing this disorder.

Diagnosis

The patient history commonly reveals recent febrile upper respiratory tract infection, viral pharyngitis, or tonsillitis. A physical examination shows supraventricular and ventricular arrhythmias, third and fourth heart sounds, a faint first heart sound, possibly a murmur of mitral insufficiency (from papillary muscle dysfunction) and, if pericarditis is present, a pericardial friction rub. ECG typically shows diffuse STsegment and T-wave abnormalities (as in pericarditis), conduction defects (prolonged PR interval), and other supraventricular arrhythmias. Echocardiography may show a weak heart muscle, an enlarged heart, or fluid surrounding the heart. Stool and throat cultures may identify the causative bacteria. An endomyocardial biopsy can confirm the diagnosis, but it’s rarely performed. Laboratory tests can’t unequivocally confirm myocarditis, but the following findings support this diagnosis: 

  • Cardiac enzyme levels (creatine kinase [CK], the CK-MB isoenzyme, aspartate aminotransferase, and lactate dehydrogenase) are elevated. 
  • White blood cell count and erythrocyte sedimentation rate are increased. 
  • Antibody titers (such as antistreptolysin O titer in rheumatic fever) are elevated. 
  • Blood cultures may indicate infection.