Myocarditis

Question 1

Definition

Answer 1

Acute inflammation and necrosis of cardiac muscle (myocardium)

Question 2

Epidemiology

Answer 2

· Incidence is difficult to measure accurately

· Coxsackie B virus is most common in Europe and USA

· Chagas disease is most common in South America

Question 3

Aetiology/Risk factors

Answer 3

· Usually IDIOPATHIC

· Viruses
o Coxsackie B
o EBV
o CMV
o Adenovirus
o Influenza

· Bacteria
o Post-streptococcal
o Tuberculosis
o Diphtheria

· Fungal
o Candidiasis

· Protozoal
o Trypanosomiasis (Chagas disease)

· Helminths
o Trichinosis

· Non-infective
o Systemic: SLE, sarcoidosis, polymyositis
o Hypersensitivity myocarditis: sulphonamides

· Drugs
o Chemotherapy agents (e.g. doxorubicin, streptomycin)

· Others
o Cocaine, heavy metals, radiation

Question 4

Presenting symptoms

Answer 4

· Prodromal flu-like illness with:
o Fever
o Malaise
o Fatigue
o Lethargy

· Breathlessness (due to pericardial effusion/myocardial dysfunction)

· Palpitations

· Sharp chest pain (suggesting there is also pericarditis)

Question 5

Signs on physical examination

Answer 5

· Signs of pericarditis

· Signs of complications (e.g. heart failure, arrhythmia)

Question 6

Investigations (bloods)

Answer 6

o FBC - raised WCC if infective cause
o U&E
o ESR/CRP - raised
o Cardiac enzymes - may be raised
o Tests to identify cause (e.g. viral/bacterial serology, ANA, TFT)

Question 7

Investigations (other)

Answer 7

· ECG
o Non-specific T wave and ST changes
o PERICARDITIS: widespread saddle-shaped ST elevation

· CXR
o May be NORMAL
o May show cardiomegaly

· Pericardial Fluid Drainage
o Measure glucose, protein, cytology, culture and sensitivity
o Helps identify causative organism

· Echocardiography
o Assesses systolic/diastolic function
o Wall motion abnormalities
o Pericardial effusions

· Myocardial Biopsy
o Rarely required