Myocarditis

Super excited for bedtime!!!!


Myocarditis:

Definition: acute inflammation of the myocardium (cardiac muscle)

                      Pericarditis may occur concurrently.

Aetiology/ risk factors:

Causes:

Idiopathic (50%)

Viral (flu, hepatitis, mumps, rubeola, Coxsackie, polio, HIV) = most common cause in UK, esp. Coxsackie virus

Bacterial (Clostridia, diphtheria, TB, meningococcus, mycoplasma, brucellosis, psittacosis, rheumatic fever, leptospirosis, syphilis, Lyme disease)

Protozoa (trypanosomiasis = Chagas disease), Fungi (candidiasis), Helminths (trichinosis)

Drugs (cyclophosphamide, Herceptin, penicillin, chloramphenicol, sulfonamides, methyldopa, spironolactone, phenytoin, carbamazepine)

Systemic disorders (SLE, sarcoidosis, polymyositis)

Radiation injury

Toxins, cocaine abuse

Vasculitis

Epidemiology: true incidence unknown as many causes not detected at the time of acute illness. Coxsackie B virus is a common cause in Europe and USA, whilst Chagas disease is a common cause in South America.

Symptoms:

-prodromal ‘flu-like’ illness-malaise, lethargy

-fatigue

-dyspnoea

-chest pain

-fever

-palpitations

Signs:

-tachycardia

soft S1

s4 gallop (just before the soft S1)- represents atrial contraction against a ventricle made stiff by any cause

-signs of complications/heart failure (e.g. bi-basal crackles of pulmonary oedema, raised JVP)

Investigations:

BloodFBC (raised WCC if infective), U&E, ESR/CRP (raised), Viral/bacterial serology

              Antistreptolysin O titre (e.g. rheumatic fever)

              ANA (SLE), serum ACE (sarcoidosis)

ECG- ST elevation or depression, T wave inversion, atrial arrhythmias, transient AV block (non-specific changes)

Troponin- in the absence of MI, positive troponin (I or T) confirms the diagnosis

CXR- may show cardiac enlargement +/- pulmonary oedema

Antimyosin scintigraphy (nuclear medicine scan)-shows myocardial damage. If negative, excludes active myocarditis.

Diagnosis is supported by demonstration of an increase in serum viral titres and inflammation on myocardial biopsy but the findings rarely influence the management and biopsy is not usually performed.

Management:

-supportive- bed rest

-treat underlying cause

-treat heart failure and arrhythmias

-steroids and immunosuppressants have been used in severe cases but are of unproven benefit

-cardiac transplantation for severe cases

Complications: chronic inflammation, heart failure (varying degrees of biventricular failure). Resolution of inflammation with different degrees of residual dilated cardiomyopathy, arrhythmias and death.

Prognosis: generally good prognosis, usually mild and self-limiting

Image result for myocarditis

On second thought, I think the guy I saw in A&E probably had myocarditis. His presentation fits more with this picture.

 

References: Cheese & Onion, Kumar & Clark’s

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