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Myocarditis (Investigations (Chest X-ray- cardiac enlargement, depending…
Myocarditis
Investigations
- Chest X-ray- cardiac enlargement, depending on the stage and virulence of the disease.
- ECG - ST and T wave abnormalities and ventricular arrhythmias. Heart block may be seen with diphtheritic myocarditis, Lyme disease and Chagas' disease .
- Echo- cardiac enlargement, focal hipo/akinesis
- Cardiac enzymes – TNT, TNI, CKMB elevated.
- Viral antibody titres may be increased
- Endomyocardial biopsy may show acute inflammation but false negatives are common by conventional criteria. Biopsy is of limited value outside specialized units.
- Viral RNA biopsy material using polymerase chain reaction (PCR). Specific diagnosis requires demonstration of active viral replication within myocardial tissue
Causes
- Idiopathic
- Toxic: catecholamines, chemotherapy, cocaine
- Drugs Causing hypersensitivity reactions, e.g. penicillin, sulphonamides, antituberculous
- Radiation May cause myocarditis but pericarditis more common
- Autoimmune An autoimmune form with autoactivated T cells and organ-specific antibodies may occur
- systemic diseases: collagen vascular diseases (SLE, rheumatoid arthritis, others), sarcoidosis,
autoimmune
Infective
- Viral: Coxsackievirus (commonest), adenovirus, CMV, echovirus, influenza, polio, hepatitis, HIV
- Parasitic: Trypanosoma cruzi, Toxoplasma gondii (a cause of myocarditis in the newborn or immunocompromised)
- Bacterial: Streptococcus (most commonly rheumatic carditis), diphtheria (toxin-mediated heart block common)
- Spirochaetal: Lyme disease (heart block common), leptospirosis
- Fungal, Rickettsial
Treatment
- The underlying cause must be identified, treated, eliminated or avoided.
- Bed rest is recommended in the acute phase of the illness and athletic activities should be avoided for 6 months.
- Heart failure should be treated conventionally with the use of diuretics, ACE inhibitors, spironolactone± ,digoxin, beta-blockers(?)
- Antibiotics should be administered immediately where appropriate.
- NSAIDs are contraindicated in the acute phase of the illness but may be used in the late phase.
- The use of corticosteroids is controversial and no studies have demonstrated an improvement in left ventricular ejection fraction or survival following their use.
Pathology
- acute phase myocarditic hearts are flabby with focal haemorrhages
- chronic cases they are enlarged and hypertrophied.
- Histologically an inflammatory infiltrate is present
lymphocytes predominating in viral causes
polymorphonuclear cells in bacterial causes
eosinophils in allergic and hypersensitivity causes
Clinical features
- asymptomatic state associated with limited and focal inflammation
- Heart failure - fatigue, palpitations, chest pain, dyspnoea and fulminant congestive cardiac failure due to diffuse myocardial involvement, idiopathic' dilated cardiomyopathy, acute heart failure
- Arrhythmias, conduction abnormalities
- Pericarditis - pericardial friction rub may be heard.
- Acute chest pain syndrome
Giant cell myocarditis
- Severe form of myocarditis
- Multinucleated giant cells within the myocardium
- The cause is unknown
- May be associated with sarcoidosis, thymomas and autoimmune disease.
- Rapidly progressive course and a poor prognosis.
- Immunosuppression is recommended.
- Inflammation of the myocardium
- Establishment of a definitive aetiology with isolation of viruses or bacteria is difficult in routine clinical practice.
- Myocarditis-> Inflammatory cardiomyopathy:
chronic myocarditis, with left ventricular dysfunction - chamber dilatation and hypokinesis
the prognosis depends on the rapidity of its development and the status of left ventricular function.