Acute Myocarditis

This is an inflammation & potentially reversible condition of the myocardium. Myocarditis or inflammatory cardiomyopathy is inflammation  of heart muscle (myocardium).

Causes:

1.      Idiopathy.

2.      Infective.

a)      Viral:

·         Coxscakei virus.

·         Adeno virus.

·         Echo virus.

·         Influenza (A and B) virus.

·         Polio virus.

·         HIV.

b)      Bacterial:

·         Streptococcus (most common Rh carditis)

·         Diphtheria (toxin-medicated heart block common)

c)      Parasitic:

·         Trypanosoma cruzi.

·         Toxoplasma gondii.

d)     Spirochaetal:

·         Lyme disease (heart block common)

·         Leptospirosis.

3.      Toxic.

4.      Drugs (causing hypersensitivity reaction):

·         Methyl-dopa, Penicillin.

·         Sulphonamides, Antituberculous.

5.      Radiation.

6.      Autoimmune: An autoimmune form with auto-activated T-cells and organ specific antibodies may occur.

Clinical features:

1.      Fever.

2.      Chest pain.

3.      Tachycardia (bradycardia in diptheric myocarditis)

4.      Cardiac failure.

5.      Pericardial friction rub.

Investigations:

1.      Chest X-ray: Cardiac enlargement.

2.      ECG demonstrates-

·         S-T and ‘T’ wave abnormalities.

·         Heart block with diptheric myocarditis.

3.      Cardiac enzymes- elevated.

4.      Viral antibody titres-increased.

5.      Endomyocardial biopsy- Show acute inflammation.

Treatment: most viral infections cannot be treated with directed therapy, symptomatic treatment is the only form of therapy for those forms of myocarditis. In the acute phase, supportive therapy, including bed rest, is indicated. For symptomatic patients, digoxin and diuretics provide clinical improvement. For patients with moderate to severe dysfunction, cardiac function can be supported by use of inotropes such as Milrinone in the acute phase, followed by oral therapy with ACE inhibitors (Captopril, Lisinopril) when tolerated. People who do not respond to conventional therapy are candidates for bridge therapy with left ventricular assist devices. Heart transplantation is reserved for patients who fail to improve with conventional therapy.

In several small case series and randomized control trials, systemic corticosteroids have shown to have beneficial effects in patients with proven myocarditis. However, data on the usefulness of corticosteroids should be interpreted with caution, since 58% of adults recover spontaneously, while most studies on children and infants lack control groups.

Advice: Avoid intense physical exertion.

Reference:

1.      Davidson’s Principles and Practice of Medicine, 21^st edition.

2.      Kumar and clark, clinical Medicine, 7^th edition.

3.      Wikipedia free encyclopedia.