Myocarditis

Question 1

What is myocarditis?

Answer 1

Inflammation of the myocardium, the muscular layer of the heart.

It often occurs alongside inflammation of the pericardium (sac that surrounds the heart) and it is then described as myopericarditis.

Question 2

What structures make up the heart wall?

Answer 2

The heart’s wall is formed by three layers: the endocardium, myocardium, and epicardium.

Endocardium is the innermost layer, which lines the cavities and valves.

Myocardium is the middle layer formed by cardiac myocytes, which depolarise autonomously under the influence of the sinoatrial node, causing them to contract so that blood can be ejected from the heart.

The final and outermost layer is the epicardium, formed by the visceral layer of the pericardium.

Question 3

When does myocarditis usually occur?

Answer 3

It often occurs following a viral infection and should be considered in young people presenting with chest pain.

Question 4

Cause of myocarditis?

Answer 4

Infectious: viral (e.g. coxsackievirus, parvovirus B-19, human herpesvirus 6 and Epstein-Barr virus), bacterial (e.g. staphylococcus, streptococcus and mycobacterium), fungal (e.g. aspergillus, candida and histoplasma) and parasitic (e.g. leishmania)

Immune-mediated: allergens (e.g. vaccines and medications like penicillin), alloimmune (e.g. rejection after heart transplant) and autoimmune (SLE, IBD, sarcoidosis and thyrotoxicosis)

Toxins: illicit drugs (e.g. amphetamines), alcohol, medications (e.g. lithium and clozapine) and radiation

Question 5

Symptoms/signs of myocarditis?

Answer 5

CP -sharp, stabbing, worse when lying down
SOB
Palpitations
Lightheadedness
Syncope
Fever and viral prodrome

Inspiratory crackles
Arrhythmias
Tachypnoea
Lymphadenopathy
Rash
Dull heart sounds
If myopericarditis a pericardial rub may be heard.

Question 6

IVx for myocarditis?

Answer 6

ECG (non-specific ST segment and T wave changes)

Bloods (raised trop, CK-MB, inflammatory markers, BNP)

Echo

Cardiac MRI

Endomyocardial biopsy (gold-standard)

Question 7

Management for myocarditis?

Answer 7

NSAIDs -pleuritic pain
Abx -bacterial cause
Treat HF -BASH
Avoid exercise for three to six months.

Question 8

Complications of myocarditis?

Answer 8

HF
Arrhythmias
Dilated cardiomyopathy