Cardiac Myopathies* and Pericarditis**

Question 1

Cardiomypathy definition

Answer 1

A cardiomyopathy is a primary abnormality of the myocardium that usually produces a change in wall thickness, chamber size and mechanical and/or electrical dysfunction.

Question 2

Cause of cardiomyopathies

Answer 2

Many cases the cause is unknown, however, some genetic abnormalities in cardiac energy metabolism or structural and contractile proteins underlie myocardial dysfunction or are secondary to a systemic or multi-organ disorder.

Question 3

Cardiomyopathies classification

Answer 3

The classification is based on its clinico-pathologic, aetiology and mechanistic concepts into:

• Dilated
• Hypertrophic
• Restrictive

Question 4

Dilated cardiomyopathy

Answer 4

This is the most common cardiomyopathy (90%) characterised by progressive cardiac dilation and contractile (systolic) dysfunction, usually with concomitant hypertrophy.

Question 5

Dilated cardiomyopathy artiology

Answer 5

Genetic: familial ocurrence in 20-50% of cases, usually but not always autosomal dominant.

Non-genetic: idiopathic, chronic alcoholism, peripartum, myocarditis (coxsackie virus B and other enteroviruses), haemochromatosis, chronic anaemia, doxorubicin,

Sarcoidosis

Question 6

Macroscopic features of dilated cardiomyopathy

Answer 6

Enlarged heart, 2-3x size of normal, with dilation of all chambers. Wall thinning accompanies dilatation, but wall thickness can be normal if hypertrophy has occurred. Mural thrombi may be seen.

Question 7

Microscopic features of dilated cardiomyopathy

Answer 7

Nonspecific changes.

Question 8

Clinical features of dilated cardiomyopathy

Answer 8

The idiopathic variety may occur at any age, including childhood but most commonly affects individuals between ages 20-50.

Signs and symptoms of heart failure.

Death is usally attributable to progressive HF over 2-5 years or an arrhythmia or may occur suddenly.

Question 9

Hypertrophic cardiomyopathy

Answer 9

Also called *idiopathic hypertrophic subaortic stenosis *and hypertrophic obstructive cardiomyopathy.

Question 10

Causes of hypertrophic cardiomyopathy

Answer 10

Caused by a mutation in one of several genes that encode proteins that are part of the sarcomere - the contractile unit of the cardiac and skeletal muscle that results in myocardial hypertrophy, abnormal diastolic filling (which is reduced) and in about 33% intermittent ventricular outflow obstruction.

Most cases are familial and usually autosomal dominant with variable penetrance. The most common are mutations in the beta-myosin heavy chain, myosin-binding protein C and troponin T and these account for 70-80% of all cases. Why mutations in these genes cause hypertrophy is unknown. Potantially, imapired contraction reuslts in release of growth factors to allow compensatory hypertrophy.

Question 11

Macroscopic features of hypertrophic cardiomyopathy

Answer 11

Massive myocardial hypertrophy usually without ventricular dilatation.

Classically (90%) of patients there is disproportionate thickening of the ventricular septum as compared with the free wall of the left ventricle 0 termed asymmetrical septal hypertrophy. The left ventricular cavity becomes banana shaped by the bulging of the ventricular septum into the umen. Often subendocardial thickening or mural plaque formation in the left ventricular outflow tract and thickening of teh anteiror mitral valve leaflet,

Question 12

Microscopic features of Hypertrophic cardiomyopathy

Answer 12

1. Extensive myocyte hypertrophy
2. Disarray of bundles of myocytes, individual myocytes and myofibres
3. Interstitial and replacement fibrosis

The heart is hypercontracting and causes primarily diastolic dysfunction (DD similar features may be seen in amyloidosis and hypertension with age related subaortic septal hypertrophy)

Question 13

Clinical features of hypertrophic cardiomyopathy

Answer 13

• Reduced chamber size and poor compliance, therefore reduced stroke volume and reduced CO.
• Harsh ejection systolic murmur caused by ventricular outflow obstruction as the anterior mitral valve leaflet moves towards the vetricular septum during systole.
• The high ventricular ischaemia may lead to focal ischaemia

Question 14

Complications of hypertrophic cardiomyopathy

Answer 14

• Sudden death
• Atrial fibrillation (risk of thrombus)

Question 15

Restrictive cardiomyopathy

Answer 15

Characterised by a decrease in ventricular compliance, resulting in impaired ventricular filling during diastole, the contractile function of the left ventricle is usually unaffected.

Question 16

Aetiology of restrictive cardiomyopathy

Answer 16

May be idiopathic or associated with radiation fibrosis, amyloidosis or sarcoidosis.

Question 17

Macroscopic features of restrictive cardiomyopathy

Answer 17

Ventricles are of normal size or slightly enlarged. Myocardium is firm. Bi-atrial dilatation is common.

Question 18

Microscopic feature of restrictive cardiomyopathy

Answer 18

Patchy or diffuse interstitial fibrosis - minimal to extensive.

Question 19

Endomyocardial fibrosis

Answer 19

Rarer cause of restrictive cardiomyopathy.

Unknown aetiology occurring in children and young adults in Africa and other tropical areas.

Question 20

Loeffler endomyocarditis

Answer 20

Rarer cause of restrictive myocarditis.

Endomyocardial fibrosis in association there is often a peripheral eosinophilia - ?myeloproliferative disorder - toxic eosinophil products initiate endocardial damage (necrosis and subsequent fibrosis).

Question 21

Endocardial fibroelastosis

Answer 21

Rarer cause of restrictive cardiomyopathy.

Manifested in the first two years of life, may be associated with a congenital cardiac anomaly, characterised by focal or diffuse fibroelastic thickening usually involving the mural left ventricular endocardium. May be fatal if diffuse involvement.

Question 22

Pericarditis classification

Answer 22

1. Serous
2. Fibrinous and serofibrinous
3. Purulent or suppurative pericarditis
4. Haemorrhagic
5. Caesous

Chronic of healed pericarditis may lead to constrictive pericarditis.

Question 23

Serous pericarditis

Answer 23

Infection, immune mediated: post AMI, rheumatic fever, post surgical

Other: neoplastic cells, renal failure.

Question 24

Fibrinous and seofibrinous pericarditis

Answer 24

Acute MI, Dressler syndrome, renal failure, rheumatic fever, SLE.

Fibrin deposition, granular roughening, may lead to organisation and constrictive pericarditis.

Question 25

Dressler’s syndrome

Answer 25

Dressler’s syndrome is a secondary form of pericarditis that occurs in the setting of injury to the heart or the pericardium (the outer lining of the heart). It consists of a triad of features: fever, pleuritic pain and pericardial effusion.

Question 26

Purulent or suppurative pericarditis

Answer 26

Direct extension from neighbouring infections, seeding from the blood, lymphatic extension, introduction through crditomy. Heart coated with an inflammatory exudate and effusion.

Question 27

Haemorrhagic pericarditis

Answer 27

Blood mixed with fibrinous or purulent effusion - malignant neoplasm spread to pericardial sac is commonest cause.

Question 28

Caseous pericarditis

Answer 28

Tuebrculosis most likely.