cardiomyopathy

Question 1

Types of cardiomyopathy?

Answer 1

There are many aetiologies but 3 distinct patterns of myocardial abnormality are recognised - dilated, hypertrophic and restrictive.

Question 2

What is dilated cardiomyopathy?

Answer 2

This is a functional abnormality of the myocardium causing poor systolic contraction and with dilatation of the ventricular cavities associated with reduced wall thickness. Mural thrombus in ventricles and atrial appendages is also frequency seen.

Question 3

What is the pathogenesis of dilated cardiomyopathy?

Answer 3

end stage of myocardial damage for many causes including: - Idiopathic (no clear cause) - Genetic mutation - Duchenne muscular dystrophy, haemochromatosis - Alcohol abuse - Infections - Coxsackievirus B virus (causes viral myocarditis) and Chagas disease (protozoal) - Chemotherapy - doxorubicin, adriomycin - Wet beri beri (thiamine deficiency) - Peripartum cardiomyopathy (3rd trimester –> weeks after delivery) - Thyrotoxicosis

Question 4

What is the presentation of dilated cardiomyopathy?

Answer 4

Fatigue, dyspnoea, pulmonary oedema, RVF, emboli, AF or VT (cardiac arrest).

Question 5

Signs of dilated cardiomyopathy

Answer 5

Tachycardia Decreased BP Raised JVP Displaced, diffuse apex S3 gallop (blood hits dilated ventricular wall during diastole) Mitral or tricuspid regurgitation Pleural effusion Jaundice Hepatomegaly Ascites

Question 6

What tests can aid in the diagnosis of dilated cardiomyopathy?

Answer 6

Bloods: BNP is a sensitive and specific markers in diagnosing heart failure, HYPOnatraemia indicates a poor prognosis - CXR: cardiomegaly, pulmonary oedema - ECG: tachycardia, non specific T wave changes, poor R wave progression - Echo: globally dilated hypokinetic heart and low ejection fraction (look for mitral, tricuspid and mural thrombus)

Question 7

How is dilated cardiomyopathy treated?

Answer 7

Bed rest, diuretics, digoxin, ACE-i, anticoagulation, biventricular pacing, ICDs, cardiac transplantation. Mortality is variable, e.g. 40% in 2 years.

Question 8

What is hypertrophic cardiomyopathy?

Answer 8

In this form of cardiomyopathy, systolic function is hyperkinetic because new sarcomeres are added in parallel to existing ones. There is marked reduction in systolic volume because of a reduction in ventricular chamber size and difficulty in diastolic filling due to reduced compliance. Both of these lead to impaired ventricular filling and reduced stroke volume (by Starlings law) leading to diastolic heart failure

Question 9

What are the signs of HCM?

Answer 9

Crescendo decrescendo murmur (loudest on Valsalva manouvre) Bifid pulse (2 pulses caused by the mitral valve moving towards the outflow tract and causing increased obstruction

Question 10

Symptoms of HCM

Answer 10

Angina (due to myocardial ischaemia) Palpitations (ischaemia to the conducting system) Syncope Dyspnoea Sudden death (most common cause of sudden cardiac death in young adults)

Question 11

What is the aetiology of HCM?

Answer 11

Most often HCM is autosomal dominant where there is a missense mutation affecting the cardiac sarcomere

Question 12

What investigations are useful in HCM?

Answer 12

) ECG - LVH; progressive T wave inversion; deep Q waves; AF 2) Echo - asymmetrical septal hypertrophy; small LV cavity with hypercontractile wall; midsystolic closure of aortic valve; systolic anterior movement of mitral valve 3) Cardiac catheterisation - may provoke VT; helps assess severity of gradient, coronary artery disease or mitral regurgitation

Question 13

How is HCM treated?

Answer 13

• beta blockers or verapamil for symptoms (the aim is reducing ventricular contrctility) - amiodarone for arrhythmias (AF, VT) - anticoagulate for paroxysmal AF or systemic emboli - surgery (septal myomectomy) is reserved for those with severe symptoms - consider ICD

Question 14

What factors are associated with a poor prognosis of HCM?

Answer 14

Age < 14 years Syncope at presentation Family history of HCM/ sudden death

Question 15

What is restrictive cardiomyopathy?

Answer 15

The ventricle is not hypertrophied by is stiff and less compliant. This impairs ventricular filling which decreases stroke volume by Starling’s law. Cardiac output falls and so restrictive cardiomyopathy causes diastolic heart failure.

Question 16

What are the causes of restrictive cardiomyopathy?

Answer 16

1) Amyloidosis - Familial Amyloid Cardiomyopathy = mutant transthyretin (TTR) protein is misfolded and deposited in the myocardium (transthyretin transports thyroxine and retinol in the blood) - Senile Cardiac Amyloidosis = accumulation of wild type transthyretin in myocardium 2) Cardiac sarcoidosis 3) Endocardial fibroelastosis 4) Loffler endo(myo)carditis - eosinophilic accumulation in the endocardium leading to inflammation and restricted filling 5) Haemachromatosis 6) Radiation

Question 17

How does restrictive cardiomyopathy present?

Answer 17

The presentation is similar to constrictive pericarditis. Right ventricular failure predominates, causing raised JVP with prominant x and y descents, hepatomegaly, oedema and ascites.

Question 18

What is endomyocardial fibrosis (EMF)?

Answer 18

This is another cause of restrictive cardiomyopathy that affects tropical and sub-tropical regions

Question 19

What is myocarditis?

Answer 19

presence of inflammatory cells in the myocardium. Clinical features are due to ventricular electrical irritability with rhythm and conduction abnormalities.

Question 20

What causes myocarditis?

Answer 20

1) Toxic or metabolic damage 2) Microbial organisms 3) Sarcoidosis 4) Rheumatic fever (pancarditis) 5) Giant cell myocarditis

Question 21

What toxins can cause myocarditis?

Answer 21

typhoid fever - streptococcal infections (esp group A beta haemolytic) - diphtheria - poisons - arsenic, phosphorus, chloroform - metabolic abnormalities - hypokalaemia and hyperkalaemia, magnesium deficiency, catecholamine excess In all of these conditions the main histological feature is focal necrosis of myocardial cells and an inflammatory cell infiltrate is not very marked.

Question 22

microbial organisms caused myocarditis?

Answer 22

1) Pyogenic bacteria: suppurative myocarditis is rare except as a terminal event in debilitating illness or immune deficiency states complicated by septicaemia 2) Viruses: Coxsackie virus infections are the best documented both as sporadic fatal cases and in known epidemics, especially neonates. Other viruses causing myocarditis are poliomyelitis, mumps and ECHO 3) Protozoa: of importance are toxoplasmosis, usually as a congenital infection in the neonatal period and in South America Chaga’s disease due to Trypanosoma cruzi 4) Syphilis: aortitis causes aneurysm and aortic valve incompetence. Gummas affecting the myocardium, particularly the conducting system in the upper interventricular septum

Question 23

What investigations are useful in myocarditis?

Answer 23

ECG changes are common but non specific. Biochemical markers of myocardial injury (e.g. troponin I and , creatinine kinase) may be elevated in the early phase. Echo may reveal left ventricular dysfunction that is sometimes regional (due to focal myocarditis) and cardiac MRI may show diagnostic patterns of myocardial inflammation or infiltration. Biopsy is sometimes used to confirm the diagnosis

Question 24

How is myocarditis managed?

Answer 24

In most patients myocarditis is self limiting and the immediate prognosis is good. However, death may occur due to ventricular arrhythmia or rapidly progressive heart failure. Some forms of myocarditis may lead to chronic low grade myocarditis or dilated cardiomyopathy - e.g. in Chaga’s disease the patient frequently recovers from an acute infection but goes on to develop a chronic dilated cardiomyopathy. There is no evidence for any benefit from treatment with corticosteroids and immunosuppressive agents.