Cardiomyopathies

ID#: 852 Česky: Idiopatická (primární) hypertr...
Gross pathology of idiopathic cardiomyopathy. Opened left ventricle of heart shows a thickened, dilated left ventricle with subendocardial fibrosis manifested as increased whiteness of endocardium. Autopsy. (Photo credit: Wikipedia)

What are cardiomyopathies?

These are intrinsic abnormalities of the heart which result in a compromise in systolic or diastolic function of the heart (meaning there will either be a problem with the pumping of blood or filling of the cavities of the heart with blood). These diseases, being intrinsic diseases of the heart, are not related to any valvular dysfunction, coronary, pericardial or chronic heart disease).

What types of cardiomyopathies are there?

Cardiomyopathies consist of dilated cardiomyopathy, hypertrophic cardiomyopathy,restrictive cardiomyopathy, arrythmogenic right ventricular cardiomyopathy and other rare types.

1. Dilated Cardiomyopathy:

Causes
Genetic (autosomsal dominant DCM, X-linked DCM), Inflammatory (post-infectious, autoimmune), Metabolic (Glycogen storage diseases),Nutritional (Thiamine and selenium deficiency), Toxic (Alcohol,Cocaine,Doxorubicin,Cyclophosphamide),Endocrine(Thyrotoxicosis,myxedema,Diabetes mellitus),Neuromuscular (Duchene muscular dystrophy, mitochondrial myopathies), Infiltrative (Hereditary hemochromatosis), Haematological (Sick cell anemia, thrombotic thrombocytopenic purpura).

Pathology
Dilated heart chambers with hypertrophy of muscle cells and intervening areas of fibrosis. Valvular dilatation is functional (due to the chambers being dilated) and there is a great risk of the development of mural thrombi.

Effect on the heart
Impairment of systolic function

Investigations
Chest X-ray shows overall enlargement of the heart.
ECG  shows nonspecific ST segment and T wave abnormalities.Sinus tachycardia, conduction abnormalities and arrhythmias can also be observed.
Echocardiogram – dilated left and/or right ventricle with overall compromise in contractility.

Signs and Symptoms:

Symptoms of cardiac failure, syncope (due to ventricular arrhythmias), sudden death, embolism (pulmonary or systemic).

Treatment:

Diuretics,ACE-inhibitors, angiotensin II receptor antagonists spironolactone, anti-arrhythmics.

2. Hypertrophic Cardiomyopathy:

Causes
Sporadic
Autosomal dominant (most cases).

Pathology
Severe myocardial cell hypertrophy, fibrosis and haphazard disarray of myofibrils. The ventricular septum is irregularly thickened and due to its contact with the mitral valve, the anterior mitral leaflet becomes thick too. Plus, the ventricular cavity assumes a ‘banana-like’ shape due to the thick ventricular septum.

Effect on the heart

Impairment of diastolic function

Investigations
Chest X-ray is usually unremarkable.
ECG – left ventricular hypertrophy and ST and T wave changes. Abnormal Q waves can also occur in around 25-50 % patients.
Echocardiogram  – is diagnostic, showing asymmetrical enlargement of left ventricular septum with mitral valve thickening.
Pedigree analysis and genetic analysis – may reveal autosomal dominant inheritance pattern.

Signs and Symptoms

Double apical pulsation (due to the forceful atrial contraction and 4ht heart sound), jerky carotid pulse (due to sudden systole which is then met with hindrance to the left outflow tract),ejection systolic murmur at the end of systole due to obstruction to the left ventricular outflow tract, pansystolic murmur as a consequence of mitral regurgitation, fourth heart sound, chest pain, syncope, dyspnea, arrhythmias, sudden death.

Treatment

Beta-blockers and verapamil, anti-arrhythmics.

3. Restrictive Cardiomyopathy

Causes
Amyloidosis (most common cause), sarcoidosis, Loeffler’s endocarditis and endomyocardial fibrosis (the latter two conditions are associated with myocardial and endocardial fibrosis along with eosinophilia), Idiopathic (can also be familial).

Pathology

Normal sized ventricles or only slightly enlarged, slight fibrosis, non compliant and non-dilating heart.

Effect on the heart

Impairment of diastolic function

Investigations

Chest X-ray – pulmonary venous congestion, the shadow of the heart might be normal or show cardiomegaly or atrial enlargement.
ECG – low voltage, ST segment and T wave abnormalities.
Echocardiogram – Impaired ventricular filling and symmetrical myocardial thickening.

Signs and Symptoms

Dyspnea, fatigue, embolic symptoms, are classical presenting complaints. Friedrich’s sign, Kussmaul’s sign, 4th heart sound in early disease and cardiomegaly, 3rd heart sound in advanced cases.

Treatment

Treat the underlying cause, treat cardiac failure and embolisms, consider heart transplant in severe and advanced cases.

4. Arrythmogenic Right Ventricular Cardiomypathy

Causes

50 % cases are familial and due to autosomal dominant pattern of inheritance, rest of them are idiopathic or associated with a rare dermatological disease, ‘Naxos disease.’

Pathology

Severe thinning of the left ventricular wall with loss of myocytes, fibrosis and fatty deposits. Affects the right side more commonly but can involve the left ventricle too.

Effect on the heart

Abnormal heart rhythms and impairment of contractility of the right side (systolic function impairment).

Investigations

Chest X-ray – no diagnostic findings.
ECG – T wave inversion in precordial leads related to the right ventricle (V1-V3). epsilon waves may be present (these are small-amplitude waves seen at the end of QRS complex), Incomplete or complete RBBB.
Echocardiogram. Often normal in early disease, advances cases show dilation of the right heart with aneurysm formation maybe even with left ventricular dilation.

Signs and Symptoms

Arrhythmias, syncope, heart failure in advanced cases, sudden death.

Treatment 

Beta-blockers for non-life threatening arrhythmias, amiodarone and sotalol for symptomatic arrhythmias, implantable cardioverter defibrillator for life-threatening arrhythmias, heart transplant in sever cases.

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