Heart hypertrophy chamber cardiomyopaties

[Pages:3]heart hypertrophy

HEART HYPERTROPHY

? from the point of view of the autopsy it may be defined as a measurable or weighable increase of the myocardium due to increased activity. There are two types of hypertrophy: ? a) simple/concentric h. - a ventricular thickening without enlargement of the chamber ? b) eccentric h. - dilatation is added

? With respect to hypertrophy, various parts of the heart enjoy independence as to their degree of participation, and even in the one chamber, there may be a difference, as for instance in the neighbourhood of a scar, or in the terminal portion of the out flow tract where hypertrophy and dilatation originate.

? Normal heart weight is: ? 250g in women ? and 300g in male

? Hypertrophic heart weight is over 400g, but when the weight is beyond 500g its blood supply becomes inadequate to feed any further muscle fibbers

cardiomyopaties

cardiomyopathies

? primary (idiopathic) heart muscle disease of unknown cause; in this sense excludes myocardial disease caused by ischemia, hypertension, valvular dysfunction, congenital anomalies, or inflammatory disorders.

? Three forms:

1. Dilated (congestive) (90%) 2. Hypertrophic 3. Restrictive (infiltrative)

dilated cardiomyopathy (DCM)

? is characterised by the gradual development of cardiac failure associated with four-chamber hypertrophy and dilatation of the heart of unknown cause.

? in 15% develops in patients with previous viral myocarditis; entrovirus RNA particles were found in biopsies of myocardium

? focal or mild lymphocytic infiltrates in the myocardium ? in some patients presence of heart-specific

autoantibodies ? occasional abnormalities of cellular immunity ? in 20% of cases familial occurrence mostly as inherited

in autosomal dominant mode with incomplete penetrance, but autosomal recessive or X-linked trait were found, also.

dilated cardiomyopathy (DCM)

Morphology: ? heart weight is 2-3 times N (900g) ? hypertrophy and dilatation with usually dilatation of all four

chambers (but chambers are more affected then atria) ? myocardium is flabby and pale with patchy small myocardial

(mostly subendocardial) fibrous scars ? mural thrombi (near the apex of the left and right ventricles and in

the atria); the endocardium in those areas tend to be thickened ? functional mitral valve regurgitation

? histological findings non-specific, although both atrophic and hypertrophic myocardial fibers could be found.

? Moreover, interstitial and perivascular fibrosis is observed. ? In ultrastructural studies decreased myofilaments with increased

mitochondria number is observed.

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dilated cardiomyopathy (DCM)

? CLINIC:

? Usually affects patients between 20 - 60 yrs, but can occur at any age.

? The disease begins insidiously. In most cases disease is slowly developing, progressive and unremitting.

? 50% of patients die within 2 yrs after diagnosis, ? only 25% survive longer than 5 years. ? The only hope for those patients is offered by

cardiac transplantation.

? Death is usually attributed to: (1) progressive heart failure, (2) arrhythmia, and (3) emboli.

Causes of DCM (secondary)

DIRECT: ? Toxic (alcohol, catecholamines, cobalt, radiation, uremia) ? Infectious (protozoan disease - Chagas' disease; viral - coxsackievirus,

enteroviruses, influenza) ? Metabolic (starvation, thiamine deficiency) ? Genetic ? Idiopathic

INDIRECT: ? Ischemic (postinfarction, cardiac surgery, anemia, thrombembolic disorders) ? Hypersensitivity (idiopathic myocarditis, drug reactions - methyldopa,

sulphonamides, foreign proteins; Chagas' disease) ? Abnormal loading conditions (hypertension, valvular heart disease,

peripartum partum cardiomyopathy) ? Endocrine (hyperthyroidism, acromegaly, diabetes) ? Infiltration (sarcoidosis, hemochromatosis, neoplastic)

DCM (secondary)

? Ethanol about 50% of DCM. Males and females are equally susceptible, but disease more commonly found in males. Usually occurs between 30 and 55 years of age, in those who have been heavily drinking for at least 10 years. The mechanism is obscure. In early stages is fully reversible.

? Cobalt foam stabilisers in some types of beer; occurs almost exclusively in alcohol abusers.

? Catecholamines e.g. pheochromocytoma; in high concentration may lead to focal myocardial necrosis.

? Anthracyclines (chemotherapeutic drugs; 35% of patients on high doses): chronic, irreversible degeneration of myoctes with their vacualisation and loss of myofibrils.

? Cocaine DCM is not a typical complication; proposed mechanism cardiomyopathy development include: vasoconstriction, sympathomimetic activity, hypersensitivity responses, and direct toxicity.

? DCM of pregnancy main risk group include black, multiparous women older then 30 years. Develops in last trimester or in first 6 months after delivery. The cause is probably related to myocarditis. In more then 50% disease is reversible. In subsequent pregnancies a high risk of DMC recurrence maternal mortality is found.

hypertrophic cardiomyopathy

(HCM)

? is an uncommon condition

? is characterised by cardiac hypertrophy out of proportion to the hemodynamic load on the heart

? develops in first 2 decades of life without an extrinsic stress

? in about 50% of cases is a single-gene autosomal dominant trait with variable expression and penetrance

? in second half of cases disease develops spontaneously without family history

? previously attributed to asymmetric septal hypertrophy or idiopathic hypertrophy subaortic stenosis; but in most cases there is no obstruction to left ventricle outflow

hypertrophic cardiomyopathy

(HCM)

PATHOGENESIS: ? mutations in cardiac -myosin heavy-chain gene

(genes on chr 14) "poison polypeptide" production ? abnormal myofibrils production.

? Moreover mutations in genes encoding cardiac troponin T, alpha-tropomyosin, and myosin-binding protein C were recognised.

? Up to now, more then 50 mutations were diagnosed.

? Mutations are not found in ATPase nor actin or myosin light chains in such cases a lethal mutation???

hypertrophic cardiomyopathy

(HCM)

Morphology: ? heart enlargement (average 500g)

? wall of left ventricle is thick and lumen small

? asymmetrical septal hypertrophy (1.5 times larger then in free wall)

? endocardial mural plaque (anterior mitral valve leaflet impinges on the septal wall

? both atria are usually enlarged

*the most typical histological finding is myofiber disarray (mostly in the septum) *also on ultrastructural level myofibrils and myofilaments within a single

myocyte are disorganised *both found not only in HCM

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hypertrophic cardiomyopathy

(HCM)

CLINIC: ? usually first diagnosed in 4th and 5th decade, but its severity does

not correlate to the level of hypertrophy; clinical symptoms include dyspnea and/or angina pectoris

? could be leading cause of sudden death in young competitive athlete

? the most prominent dysfunction is decreased left ventricular compliance (diastolic dysfunction)

? the regular treatment for heart failure with drugs increasing contractility (glycosides) and reduction of blood volume (diuretics) aggravate symptoms, while drugs reducing contractility (blockers and Ca-channel blockers) improve left ventricle relaxation and diminish symptoms.

restrictive cardiomyopathy

(RCM)

? is characterised by the endocardial and myocardial abnormalities that limit diastolic filling, while contractile function is normal

? hemodynamic consequences are: increased end-diastolic pressure, atrial dilatation, and venous congestion

? uncommon in Europe but more often occurring in Africa (equatorial), South America and Asia

? could be caused by: ? (1) amyloid infiltration, ? (2) endomyocardial disease, ? (3) storage disease (including hemochromatosis), ? and (4) marked interstitial fibrosis

? only about 10% of patients survive longer then 10 years. There is no specific treatment.

restrictive cardiomyopathy

(RCM)

? Amyloidosis deposites in interstitium, perivascular or endocardial (mainly in atria). Leads to cardiac enlargement but without ventricular dilatation. Complications include: right side heart insufficiency, arrhythmias, and sudden cardiac death.

? Senile amyloidosis deposits of prealbumin, (transthyretin) in heart of elderly. 25% patients over 80 years. Deposits are also found in the lungs and rectum. It could be found in perivascular area in many organs but almost never in kidney (!!!). Clinical significance almost minimal.

? **Endomyocardial fibrosis particularly common in equatorial Africa (10-20% of all cardiac deaths). Most common in children and young adults but might occur up to 70 years. Leads to progressive cardiac failure with poor prognosis (but even 12 year survivals were recorded).

? **Eosinophilic endomyocardial disease (L?ffler endocarditis) characterised by hypereosinophilia (up to 50,000/?l) in males in 5th decade and with rash. The disease progress to congestive heart failure and death (corticosteroids may improve prognosis).

restrictive cardiomyopathy

(RCM)

? ** myocardial injury is produced by cardiotoxic constituents of eosinophilic granules. Their development goes through: 1- the necrotic stage (up to several month); 2- the trombotic stage (a year later); and 3- the fibrotic stage

? Glycogen storage diseases Pompe (type II; !!!), Cori disease (type III), and Andersen disease (type IV)

? Mucopolyscahharidoses narrowing of coronary arteries leading to MI (Hunter and Hurler); Aortic stenosis (Scheie syndrome); mitral regurgitation (Hurler and Morquito symndromes);

? Sphingolipidoses Fabry disease (accumulation of glycophospholipids) and Gaucher disease (cerebroside-laden macrophages

? Hemochromatosis features of DCM and restrictive cardiomyopathy. ? Sarcoidosis features of DCM and restrictive cardiomyopathy with symptoms in

less then 5% of cases.

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