Transcript Cardiomyopathies

Cardiomyopathies
• Myocardial diseases “of unknown cause” –
excludes hypertensive, valvular, ischaemic
cardiomyopathies.
Cardiomyopathy
• Dilated (congestive)
– Progressive congestive failure with a dilated
heart ( need to consider ischaemia, toxins,
viruses)
– Nutritional deficiency (protein, thiamine (B1),
other vitamins)
– Some cases apparently familial
• Dilated cardiomyopathy or DCM, also known as
congestive cardiomyopathy, is a condition in which
the heart becomes weakened and enlarged, and
cannot pump blood efficiently.
• The decreased heart function can affect the lungs,
liver, and other body systems.
• In DCM a portion of the myocardium is dilated, often
without any obvious cause.
• Left and/or right ventricular systolic pump function
of the heart is impaired, leading to progressive
cardiac enlargement andhypertrophy, a process
called remodeling.
• Dilated cardiomyopathy is the most common
form of cardiomyopathy.
• It occurs more frequently in men than in
women, and is most common between the
ages of 20 and 60 years.
• About one in three cases of CHF is due to
dilated cardiomyopathy.
• Dilated cardiomyopathy also occurs in
children.
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Causes:
• Although no cause (etiology) is apparent in many cases,
dilated cardiomyopathy is probably the end result of
damage to the myocardium produced by a variety of
toxic,metabolic, or infectious agents.
• It may be the late sequel of acute viral myocarditis, possibly
mediated through an immunologic mechanism.
• Autoimmune mechanisms are also suggested as a cause for
dilated cardiomyopathy.
• A reversible form of dilated cardiomyopathy may be found
with alcohol abuse,pregnancy,thyroid disease, stimulant
use, and chronic uncontrolled tachcardia.
• Many cases of dilated cardiomyopathy are described as
idiopathic - meaning that the cause is unknown.
Genetics
• About 20-40% of patients have familial forms of the disease,
with mutations of genes encoding cytoskeletal,contractile,
or other proteins present in myocardial cells.
• The disease is genetically heterogeneous, but the most
common form of its transmission is an autosomal dominant
pattern.
• Autosomal recessive, as found, for example, in Alstrom
syndrome,
• X-linked, and mitochondrial inheritance of the disease is
also found.
• Relatives of dilated cardiomyopathy patients have been
found to show preclinical, asymptomatic heart-muscle
changes.
• Although the disease is more common in African-Americans
than in whites, it may occur in any patient population.
DCM Morphology:
Cardiomyopathy
• Hypertrophic cardiomyopathy
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Asymmetric left ventricular hypertrophy
Affects septum
Associated with sudden death
Often familial with structural protein
abnormalities (tropomyosin)
• Hypertrophic cardiomyopathy (HCM) is a genetic disorder
that is typically inherited in an autosomal dominant fashion
with variable penetrance and variable expressivity.
• The disease has complex symptomatology and potentially
devastating consequences for patients and their families.
• The disorder has a variable presentation and carries a high
incidence of sudden death. In fact, HCM is the leading cause
of sudden cardiac death in both preadolescent and
adolescent children.
• The hallmark of the disorder is myocardial hypertrophy that
is inappropriate, often asymmetric, and occurs in the
absence of an obvious inciting hypertrophy stimulus.
• This hypertrophy can occur in any region of the left ventricle
but frequently involves the interventricular septum, which
results in an obstruction of flow through the left ventricular
(LV) outflow tract.
Microscopy:
• Microscopically, there is a characteristic whorled
pattern of disorganized muscle bundles.
• There are abnormalities in the cell-to-cell
arrangement and in the myofibrillar architecture
within individual cells.
• There is fibrosis and scar formation.
• Most patients have abnormal intramural coronary
arteries in affected areas, with thickened vessel
walls and luminal narrowing, and these
abnormalities may contribute to myocardial
ischemia in these patients
Myocardium in HCM:
Pathophysiology:
• Most patients have abnormalities of diastolic
function due to high filling pressures.
• A minority of patients exhibit a sub-aortic pressure
gradient, which is thought to be due to abnormal
anterior motion of the mitral valve towards the
hypertrophied septum during systole, "systolic
anterior motion" (SAM).
• Many exhibit myocardial ischemia, probably related
to abnormally narrowed intramural vessels,
increased oxygen demand, and increased
intraventricular pressures resulting in
subendocardial ischemia.
Symptoms:
• Most patients with hypertrophic cardiomyopathy
are asymptomatic.
• The most common symptom is dyspnea. angina,
fatigue, and syncope are also common.
• Palpitations, paroxysmal nocturnal dyspnea,
congestive heart failure, and dizziness are less
frequent.
• Syncope may result from inadequate cardiac output
with exertion or be a result of arrhythmias.
Hypertrophic cardiomyopathy
Restrictive cardiomyopathy
• A “stiff” heart with reduced filling in diastole
• Dilated atria
• Endomyocardial fibrosis (EMF,tropical)
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Subendocardial fibrosis with thrombosis
• Loeffler endomyocarditis
• Similar to EMF but with eosinophil infiltrate
(possibly related to parasite infection)
• Amyloid heart disease has similar features
Definition of RCM:
• Restrictive cardiomyopathy refers to a group of disorders in
which the heart chambers are unable to fill with blood
properly because of stiffness of the heart.
• In restrictive cardiomyopathy, the heart is normal in size or
only slightly enlarged, but it cannot relax normally during
diastole (that is, the time between heartbeats in which the
blood returns from the body to the heart).
• Later in the disease, the heart may not pump blood
efficiently. The abnormal heart function can affect the lungs,
liver, and other body systems. Restrictive cardiomyopathy
may affect either or both ventricles and may or may not be
associated with a disease of the heart muscle.
Causes
• The most common causes of restrictive
cardiomyopathy are amyloidosis and idiopathic
myocardial fibrosis (a scarring of the heart of
unknown cause). It frequently occurs after a heart
transplant.
• Other causes of restrictive cardiomyopathy include
sarcoidosis, hemochromatosis, radiation fibrosis,
and various tumor infiltrations of the heart.
• More rarely, restrictive cardiomyopathy is caused by
diseases of the endocardium such as
endomyocardial fibrosis and Loeffler's syndrome.
Symptoms
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Excessive tiredness (fatigue) .
Swelling of the feet and ankles.
Cough.
Difficulty breathing:
– especially with exertion
– at night
– when lying flat
• Easily fatigued (poor tolerance of exercise).
• Swelling of the abdomen.
Diagnosis :
• Restrictive cardiomyopathy may be hard to
differentiate from constrictive pericarditis.
• A biopsy of the heart muscle may be used to
confirm the diagnosis.
Prognosis:
• People with restrictive cardiomyopathy may
be candidates for heart transplant.
• Prognosis is dependent on the underlying
cause but it is usually poor.
• Average (mean) survival after diagnosis is 9
years.
Possible Complications:
• Progressive heart failure.
• Mitral regurgitation.
• Tricuspid regurgitation.
Endomyocardial fibrosis:Histologic
Findings:
• The heart size is not usually enlarged in EMF.
• The ventricular cavities are frequently laden with
thrombi and, in severe cases, may be nearly totally
obliterated by endocardial thickening and
thrombosis.
• The histologic findings of EMF are characterized by
reactive fibrosis associated with a selective increase
in type I collagen deposition, subendocardial
infarction and fibrosis, and thrombus formation.
• Additionally, specific features of other diseases, such
as those associated with hemochromatosis or
glycogen storage disease, are notably absent.
RCM due to hemochromatosis:
• Prussian Blue reaction
shows iron deposits in
myocardium.
Restrictive cardiomyopathy with
amyloidosis