Cardiomyopathies

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Cardiomyopathies

• Myocardial diseases of unknown cause excludes
  hypertensive, valvular, ischaemic
  cardiomyopathies.

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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

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• 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.

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• 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.

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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.

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DCM Morphology
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Cardiomyopathy

• Hypertrophic cardiomyopathy
• Asymmetric left ventricular hypertrophy
• Affects septum
• Associated with sudden death
• Often familial with structural protein
  abnormalities (tropomyosin)

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• 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.

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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

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Myocardium in HCM
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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.

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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.

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Hypertrophic cardiomyopathy
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Restrictive cardiomyopathy

• A stiff heart with reduced filling in diastole
• Dilated atria
• Endomyocardial fibrosis (EMF,tropical)
• Subendocardial fibrosis with thrombosis
• Loeffler endomyocarditis
• Similar to EMF but with eosinophil infiltrate
• (possibly related to parasite infection)
• Amyloid heart disease has similar features

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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.

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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.

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Symptoms  

• 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.

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Diagnosis

• Restrictive cardiomyopathy may be hard to
  differentiate from constrictive pericarditis.
• A biopsy of the heart muscle may be used to
  confirm the diagnosis.

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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.

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Possible Complications   

• Progressive heart failure.
• Mitral regurgitation.
• Tricuspid regurgitation.

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Endomyocardial fibrosisHistologic 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.

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RCM due to hemochromatosis

• Prussian Blue reaction shows iron deposits in
  myocardium.

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Restrictive cardiomyopathy with amyloidosis