Pathology of the Heart by oyc99684

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									Pathology of the Heart



        4/22/09
      Dr. Winokur
   The Heart as a Pump

• Pump parts         -     Cardiac equivalent
  •   Powersource -        Blood supply/oxygen
  •   Motor           -    Myocardium
  •   Pump with valves -   Cardiac valves
  •   Control circuit -    Conducting system and
                           neurohumoral control
Pathologic consequences of
       pump failure
   • Blood vessels/Oxygen supply - Ischemic heart disease
   • Myocardium - Cardiomyopathy
   • Valves - Inadequate forward flow/Increased back
     pressure
   • Conducting system - Arrythmias
   • Neurohumoral system - Inadequate compensation for
     pathologic processes

   Failure of any of these components can result in
     inadequate oxygen delivery to peripheral tissues
     otherwise known as HEART FAILURE
               Case 1


• 65 yo man with past medical history
  significant for diabetes mellitus,
  hypertension, and hypercholesterolemia
  presents to the ED complaining of crushing
  substernal chest pain that radiates to the
  jaw.
• Physical Exam
  • Tachycardia
  • Diaphoretic
• EKG
  • Abnormal with Q-wave
• Labs
  • Elevated troponin I and CK-MB
         DIAGNOSIS?

• Myocardial infarct
 Ischemic heart disease

• Mismatch between oxygen supply and
  demand
• Typically results from atherosclerotic
  narrowing of the coronary arteries
  • Other causes include vasculitis, intramyocardial
    coronary arteries
• Can result from unusual oxygen demand
  • Thyrotoxicosis
  • Tachycardia
Presentation of ischemic heart
           disease
  • Chest pain with exertion - Angina pectoris
  • Myocardial infarct
    • Many MI s are the initial presentation
  • Sudden death
  • Cardiac failure-chronic disease
  Note that in women the presentation is
    frequently atypical ie decreased exercise
    tolerance rather than pain with exercise
          Epidemiology

• Typically occurs in men in their older than
  60 and in women about 10 years later
• Risk factors
  •   Hyperlipidemia, especially LDL cholesterol
  •   High blood pressure
  •   Smoking
  •   Diabetes
Coronary pathology of MI

• Coronary arteries are partially to completely
  occluded by atherosclerosis
  • Significant changes of blood flow occur with
    >75% narrowing of the arteries
• Plaques rupture resulting in thrombosis
• Complete occlusion
• Myocardial necrosis
Pathology of myocardial
       infarction
• Early changes occur in the 1st .5-1hr and are seen
  only at the ultrastructural level
   • Early intervention with thrombolytics or angioplasty
     can save myocardium
• Over the ensuing half day irreversible necrosis
  occurs and can be identified by the light
  microscope
• By 24 hours there is clear necrosis and neutrophils
  begin to invade the infarct
   • This is the first time the infarct is identifiable by gross
     examination.
Serum enzymes in MI




    24 hrs   48 hrs   72 hrs

Troponin
CK-MB
• Over the ensuing week the infarct is overrun
  by neutrophils, then the dead tissue is
  removed by macrophages
• The infarct is repaired by granulation tissue
  followed by fibrosis
Complications of myocardial
        infarction
 •   Cardiac arrhythmias
 •   Cardiac failure/cardiogenic shock
 •   Extension of infarct
 •   Thromboembolism
 •   Ventricular rupture
 •   Papillary muscle rupture
 •   Ventricular aneurysm
 •   Post MI pericarditis
Other presentations of ischemic
         heart disease
   • Sudden death
     • Frequently cause cannot be determined but
       there is a strong association with coronary
       atherosclerosis
   • Chronic ischemia with heart failure
     • Poor oxygenation results in myocardial atrophy
       and some myocyte loss resulting in poor
       cardiac performance
     • Revascularization can help in large vessel
       disease
 Myocarditis/Myocardial
     Inflammation
• Can be caused by infections
   • Viral
   • Bacterial
   • Fungal
• May be secondary to infections resulting in an
  autoimmune inflammation of the myocardium
   • Post viral
   • Post bacterial- Rheumatic heart disease
   • Autoimmune diseases-Lupus
Motor failure/cardiomyopathy

  • The heart muscle can fail from primary or
    secondary causes
    • Primary dysfunction is related to genetic
      diseases
    • Secondary cardiomyopathies result from toxic,
      infectious and degenerative diseases
Three types of cardiomyopathy
  • Cardiomyopathy is a primary disease of the heart
    muscle (excludes myocardial changes resulting
    from hypertension, valvular disease, ischemic
    disease and pericardial disease)
     • Dilated
        • The ventricular chamber is dilated and the myocardium is
          modestly thickened
     • Hypertrophic
        • The myocardium is markedly thickened especially the septum
     • Restrictive
        • The myocardium is can be of normal thickness but it is stiff
          and unable to relax in diastole
Dilated cardiomyopathy

• Causes include genetic, viral/autoimmune and
  toxic insults
   • Many cases are idiopathic and are thought to be
     secondary to previous viral infections
   • Alcohol is the most common toxic cause
• Patients frequently present in heart failure with
  huge hearts and poor contractility
• The prognosis of this condition is poor
   • 5 year survival is <50%
      • Patients die from heart failure and arrhythmias
Hypertrophic cardiomyopathy
  • Primarily a genetic disease and may persist
    subclinically
  • Patients present with dyspnea, syncope or
    sometimes with sudden death
  • Echocardiography is the best diagnostic modality
    but may be detected on ECG and physical exam
  • Pathology- marked hypertrophy of the left
    ventricle with septal thickening
  • Septal hypertrophy causes outflow tract
    obstruction
  • These patients can frequently be successfully
    managed
Restrictive cardiomyopathy

 • Fibrosis or infiltration of the myocardium
   causes marked stiffness and poor relaxation
 • Causes include fibrosis, amyloid deposition,
   sarcoidosis, hemochromatosis, storage
   diseases
 • Cardiac filling is impaired and patients
   present with diastolic heart failure
 • Poor prognosis unless the underlying cause
   can be treated
   Cardiac hypertrophy

• There are two patterns of hypertrophy
   • Concentric hypertrophy
      • Caused by pressure overload ie hypertension, valvular stenosis
      • Results in marked wall thickening with a smaller chamber
      • Good contractility but poor relaxation
   • Eccentric hypertrophy
      • Caused by volume overload ie valve regurgitation or septal
        defects
      • Results in wall thickening with dilation of the chamber
      • Good contractility and acceptable relaxation
                   Cell length




New sarcomeres
added lengthwise
       Cor Pulmonale

• Right sided hypertrophy secondary to
  pulmonary hypertension followed by
  dilatation and right heart failure
  • Acute - 2° to pulmonary thromboembolism
  • Chronic - Secondary to primary pulmonary
    hypertension or chronic obstructive pulmonary
    disease (COPD)
       Valvular disease

• All of the four valves are subject to disease
  • Left sided valves are more commonly affected
    and produce more problems
• Diseases include degenerative, infectious
  and autoimmune
 Infectious endocarditis

• Damage to the valve surface provides a site for
  bacterial adherence
   • Chronic valve disease
   • Prosthetic valves
• Bacteria in the blood stream adhere to the surface
  and proliferate
   • Bacteria can be derived from oral cavity, other bacterial
     infections or the GI tract during procedures
   • Bacteria can be injected by IV drug abusers and result
     in right sided endocarditis
• Infection can be indolent growth of bacterial
  colonies or highly destructive infection with valve
  destruction and incompetence
   • Strep viridans typically results in an indolent infection
   • Staph aureus is highly destructive
   • Prosthetic valves are frequently infected by coagulase
     negative Staph species


• Aggressive and indolent bacteria can embolize and
  produce peripheral abcesses including the CNS
Non bacterial thrombotic
  endocarditis (NBTE)
• Small vegetations usually occuring at the
  valve closure lines
  • Associated with other diseases especially
    adenocarcinomas and cachexia
  • Usually asymptomatic and discovered
    incidentally
  • Can undergo bacterial colonization leading to
    infectious endocarditis
       Rheumatic fever

• An acute, immunologically mediated,
  multisystem inflammatory disease that
  follows an untreated episode of group A
  streptococcal pharyngitis after an interval of
  a few weeks
• Relatively rare in developed countries
• Peak incidence is 5-15 yo.
• Inflammatory infiltrates may occur in a
  wide range of sites including the heart
Acute Rheumatic Carditis

• Inflammatory changes in all three layers of
  the heart
  • Pericardium – fibrinous pericarditis; effusions
  • Myocardium – heart failure
  • Endocardium – valvular damage
Rheumatic endocarditis

• Repeated episodes of damage eventually damage
  the valve and associated apparatus
   • Results in valve stenosis with or without regurgitation
• Mitral and aortic valves are most affected
   • 99% of mitral stenosis is secondary to rhd
   • Virtually the only cause of simultaneous mitral and
     aortic stenosis
• Can be the substrate for infectious endocarditis
 Calcific aortic stenosis

• Most common cause of aortic stenosis
• Irregular calcium deposits behind valve
  cusps
• Congenitally bicuspid valves
• Normal valves as an age-related
  degenerative change
   Mitral valve prolapse

• Most frequent valvular lesion (7%)
• Young women
• Stretching of posterior mitral valve leaflet
  • Systolic murmur with midsystolic click
• Can result in mitral insufficiency
• Predisposes to infective endocarditis
           Arrythmias

• Normal cardiac automaticity requires
  coordination of the SA node, AV node and
  the intervening myocardium
• Disruption of any players can result in
  arrythmias
• Common causes of arrythmias include
  infarcts, alter chamber geometry (dilation
  and hypertrophy), viral infections affecting
  the pacemakers
Congenital Heart Disease

• Left to Right Shunts
  • ASD
  • VSD
  • PDA
• Right to Left Shunts
  • Tetralogy of Fallot
  • Transposition of the Great Arteries
• Obstruction
  • Coarctation of the aorta
Right to Left Shunts

•Cyanosis at or near birth
    Pericardial Diseases
• Pericarditis – inflammation of pericardium
   • Primary – viruses
   • Secondary
      • Acute MI, cardiac surgery, uremia, acute rheumatic fever
• Pericardial Effusions
   • Serous – heart failure
   • Serosanguinous – trauma, malignancy
   • Chylous
• Hemopericardium
   • Cardiac tamponade
Pericarditis
      Cardiac Tumors

• Metastatic neoplasms
  • Lung and breast
• Primary neoplasms
  • Myxomas
  • Cardiac rhabdomyomas
Myxoma

								
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