Hemodynamic Disorders

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Hemodynamic Disorders

• Heart
• Aorta and Arteries
• Microcirculation
• Veins and Venules
• Interstitium
• Lymphatics

Bruce A. Fenderson, Ph.D. Jefferson Medical
College
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Microcirculation - site of gas and nutrient/waste
exchange with tissues of the body
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Hemodynamic Disorders

• Hyperemia
• Active
• Passive (chronic passive congestion)
• Hemorrhage
• Thrombosis
• Embolism and Infarction
• Edema
• Shock

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Hyperemia

• Hyperemia is defined as excess amount of blood in
  an organ.
• Active hyperemia is an augmented supply of blood
  to an organ usually as a response to increased
  functional demand (eg inflammation).
• Passive hyperemia (congestion) refers to
  engorgement of an organ with venous blood due to
  an impediment to venous return.

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Passive Congestion of Liver
With the hepatic veins emptying into the vena
cava immediately inferior to the heart, the liver
is vulnerable to chronic passive congestion. The
changes are referred to as nutmeg liver.
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Passive Congestion of Lungs (CHF)

• Increased pressure in the pulmonary alveolar
  capillaries has 4 major consequences
• Microhemorrhages release erythrocytes into the
  alveolar spaces (iron-laden macrophages).
• Pressure forces fluid into the alveolar spaces
  (pulmonary edema).
• Increased pressure stimulates fibrosis.
• Increased capillary pressure causes pulmonary
  hypertension.

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Heart Failure Cells(Iron-Laden Macrophages)
Prussian Blue Stain for Iron
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Hemorrhage

• Hemorrhage is discharge of blood from the
  vascular compartment to the exterior of the body
  or into nonvascular body spaces.
• A person may hemorrhage into an internal cavity
• bleeding peptic ulcer (arterial hemorrhage)
• esophageal varicosity (venous hemorrhage).
• Bleeding into an open (serous) cavity can result
  in the accumulation of a large amount of blood to
  the point of exsanguination.

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Examples of Hemorrhage

• Hematoma - hemorrhage into soft tissue
• Hemoperitoneum - bleeding into peritoneum
• Hemarthrosis - bleeding into joint space
• Purpura - diffuse superficial hemorrhage
• Ecchymosis - larger superficial hemorrhage
• Petechia - pinpoint hemorrhage

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Petechia (pin-point hemorrhages appear as red
dots)
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Woman with Vaginal Bleeding

• Squamous Cell Carcinoma of the Uterine Cervix.

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Man with Bleeding Peptic Ulcer
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Blunt Trauma to the Head
Epidural Hematoma
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Rupture of Heart MuscleHemopericardium - Cardiac
Tamponade
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Thrombosis

• Thrombosis refers to the formation within a
  vascular lumen of a thrombus, defined as an
  aggregate of coagulated blood containing
  platelets and fibrin.
• A thrombus is by definition adherent to the
  vascular endothelium and should be distinguished
  from a simple blood clot.
• The most common cause of arterial thrombosis is
  atherosclerosis.

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Platelet Activation

• Pathogenesis of Thrombosis
• Damage to the endothelium
• Alterations in blood flow
• Increased coagulability of blood
• Thrombin converts fibrinogen to fibrin.

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Venous Thrombosis
Thrombi are adherent to the vessel wall. They
are composed of fibrin, platelets, and blood
cells..
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Deep Venous Thrombosis

• Large majority (gt90) of venous thromboses occur
  in the deep veins of the legs (DVT).
• Occlusive thrombosis of the femoral or iliac
  veins leads to severe congestion, edema, and
  cyanosis.
• DVT is treated with systemic anti-coagulants.
• Conditions that favor the development of deep
  venous thrombosis include
• Stasis of blood flow
• Injury Inflammation (phlebitis)
• Hypercoagulability of blood
• Advanced age

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Arterial Thrombosis
?
Coronary artery
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Infarction is a Complication of Arterial
Thrombosis

• Arterial thrombosis is the most common cause of
  death in Western industrialized countries.
• Thrombosis of a coronary or cerebral artery
  results in myocardial infarct (heart attack) or
  cerebral infarct (stroke).

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Mural (Heart Wall) Thrombosis

• Myocardial infarction
• Atrial fibrillation
• Cardiomyopathy
• Endocarditis

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Arterial Thrombi Are Laminated
Note laminations of platelets and fibrin (lines
of Zahn)
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Fate of Thrombi

• Lysis
• Propagation
• Organization (in-growth of connective tissue)
• Canalization
• Detachment and Embolization

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VenousEmboli

• Sources of venous emboli shown.
• Venous emboli travel through the heart to the
  lungs.

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Pulmonary Embolism

• Embolism is passage through the venous or
  arterial circulation of any material capable of
  lodging in a blood vessel.
• Pulmonary embolism remains an important
  diagnostic and therapeutic challenge. Pulmonary
  thromboemboli are reported in more than half of
  all autopsies.
• This complication occurs in 1 to 2 of
  post-operative patients over the age of 40.

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Pulmonary Saddle Embolism
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Amniotic and Fat Emboli

• Amniotic fluid embolism refers to the entry of
  amniotic fluid containing fetal cells and debris
  into the maternal circulation through the open
  uterine and cervical veins.
• Fat embolism describes the release of emboli of
  fatty marrow into damaged blood vessels following
  severe trauma to fat-containing tissue,
  particularly accompanying bone fractures.

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Fat Embolism
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Fat Embolism
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Arterial Embolization

• The heart is the most common source of arterial
  emboli, which usually arise from mural thrombi or
  diseased heart valves.
• The major complication of thrombi in the heart is
  detachment of fragments and transport to distant
  sites (arterial thromboembolism).
• Organs that suffer the most from arterial
  embolism (ie undergo infarction) include
• Brain
• Lower extremity
• Kidney
• Heart

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Sources
Sources of arterial emboli..
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Infarction
Common sites of infarction from arterial emboli.
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Infarction

• Infarction is defined as the process by which
  coagulative necrosis develops in an area distal
  to the occlusion of an end-artery. The necrotic
  zone is termed an infarct.
• Pale infarcts are typical in the heart, kidneys,
  brain, and spleen.
• Red infarcts, which may result from either
  arterial or venous occlusion, are also
  characterized by coagulative necrosis but are
  distinguished by bleeding.

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Arterial Embolism Infarction
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Multiple Splenic Infarcts
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Cystic Brain Infarct
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(No Transcript)
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Myocardial Infarct (Pale)
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Pulmonary Infarct (Red)
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Extravascular Fluid and Edema

• Edema refers to the presence of excess fluid in
  the interstitial spaces of the body. Edema may
  be generalized or local. Local edema is often
  associated with acute inflammation.
• Non-inflammatory edema is due to either a
  decrease in blood oncotic pressure or an
  increase in blood hydrostatic pressure.
• Control of extracellular fluid volume depends
  largely on the regulation of renal sodium
  excretion, which is influence by
• Atrial natriuretic factor
• Renin-angiotensin system
• Sympathic nervous system activity

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Summary
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Examples of Edema

• Congestive heart failure (gthydrostatic pressure)
• Cirrhosis of the liver (ltoncotic pressure)
• Nephrotic syndrome (ltoncotic pressure)
• Cerebral edema
• Pulmonary edema
• Fluid in body cavities (effusions)
• Edema due to lymphatic obstruction

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Congestive Heart Failure (CHF)

• CHF describes the consequences of inadequate
  cardiac output relative to the needs of the body.
  
• It is estimated that two to three million people
  in the United States have congestive heart
  failure and 15 die annually.
• Failure of the left ventricle is associated
  principally with passive congestion of the lungs
  and pulmonary edema.

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Pulmonary Edema in CHF
CHF leads to increased capillary hydrostatic
pressure. Venous engorgement of the lungs leads
to the accumulation of a transudate in the
alveoli, a condition termed pulmonary edema.
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Clinical Features of Pulmonary Edema in CHF

• Pulmonary edema refers to increased fluid in the
  alveolar spaces and interstitium of lungs.
• The patient becomes acutely short of breath and
  bubbly rales are heard. In extreme cases, frothy
  fluid is coughed up or wells up out of the
  trachea.
• Pulmonary fluid accumulation may go unnoticed
  initially, but eventually dyspnea and coughing
  become prominent.
• Hypoxemia is manifested as cyanosis.

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CHF
Complications of Congestive Heart Failure.
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Pitting Edema in CHF
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LymphEdema
Is this elephantiasis or elephantitis?
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Cardiac Tamponade

• Pericardial fluid (effusion) may accumulate
  rapidly, particularly with hemorrhage caused by a
  ruptured myocardial infarct, dissecting aortic
  aneurysm, or trauma.
• In this circumstance, the pressure in the
  pericardial cavity rises to exceed the filing
  pressure of the heart, a condition termed cardiac
  tamponade.

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Fluid Loss and Overload

• Dehydration
• Over-hydration

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Shock

• Shock is a condition of profound hemodynamic and
  metabolic disturbance characterized by failure of
  the circulatory systems to maintain an
  appropriate blood supply to the microcirculation,
  with inadequate perfusion of the vital organs.
• Shock is not synonymous with low blood pressure,
  although hypotension is commonly a part of the
  shock syndrome.

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Cardiogenic and Hypovolemic Shock

• Cardiogenic shock is usually caused by myocardial
  infarction and less commonly by myocarditis.
• Hypovolemic shock is secondary to a pronounced
  disease in blood volume, caused by the loss of
  fluid from the vascular compartment (eg,
  diarrhea, excessive urine formation, and
  perspiration are the major mechanisms of external
  fluid loss.

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Septic Shock

• Pathogenesis of septic shock involves
• Release of TNF by activated macrophages
• Injury to endothelial cells
• Increased vascular permiability

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Hemorrhagic Infarction of Adrenal Glands in
Septic Shock
Normal Gland
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Organ Pathology of Shock

• Heart - Petechial hemorrhages
• Kidney - Acute tubular necrosis
• Lung - Adult respiratory distress syndrome
• Gastrointestinal tract - Erosive gastritis
• Liver - Centrilobular congestion and necrosis
• Pancreas - Acute hemorrhagic pancreatitis
• Adrenals - Necrosis and insufficiency

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Complications of Shock
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Path Key Words

• Active hyperemia
• Air embolism
• Cardiogenic shock
• Chronic passive congestion
• Dissecting aneurysm

• Fat embolism
• Hematoma
• Hemopericardium
• Hypovolemic shock
• Petechia
• Pulmonary edema
• Thromboembolism