hyperemia
- active process
- dilatation of arterioles and increased blod inflow
- hyperemic tissues are redder than normal due to inflow of oxigenated blood
Examples -> blushing, exercise, inflammation
Congestion
- passive process
- impaired venous outflow
-it can occure sistematically or locally
- congested tissues are cyanotic (bluish) due to accumulation of
deoxigenated hemoglobin
Examples -> heart failure, venous obstruction
Chronic liver congestion
nutmeg liver (seen in gross examination)
central areas are slightly depressed due to pericentral hepatocite necrosis
the uncongested zones are tan, sometimes fatty
types of edema
inflammatory
hydrostatic
oncotic
obstructive
hpervolemic
inflammatory edema
inflamation-increased vascular permeability
-general congestive heart failure, constrictive pericarditis
- local-deep venous thrombosis, external pressure
nephrotic syndrome, liver cirrhosis, protein malnutrition
Obstructive
lymphatic obstruction by tumor cells parasites chronic inflammation, surgery or irradiation
hypervolemic
primary hyperaldosteronism (adrenal hyperplasia, adrenal adenoma)
edema of heart failure
combi of hydrostatic and hypervolemic
left sided heart failure
leads to pulmonary congestion, edema and pleural effusion
right sided heart failure
leads to chronic congestion of liver and spleen, ascites, congestion and edema of lower extremities
pulonary edema
most commonly due to left-sided heart failure
elephantiasis
massive edema of lower extremity caused by parasitic infection by wucheria nabcrofti
anasacra
severe generalised edema with profound swelling of subcutaneous tissues and accumulation of fluid in body cavities (hydrotorax, hydropericardium, ascites)
lymphatic obstruction
the cancer cells block the dermal lymphatics and produce a “peau d’orange” appearance of the breast skin.
clinical importanat forms of hemorrage
• Hematemesis
• Hemoptysis
• Hematuria
• Hematochezia
• Hemotorax
• Hemopericardium
• Hemoperitoneum
• Hemartrosis
trombosis
blood clot formation in intact vessel
virchow triad
endothelial injury
stasis or turbulent blood flow
hypercoagulability of the blood
procoagulant changes
- downregulated expression of
thrombomodulin - sustained activation of thrombin
- activation of platelets and induction of inflammation
- downregulation of anticoagulants (prote C, tissue factor protein inhibitor)
anti-fibrinolytic effects
- secretion of plasminogen activator inhibitors (PAI)- lower fibrinolysis
primary (genetic hypercoagulability
Factor V mutation (2-15%)
-mutation alters an amnio-acid and makes it resistant to proteolysis by protein C
-heterozygotes 5-fold increased risk and homozygotes 50-fold increased risk for venous thrombosis
Prothrombin mutation (1-2%)
-single nucleotide substitution (G-A) in the prothrombine results inincreased prothrombine transcription
-3-fold increased risk for venous thrombosis
secondary (aquired) hypercoagulability
• Immobilization
• Myocardial infarction
• Atrial fibrilation
• Tissue injury (burns, surgery)
• Cancer
• Pregnancy
mural thrombi
myocardial infarction, arrhytmias, dilated cardiomyopathy, endomyocardial injury, myocarditis, catheter trauma
valvular thrombi
infective- bacterial or fungal infection
sterile-hypercoagulable states
arterial thrombi
atherosclerosis, vasculitis, trauma
venous thrombi
stasis-immobilisation, hypercoagulable states (burns, pregnancy, cancer)
thrombus vs. post mortem clot
thrombus: clot adherent to cell wall, laminated
p.m. clot: not adherent to vessel wall. plasma and rbc seperate
embolism
Embolus- detached intravascular solid, liqiud or gaseous mass that is carried by the blood from its point of origin to a distant site resulting in partial or complete vascular obstruction.
types of emboli
1) Thromboemboli: fragments of thrombi
2) Liquid emboli: fat, amniotic fluid
3) Gaseous emboli: air injection, decompression sickness
4) Solid particle emboli: cholesterol crystals, tumor cells,
bone marrow
venous emboli
originate in veins, are carried by venous circulation to the lungs and cause pulmonary embolism
aterial emboli
originate in the left heart, aorta or major arteries and cause infarcts in many organs (brain, kidneys, spleen, intestines, legs)
paradoxical
originate in the deep leg veins but move through a foramen ovale or ventricular septal defect (VSD), causing symptoms similar to those of arterial emboli
pulmonary thromboembolism
mostly originates from deep veins
large embolus lodge at bifurcation -> sudden death
medium sized -> pul. hemmorage/infarction
smal sized in small end ateriolar -> infarction
=> multiple emboly cause hypertension and RVF
fat embolism
soft tissue crush / long bone fracture -> fat & bm into circulation
fat embolism syndrome
1-3 days after injury
pulmonary insufficiency
neurologic symptoms
anemia, thrombocytopenia
diffuse petechial rash
● Patogenesis: occlusion of pulmonary and cerebral microvasculature by fat
globules followed by platelet and RBC aggregation
Amniotic fluid embolism
amniotic fluid in maternal circulation
mortality rate 80% but rare
clinical symptoms: dyspnea, cyanosis, hypotensive shock, coma, DIK
Patogenesis: mechanical obstruction of pulmonary vessels and activation of coagulation system by release of thrombogenic substances from amniotic fluid- disseminated intravascular coagulation (DIC)
air embolism
can obstruct blood flow -> ischemia
decompression sicknes
white infarcts
caused by arterial occlusion in solid organs with end- arterial circulation such as the heart, spleen, or kidney.
red infarcts
caused by:
venous occlusion (ovarian or testical torsion)
loose, spongy tissues where blood can permeate infarcted zones (lung)
organs with a dual blood supply (lung, intestines)
cardiogenic shock
myocardial infarction
arrhytmia
pulmonary embolism
cardiac tamponade
hypovolemic shock
hemorrhage
fluid loss (vomiting, diarea, burns)
septic shock
gram-positive septicemia
gram-negative sepsis
anaphylactic shock
• IgE mediated hypersensitivity
Stages of shock
initial nonprogressive phase
progressive phase
irreversible phase
Initial nonprogressive phase
vital organ perfusion is maintained due to activation of compensatory mechanisms :
- tachycardia
- peripheral vasoconstriction (cool, pale skin)
- renal fluid retention (activation of renin-angiotensin-aldosteron axis)
tissue hypoperfusion and hypoxia resulting in anaerobic glycolises, metabolic acidosis and decreased vasomotor response
-dilatation of arterioles and peripheral pooling of the blood
-vital organs began to fail
Irreversible phase
severe cellular and tissue injury, survival is not possible even if underlying cause is corrected
- worsening of myocardial contractile function
- progressive renal failure
acute pulmonary congestion is marked b y
blood engorged alveolar capillaries and variable degrees of alveolar septal edema and intraalveolar hemorrage
in chronic pulmonary congestion
the septa become thiken and fibrotic
alveolar spaces contain numerous macrophages laden with hemosiderin (heart failue cells) derived from phagocytosed red cells
thrombi in heart valves are called
vegetations
Disseminated Intravascular Coagulation (DIC)
widespread throbosis in microcorculation may be sudden
consumes platelets and coagulation proteins
may coexixst with exessive clotting and bleeding
most systemic emboli arise from
intracardial mural thrombi -> 2/3 LV infarcts
aterial emboli travel
75% lower extreities
10% CNS
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