Hemodynamic Disorders Flashcards
hyperemia
local increase in blood volume. increased arterial inflow due to arteriolar dilation. well oxygenated blood flowing into tissue=bright red erythema. warm. ACTIVE process
examples of hyperemia
inflammation, exercise, blushing
cause of hyperemia
vasodilation of artery leading to locally increased blood flow
hyperemic border around necrosis
white necrosis due to arterial thrombi-occlusion or thromboembolism and subsequent acute inflammatory response dilates border vessels
congestion
local increase in blood volume due to decreased venous outflow from an organ. blue-red tissue=cyanosis from increased deoxygenated blood. PASSIVE process
cause of congestion
impaired venous outflow due to compression, constriction, or functional problem of heart
how does congestion cause edema
hydrostatic pressure at venule end increases and exceeds osmotic pressure so that fluid is driven out everywhere via Starling forces and lymphatics are overwhelmed
what typically accompanies congestion?
edema
venous thrombosis and congestion
blocks blood from exiting tissue. initially there is congestion, which causes increased hydrostatic pressure in vessel and edema. but most tissues have multiple venous drainage pathways, so additional channels open and help bypass obstructed vein.
right heart failure
back up of blood into systemic veins (IVC/SVC), which commonly affects the liver.
left side heart failure
back up of blood into lungs, shortness of breath
where is liver congestion due to right sided heart failure found?
central vein (hepatic vein to IVC)
nutmeg liver
centrilobar congestion and periportal fatty change= chronic passive congestion of liver. impaired o2 delivery to hepatocytes which then accumulate fat
hemorrhage
extravasation of blood due to vessel rupture
hematoma
space occupying lesion of blood
tissue hemorrhages small to big
petechiae (1-2mm), purpura (>3mm), ecchymoses (>1-2cm)
thrombus
pathologica hemostatic plug within a blood vessel that is composed of platelets, fibrin, and trapped RBCs
embolus
intravascular solid, liquid, or gas that is carried from site of origin to a distal site in the bloodstream. doesn’t mix with aqueous portion of blood
thromboembolus
detached thrombus that embolizes
how to identify thrombi
lines of zahn and adhesion to vessel wall
virchows triad
endothelial injury, hypercoaguability, abnormal blood flow all lead to thrombi
important factors leading to arterial thrombi
endothelial cell injury and turbulent flow. atherosclerosis, inflammation
characteristics of arterial thrombi
prominent lines of zahn, white appearance (more platelets/fibrin than RBCs)
where are arterial thrombi more likely to occur
small to medium arteries (coronary, cerebral, femoral). often occlusive and present risk of infarction. less common in aorta (present as mural thrombi that stick to wall but don’t occlude. still risk embolization)
important factors leading to venous thrombi
stasis, hypercoagulative states due to increased concentration of activated coag factors and depletion of inhibitors