hemodynamic disorders

what is infarction?

ischemic cell death

what is thrombosis?

inappropriate clotting of blood

what is embolism?

migration of clots

differentiate between hyperemia and congestion

hyperemia is an active process resulting from arteriolar dilation and increased blood inflow, as occurs at sites of inflammation or in exercising skeletal muscle. (redness in tissue)

Congestion is a passive process resulting from impaired
outflow of venous blood from a tissue. It can occur systemically, as in cardiac failure, or locally as a consequence of an isolated venous obstruction. (blueness of tissue)

characteristics of hyperemic tissue

redder than normal

characteristics of congested tissue

cyanosis (blue-red color) due to accumulation of deoxygenated hemoglobin

chronic congestion can lead to...

parenchymal cell death, secondary tissue fibrosis (due to hypoxia)

edema or sometimes ruptured capillaries (due to high pressure)

characteristics of the cut surface of hyperemic or congested tissue

wet, ooze with blood

actue pulmonary congestion vs. chronic pulmonary congestion

acute pulmonary congestion: blood-engorged alveolar capillaries, alveolar septal edema, and intraalveolar hemorrhage.

chronic pulmonary congestion: the septa become thickened and fibrotic, alveolar spaces contain macrophages

acute vs chronic congestion of liver

acute hepatic congestion: central vein and sinusoids are distended with blood, necrosis of centrally located hepatocytes. The periportal hepatocytes experience less severe hypoxia and may develop reversible fatty change.

chronic hepatic congestion: the central regions of the hepatic lobules are red-brown and slightly depressed and are accentuated against the surround zones of uncongested tan/fatty, liver (nutmeg liver), centrilobular hepatocyte necrosis, hemorrhage, and macrophages.

what is edema?

accumulation of interstitial fluid within tissues

effusion vs edema

edema: accumulation of interstitial fluid within tissues
effusion: accumulation of extravascular fluid in body cavities

two factors that contribute to increased hydrostatic pressue

Impaired Venous Return and Arteriolar Dilation

how can liver cirrhosis cause edema?

cirrhosis can cause reduced plasma osmotic pressure due to hypoproteinemia.

5 causes of edema

increased hydrostatic pressure, decreased plasma osmotic pressure, lymphatic obstruction, sodium retention, inflammation

most important cause of albumin loss from the blood

nephrotic syndrome

what is elephantiasis

massive edema of the lower extremity and external genitalia

what is peau d'orange?

infiltration and obstruction of superficial lymphatics by breast cancer causes edema of the overlying skin

why is edema most pronounced in the legs?

because fluid usually accumulates preferentially in parts of the body positioned the greatest distance below the heart, where hydrostatic pressures are highest.

what is hemorrhage?

extravasation of blood from vessels, resulting from damage to blood vessels or defective clot formation.

what are hemorrhagic diatheses?

clinical disorders that increase the risk of hemorrhage.

what is hematoma?

accumulation of blood due to hemorrhage in tissues

due to massive breakdown of red blood cells, extensive hemorrhage can result in...

jaundice

what are purpura?

hemorrhages that are 3mm-5mm in size

what are petechiae?

pinpoint, round spots that appear on the skin as a result of bleeding.

what are Ecchymoses?

subcutaneous hematomas that are 1cm-2cm in size

what is hemostasis?

precisely orchestrated process involving platelets, clotting factors, and endothelium that occurs at the site of vascular injury and culminates in the formation of a blood clot, which serves to prevent or limit the extent of bleeding.

4 steps of hemostasis

arteriolar vasoconstriction
primary hemostasis (formation of the platelet plug)
secondary hemostasis (deposition of fibrin)
clot stabilization

4 main functions of thrombin

Conversion of fibrinogen into crosslinked fibrin
Platelet activation
Proinflammatory effects
Anti-coagulant effects (thrombin changes from a procoagulant to an anti-coagulant; this reversal in function prevents clots from extending beyond the site of the vascular injury.)

factors involved in coagulation

sequential enzymatic conversion by a cascade of circulating and locally synthesized proteins.

most important initiator of the coagulation cascade in vivo is...

Tissue factor

4 ways normal coagulation is limited in the body

limiting enzymatic activation to phospholipid surfaces
circulating inhibitors of coagulation factors
expression of thrombomodulin on normal endothelial cells, which bind thrombin and convert it into an anti-coagulant
activation of fibrinolytic pathways (e.g., by association of tissue plasminogen activator with fibrin).

what is the PT assay?

assesses the function of the proteins in the extrinsic pathway (tissue factor, phospholipids, and calcium are added to plasma and the time for a fibrin clot to form is recorded)

what is PTT assay?

screens the function of the proteins in the intrinsic pathway

3 types of antithrombotic properties in the endothelium

Platelet inhibitory effects
Anticoagulant effects
Fibrinolytic effects

3 abnormalities that lead to thrombosis are...
these 3 abnormalities are collectively called...

endothelial injury, stasis or turbulent blood flow, hypercoagulability of the blood
“Virchow triad”

what are mural thrombi?

Thrombi occurring in heart chambers or in the aortic lumen

cardiac and arterial clots are rich in....

platelets

why is aspirin used to treat coronary artery disease and myocardial infarction?

it is believed that platelet adherence and activation is a necessary prerequisite for thrombus formation under high shear stress, such as exists in arteries.

compare and contrast stasis and turbulence.

stasis is when blood flow completely stops, while turbulence, is when fluid layers mix together via eddies and swirls.
Both promote endothelial cell activation and enhanced procoagulant activity, in part through flow-induced changes in endothelial gene expression.
Stasis allows platelets and leukocytes to come into contact with the endothelium when the flow is sluggish.
Stasis also slows the washout of activated clotting factors and impedes the inflow of clotting factor inhibitors.

what is hypercoagulability?

an abnormally high tendency of the blood to clot, and is typically caused by alterations in coagulation factors.

examples of primary hypercoaculability

Increased levels of factor VIII, IX, or XI or fibrinogen
Prothrombin mutation
Fibrinolysis defects etc.

examples of acquired hypercoagulability

Prolonged bed rest or immobilization, Myocardial infarction, Atrial fibrillation, Tissue injury, Cancer
Prosthetic cardiac valves, Cardiomyopathy, Hyper-estrogen, Oral contraceptive, Sickle cell anemia, Smoking

Elevated levels of what contributes to arterial and venous thrombosis, as well as to the development of atherosclerosis??

homocysteine

Most venous thrombi occur in...

deep veins of the leg

what types of deep venous thromboses are more likely to embolize?

larger leg veins at or above the knee joint (e.g., popliteal, femoral, and iliac veins)

4 fates of thrumbus

propagate, resolve, become organized, or embolize.

pulmonary embolism originates from...

deep venous thromboses

fat and marrow embolism can occur in a patient with...

severe skeletal injuries

what is the most common cause of maternal death in the developed world

amniotic fluid embolism

symptoms of amniotic fluid embolism?

sudden severe dyspnea, cyanosis, and hypotensive shock, followed by seizures and coma.

decompression sickness is caused by...

sudden changes in atmospheric pressure. Scuba divers, underwater construction workers, and persons in unpressurized aircraft who undergo rapid ascent are at risk.

5 characteristics of red infarcts

caused by venous occlusions

located in in loose tissues where blood can collect in infarcted zones, such as the lung

located in tissues with dual circulations such as lung and small intestine

located in previously congested tissues

flow is reestablished after infarction has occurred

white infarcts

occur in solid organs with end-arterial circulations (e.g., heart, spleen, and kidney)
wedge-shaped

ischemic tissue injury in the central nervous system results in

liquefactive necrosis

what are Septic infarcts?

occur when infected cardiac valve vegetations embolize, or when microbes seed necrotic tissue.

2 factors that influence infarct development

Anatomy of the vascular supply (the number of routes to blood supply), Rate of occlusion (the faster the rate, the higher chance of causing infarcts), tissue vulnerability to hypoxia (if damage is reversible or irreversible)

what is shock?

a state in which diminished cardiac output or reduced effective circulating blood volume impairs tissue perfusion and leads to cellular hypoxia

what is cardiogenic shock?

results from low cardiac output as a result of myocardial pump failure.

what is hypovolemic shock?

results from low cardiac output due to loss of blood or plasma volume (e.g., resulting from hemorrhage or fluid loss from severe burns).

what is septic shock?

caused by massive outpouring of inflammatory mediators from innate and adaptive immune cells that produce arterial vasodilation, vascular leakage, and venous blood pooling.

causes of septic shock

inflammatory/couterinflammatory responses
Endothelial activation and injury
Induction of a procoagulant state
Metabolic abnormalities
Organ dysfunction

the 3 stages of shock

nonprogressive stage (reflex compensatory mechanisms are activated and vital organ perfusion is maintained)
progressive stage (tissue hypoperfusion and onset of worsening circulatory and metabolic derangement, including acidosis)
irreversible stage (cellular and tissue injury is so severe that even if the hemodynamic defects are corrected, survival is not possible)

what is "shock lung"

when sepsis or trauma precipitates alveolar damage

symptoms of shock

hypotension, a weak rapid pulse, tachypnea, and cool, clammy, cyanotic skin. As already noted, in septic shock, the skin may be warm and flushed owing to peripheral vasodilation.