Common Vascular Events In Disease And Injury Flashcards
Hemorrhage
Discharge of blood from the blood vessels
Extravasation
Process of discharging blood from the blood vessels into the surrounding tissues
Splinter hemorrhage
Tiny blood clots that tend to run vertically under the nails
Associated with endocarditis
Melena
Black stool - upper GI bleed
Hematochezia
Lower GI bleed - blood in stool that is bright red
Peripartum Hemorrhage
Reproductive - after giving birth
Gross hematuria
Blood in urine
Hemoparicardium
Bleed fills up the pericardial sac
Hemothorax
Bleed in lung - fills up pleural space and may compress the lung
Subdural hematoma
In brain region
Hematoma
Collection of extravasated blood within the surrounding tissues or body space
Epidural bleed - outside the dura
Subdural - below the dura
Intracerebral - inside brain tissue
…
Ecchymosis
Hematoma associated with skin or mucous membrane that measures greater than 1cm in diameter
The terms hematoma, ecchymosis, contusion and bruise are often used interchangeably…contusion implies trauma - whereas the other terms may or may not be the cause
…
Exsanguination
“Bleed to death,” fatal loss of blood from massive hemorrhage
Exsanguination may be used medically with…
May be used in surgery in a localized sense, when using a tourniquet and temporarily draining blood from a region - “bloodless surgical field”
Hemostasis
Normal and tightly regulated process that maintains blood in a fluid state when appropriate and aims to arrest bleeding in the event of traumatic vessel damage
In the event of traumatic vessel damage, set of regulated steps aims to arrest bleeding, beginning with….
Arteriolar vasoconstriction
The trio in hemostasis?
Vasculature and hydrodynamics of blood flow:
- endothelium
- smooth muscle
- basement membrane
Platelets:
- receptors for binding, aggregation, activation
- phospholipid surface
Coagulation cascade:
-proteins with enzymatic activity leading to fibrin mesh work
Vessel spasm
First response in tissue injury to blood vessel
Reduces the flow of blood from the vessel rupture
Booth local nervous reflexes and humoral factors released from plates (thromboxane) contribute to vasoconstriction
The endothelium normally secretes prostaglandins and nitric oxide to promote vasodilation and keep platelets away. Disruption exposes collagen and releases..
Von Willebrand factor!! (VWF) - triggers platelet adhesion and activation)
Von willebrand factor is released from the endothelium and binds to platelet receptors causing adhesion of the platelets to exposed collagen fibers. As the platelets adhere to the collagen fibers on the damaged vessel wall, they become activated and release ADP and TXA2. The ADP and TXA2 attract additional platelets, leading to platelet aggregation.
…
Activated platelets send out processes that help them enmesh.
…
What is the goal of the coagulation cascade?
Create fibrin glue to support plug until endothelium and extracellular matrix remodel
Two coagulation pathways
1) intrinsic - begins in the circulation and is initiated by activation of circulating factor XII
2) extrinsic - activated by cellular lipoprotein tissue factor that becomes exposed when tissues are injured.
Both pathways lead to the activation of factor X, conversion of prothrombin to thrombin, and conversion of fibrinogen to fibrin threads that hold the clot together
Fibronigen to fibrin is catalyze by what?
Thrombin
Activated platelet surface provides phospholipids needed to trigger the coagulation cascade
…
Primary hemostasis
Platelets release thromboxane - activates and recruits more platelets and they aggregate
Secondary hemostasis
Fibrin deposited now
Thrombus and antithrombotic events (after primary and secondary hemostasis)
Release of TPA (fibrolysis) and thrombomodulin (blocks coagulation cascade)
Flipping of phosphatidylserine from inner to outer membrane surface… exposure on platelets results from damage or from platelet damage itself
…
Plasmin, antithrombin, and proteins C and S… involved in localization of hemostasis…?
…
Hemostasis is problematic when it leads to the complete obstruction of key blood vessels..also known as thrombotic occlusion
…
Thrombus
Clot adherent to vascular endothelium
Two worst places for thrombus - coronary (HA) or cerebrovascular places (Strokes)
…
A group of three underlying conditions increases the risk of thrombosis. That group is… and is called…
Virchow’s triad
Relates to:
1) endothelium (injury)
2) blood flow (stasis or turbulence)
3) coagulation pathway (hypercoagulability state)
Ex. Atrial fibrillation - turbulent
Paralysis - embed blood flow
Protein C or S deficiencies lead to clot formation
Blood flow abonormalities
Atrial fibrillation
Bed rest, paralysis
Venous obstruction
Contact surface abnormalities
Atherosclerosis
Vascular injury/trauma
Abnormal heart valve
Indewelling vascular catheter
Clotting component abnormalities
Elevated factor VIII Factor V Leiden Prothrombin 20210 Protein C/S deficiency Antithrombin deficiency Estrogen therapy/pregnancy Malignancy
Thrombus formation is one mechanism of creating an obstruction that narrows or occludes blood flow. Another mechanism is through disordered vessel development, such as…
Congenital stenosis or atresia
Atresia
Not properly formed valve
Stenosis
Narrowing of valves/vessels
Another mechanism of obstruction to blood flow is compression from an enlarging newborn gene structure called….
Mass effect
Ex. Gravid uterus
Neoplasm
Pregnancy
Another mechanism for obstruction of blood flow is torsion…
Testicular torsion ex.
Twisting of the spermatic cord cuts off venous drainage of the testis…
Bowel volvulus has a similar torsion mechanisms
Another mechanism of obstruction to blood flow is pressure from edema… called….
Compartment syndrome
Blood flow to distal limb is compromised due to compression from surrounding swollen tissue
Another mechanism of obstruction to blood flow is atherosclerosis….
The resultant atheromas (also called atheromatous plaques) cause protrusions into vessel lumens, narrowing them
Ischemia
Hypoxia (low o2) due to reduced blood flow
Infarct
Area of ischemic necrosis caused by occlusion of arterial supply (or venous damage)
Most infarcts are from…
Thrombotic or emboli arterial occlusion
Venous infarcts are far less common than arterial infarcts…
Arteries have tissue turn white
Veins have tissues turn red (Cant drain blood)
…
Embolus
Detached mass (solid, liquid, or gas) carried by blood to a site distant from its point of origin…
Most common type are thromboemoli…
Among other types are fat, marrow, air, tumor, amniotic fluid
Only few places in the body where you have a collateral supply so generally emboli can be a problem anywhere in the body
…
Shock
Global underperfusion of tissues resulting in cellular hypoxia (commonly associated with systemic hypotension)
3 main types of shock
2 minor
Cardiogenic, hypovolemic, septic
Neurogenic, anaphylactic
Both septic and anaphylactic shock involve the immune system…
…
Cardiogenic shock
Pump failure (heart)
Hypovolemic shock
Massive fluid loss, fluid loss from sever burns
Septic shock
Systemic immune rxn to infection, get vasodilation and peripheral blood pooling
Cardiogenic shock can occur days after HA
…
Hyperemia
Locally increased blood flow from the active process of arteriolar dilation (ex. Muscle exercising)
Congestion
Blood stasis from reduced outflow from tissue = passive process (ex. Venous obstruction)
Edema
Abnormal increase of interstitial fluid within tissues
Causes of edema
- reduced plasma oncotic pressure (reduced albumin in liver failure)
- lymphatic obstruction (e.g. Filarial worms = elephantiasis)
- increased hydrostatic pressure (e.g. Increased venous pressure of congestive heart failure)
There are specialized names for hemorrhages of skin (“rash”) and mucous membranes (“enanthem”)
Exs. Petechiae, purpura, ecchymosis (all for skin, and increase in size)
…
Petechiae come from viral infection. Purpura comes from bacterial infection… generally
…
