Hemodynamics and Shock (not on test) Flashcards
Embolus
A freely movable, intravascular mass that is carried from one anatomic site to another by blood
Name the 4 types of emboli
- Thromboemboli
- Liquid emboli
- Gaseous emboli
- Solid particle emboli
Thromboemboli
fragments of thormbi carried by venous or aterial blood. (infected thrombi give rise to septic emboli)
Liquid emboli
fat emboli - occur after bone fracture
amniotic fluid emboli - caused by entry of amniotic fluid into the uterine veins during delivery
Mural thrombus
- arterial embolus
- most often in patients with Afib
Acute bacterial endocarditis
- creates a septic embolus
- Staph aureus is the #1 cause (likes to form abcesses)
What is the classic triad for a fat embolism?
After trauma (breakage of long bone- femur, tibia)
- Difficulty breathing
- Neurosymptoms (disorientation, coma)
- Thrombocytopenia (platelets love to adhere to fat globules)
Gaseous emboli
air embolism can be produced by injecting air into veins (also with decompression sickness, ie the Bends)
Solid particle emboli
Ex.
- cholesterol crystals can detach from atherosclerotic plaques
- tumor cells
- bone marrow emboli
Which type of malignancy is notorious for creating tumor emboli?
Renal cell carcinoma (especially renal vein)
Which type of emboli is most common?
thromboemboli
classified on basis of vessels through which they are carried in blood
Where do venous emboli originate and lodge?
these originate in veins and typically lodge in the pulmonary artery and its branches
Where do arterial emboli originate?
- left atrium
- ventricle
- aorta
- major arteries
Paradoxical emboli
venous emboli that enter arterial circulation through the foramen ovale or interventricular septal defect
Name 3 common places arterial emboli originate from
- endocardium
- valve
- ulcerated atherosclerotic plaques of the aorta
Where sized arteries do arterial emboli tend to lodge in?
- Medium-sized arteries
- smaller arteries
*fragment because arterial blood flows fast
Which organ is at greatest risk for arterial emboli?
Emboli of cerebral circulation
*typically lodge in the middle cerebral artery and causes infarcts of the basal ganglia
Where do arterial emboli typically lodge in the brain?
middle cerebral artery
What does an embolism in the middle cerebral artery cause?
infarct of the basal ganglia
What organs are vulnerable to arterial emboli?
- Spleen
- Kidney
- Intestine
Sharp subcostal pain is associated with what type of emboli?
splenic infact (arterial embolism)
Thrombus
transformation of the fluid bood into a solid aggregate encompassing blood cells and fibrin
Fibrin
polymerized fibrinogen that forms a meshwork of thin filaments that bind together the cellular elements of the blood
Pathologically, how are thrombi classified?
based on location
Name the 3 types of thrombi
- Intramural thrombi
- Arterial thrombi
- Venous thrombi
Intramural thrombi
attached to the mural endocardium of the heart chambers and commonly are found overlying a MI which may embolize
Arterial thrombi
attached to arterial wall and typically cover ulcerated atheromas in an atherosclerotic aorta or the coronary arteries
Venous thrombi
-found in dilated veins (varicose veins)
(Long-standing venous thrombi are organized by granulation tissue, which may give an impression of inflammation (thrombophlebitis))
Name 5 common sites of thrombus formation
- Varicose veins
- Heart (valves, over myocaridal infarct)
- Aorta (atherosclerosis, aneurysm)
- Coronary arteries
- Carotid and cerebral arteries
Name the two types of thrombi (based on pathologic features)
- Red thrombi
2. Layered thrombi
Which throbus type is composed of tightly intermixed RBC’s and fibrin
Red thrombi
Which thrombus type shows distinct layering of cellular elements and fibrin
Layered thrombi
Thrombi in small vessels tend to be _______
red thrombi
Thrombi in larger arteries and veins, and mural thrombi tend to be _______
layered thrombi
“Lines of Zahn”
white layers of fibrin in microscopic thrombi
What type of thrombi are lines of Zahn associated with?
layered thrombi
Infarct
insufficiency of blood supply of sudden onset that results in an area of ischemic necrosis
Most infarctions are caused by? (2)
- Thrombosis
2. Emboli
How can infarcts be classified pathologically?
Gross appearance
- white
- red
White infarcts
- white or pale
- arterial occlusion
- solid organs (heart, kidney, etc)
In what type of infarction would you expect to see an area of ischemic necrosis caused by the arterial obstruction, typically paler than the surrounding tissue, often rimmed by a thin red zone containing extravasated blood that was destined to reach the ischemic zone from surrounded anastomotic blood vessels
White infarct
Red infarct
- venous obstruction
- involve intestines (volvulus) or testes (torsion)
- Typical of organs with dual blood supply (ex. liver and lungs)
*venous circulation interrupted by twisting of the organ
What happens as a result of venous compression with red infarct?
- venous congestion
- local ischemia
- necrosis
Which two organs cannot be repaired after infarction?
Heart and Brain
What happens to heart tissue after infarction?
damaged cells are replaced with fibrous tisssue, resulting in myocardial fibrosis and scarring
What happens to necrotic brain tissue after infarction?
liquefied brain tissue is resorbed, leaving behind cyst fillled with clear fluid that later undergoes gliosis
Shock
state of hypoperfusion of tissues with blood
Name the 3 mechanisms of shock
- Cardiogenic shock (heart fails to pump)
- Hypovolemic shock (loss of fluid/blood)
- Septic shock (gram negative bacteremia)
What is characteristic of all 3 forms of shock?
- collapse of circulation
- disproportion between circulating blood volume and vascular space
What does cellular or tissue hypoxia cause?
- shift from aerobic to anaerobic metabolism
- increased lactic acid production (lactic acidosis)
How does cardiogenic shock most often take place?
results from pump failure of the heart usually after an area of heart muscle infarcts and dies
Causes of hypovolumic shock
- massive hemorrhage
- diarrhea
- burn
- vomiting
