GP 32 - Hemodynamic Disorders 4 Flashcards
List the key differences between a clot and a thrombus.
What are lines of Zahn?
Alternating pale and dark lines
Light lines - platelets and fibrin
Dark Lines - RBCs
T/F - anti-coagulants are the apropriate treatment for thrombi
Partly True
Arterial thrombi are mostly platelets so anti-coagulants are useful for dissolving them. However, after some time, the fibrin in these thrombi begin to cross-link and it becomes less susceptible to anti-coagulants.
Venous thrombi are mostly RBCs so anti-coagulants are not useful for dissolving them
Describe the possible fates of a thrombus
- Resolution - thrombus is dissolved
- Embolization - thrombus breaks off and lodges somewhere else
- Organization - the endothelium, fibroblasts, and smooth muscle cells begin to grow around the thrombus causing:
- First - recanalization
- Second - incorporation into vessel wall
List the most commonly seen arterial thrombi in order
- Coronaries
- Carotids, cerebral
- Femoral
- Mesenteric
List the special thrombi names we need to know and where they’re found?
Mural Thrombi - thrombi that form in cavities like a heart chamber or aneurysm
Occlusive - thrombi that form in smaller arteries and cause occlusions
How can venous thrombi be distinguished from arterial thrombi? Where do venous thrombi typically form and how often do they embolize?
- Venous thrombi take the shape of the vessels in which they form, arterial thrombi do not
- Redder than arterial thrombi
Most venous thrombi form in the deep veins of the legs and often embolize due to muscle contractions
Some thrombi form in the superficial veins of the legs, forming varicosities. These rarely embolize
What percentage of thrombi formations are asymptomatic?
50%
due to collaterals
What is Trousseau’s Syndrome? What is it indicative of?
Unexplained and recurrent thrombophlebitis. This is a common feature of thrombus and is often indicative of an underlying abdominal malignancy, like pancreatic cancer.
What are the general effects of thrombi on organs?
For arterial thrombi, it depends on the thrombus progression:
- If acute (or it embolizes), it will cause an infarct and necrosis
- If slow, it will cause atrophy and fibrosis
For Venous thrombi
- It will cause edema and congestion which, if bad enough, can cause occlusion of a nearby artery
- If it embolizes, it will most likely end up in the lungs
What are the commonest forms of embolism?
- Deep leg vein thromboembolism to the lungs. However, most of these are asymptomatic.
- The most common clinically significant embolism is a thromboembolism from the heart to the legs or brain
Describe the severity classification system for pulmonary embolisms.
- Massive - sudden obstruction of 60% of pulmonary vasculature causing sudden death. No time to develop infarction
- Major - multiple medium sized vessels occuled causing dyspnea and pain, Infarction in only 10% of tissues due to collateral circulation
- Minor - small vessels obstructed. Embolism will get lysed as treatment. Asymptomatic
What is a fat embolism and what usually cause it? What are the general symptoms?
A fat embolism is when fat globules enter the circulation, aggregate with platelets, and then lodge themselves somewhere.
Usually caused by bone trauma rupturing the marrow vascular sinusoids or venules, releasing fat globules. Also caused by damage to subcutaneous tissue and burns
Usually asymptomatic
What is fat embolism syndrome?
While fat embolisms are typically asymptomatic, if the embolism is large and widespread enough, fat embolism syndrome can appear 1 to 3 days after the injury. It is characterized by:
- Pulmonary Insufficiency
- Neurologic Symptoms
- Anemia (RBCs get trapped in embolism)
- Thrombocytopenia (WBCs get trapped in embolism)
All of this causes tachypnea, dyspnea, tachycardia, petechiae, irritability, restlessness, and/or delirium/coma
How are fat emboli diagnosed?
- Fat globules in sputum or urine
- Postmortem - H&E slide wil show round empty spaces in the thrombus (where the fat cells were washed out during prep). Refer to image.
