Flashcards in Module 3-Path Continued Deck (59):
What is a thrombus?
Occurs inside a vessel and attached to a wall
Platelets involved in formation
Always in alive people
What is the key histological feature of a thrombus?
Lines of Zahn (indicate blood flow)
-pale: platelets and fibrin
A thrombus is composed of what three components?
Platelets, fibrin and RBC
Arterial Thrombi is most commonly due to what?
most common due to endothelial injury
Arterial thrombi are usually pale when observed on gross specimen why?
because of high velocity of blood and more platelets then RBCs
(propagates retrograde to blood flow)
Venous thrombi are usually red when observed on gross specimen why?
red because slow velocity of blood and usually more RBCs then platelets
Venous thrombi is most commonly due to what?
(propagate anterograde to blood flow) (90% in deep veins of the legs)
What are the three components of Virchows Triad?
Turbulent Blood Flow (loss of laminar flow)-> stasis (allows buildup of platelets and coagulative factors)
What are the genetic conditions that lead to hypercoagulability?
Factor V laden mutation (most common)
Protein C and S deficiency
Anti- Thrombin III deficiency
(check for these before thinking of an acquired reason for hypercoagulability)
What are some acquired reasons for hypercoagulability?
Cancer (Trousseau's syndrome)
Pregnancy and Birth Control Pills
What are the 4 fates of a thrombus?
1. Propagate--> accumulate platelets and obstruct vessel
2. Embolize-->dislodge/fragment and carried by blood to a distant site
3. Dissolution --> removed by fibrinolytic activity (By tissue plasminogen activator)
4. Reorganization/Recanalization --> induce inflammation and fibrosis (organization) --> re-establish some degree of flow (recanalization)
If a patient develops a thrombus in the LV and forms an embolus where will this embolus travel?
In regards to a clot what is a clot?
Has only one component --> fibrin formation
Fibrin + trapped cells
Platelets are not involved
Occurs outside vessel (test tube, hematoma)
Not attached to the vessel wll
If an arterial thrombi is in the heart what is it called?
(also called mural for aneurysm)
Another site of thrombosis is aorta this is secondary to what?
Venous thrombosis occurs in what veins??
Deep veins of legs (90%)
deep calf veins (At or above the knee)
femoral, popliteal or iliac
note--> superficial veins of legs rarely embolize
What are some clinical features of deep leg venous thrombus?
Edema of ankle, foot, pain and tenderness
asymptomatic in 50% - due to collaterals
high risk of embolization
What is trousseau's syndrome?
Unexplained thrombophlebitis, recurrent-> look for underlying abdominal malignancy like pancreatic cancer
Explain an acute vs slow arterial thrombus?
Acute -> Infarct
Slow --> atrophy and fibrosis (cells will adapt and start shrinking)
(heart = systemic emboli)
A patient has a DVT but has a co-existing history of a right to left shunt where is the most common location that the clot will go?
To the other leg (right to left) --> called a paradoxyl embolus so it goes to the artery in the other leg because it enters systemic circulation
What is a post-mortem clot?
No lines of Zahn and do not attach to the vessel
fibrin + trapped cells
On gross image of an artery with post mortem clot, the superior red part of the artery is representative of what?
yellow chicken fat appearance of coagulated plasma (supernatant)
On gross image of an artery with post mortem clot, the inferior cherry red part of the artery is representative of what?
currant jelly appearance of emmeshed RBCs (sediment) due to gravity
Are platelets involved in formation of a post mortem clot?
Does a post mortem clot occur inside or outside a vessel?
outside a vessel
What is an embolism?
Occlusion of a part of vascular tree by a mass (solid, liquid, gas) that is carried by the blood to a site distant from its point of origin to the site where it becomes impacted
What is the most common origin of a Pulmonary Artery embolism?
Deep leg veins --> lungs (however most of these are clinically silent)
What is the most common origin of a embolism that is clinically significant?
Thromboemboli arose from heart --> embolize in lower extremities and brain
99% of emboli represent part of dislodged thrombus, what is this called?
What is the major contributor to death in 15% of hospitalized patients?
(occurs the first time they get out of bed)
There are three classifications of pulmonary thromboembolism, each card will go through one. 1--> Massive
1. Massive (saddle embolus) --> straddles the bifurcation of the pulmonary arteries; caused by DVT
--sudden death and no time to develop infarction
2nd classification of pulmonary artery embolism
2. Major (medium vessels) - present with dyspnea, pleuritic chest pain, and hemoptysis and V/Q mismatch
-if bronchial arteries are intact = pulmonary hemorrhage, no necrosis (bronchial arteries vasodilate)
-if bronchial arteries are compromised = red infarct (usually in lower lobes) (coagulative necrosis)
3rd classification of pulmonary artery embolism
3. Minor (small vessels) - asymptomatic
-if you have a series of recurring minor embolisms --> marginate on the wall of the pulmonary artery --> flow encounters increased resistance --> pulmonary HTN --> right heart failure without left heart failure -- >leds to nutmeg liver
Another example of an embolism is a fat embolism, what is the cause of this?
Due to long bone fractures (yellow bone marrow) , trauma to SQ tissue and burns
What is the pathogenesis for a fat embolism?
Fat globules enter circulation --> mechanical blockage adhere to fat globules --> biochemical injuries as FFAs released from adipose damage endothelial cells of vessels --> recruit coagulation factors --> DIC, clogging of pulmonary and systemic arteries
After 1-3 days post fracture a patient may develop fat embolism syndrome, what are some features?
Pulmonary Insufficiency (dyspnea, tachypnea, tachycardia)
Neurological Symptoms (irritability, restlessness, delirium, coma)
Anemia and Thrombocytopenia (petechiae)
How would the physician diagnosis fat embolism?
Fat globules in urine and sputum
On a post mortem specimen of the patient with fat embolism syndrome, what would be seen?
Frozen section (fat will dissolve if process done with alcohol)
Has to be done underwater
What stains would you use for a fat embolism?
Suden IV (Stains red) , oil red (Stains red), osmium/osmic acid (Stains black)
What is a bone marrow embolism?
In small pulmonary vessels --from aggressive CPR
(injury to flat bones of the ribs -red bone marrow)
Is bone marrow embolism a cause of death?
NOT cause of death, incidental finding
What is the morphology of bone marrow embolism on stain?
Fat and hematopoetic cells
When does an amniotic fluid embolism occur?
sudden event after labor
What is the morphology of an amniotic fluid embolism stain?
Squames, hair, meconium in pulmonary vessels
What is the pathogenesis for an amniotic fluid embolism?
Entry of amniotic fluid into maternal circulation via a tear in the placental membrane and rupture of the uterine veins
What are the symptoms in a patient who develops amniotic fluid embolism?
Dyspnea w/in 1 hour
Diffuse alveolar damage
If a patient survives an amniotic fluid embolism, what condition will develop
The release of thrombogenic agents (mucin) from the amniotic fluid leads to DIC
What would the patients lab values look like t that has amniotic fluid embolism?
Decreased platelets and clotting factors
On H and E stain an amniotic fluid embolism contains swirls, what other disease also has this appearance?
1. Silicosis --> swirls of collagen, no nuclei, eosinophilic
2. Leiyomyoma -> swirls of smooth muscle (criss cross formation)
3. Malignant HTN (hyperplastic) --> onion looking
4. Cervical Carcinoma --> looks like Keratin Pearls
5. Squamous Cell Carcinoma --> keratin pearls
What does an atheromatous emboli involve?
Small dislodged fragments of atherosclerotic plaques
part of aorta below renal artery bifurcation, infrarenal artery.)
Second most common vessel is coronary artery
What are the key findings on H and E of an atheromatous emboli?
Foam cells (macrophages)
What is the most common presentation of an atheromatous emboli (Cholesterol Emboli) ?
(incidental finding on autopsy unless there is complete occlusion of the vessel)
What are the most commonly affected vessels for an atheromatous emboli?
Peripheral arteries of lower limbs
(iliac, femoral, posterior tibila arteries)
what is a systemic thromboembolism?
Thrombi that travels in arterial circulation
What is the site of origin of a systemic thromboembolism?
aorta (ulcerated atherosclerotic plaques) and
Venous circulation (paradoxical through ASD, VSD)
What is the effect of a systemic thromboembolism?
Embolize to the lower extremities and brain --> block an end artery --> infarct
what is the best investigation for a pulmonary artery embolism?
Spiral CT or
CT angiogram (CT PE study)
What is the most common way of getting an atheromatous emboli?
Vascular procedures like angiograms where the plaques on these arteries get bumped