Hemostasis Flashcards
Define Hemostasis…
sealing an injured vessel to prevent blood loss Can be: 1. Physiological 2. Surgical 3. Pathological
What is the Pathological form of Hemostasis?
Thrombosis
What are the requirements for Thrombosis?
- vascular wall -> endothelium
- platelets -> primary CLOT and THROMBUS component
- coagulation cascade
True/False: The extracellular matrix has low thrombogenicity.
False - the extracellular matrix has high thrombogenicity
What is Endothelin?
A secretion factor that is a potent endothelium-derived vasoconstrictor.
What is the end result of Primary Hemostasis?
Creating a Primary Hemostatic Plug
What are the 5 MAIN steps of Primary Hemostasis following injury?
- Platelet Aggregation
- Change in Platelet shape
- Granule Release
- Recruitment
- Primary Hemostatic Plug formation
What is the purpose of Secondary Hemostasis?
Creating THROMBIN
Why is thrombin so important?
It cleaves circulating fibrinogen into fibrin.
It also recruits more platelets and stimulates further granule release.
What does Fibrin do?
Fibrin wraps around the aggregated platelets and forms the Secondary Hemostatic Plug
What is the difference btw the Primary Hemostatic and Secondary Hemostatic Plug?
Secondary Hemostatic Plug lasts longer!
What are the 2 molecules released that limit the hemostatic plug to the site of injury?
- t-PA
2. thrombomodulin
If you do NOT stop the coagulation cascade, it may lead to…
Thrombus
What is Thrombus?
Aggregate of platelets, fibrin and entrapped blood cells.
What is the difference between a Thrombus and a Blood Clot?
Thrombus is attached to the vascular wall
What are the distinguishing characteristics of a thrombus vs. a post-mortem blood clot?
Thrombus:
surface: more dull and granular
attached to the vessel wall
Post-Mortem Clot:
Red/Pale/Shiny and smooth
Not attached to the vessel wall
Cats with Cardiomyopathy will have a thickened left side of the heart. Where is a thrombus more likely to develop?
in the Left Atrium
What are the 5 thrombi that we are most likely to encounter in veterinary medicine?
- mural thrombus
- pulmonary thrombus
- verminous thrombus
- saddle thrombus
- vena cava thrombus
Where is a mural thrombus located?
Heart Endothelium
Where is a Pulmonary Thrombus located?
Pulmonary Artery…duh!
Pulmonary thrombosis is most common seen in dogs. What are 2 predisposing conditions to pulmonary thrombosis in canines?
- severe renal glomerular disease
2. severe heartworm disease
Severe renal glomerular disease results is a protein losing nephropathy, causing proteinuria. What anticoagulant protein is significantly lost in this condition?
Antithrombin III - a MAJOR inhibitor of thrombin
Antithrombin III allows the blood to remain more fluid-like.
What parasite is the most likely cause of Verminous Thrombus in Horses?
Strongylus vulgaris infection
What are the main arteries that are likely to develop verminous thrombus in horses?
Cecal/Colonic as.
Cranial Mesenteric a.
If the cecal/colonic as. develop verminous thrombus in Strongylus vulgaris infections, what are the resulting consequences?
Ischemic damage to the intestine –> infarction –> death
Cats with Hypertrophic Cardiomyopathy are likely to develop a thrombus in the Left Atrium. This can cause Saddle Thrombus. Where is Saddle Thrombus located and what are the clinical signs?
Location: trifurcation of the abdominal aorta
CS: acute onset of Left-Sided congestive heart failure, respiratory distress, pelvic paralysis
What is an Embolus?
Any type of intravascular particle that travels through circulation distal to the site of origin
What is the mechanism of development for vena cava thrombus in cattle?
Grain overload –> ruminal acidosis –> rumen mucosal damage –> ruminal bacteria are able to reach circulation via the portal v. –> hepatic abscess close to the Caudal Vena Cava –> vena cava thrombus
What are the outcomes of thrombi?
- lysis
- propagation
- embolization
- organization/recanalization
You are working Emergency rotation when a 3 year old pitbull terrier is brought in presenting with:
acute onset of neurological disease and severe pain
and dies shortly after. You get permission from the owner to perform a necropsy and find areas of necrosis in the spinal cord. You suspect spinal cord infarcts. What type of embolism is present and what are the resulting consequences?
Obliterating emboli made of fibrinocartilage –> ischemia myelomalacia –> hemorrhage and necrosis –> death
Histologically, if you see adipose cells and haematopoetic cell precursors you have a…
Fat Embolism
Fat Embolisms are common complications of…
bone fracture fragments that reach systemic circulation causing pulmonary embolism
Upon performance of a cattle necropsy, you find a friable, patent material localized and attached to the Right Tricuspid valve. At the pulmonary artery you find a septic embolism and development of severe pulmonary abscess.
What caused the death of this cow?
bacterial valvular endocarditis of the right atrioventricular valve
**Chronic, suppurative conditions –> inflammation –> bacteremia –> bacteria localize in the heart valves –> septic thrombi attach to the valves –> pieces break off and septic emboli get stuck in the pulmonary a. –> severe pulmonary abscess
Histophilus someone can cause neurological diseases, arthritis, pneumonia, myocarditis, and vasculitis. Which of these leads to endothelial damage, predisposing the vasculature to thrombi formation?
Vasculitis –> endothelial damage –> predisposing the vasculature to thrombi formation
What is the name of the condition from Histophilus somni infection that results in thrombi formation in the brain?
Thrombotic meningoencephalitis (TME)
DIC is a very important condition that veterinarians must know! What is the ultimate result of DIC and what causes it?
The Result: DEATH! DIC is fatal!
Present in many diseases –> Endothelial damage –> WIDESPREAD COAGULATION CASCADE –> fibrin-thrombi EVERYWHERE! –> systemic hypoxia –> multi-organ failure
–> death
The Fibrin-Thrombi are stained by what?
PTAH Stain
What is an Infarct?
localized ischemic/necrosis hypoxic injury caused by occlusion of an artery/vein
