Haematology 1a Haemostasis & Bleeding disorders Flashcards
What two mechanisms act simultaneously during Haemostasis?
- Primary
- Secondary
What is the role of vWF? (2)
- Being the intermediary that joins platelet to collagen
- Allows platelet aggregation
Describe the events during primary haemostasis (2)
- Reflex vasoconstriction amongst damaged and adjacent vessels
- Platelet plug formation via vWF
What are the three pathways in secondary haemostasis?
- Intrinsic Pathway
- Extrinsic Pathway
- Final Common Pathway
What is the essential role of the coagulation cascade?
The aim of coagulation is ultimately to reinforce the platelet plug with fibrin
When is the intrinsic pathway initiated?
When collagen is exposed
When is the extrinsic pathway initiated?
The extrinsic pathway is initiated when damaged tissue releases the protein, tissue factor (Factor III)
Which factor is ultimately activated through both pathways?
Factor X
All clotting factors with the exception of Factor VIII are manufactured where?
The Liver
All clotting factors are manufactured in the Liver besides?
Factor VIII
Where are Factor VIII and vWF produced?
Endothelial cells of blood vessels
Which factors are vitamin K-dependent?
Factors II, VII, IX and X
2,7,9,10
Vascular disorders are which type of haemostatic disorder?
Primary haemostatic disorder
vWF disease is which type of haemostatic disorder?
Primary and Secondary haemostatic disorder
Platelet disorders are which type of haemostatic disorder?
Primary haemostatic disorder
Clotting Factor disorders are which type of haemostatic disorder?
Secondary haemostatic disorder
What is a congenital disorder
A congenital disorder is a medical condition that is present at or before birth.
Explain how vWF disease is both a primary and secondary disorder
- vWF helps to strengthen factor VIII
- Therefore a deficiency in vWF also affects secondary
Haemophilia A and Haemophilia B are examples of congenital or acquired disorders?
Congenital disorders
Haemophilia A affects which clotting factor?
Factor VIII
Haemophilia B affects which clotting factor?
Factor IX
Hereditary Haemorrhagic Telangiectasia:
- Inheritance?
- Appearance?
- Clinical features? (2)
- Autosomal dominant hereditary condition
- Malformations in the skin, mucosa and viscera
- Recurrent nose bleeds
- GI lining bleeding due to chronic iron deficiency
What are the dental aspects to consider with Hereditary Haemorrhagic Telangiectasia? (2)
- Bleeding from oral surgery (not troubling)
- Regional LA, Best avoided due to risk of deep tissue bleeding
Von Willebrand disease (vWD):
- Causation?
- Inheritance?
- Clinical features? (3)
- Caused by vWF deficiency
- Inherited but not sex linked
- Bruising
- Nose Bleeds
- GI bleeding
What drug would be given to manage mild Form Von Willebrand disease (vWD)?
How does it help?
- Desmopressin
- Stimulates release of vWF and factor VIII
Dental Relevance of Von Willebrand disease (vWD)? (3)
- Prolonged bleeding into muscles post extraction
- Avoid regional LA
- Avoid NSAIDs
What does a dentist need to investigate when treating someone with platelet deficiency?
Need to investigate platelet count before treating as there may be a risk of spontaneous bleeding
What are the dental aspects to consider when someone has platelet dysfunction? (3)
Drugs they are taking?
Treatment given?
Problems post treatment?
- Can continue medication during minor dental procedures
- Limit initial treatment area (single extraction at a time)
- Combat post extraction bleeding (ie suture)
What type of inheritance causes Haemophilia?
X-Linked inheritance
Severity of bleeding in Haemophilia:
- Mild?
- Moderate?
- Severe?
- Bleed minimally, and is usually associated with surgery
- Bleed after minor injury and requires urgent attention
- Bleed very often with or without provocation
Haemophilia:
Comment on surgical intervention
This condition increases the risk of what?
What clotting factors have to be regulated?
- Minimise surgical intervention
- High risk of haemorrhage post surgery/LA
- Regulate levels of clotting factor (VIII/IX)
List some complications treated by anticoagulant therapy
- Myocardial infarctions
- Strokes or transient ischaemic attacks (mini strokes)
- Deep vein thrombosis
- Pulmonary embolus, a blocked blood vessel in your lung.
- Thrombosis on prosthetic heart valves
What does warfarin inhibit? (4)
Inhibits vitamin K dependent clotting factors II, VII, IX, X
What are the dental aspects to consider with a patient who is on Warfarin? (2)
- Minimise surgical intervention
- Measure INR 24 hours within surgery
How would you manage severe Form Von Willebrand disease (vWD)?
vWF replacement using human plasma rich in vWF and factor VIII
