Anti coagulation in general surgery

1. Anti coagulation when
and where to use ?
D R K R I SHNA S .
A S ST P RO FESSOR
D E PT O F C T V S
G OVT M E DI CAL CO L L EGE T H I RUVANANTHAPURAM

2. Main topics
Blood coagulation
History
Classification of Anti coagulants
Uses
Monitoring
Adverse effects and contra indications

3. Coagulation
Blood Blood Clot
 Four steps
Constriction of blood vessels
Formation of platelet plug
Activation of coagulation cascade
Formation of fibrin plug

4. Coagulation Pathway

5. History of Anti Coagulation

6. History of Anti Coagulation

7. Classification of Anti Coagulants
Route of Administration
Targets
Examples

8. Parenteral
Route of Administration
Targets
Examples

9. Heparin
● Heparin naturally-occurring basophils and mast cells prevent formation
and extension of blood clots
● Does not disintegrate clots that have already formed. It permits fibrinolysis, to
work normally to break down previously formed clots
● As the thrombokinase is released, it neutralizes the action of heparin to allow
clotting to occur

10. Heparin
● Administered intravenously or subcutaneously
● Derived from porcine intestinal mucosa, standardized for anticoagulant activity
● Works by inhibiting the three major clotting factors (thrombin, thromboplastin, and prothrombin)
● It slows the process of thromboplastin synthesis, decelerates the conversion of prothrombin to
thrombin, and inhibits the effects of thrombin on fibrinogen, blocking its conversion to fibrin
● The agent also causes an increase in the number of negatively charged ions in the vascular wall,
which helps prevent the formation of intravascular clots.

11. Heparin - MOA
HEPARIN
Activates plasma AT III
Heparin-AT III complex
Binds to clotting factors of intrinsic and common pathways
(Xa, IIa, IXa, XIa, XIIa and XIIIa) and inactivates them

12. Heparin
• Heparin does not cross blood-brain barrier or placenta (anticoagulant of choice during pregnancy)
• Heparin should not be mixed with penicillin, tetracyclines, hydrocortisone or NA in the same syringe
or infusion bottle
• Heparinized blood is not suitable for blood counts (alters the shape of RBCs and WBCs), fragility
testing and complement fixation tests

13. Low-molecular weight heparin
•Selectively inhibit factor Xa with little effect on IIa
•Act only by inducing conformational change in AT III
•Hence LMW heparins have smaller effect on aPTT and whole blood clotting time than unfractionated
heparin (UFH)
•Also, they have lesser antiplatelet action—less interference with haemostasis
•Lower incidence of haemorrhagic complications compared to UFH
•Elimination - primarily by renal excretion
•Better subcutaneous bioavailability (70–90%) compared to UFH (20–30%)

14. Oral Anti Coagulants
Route of Administration
Targets
Examples

15. Oral Anti Coagulants
Route of Administration
Targets
Examples

16. Oral Anti coagulants
Act indirectly by interfering with the synthesis of vit K dependent clotting factors in liver

17. Warfarin
● Warfarin is an oral medication
● It is a synthetic derivative of coumarin, a chemical found naturally in many plants -- it
decreases blood coagulation by interfering with vitamin K metabolism
● It stops the blood from clotting within the blood vessels and is used to stop existing clots
from getting bigger (as in DVT) and to stop parts of clots breaking off and forming emboli
(as in PE)
● Warfarin inhibits the effective synthesis of biologically active forms of the vitamin K-
dependent clotting factors: II, VII, IX and X, as well as the regulatory factors protein C,
protein S and protein Z

18. Other VKA
•ACENOCOUMAROL (Nicoumalone – Acitrom)
•Brodifacoum
•Clorindione
•Coumatetralyl
•Dicoumarol
•Diphenadione
•Flocoumafen
•Phenindione
•Phenprocoumon
•Pindone
•Superwarfarin
•Tecarfarin
•Tioclomarol

19. Oral Anti Coagulants
Route of Administration
Targets
Examples

20. Dabigatran
● Dabigatran etexilate is a new oral direct thrombin inhibitor and the prodrug of dabigatran
● Dabigatran is a small molecule that reversibly inhibits both free and clot-bound thrombin by
binding to exosite 1 and/or the active site of thrombin

21. Oral Anti Coagulants
Route of Administration
Targets
Examples

22. Rivaroxaban
● Rivaroxaban is an orally available, small-molecule, active site-directed factor Xa inhibitor
● There are no significant interactions between food, antacids, digoxin, aspirin, naproxen and
rivaroxaban have been noted suggesting that dose adjustment of rivaroxaban would not be
required when these agents are concurrently administered

23. Uses
● Vascular surgery
● Deep vein thrombosis (DVT) and pulmonary embolism (PE)
● Myocardial infarction (MI)
● Unstable angina
● Rheumatic heart disease; Atrial fibrillation(AF)
● Cerebrovascular disease
● Prosthetic heart valves, retinal vessel thrombosis, extracorporeal circulation, haemodialysis

24. Perioperative Anti coagulation
HEPARIN

25. Postoperative Anti coagulation
HEPARIN +VKA
Target aPTT and PT- INR
Taper and stop heparin
VKA continued
Monitoring if required

27. Signs of Excessive Anti coagulation

29. What we attain?
VASCULAR REPAIR WITH PATENT LUMEN AND NO THROMBUS
DVT & PE PROPHYLAXIS IN ADDITION

30. THANK YOU