1. How we clot (and how not to clot) Sema Yilmaz, MD, Assoc. Prof.
Pediatric Hematology and Oncology

2. Objectives Understand the physiology of clot formation
What the aPTT/PT tells you (and what it doesn’t tell you)
How to stop the clot
How to treat the clot

3. (coagulation proteins)
What is in a clot?
Platelets
Fibrin
(coagulation proteins)
VENOUS
Slow flow
RED-(rbc’s)
ARTERIAL
Fast flow
WHITE (plts)

4. Activation of thrombin
Goal: make THROMBIN
intrinsic
extrinsic
Activated Platelets
Activation of thrombin
and fibrin formation
THROMBIN
Fibrin

5. How we clot Cut in the endothelium Platelet Activation Thrombin
And fibrin
deposition
Exposes platelet binding sites
Exposes tissue factor for activating coagulation
Tissue factor TF
vWF F F
vWF
vWF
vWF F F
collagen
vWF
Platelet Activation
Platelet granule secretion
Activate fibrinogen receptor
Provides site for prothrombinase complex

6. How we clot Cut in the endothelium Platelet Activation Thrombin
Exposes platelet binding sites
Exposes tissue factor for activating coagulation
Thrombin
Activation
And fibrin
deposition TF
vWF
collagen
vWF
collagen TF TF TF
collagen
vWF
vWF
vWF TF TF TF
collagen
vWF
Platelet Activation
Platelet granule secretion
Activate fibrinogen receptor
Provides site for prothrombinase complex

7. This is how a clot is made
RED--platelets
GREEN—tissue factor
BLUE--fibrin
Blood flowing this way
Falati et al., Nature Medicine 2002 (mpeg)

8. How a clot is made in a person
Initiated by TISSUE FACTOR (microparticles?)
NEED a PLATELET SURFACE for coagulation factors
to assemble

9. Coagulation Cascades
reality in a test tube?
… the often-asked question: “Why is coagulation so complicated?”
resolves itself into the question: “Why are there so many stages?”
R.G. Macfarlane, Nature 1964

10. “I am more than just a number”
Coagulation Cascades
“I am more than just a number”
Understanding eitiologies of elevated PT/PTT
What really happens in vivo?
Think enzyme complexes (only 3)
How to turn off the cascade?

11. Some concepts to remember…
Coagulation Cascades
Some concepts to remember…
Highly regulated complexes of
serine proteases and co-factors
All paths lead to thrombin activation
Goal is to make a fibrin clot
They are not just a number—
they have a personality too!!!
thrombin
fibrin

12. All roads lead to thrombin
IIa
Fibrinogen
FV, FVIII, FVII
FXIII
TAFI (fibrinolysis inhibitor)
Platelet Activation
Protein C
procoagulant
anticoagulant

13. How we clot IXa VIIIa TF VIIa Xa Va II IIa prothrombin thrombin
prekallikrein
HMWK XII XI
How we clot
IXa
VIIIa
Ca++, PL
intrinsic
tenase TF
VIIa
extrinsic
tenase Xa Va
Ca++, PL
“Prothrombinase”
Fibrin monomers
Fibrinogen II
prothrombin
IIa
thrombin

14. PTT PT IXa TF VIIIa VIIa Xa Va II IIa Fibrin monomers Fibrinogen
prekallikrein
HMWK XII XI PT
IXa
VIIIa
Ca++, PL
intrinsic
tenase TF
VIIa
extrinsic
tenase Xa Va
Ca++, PL
“Prothrombinase” II
IIa
Fibrin monomers
Fibrinogen

15. IXa TF VIIIa VIIa Xa Va INITIATION II IIa AMPLIFICATION PROPAGATION
prekallikrein
HMWK XII XI
INITIATION
IIa
IXa
VIIIa
Ca++, PL
intrinsic
tenase TF
VIIa
extrinsic
tenase
“Prothrombinase” Xa Va
Ca++, PL
AMPLIFICATION
PROPAGATION II
Fibrin monomers
Fibrinogen

16. Only need to know 3…
enzyme complexes: protease cofactor
Prothrombinase Xa Va
Intrinsic tenase IXa VIIIa
Extrinsic tenase VIIa TF
Also need Calcium and a phosholipid surface

17. Clot formation--physiology
initiation X
IXa
VIIIa
Ca++, PL TF
VIIa Xa Va
Ca++, PL
propagation
Fibrin monomers
Fibrinogen II
prothrombin
IIa
thrombin

18. Fibrinogen Structure

19. Fibrin Clot formation and fibrinolysis
Thrombin (IIa) A B
fibrinopeptides D E
fibrinogen D E D E D E D E D E D E D E
Factor XIII D E D E
plasmin D E

20. Plasmin activation Natural activators of plasminogen:
t-PA: fibrin homeostasis
u-PA: tissue remodeling
Natural inhibitors of plazmin:
PAI-1, PAI-2
a2 antiplasmin
a2 macroglobulin

21. How to stop the clot IXa VIIIa VIIa Xa Va Protein C Protein S AT III
TFPI
IXa
VIIIa
VIIa Xa Va
Protein C
Protein S
AT III II
IIa
thrombomodulin
IIa

22. Turning off the clot:
only 3 systems to know…
Protein C VIIIa, Va (the cofactors)
Protein S
Antithrombin IIa, Xa (serine proteases)
TFPI VIIa/TF

24. Bleeding
Thrombosis

25. bleeding coagulation Anti coagulants Pro coagulants Pro coagulants

26. Coagulation Thrombin Fibrinogen Fibrin Intrinsic pathway clotting
Extrinsic pathway
Common pathway
Thrombin
Fibrinogen
Fibrin
thrombocytes
clotting TF
collagen
Blood vessel

27. Virchow Triadı HİPERKOAGULABİLİTE PRE-TROMBOTİK DURUM
1. Blood Flow (Venous Stasis)
2. Vascular Wall
(Endothelial damage)
Dr. Virchow-1856
3. Circulating Blood Factors (Hypercoagulability)
Tromboz patogenezinde ünlü Alman patolog Roludf Virchow’ un 1856’da ortaya attığı triad geçerliliğini bugün de korur:
Hemostaz dengesinin bozulması anlamına gelen bu değişiklikler günümüzde “hiperkoagülabilite” ya da “pretrombotik durum” sözcükleri ile de belirtilir. Son yıllarda, moleküler genetik yöntemlerinin venöz tromboz etiyopatogenezinde sağladığı yeni bilgiler Virchow triadının bu üçüncü öğesi ile ilgilidir.
Venöz tromboz oluşumunda kan akımında staz ve hiperkoagülabilite ön planda rol oynarken, arteryel tromboz oluşumunda, damar endoteli lezyonları (ateroskleroz) ve başta trombositler olmak üzere kanın bileşimindeki değişiklikler önem taşır.
HİPERKOAGULABİLİTE
PRE-TROMBOTİK DURUM

28. Hemostasis Vascular endothelium Blood flow rheology (hemorheology)
Thrombocytes
Coagulation cascade
Anticoagulant system
Fibrinolytic system 2

29. Hemostasis Procoagulant Anticoagulant PAI-1 Antiplasmin Prot. C
Prot. S
Antiplasmin
Prot. C
Tissue factor
TFPI
Coagulation factors
Fibrinolytic system
ATIII
Procoagulant
Anticoagulant

30. TFPI V Trombin PLT XI TF VII IX XIa VIIa/TF IXa VIII VIIIa X Xa Va PLT
Protrombin
Trombin
Fibrinojen
Fibrin

31. pZ TFPI AT Heparin PS V APC Trombin PC TAFİ FDP Trombomodulin PLT XII
VII
XIIa IX
XIa
VIIa/TF
TFPI
IXa
VIII
VIIIa AT
Heparin X Xa PS V Va
PLT
APC
Plazminojen
Protrombin
PLT
tPA-i
tPA
Trombin
Trombin PC
TAFİ
Plazmin
FDP
Fibrinojen
Fibrin
Trombomodulin

32. Epidemiology Insidens 1-2/ 1000 adult
0.7 – 1.9 / child
0.51 / newborn
1-2/ 1000 adult
2-5 individuals in every 100 have thrombosis at least ones.

33. Adult – child thrombosis
Rare in children
80% of reasons are certain in adults
Hypertension, diabetes, cigarette in adults
Low extremities in adults
Both extremities in children

34. Thrombosis in children
Mostly seen in newborn and adolescents

35. Causes of thrombosis
acquired and congenital.

36. Almost all of thrombosis are MULTIFACTORIAL in childhood.

38. Ethiology 76% of children have medical reasons: infection and catheter
25-56% are congenital

39. In infection:
vWf
Factor VIII
PAI-1
C4bp
increase.

40. In infection:
Alb.
Pr. C
Pr. S
decrease.

41. Common causes AT deficiency PC, PS deficiency Faktör V Leiden
Protrombin A mutation
Hyperhomosisteinemi
Elevated Factor VII
Antiphospholipid antibody

42. Incidence in thrombotic patients %
Risk
Disorders
Incidence %
Incidence in thrombotic patients %
APC resistance
3-8 20
Elevated F VIII 11 25
Protrombin 20210
1-2 6
Hyperhomosisteinemi
5-10
10-25
AT deficiency
0,02 1
Pr C
0,2 3
Pr S
0,1

49. VENA KAVA SUPERİOR TROMBOZU
BEHÇET HASTALIĞI

50. Diagnosis
First think!

51. Thrombosis Everywhere has vessels.
It should be considered in every symptoms.

52. The physician:
74% hemato-oncologist
11% neonatologist
7% intensivist

53. Aim
Early diagnosis!

54. Diagnosis
Imaging
Lab tests

61. Diagnosis TE location İdeal tanı a. Geçerli uygulama Upper DVT
venography
intratorasic:venog.
Servical d.:ultrasonography
Lower DVT
US; venog. PE
Pulm.angio ?
V/Q scan
V/Q scan, spiral BT
Right atrial TE
echocardiog.
Arterial
angiography
Physical exam.,doppler,
Acute ischemic stroke
MRA,MR
SVT
angiography?
MRV,MR

62. Laboratory tests 1. First line tests CBC, Per. smear, glucose,lipids
APCR , FVL
Prothrombin 20210
Homosistein level (after 12 hours fasting)
AT, PRC, PRS and free PRS levels
FVIII
Lupus anticoagulants and anticardiolipin antibodies
Hb elektrophoresis, sickle cell anemia

63. 2. Second line tests: Lipoprotein (a) Plasminogen activity DFYI
Fibrinogen
PNH
FXII, XI,IX,VII, vWF
Spontan. tromb. agreg.
Heparin cofactor-II
t-PA
DFYI
Thrombomodulin
MTHFR ?
Euglobin lizis time

64. D-dimer D-dimer is a fibrin degradation product (FDP).
A small protein fragment present in the blood after a blood clot is degraded by fibrinolysis.
Below than 0.5 (high than 500 µg/L= pulmonary embolism)
D-dimer increases in acute thrombosis.
If D-dimer is not high, the diagnosis of thrombosis is suspicious.
D-dimer increases in bleeding, postoperative, malignancy and sepsis.
Deep venous thrombosis (DVT), pulmonary embolism (PE) or disseminated intravascular coagulation (DIC)
It is not specific for thrombosis.
But if D-Dimer is negative, does not rule out the diagnosis (negative predictive )

65. D-dimer FIBRIN POLYMER D E D D E D D E D D E D D E D D D FDP D-DIMER E

66. Thrombosis
The common reason:
High F VIII,
FVL and
anticardiolipin

67. Arterial
Lpa and homocysteine

68. Venous Thromboembolism Treatment
Heparin
Heparin-LMW
Trombolytic efficacy-tissue plasminogen activator
Oral anticoagulants-warfarin
Direct thrombin inhibitors
Direct Factor Xa inhibitors
Indirect Factor Xa inhibitors

69. Anti Xa level PT/INR PTT ANTICOAGULANTS HEPARIN-ANTITROMBIN WARFARIN
Factor XIIa
Factor XIa
Factor IXa
Factor Xa
TROMBIN (IIa)
LMWH
Factor VII
Factor IX
Factor X
PROTROMBIN (II)
Faktör Xa
Anti Xa level
PT/INR
PTT

70. Treatment period???? No risk factors: 3 months (6-12 hafta)
Genetic and predisposing factors: 4-6 months
Definite treatment ????
Depends on patient
Prevention is important!