Coagulation: In medicine, the clotting of blood. The process by which the blood clots to form solid masses, or clots. More than 30 types of cells and substances in blood affect clotting. The process is initiated by blood platelets. Platelets produce a substance that combines with calcium ions in the blood to form thromboplastin, which in turn converts the protein prothrombin into thrombin in a complex series of reactions. Thrombin, a proteolytic enzyme, converts fibrinogen, a protein substance, into fibrin, an insoluble protein that forms an intricate network of minute threadlike structures called fibrils and causes the blood plasma to gel. The blood cells and plasma are enmeshed in the network of fibrils to form the clot.

1. Lecture
8
Thrombophilia

2. Thrombophilia
• Arterial
Thrombosis
• Stroke
and
myocardial
infarc:on
are
major
causes
of
death
▫ Every
45
seconds
someone
in
the
US
suffers
a
new
or
recurrent
stroke
▫
800,000/year
– Every
34
seconds
someone
in
the
US
suffers
a
new
or
recurrent
MI
– 1.5
million/year
à
~
1/3
will
die
2

3. Atherosclerosis
• Atherosclerosis
–
thickening
of
the
arterial
wall
–
primary
cause
of
coronary
artery
disease
and
cerebrovascular
disease
– Arterial
wall
thickens
to
form
an
atherosclero:c
plaque
– Reduces
the
blood
supply
to
the
organ
(heart
and
brain
–
most
common)
• Atheroma
–
accumula:on
of
intracellular
and
extracellular
lipid
in
the
in:ma
of
large
and
medium
sized
arteries

4. Atherosclerosis
• Mechanism
1. A
lesion
begins
as
a
faTy
streak
(preatheroma)
that
protrudes
into
the
in:ma
• LDL
enters
the
in:ma
–
modified
by
oxida:on
and
aggregates
within
the
extracellular
in:ma
space
• Smooth
muscle
cells,
T-­‐lymphocytes
,
and
macrophages
migrate
into
the
area
–
macrophages
phagocy:ze
the
oxidized
lipids
• Proteoglycans,
collagen
and
elas:c
fibers
migrate
into
the
area
2. Fibro-­‐faTy
lesion
forms
–
diffuse
in:mal
thickening
occurs
• Atheromatous
plaque
3. Complicated
plaque
• Eggshell
briTleness,
ulcera:on
of
the
luminal
surface,
micro-­‐emboli
released
into
the
blood
stream,
decreased
blood
flow
results
in
more
thrombus
forma:on

5. Pathogenesis
1. Chronic
inflammatory
response
of
the
vascular
wall
to
endothelial
injury
or
dysfunc:on
2. Elevated
plasma
LDL
levels
causing
the
deposit
of
LDL
in
the
subendothelium
of
blood
vessels
3. Oxida:on
of
transmigrated
LDL
4. Ac:va:on
of
endothelial
cells
5. Recruitment
of
monocytes/macrophages
which
ingest
ox-­‐LDL
through
scavenger
receptors
6. Forma:on
of
foam
cells
–
faTy
streaks
7. Prolifera:on
of
smooth
muscle
cells
8. Deposi:on
of
extracellular
matrix
proteins

6. Atherosclero:c
Plaque

7. • Coronary
Atherosclerosis
hTp://upload.wikimedia.org/wikipedia/commons/9/9a/
Endo_dysfunc:on_Athero.PNG

8. Mechanism
of
Arterial
Thrombosis
hTp://www.drugs.com/health-­‐guide/images/205452.jpg8

9. CORONARY
ARTERY
DISEASE
1. Artery
narrowed
by
cholesterol
containing
atheroma
–
note
how
the
tube
which
the
blood
flows
through
has
been
narrowed
and
restricted
2. Once
the
surface
of
the
vessel
is
damaged,
platelet
clot
accumulates
restric:ng
flow
–
this
may
resolve
or
worsen
3. Platelets
may
accumulate
so
that
blood
flow
is
limited
by
the
clot
and
this
causes
starva:on
of
oxygen
death
of
muscle
and
a
heart
aTack

10. Pathogenesis
of
coronary
heart
disease
(CHD)

12. Thrombophilia
▫ Venous
Thrombosis
▫ DVT/PE
à
~
900,000
to
2,000,000/year
▫ 60,000-­‐100,000
individuals
will
die
of
DVT/PE
▫ 10-­‐30%
will
die
within
one
month
of
diagnosis
▫ ~25,000
of
these
deaths
result
from
VTE
contracted
in
hospitals
▫ >25X
the
number
of
deaths
from
MRSA
▫ >Combined
total
deaths
from
BC
+
AIDS
+
MVA
• Ironically
–
fatal
PE
caused
by
DVT
may
be
the
most
common
preventable
cause
of
hospital
death
in
the
US
–
only
1/3
of
hospitalized
paBents
with
risk
factors
for
VTE
receive
preventaBve
measures
12

13. Mechanism
of
Venous
Thrombosis
13
• Most
common
manifesta:ons
– Deep
vein
thrombosis
– Pulmonary
embolism
– Postphlebi:c
syndrome
• Mechanism
– Endothelial
damage
• Trauma,
surgery
• TF
• Thrombin
genera:on
• Primary
hemosta:c
plug
with
fewer
platelets
• Venous
stasis
– Red
clots
Nature,
451(21)
Feb
2008

14. What
Causes
a
Thrombus
to
Form?
Venous
Thrombogenesis
– Thrombi
begin
in
regions
of
slow/disturbed
blood
flow
Damaged
veins,
valve
cusp
pockets
– Inherited/acquired
hypercoagulable
states
important
– Stasis
is
a
major
risk
factor
– Variable
response
to
thrombus
• Classical
signs/symptoms
DVT
• Minimal
signs/symptoms

15. DVT/PE
15

17. Venous
Clot

18. Thrombosis
(Blood
Clots)
Intracoronary
Clot
DVT
PE

19. Hemorrhage
(Bleeding)
Intracranial Bleed
Hemorrhagic Stroke
Gross
specimen,
coronal
sec:on
of
brain,
large
subcor:cal
hypertensive
ICH

20. Post phlebitic syndrome
Chronic
venous
ulceration
Very
difficult to
manage
Pain (dull and aching), leg cramps, heaviness, itching and altered sensation

21. Arterial
versus
Venous
Thrombosis
Arterial
Thrombosis
Venous
Thrombosis
— Arterial
thrombosis
— Occur
under
high
shear
condi:ons
— Rich
in
platelets
— Involved
disrupted
atherosclero:c
plaque
— Platelet
adhesion,
ac:va:on,
and
aggrega:on
prior
to
ac:va:on
of
coagula:on
cascade
— White
clots
— Myocardial
infarcBon
and
stroke
— AnBplatelet
agents
— AnBfibrinolyBc
and
anBthromboBc
agents
• Venous
thrombosis
– Under
low
shear
stress
– Fewer
platelets
involved
– TF
generates
thrombin
prior
to
platelet
ac:va:on
– Red
clot
– DVT,
PE
– AnBcoagulaBon
agents
for
venous
thrombosis
21

22. Arterial
vs
Venous
Clot
hTp://www.emedicinehealth.com/
slideshow_pictures_deep_vein_thrombosis_dvt/ar:cle_em.htm
hTps://www.med.unc.edu/wolberglabl/scien:fic-­‐images/arterial
%20thrombosis.jpg/view

23. Virchow’s
Triad
23
Stasis
Thrombosis
Changes
in
Blood
Composi;on
Vascular
Injury
Arterial
Rudolph
Virchow
Post-­‐operaBve
state
CasBng/splinBng
Sedentary
state
Leukostasis
syndrome
(AML)
Congenital
heart
disease
Central
line,
Sepsis
Trauma,
APA
Chemotherapy/toxins
Hyperhomocysteinemia
Inherited
thrombophilia
Acquired
thrombophilia

24. Virchow’s
Triad
Thrombosis
involves
3
interrelated
factors:
1. Abnormali:es
of
the
blood
vessel
wall
2. Abnormali:es
in
blood
flow
3. Abnormali:es
in
the
blood
cons:tuents
• Cells
-­‐
Erythrocytes,
leukocytes,
platelets
• Plasma
proteins

25. Risk
Factors
25
• Mul:ple
risk
factors—mul:-­‐factorial
process
– Hereditary
– Acquired
• Mul:-­‐hit
hypothesis
– Most
hereditary
and
acquired
risk
factors
have
a
rela:vely
small
individual
effect
– Risk
is
greatly
increased
when
two
or
more
risk
factors
combine
• Classifica:on
of
Thrombophilia
– Inherited
– Acquired—Physiologic,
Environmental

26. Thrombophilia
26
• Acquired
or
inherited
causes
• Venous
and
arterial
events
• Occurs
when
the
cloqng
system
is
ac:vated
1. Excessive
genera:on
of
prothrombo:c
factors
2. Failure
in
the
regulatory
mechanisms
to
down-­‐
regulate
the
coagula:on
cascade
3. Inhibi:on
of
the
fibrinoly:c
system

27. Thrombophilic
Risk
Factors
Congenital
Risk
Factors
Mechanism
27
¤ Protein
C
¤ Protein
S
¤ AT
¤ FVL
¤ PG20210
¤ FVIII
¤ Homocysteine
(acquired
also)
¨ Non-­‐modifiable
Inhibitory
Prothrombotic

28. Acquired
Risk
Factors
28
¨ Acquired
risk
factors
¤ Pregnancy
¤ Malignancy
¤ Surgery
¤ Immobiliza:on
¤ Hormone
therapy
(HRT,
OCT)
¤ An:phospholipid
an:bodies
¤ Trauma
¤ Obesity
¨ Physiologic
risk
factors
¤ Gender
(hormonal
changes)
¤ Age
–Increases
~1%/year
of
age
n Childhood
=
1/100,000
n 40
years
=
1/1000
n 75
years
=
1/100
Modifiable
Non-­‐modifiable
¨ IdenBfy
a
populaBon
at
risk
but
have
low
predicBve
value
for
individuals

29. Prevalence
of
Risk
Factors
Congenital
Risk
Factors
Acquired
Risk
Factors
25%
20%
15%
10%
5%
0%
% Risk
Prevalence of Inherited Risk Factors
FVL PG AT PC PS FVIII
Risk Factor
General Population Selected: 1st Thrombotic Event
Prevalence of Acquired Risk Factors
90
80
70
60
50
40
30
20
10
0
Fractures
Hip
Cancer
APAS
OCT
Pregnancy
HRT
Hcys
FVIII
Risk Factor
Increase
29

30. Who
should
be
tested
30
¨ Pa:ents
presen:ng
with
¤ Venous
thrombo:c
event
before
40-­‐50
years
of
age
¤ Unprovoked
or
Recurrent
thrombosis
at
any
age
¤ Thrombosis
at
unusual
site
¤ Posi:ve
family
history
of
thrombosis
¤ Unexplained
abnormal
laboratory
test
(PT,
aPTT)
¨ Age
of
first
episode
¤ 0-­‐12
years
Rare
¤ 13-­‐45
years
Highly
probable
¤ 45-­‐60
years
Probable
¤ 60+
years
Possible
Congenital
Risk
Factors

31. When
to
test
31
¨ Op:mal
Times
for
Tes:ng
• Asymptoma:c
• Not
on
an:coagulant
therapy
• Any:me
for
DNA
tes:ng
¨ To
establish
• Pathologic
basis
for
the
thrombo:c
event
• Dura:on
and
intensity
of
therapy
• Prophylaxis
for
high
risk
pa:ents
• To
alert
the
pa:ent's
immediate
family
members
to
the
presence
of
possible
inherited
risk
factors

32. Laboratory
Assays
for
Thrombophilia
32
• Plasma-­‐based
assays
– AT
– PC
– PS
– APC-­‐R
– Lupus
An:coagulant/An:phospholipid
An:bodies
• Dilute
Russell
Viper
Venom
Test
(dRVVT)
• An:cardiolipin
An:bodies
• An:-­‐β2-­‐Glycoprotein
An:bodies
– Factor
VIII
– Homocysteine
• DNA-­‐based
assays
– FVL
– PG20210
– MTHFR

33. An:thrombin
Deficiency
33
• Eggberg,
1965
• Reported
the
first
inherited
thrombophilic
state
• Func:ons
as
a
naturally
occurring
inhibitor
of
the
coagula:on
cascade
• Most
severe
of
the
inherited
condi:ons
• Rela:vely
uncommon
(~1%
of
first
DVT)
•
Clinical
Manifesta:ons
– Increased
incidence
of
venous
thrombosis
– AT
levels
<40-­‐50%
– Ini:a:ng
events
leading
to
thrombosis
• Surgery
• Trauma
• Pregnancy
• OCT

34. Protein
C
Deficiency
34
¨ Griffin,
early
1980’s
¨ 75%
of
individuals
will
experience
one
or
more
events
¨ Thrombosis
may
be
spontaneous
¨ Func:ons
as
a
naturally
occurring
inhibitor
of
the
coagula:on
cascade
¨ 50%
of
heterozygotes
will
experience
VTE
by
40
years
of
age
¨ Common
Manifesta:ons
¤ DVT
¤ PE
¤ Superficial
thrombophlebi:s
¤ Cerebrovascular
events
¤ Myocardial
events

35. Protein
S
Deficiency
¨ Described
in
1984,
Comp
¨ TOTAL
PS
circulates
in
2
forms:
¤ Bound
PS—60%
n C4B-­‐BP—nonfunc:onal
¤ Free
PS—40%-­‐func:onal
¨ Serves
as
a
cofactor
for
PC
¨ Binds
aPC
to
the
phospholipid
surface
¨ 50%
of
heterozygotes
will
experience
VTE
by
40
years
of
age
Free
PS
35
Total
PS
C4bBP

36. 36
aPC-­‐Resistance—Screening
assay
• aPC-­‐resistance
– Dahlbäck
et
al
in
1993
– Func:ons
as
a
natural
an:coagulant
– Poor
an:coagulant
response
of
aPC
to
degrade
FVa
and
VIIIa
– Ra:o
of
2
aPTT’s—(+/-­‐
APC)
__(aPTT
plus
APC)__
(aPTT
minus
APC)
• “Screening
assay”
for
FVL
muta:on
• http://www.wardelab.com/arc_2.html
Approximately
90%
of
APC
Resistance
is
caused
by
a
defect
in
the
Factor
V
molecule,
known
as
the
Factor
V
Leiden
gene
muta:on

37. Factor
V
Leiden—Confirmatory
Assay
for
FVL
Muta:on
– Muta:on
later
described
in
1994
by
Ber:na
et
al
– Caused
by
single
point
muta:on
in
the
FV
gene
• A
single
nucleo:de
subs:tu:on
of
adenine
for
guanine
at
nucleo:de
1691
of
the
FV
gene
• Replacement
of
Arg
(R)
with
Gln
(Q)
at
pos
506
in
F.V
protein
– Higher
risk
for
thrombosis
– Venous
thrombosis
most
common
manifesta:on
37

38. PG20210
Muta:on
¨ Poort
et
al,
1996
¨ Single
nucleo:de
subs:tu:on
G20210A
in
the
3’
UT
region
of
the
prothrombin
gene
¤ G
→
A
subs:tu:on
at
nucleo:de
20210
in
prothrombin
gene
¨ Results
in
elevated
levels
of
prothrombin
(~30%
increase)
¨ No
screening
test
available
¨ Occurs
primarily
in
Caucasians
-­‐-­‐~3%
in
general
popula:on
¨ 2-­‐5-­‐fold
increased
risk
of
VTE
38

39. Homocysteine
39
¨ McCully
suggested
an
associa:on
between
elevated
levels
of
homocysteine
in
plasma
and
arterial
disease
¨ Most
common
congenital
form
due
to:
1. (C677T)*
in
MTHFR
gene
2. B-­‐cystathionine
synthase
gene
¨ Acquired
form
due
to
deficiencies
in
Folate,
B-­‐6,
B-­‐12
¨ Gene:c
tes:ng*
is
controversial
¤ Homocysteine
levels
may
provide
more
informa:on
¨ Normal
values
increase
with
age
¤ Higher
in
males
www.naturaleyecare.com/ar:cles/elevated-­‐homocysteine-­‐and-­‐eye-­‐...

40. 40
An:phospholipid
An:bodies
• An:phospholipid
an:bodies
– Acquired
thrombophilic
disorder
– An:bodies
directed
against
proteins
that
bind
to
phospholipid
membrane
surfaces
– Autoimmune
process
• Subgroups
of
APLAs
– Lupus
An;coagulant
– An;-­‐
Cardiolipin
an;bodies
– An;-­‐Beta-­‐2-­‐glycoprotein
I
an;bodies
– An:-­‐Prothrombin
an:bodies
– An:-­‐Phospha:dylserine
an:bodies
– An:-­‐Phospha:dylethanolamine
an:bodies
– An:-­‐
Phospha:dylinositol
an:bodies
hTp://circ.ahajournals.org/cgi/reprint/112/3/e39

41. Clinical
Diagnosis
APAS
• Acquired
disorder
which
occur
in
1-­‐5%
of
the
general
popula:on
• Pa:ent
must
present
with
one
clinical
and
one
laboratory
criteria
• Clinical
Manifesta:on
– Vascular
thrombosis
• One
or
more
clinical
episodes
of
arterial,
venous
or
small
vessel
thrombosis
in
any
:ssue
or
organ
– Pregnancy
Morbidity
• One
or
more
spontaneous
abor:ons,
severe
preeclampsia,
eclampsia,
death
of
a
normal
fetus
at
or
near
10
months
gesta:on
• Laboratory
Criteria
– Posi:ve
test
in
the
APA
test
panel
on
2
separate
occasions,
>
6-­‐12
weeks
apart
• Lupus
An:coagulant
• An:cardiolipin
An:body
• An:
–B2-­‐Glycoprotein
I
An:body
41

42. Lupus
An:coagulant
• Heterogeneous
group
of
an:bodies
(IgG,
IgM,
or
both)
that
prolongs
phospholipid-­‐dependent
coagula:on
tests
– Immunoglobulin
that
acts
as
a
coagula:on
inhibitor
– Does
not
recognize
a
“specific”
coagula:on
factor
– Retards
the
rate
of
thrombin
genera:on
and
clot
forma:on
in
vitro
by
interfering
in
phospholipid-­‐
dependent
reac:ons
• Detected
in
in
vitro
coagula:on
assays
only
42

43. Lupus
An:coagulant
• Affect
2-­‐4%
of
the
U.S.
popula:on
• Discovered
accidentally—prolonged
aPTT
found
during
a
pre-­‐opera:ve
evalua:on
• O|en
cause
a
variety
of
clinical
and
laboratory
effects
– O|en
there
are
no
clinical
consequences
other
than
the
need
to
explain
the
reason
for
the
long
APTT
– Minority
of
pa:ents
with
LA
have
a
hypercoagulable
state
manifested
by:
• Recurrent
thromboses
• Mul:ple
spontaneous
miscarriages
• Migraine
headaches
• Stroke
• Rarely
pa:ents
may
experience
bleeding
– Bleeding
due
to
an:bodies
to
prothrombin
• Lupus
an:coagulants
(LA)
are
a
heterogeneous
group
of
an:bodies
that
cause
a
variety
of
clinical
and
laboratory
effects
43

44. Lupus
An:coagulant
• Results
in
prolonga:on
of
phospholipid-­‐dependent
assays
• LA
is
o|en
iden:fied
during
rou:ne
screening
with
the
standard
aPTT
– In
vitro
à
results
in
a
prolonged
aPTT
• Prolonga:on
due
to
reagent
sensi:vity
to
lupus
an:coagulant
• Usually
does
not
result
in
clinical
bleeding
– In
vivo
à
usually
results
in
thrombosis
rather
than
clinical
bleeding
• Abundance
of
phospholipid
– These
neutralize
the
an:body
– May
explain
why
bleeding
does
not
occur
in
vivo
• An:body
may
be
persistent
or
transient
44

45. Lupus
An:coagulant
• All
lupus
an:coagulants
are
APAs,
but
not
all
APAs
are
lupus
an:coagulants
• Targets
specific
proteins
• B2GPI
• Prothrombin
• Proteins
C,
S
• Annexin
V
45
ANTIBODY-­‐MEDIATED
THROMBOSIS
Phospholipid
Associated
Proteins:
•Protein
C,S
•β2GPI
•Prothrombin
•and
others
Phospholipid Membrane
Antibody:
•lupus
anticoagulant
•anticardiolipin
•antiphosphatidylserine
•anti
b2GPI
•anti
Annexin
V
•anti
Prothrombin

46. Lupus
An:coagulant
and
Thrombosis
The Paradox...
How does an anticoagulant in vitro, become
a risk factor for hypercoagulability in vivo ?
Coagulation Factor/Protein = Phospholipid
CA+2
Calcium
Anchor
46
=PL
46

47. Clinical
Significance
of
the
APAs/LA
47
• Prevalence
in
venous
and
arterial
thrombosis
• DVT
~32%
• Stroke
~15%
• Superficial
thrombophlebi:s
~9%
• Pulmonary
embolism
~9%
• Fetal
loss
~8%
• TIA
~7%
• Associated
with
2
broad
categories
of
phospholipids
an:bodies
– An:cardiolipin
an:bodies
• Most
likely
to
be
clinically
significant
with
high
:ters
for
IgG
and
IgA
– β2-­‐GPI
an:bodies
• More
specific
for
thrombosis
and
other
clinical
complica:ons
of
the
APAS

48. E:ology
of
LA
• Exact
e:ology
of
LA
is
unclear
• An:bodies
are
commonly
found
in
asymptoma:c
elderly
individuals
• Pa:ents
with
autoimmune
disorders
• SLE
have
the
highest
incidence
(20-­‐45%)
• Pa:ents
with
HIV
infec:on
have
a
high
incidence
of
LA
at
some
:me
in
the
course
of
their
disease
• A
number
of
drugs
are
known
to
induce
LA,
most
notably
– Procainamide
– Hydralazine
– Isoniazid
– Dilan:n
– Phenothiazines
– Quinidine
– ACE
inhibitors
are
known
to
induce
LA
48

49. Lupus
An:coagulant
and
Thrombosis
• LA
are
one
of
the
most
common
acquired
predisposing
causes
of
thrombosis
– cerebral
thrombosis
– deep
venous
thrombosis
– renal
vein
thrombosis
– pulmonary
emboli
– arterial
occlusions
– stroke
• Reports
indicate
that
LA
are
found
in:
– 8-­‐14%
of
pa:ents
with
deep
venous
thrombosis
– 1/3
pa:ents
with
stroke
<50
years
of
age
– Evidence
that
recurrent
thrombo:c
events
tend
to
be
persistent
over
:me
in
the
same
pa:ent
49

50. LA
in
Thrombocytopenia
and
Pregnancy
• LA
and
thrombocytopenia
– An
immune
type
thrombocytopenia
has
been
observed
in
a
small
percentage
of
pa:ents
with
LA
– This
may
be
due
to
reac:ons
between
an:bodies
and
platelet
membrane-­‐associated
phospholipids
• LA
and
Pregnancy
– increased
risk
of
fetal
loss
due
to
pre-­‐eclampsia,
placental
abrup:on,
intrauterine
growth
retarda:on,
and
s:llbirth
– Some
evidence
suggests
that
this
may
be
due
to
an:bodies
against
the
placental
an:coagulant
protein,
annexin
V
– Placental
infarc:on
has
been
suggested
as
the
cause
of
the
failure
to
carry
to
term
but
pathological
analysis
has
not
definitely
supported
this
conten:on
50

51. Mechanisms
of
the
Reduc:on
of
Annexin
V
Levels
and
the
Accelera:on
of
Coagula:on
Associated
with
An:phospholipid
An:bodies
Rand
J,
NEJM
1997;337:154-­‐160
• Annexin
V
– Phospholipid
dependent
an:coagulant
proper:es
on
cell
membranes
– Placental
an:coagulant
(shield
on
placental
villi)
– Vascular
an:coagulant
51

52. Proposed
Mechanisms
of
Thrombosis
• Impaired
Fibrinolysis
• Inhibi:on
of
Protein
C
and
S
system
• Inhibi:on
of
Prostacyclin
release
from
endothelial
cells
• Inhibi:on
of
Annexin
V
–
Tissue
Pathway
Down
Regula:on
• Inhibi:on
of
B2GPI
–
may
affect
Protein
S
52

53. An:cardiolipin
An:body
ELISA
53