coagulation cascade
DESCRIPTION
Coagulation Cascade. Amplification. Initiation. Introduction. Congenital bleeding disorder caused by low levels of specific coagulation factors Hemophilia A: 85%, factor VIII deficiency Third most common X-linked disorder Hemophilia B: 10%-15%, factor IX deficiency. Genetics. - PowerPoint PPT PresentationTRANSCRIPT
Coagulation Cascade
Initiation
Am
plification
Introduction
• Congenital bleeding disorder caused by low levels of specific coagulation factors
• Hemophilia A: 85%, factor VIII deficiency
Third most common X-linked disorder
• Hemophilia B: 10%-15%, factor IX deficiency
Genetics
• X-linked recessive disorder• FVIII gene is on Xq28; most common (45%) defe
ct is inversion and translocation of exons 1-22 away from 23-26, others: point mutation
• 1/10,000 live male births • 女性也可能為 symptomatic carriers (ex. extreme
“Lyonisation” of the normal X chromosome)• 約 1/3 為 mutation
Classifications
依血液中凝血因子的剩餘含量而定• Severe: < 1 unit/dL (1% activity)• Moderate: 1%-5%• Mild: > 5%
Definition• 1 unit = the amount found in 1ml of normal pool plasma• 100% activity = the actvity found in 1ml of normal pool pl
asma
Bleeding Manifestations in Hemophilia
Sites of bleeding• Serious Joints (hemarthrosis), muscle/soft tissue, mouth/gum/nose, hematria• Life-threatening CNS, GI, neck/throat, severe trauma• Incidence of different sites of bleeding Hemarthrosis: 70-80% Muscle/soft tissue: 5-10% CNS: <5%
Clinical Manifestations
• 嚴重者,出生時就可能出現 subgaleal hematoma and/or ICH 〈應特別留意嬰兒室頭圍迅速增大的新生兒〉
• 症狀可能多在開始爬及走路時才出現• The hallmark of hemophilic bleeding: 自發性的關節出血 (hemarthrosis) and intramuscular hematoma
• 1-2 % ICH
其他出血的警訊• 腦出血: infants with “meningitis”
• 後腹腔出血:嚴重腹痛,可能誤為盲腸炎• 頸部、咽喉出血:喉痛、吞嚥困難,可能阻塞呼吸道
• Toddler: ankle most, than knee
• Child: knee most, than ankle
Diagnosis and Laboratory Tests
• Family history
• Normal platelet count, bleeding time, PT
• Prolonged PTT
• Specific factor assays
• Genetic testing
• Prenatal diagnosis
Management• History of hemophilia treatment
Decade Milestone (s)
1840s First transfusion administered
1940s Transfusion therapy estabilished
1950s FFP; early factor concentrates
1960s Cryoprecipitate
1970s Intermediate-purify factor concentrates; DDAVP
1980s Monoclonal antibody-purified and high-prify factor VIII concentrates; effective viral inactivation
1990s High-purify factor IX concentrates; recombinant factor VIII and IX threapy
2000s Improved recombinant products; gene therapy ?
治療• A 型: FFP , cryoprecipitate 或 factor VIII co
ncentrate (dose: desired rise level % × BW × 0.5)• B 型: FFP 或 factor IX concentrate (dose: desired rise level % × BW × 1.2~1.5)• Factor concentrate: plasma-derived or recombin
ant product• DDAVP for mild or moderate form• Antifibrinolytic therapy
On-demand Therapy
• 一有症狀出現就及早注射(即補充)凝血因子
• 劑量及次數視體重、病情輕重、出血程度及出血部位而定
Recommeded Plasma Factor Level and Duration of Administration
Type of hemorrhage
Hemophilia A Hemophilia B
Desired level
Duration (days)
Desired level
Duration (days)
Joint 40-60% 1-2 or longer 40-60% 1-2 or longer
Muscle 40-60% 2-3 or longer 40-60% 2-3 or longer
Iliopsoas
Initial 80-100% 1-2 60-80% 1-2
Maintenance 30-60% 3-5 or longer 30-60% 3-5 or longer
CNS/head
Initial 80-100% 1-7 60-80% 1-7
Maintenance 50% 8-14 30% 8-14
Type of hemorrhage
Hemophilia A Hemophilia B
Desired level Duration (d) Desired level Duration (d)
Throat and neck
Initial 80-100% 1-7 60-80% 1-7
Maintenance 50% 8-14 30% 8-14
GI
Initial 80-100% 1-6 60-80% 1-6
Maintenance 50% 7-14 30% 7-14
Kidney 50% 3-5 40% 3-5
Surgery (major)
Pre-op 80-100% 60-80%
Post-op 60-80%
40-60%
30-50%
1-3
4-6
7-14
40-60%
30-50%
20-40%
1-3
4-6
7-14
Prophylactic Therapy
• 原理:將重度缺乏者的凝血因子提升至 >1%
• 有效減少自發性出血• 避免關節出血及進一步關節病變• 瑞典最早開始, A 型血友病自 1958 年起,
B 型血友病自 1972 年起
Prophylaxis
• Initial observation: persons with moderate hemophilia (1-5% FVIII) have decreased joint disease
• Hypothesis: converting a person from severe hemophilia to moderate with prophylaxis would decrease incidence of joint disease
• Goat: to raise FVIII above 1% was commenced in Malmo, Sweden in 1958
• Lovqvist, et al: J Intern Med 1997
When to Start: The Swedish Experience
Conclusion: prophylaxis should be started in the first years of life, before age 3 Astermark et al: Br J Hematol 1999
一般照護• 預防注射 : 最小的針頭接種• 不可接受其他肌肉注射• 勿吃含有阿斯匹靈的止痛藥, 但 Panadol,
Ponstan, Codeine 可以服用• 牙齒的保護
長期的關節病痛問題• Target joints: 膝關節、踝關節及肘關節• 惡性循環下,發生慢性關節炎• Arthropathy: most significant chronic morbi
dity
• 預防是最佳的處理方法• Arthroscopic synovectomy
• Joint replacement
輸血引發的感染• 經加熱等特殊程序處理血液製品後, 1985年以後出生的血友病患者,至今並無因注射凝血因子而感染愛滋病的報告
• HBV, HCV infection
(vaccination using is recommended)
• Recombinant product 可完全免除這種潛在的危險
凝血因子抗體 • 14-25% of severe hemophilia A, very rare i
n hemophilia B
• 可能與基因有關• 輕者可能需要大量而頻繁的注射才可能止血
• 嚴重的就可能對注射凝血因子無效,必須使用其他凝血因子 (by-pass)
What are inhibitors ?
• Antibodies directed against coagulation factors Alloantibody in patients with hemophilia A or B Autoantibody in people without hemophilia
• Incidence Antifactor VIII inhibitors in hemophilia A: 25% Antifactor IX inhibitors in hemophilia B: 1-3% Antifactor VIII autoantibody inhibitors: 1/106/year• Usually result in loss of coagulation factor functio
n
Factor VIII inhibitors
• The most common inhibitor
• Polyclonal IgG antibodies, esp IgG4
• Bleeding is more severe in autoantibody patients than in hemophilia A inhibitor patients
EtiologyDefinite Factors Involved
• FVIII gene mutation No FVIII protein means high risk• Adjuvants in FVIII products• Race Higher in African-Americans• HLA status• Immune modifiers IL10 polymorphism
Classification of Inhibitors
Definitions• “High” responders IgG inhibitors of titer > 5 Bethesda Units (BU) Inability to overwhelm with native factor• “Low” responders < 5 BU Transient Less likely to have anamnestic responses Amenable to treatment by overwhelming inhibitor with native factor VIII or XI
Treatment Options for High-responder Inhibitors
Bypassing agents• Low-purity, plasma-derived concentrates Prothrombin complex concentrates Activated prothrombin complex concentrates Recombinant VIIa• Emergency treatments Recombinant VIIa Plasmapheresis Porcine VIII and new recombinant procine VIII
Treatment Options for High-responder Inhibitors
• Immune tolerance induction• Rituximab Anti-CD20 chimeric antibody reliably depletes peripheral B cells Several reports of success in acquired hemophilia (an autoimmune disorder) NHLBI-sponsored clinical trial through Transfusion Medicine/Hemostasis research network to begin May 2006
• Fox et al, Hemophilia 2006
von Willebrand Disease
• Disorder first described by Erik von Willebrand in 1925 in persons living off the coast of Finland
• Marked heterogeneity in phenotype, autosomal Dominant or Recessive Inheritance
• Deletion in chromosome 12 is most common• Overall prevalence 1:100 to 1: 500• Incidence equal among Man and Women (chrom
osome 12)
1994 Classifications of VWD by TSTH
1994 Term
1994 Definition Genetics, Comment
Type 1 Partial quantitative deficiency Dominant with variable expression; phenotype influenced by multiple genes
Type 2 Qualitative defect
Type 2A Decreased platelet-dependent function with absence of largest multimers
Dominant
Type 2B Increased VWF affinirty for platelet GPIb
Dominant. May be associated with thrombocytopenia, especially after DDAVP
Type 2M Decreased platelet-dependent function with presence of largest multimers
Dominant
Type 2N Decreased VWF affinity for FVIII Recessive, often mistaken for mild-moderate hemophilia A
Type 3 Virtually complete deficiency Recessive: homozygous or doubly heterozygous
Platelet-type (pseudo-VWD)
Not a defect of VWF, not to be considered a form of VWD
Dominant. A platelet disorders: increased affinity of platelet GPIb for VWF. Thrombocytopeinia may be present.
vWF Genetics
• http://www.vwf.group.shef.ac.uk/pictures.html
Location of Gene: chromosome 12 (p13.3)
vWF Protein
• A1: binds to Gp IB alpha• A3: Collagen binding Domain• D’/D3: Interacts with Factor VIII• C2: Interacts with GpIIb/IIIa
• http://www.vwf.group.shef.ac.uk/pictures.html
vWF Protein
• A1: type 2B and 2M• A2: type 2A, cleavage site for ADAMTS 13• D’/D3: type 2N
• http://www.vwf.group.shef.ac.uk/pictures.html
Diagnosis
vWD Tests: Initial Work-up
• Quantitative
• Factor VIII level
• vWF Antigen level
• vWF Multimers
• Qualitative
• Ristocetin Cofactor Assay: studies function of Vwf/Platelet interaction
Lab Values in vWD Subtypes
Variants of vWD
Official Abbreviated Terms as Designated by ISTH
Factor VIII Von Willebrand factor
Type of Test Official Old or informal
Official Old or informal
Immunological
(total amount, functional or not)
FVIII:Ag FVIII:CAg VWF:Ag FVIIIR:Ag
AHF:Ag
Functional
(functional assay)
FVIII FVIII:C, AHF, AHG
VWF:RCo
(ristocetin cofactor)
VWF:CB(collagen binding)
VWF:FVIIIB
(factor VIII binding)
FVIIIR:RCo and others
VWF:CBA
ISTH: International Society on Thrombosis and Hemostasis
Differential Diagnosis Hemophilia A & von Willebrand Disease
Management• Education• Cryoprocipitate (dose: desired rise level % × BW × 0.75)
• DDAVP for type 1• Amicar (antifibrinolytic agent) for mucosal bleeds• Humate-P (factor 8 and vWF) for surgery, traum
a• Platelet for pseudo-vWD• Recombinant factor 7a, correct underlying disord
er (hypothyroidism) for acquired vWD
Platelet
Platelet Anatomy
• Disc-shaped, anuclear fragment
• Size: 1.5 μm
• Normal maturation time 4-5 days
• Circulating life span 9-10 days
Platelet Anatomy
• Peripheral zone Plasma membrane Open canalicular system Extension of the plasma membrane Forms interconnecting network, greatly increases the surface area Membrane proteins: receptors for agonists and adhesive glycoproteins, signal transduction molecules IIb-IIIa: fibrinogen, vWF, fibronectin Ib-IIa: collagen Ib-IX-V: insoluble Vwf VI: collagen
Platelet Anatomy
• Submembranous zone Contractile protein system: regulates shape and carry out events such as secretion of granules and retraction of clots• Organelle zone Platelet specific storage granules Dense bodies: serotonin, ADP, ATP, Ca α granules: platelet factor 4, thromboglobulin, PDGF, vWF Lysosomes, peroxisomes
Hemostasis: Adhesion
• Initial event in hemostasis• Platelets contact subendothelial components ex
posed after vessel injury• vWF secreted into extracellular matrix from endo
thelial cells binds to GPIb-V-IX on platelet surface
• vWF on endothelial cells forms a bridge between the subendothelium and platelet
Hemostasis: Activation
• Interaction between GP Ia-IIa and GP VI with collagen results in platelet arrest and activation
• Forms a firm adherence
• Leads to intracellular signaling processes that initiate secretion
• Activated platelets express a procoagulant surface
Hemostasis: Secretion
• Undergo shape change• Spherical• Pseudopods• Spread over the exposed subendothlium• Contents of platelet granules are released• α granules: fibrinogen, vWF, thrombospondin, fa
ctor V, vitronectin• Dense granules: ADP, ATP, serotonin, calcium
Hemostasis: Aggregation
• Once activated, platelets become adhesive to each other
• Interact via fibrinogen bound to their GPIIb-IIIa receptors
• Microthrombus of aggregated platelets is formed
Presentation of Disorders of Platelet Function
• Mucocutaneous bleeding• Gingiva• Epistaxis• Menorrhagia• Petechiae• Ecchymoses• Bleeding after trauma and surgery• Rare: ICH, joint, muscle
Clinical Presentation of Bleeding Disorder
Clinical signs Disorders of coagulation
Disorder of platelets or vessles
Petechiae Rare Characteristics
Ecchymoses Common, large Characteristics, small
Bleeding from superficial cuts
Minimal Persistent
Delayed bleeding Common Rare
Deep hematomas Characteristics Rare
Hemothrosis Characteristics Rare
Diagnostic work up
• Initial• Platelet count and morphology• PT, PTT (mixing studies)• Platelet function analyzer (PFA)-100• Bleeding time• vWD panel• Platelet aggregation• Flow cytometry, electron microscopy• Detailed drug history
Inherited Platelet Function Disorders
• Adhesion Bernard Soulier Syndrome Collagen receptor deficiency• Aggregation Glamzman’s Thrombasthenia• Secretion Storage pool disorders• Coagulant activity Scott syndrome
Bernard-Soulier Syndrome
• First described in 1948• AR• Present in infancy or early childhood• Thrombocytopenia, giant platelets, bleeding tend
ency• Abnormality of the GP Ib-IX-V complex• Normally binds to vWF• Initial platelet adhesion to the subendothelium• Mutations in Ibα, Ibβ, or IX
Bernard-Soulier Syndrome
• Prolonged bleeding time• Thrombocytopenia, variable• Abnormal smear, enlarged platelets• Aggregation• Normal in response to ADP, epinephrine, aracha
donic acid, collagen• Fails in response to ristocetin• Cannot be corrected by the addition of normal pl
asma containing vWF• Abnormal flow cytometry
Glanzmann Thrombasthenia
• First described in 1918• AR• Present with mucocutaneous bleeding as neonat
e or infant• Bleeding tendency, normal platelet count• Deficiency of GPIIb/IIIa• Normally binds to fibrinogen and vWF• Cross links adjacent platelets to form platelet plu
g
Glanzmann Thrombasthenia
• Normal platelet count and morphology• Prolonged bleeding time• PFA-100• COL/EPI abnormal• COL/ADP abnormal• Aggregation• Abnormal in response to all agonists except risto
cetin• Flow cytometry abnormal
Storage Pool DisordersGray Platelet Syndrome
• Absence of αgranules (normal ~ 50)• AR• Molecular defect unknown• Mild mucocutaneous bleeding• Variably prolonged bleeding time• Moderate thrombocytopenia• Reticulin fibrosis of BM• Large gray platelet• EM: small, empty or absent αgranules
Storage Pool DisordersDense Granule Disorders
• Normal dense granules
• 3-6/platelet
• Serotonin, ADP, ATP, Ca
• Heterogeneous group of disorders
• Molecular defect unknown
• Mild to moderate bleeding
Storage Pool Disorders
• Two autosomal recessive syndromes associated with albinism
Chediak-Higash Hermansky-Pudlack• Non-albino syndromes Wiskott-Aldrich Thrombocytopenia absent radii Osteogenesis imperfecta
Storage Pool Disorders
Chediak-Higash• Partial oculocutaneous al
binism• Frequent pyogenic infecti
on• Giant lysosomal granules
in cells• Thrombocytopenia• Dense granule deficiency
Hermansky-Pudlack• Oculocutaneous albinism• Inclusions in the cells of
RES• Thrombocytopenia• Dense granule deficiency• Common in Puerto Rico
Storage Pool Disorders
• Clinical presentation• Platelet morphology normal• Bleeding time usually, not always prolonged• Aggregation• Marked impairment with weak agonists ADP,
epinephrine and low concentrations of collagen• Response to higher concentration may be
normal• Absent second wave of aggregation when
stimulated by ADP and epinephrine
Disorders of Procoagulant ActivityScott syndrome
• AR• Severe bleeding• Decrease transport of phospholipids to surface o
f activated platelet• Decreased expression of factor Xa binding sites• Failure of factor Xa to bind• Incapacity of the activated cell surface to transfo
rm prothrombin to thrombin• Prothrombin consumption test is the only abnor
mal test
Thrombocytopenia
• Increase platelet destruction Immune Non-immune• Decreased platelet production Congenital Acquired• Sequestration• Qualitative platelet disorders
Qualitative Platelet Disorders
• Wiskott-Aldrich syndrome X-linked; small platelet• Bernard-Soulier syndrome AD, large platelets• May-Hegglin anomaly AD, giant platelet, Dohle bodies• Gray platelet syndrome Pale/oval platelet• Glandzmann’s thrombesthenia
Sequestration
• Kasabach-Merritt syndrome• Hypersplenism
May be associated with infiltrative disease
(leukemia)
May arise from liver disease, portal hypertension• In Vitro platelet clumping• Easily diagnosed by peripheral smear evaluation
Decreased Platelet Production Congenital
• Thrombocytopenia-Absent Radius syndrome Absence of radii at birth Association with congenital heart disorder• Amegakaryocytic Thrombocytopenia Presents in neonatal period No skeletal anomalies• Fanconi Anemia Due to aplastic anemia Short stature, thumb and radii hypoplasia, microcephaly
Thrombocytopenia-Absent Radius
Decreased Platelet Production Acquired
• Leukemia
• Aplastic anemia
• Neuroblastoma
• Due to bone marrow metastasis
• Drugs
• Nutritional deficiency
• Megaloblastic anemia
Increased Platelet DestructionNonimmune
• Hemolytic-uremic syndrome
Microangiopathic anemia
Bloody diarrhea (E coli O157:H7)
• Disseminated intravascular coagulation
Microangiopathic anemia; low fibrinogen
Sepsis
• Cyanotic heart disease
Increased Platelet DestructionImmune
• HIV
• Post transfusion
• Drugs
• Collagen-vascular disease
• Neonatal alloimmune thrombocytopenia
• Idiopathic thrombocytopenia
Heparin and Thrombocytopenia
• Immune Heparin-induced thrombocytopenia• Initially presents as decrease in platelet with or
without thrombosis• Two distinct syndromes:• 1 Uaually mild and transient thrombocytopenia w
ith rapid recovery upon discontinuation of heparin
• 2 Severe thrombocytopenia often complicated by thrombosis or DIC
Neonatal Thrombocytopenia
Child born to Mother with ITP
• Mother with thrombocytopenia
• Resolves within about 6 weeks
• Risk of ICH 1%• Avoid maternal platelet
transfusion
Neonatal alloimmune thrombocytopenia
• Mother with normal platelet
• Resolves with about 6 weeks
• Risk of ICH 10-30%• Maternal platelet transfusi
on for bleeding• Severity increases with s
ubsequent siblings
Idiopathic Thrombocytopenia Purpura
• Diagnosis is based primarily on the history, PE, CBC, and peripheral smear examination
• CBC must show isolated and usually severe thrombocytopenia
• Bone marrow aspiration should be performed in patients with thrombocytopenia lasting more than 6 to 12 months, and in those unresponsive to IVIG therapy
Idiopathic Thrombocytopenia Purpura
• Clinical features• M=F• Child is well with rapid onset of thrombocytopenia• Generally seen in children 1 to 9 years old• Peak incidence is between 2 to 5 y/o• 1 in 1500 persons with get ITP in childhood• Seasonal presentation• More common in winter and fall• Platelet-specific autoantibodies seen 4-8 weeks following
a viral illness or exposure
ITP Treatment
• Severe life-threatenin bleeding• IVIG, steroids, platelet transfusion• Platelet counts > 30k• Asymptomatic or only minor purpura: no treatment• Platelet counts < 20k• Significant mucosal bleeding• Treatment with IVIG or steroids• Platelet counts < 10k• Only minor purpura• Treatment with IVIG or steroids
ITP Treatment
• IVIG• More rapid increase in platelet counts• The mean platelet count in the IVIG group was a
pproximately 2.5 times than steroid gr• Average platelet count rose over 30k by 24 hrs i
n IVIG, and by 48 in steroid gr. At one week the levels were equal
• IVIG will not affect subsequent BM biopsy results
• Dosing: 1g/k on 1 day
ITP Treatment
• Steroids
• IVIG costs about 150 times as much as treatment with steroids
• IVIG can cause aseptic meningitis
• Causing an emergent diagnostic evaluation to rule out ICH
• Dosing: 2mg/k/day
Chronic ITP
• Defined as thrombocytopenia lasting longer than 6 months
• Child may present with recurrent upper an lower respiratory tract infections, GERD, and FTT
• Family history is often positive for ITP or other autoimmune disease (SLE)
Acquired Platelet Defects
• Medications• Chronic renal failure• Abnormal platelet aggregation, reduced secretio
n in response to many agonists• May be caused by both dialyzable and nondialyz
able substances• Cardiopulmonary bypass surgery• SLE• Chronic myeloproliferative disorders and acute l
eukemia
DIC
Clinical Conditions Associated with DIC
• Sepsis/severe infection (any microorganism)• Trauma (polytrauma, fat embolism)• Organ destruction (severe pancreatitis)• Malignancy (solid tumors, hematological malignancy)• Obstetrical calamities (amniotic fluid embolism, abruptio
placentae)• Vascular abnormalities (Kasabach-Merritt syndrome, larg
e vascular aneurysms)• Severe hepatic faliure• Severe toxic or immunologic reactions (snake bites, tran
sfusion reactions, transplant rejection)
Pathogenesis: Initiation of Fibrin Deposition
Hambleton, J. et al. Hematology 2002
Pathogenesis: Amplification of Fibrin Deposition
Hambleton, J. et al. Hematology 2002
Pathogenesis: Amplification of Fibrin Deposition
Hambleton, J. et al. Hematology 2002
Pathogenesis: Propagation of Fibrin Deposition
• Fibrinolytic system is downregulated at the time of max. activation of coagulation
• In baceremia, endothelial cells release plasminogen activators
• Increase plasminogen activator inhibitor, type 1 (PAI-1) immediately to suppress of fibrinolytic activity
• High PAI-1 level strongest predictors of mortality (ref 3)• 4G/5G polymorphism, functional mutation of PAI-1 gene
indicated higher PAI-1, increased risk of death in bacteremia (ref 38)
Diagnosis• 1 Underlying disorder• 2 Global coagulation tests (platelet; PT;
fibrinogen; FDP)
Score 0 1 2
Platelet () > 100 < 100 < 50
FDP No increase Moderate Strong
PT (sec.) < 3 3-6 >6
Fibrinogen (g/L) >1 <1
• If score 5: DIC, repeat daily≧• If score < 5: non-overt DIC, repeat next 1-2 days
Management
• 1.Plasma and platelet substitution therapy
• Only in active bleeding, requiring an invasive procedure, at risk for bleeding complications
• 2.Anticoagulants
• 3.Restoration of anticoagulant pathways