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Inflammation, Thrombosis, and Bleeding

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Presentation on theme: "Inflammation, Thrombosis, and Bleeding"— Presentation transcript:

1 Inflammation, Thrombosis, and Bleeding
Jerrold H. Levy, MD Professor of Anesthesiology Deputy Chair for Research Emory University School of Medicine Director, Cardiothoracic Anesthesiology Emory Healthcare Atlanta, Georgia

2 Everybody talks about it, only a few people seem to understand it.
LOVE=COAGULATION Everybody talks about it, only a few people seem to understand it.

3 Normal Hemostasis II TF-Bearing Cell II II Platelet IIa IIa VIIa
X VIII/vWF TF VIIa Xa Va IIa TF-Bearing Cell VIIIa TF VIIa V Va IX Platelet II IXa X Normal Hemostasis This slide represents a schematic model of normal hemostasis that requires activation of both FX and FIX. FVIIa/tissue factor (TF)-activated FXa and FIXa play distinct roles in coagulation. FXa cannot move to the platelet surface because of the presence of normal plasma inhibitors, but instead remains on the TF-bearing cell and activates a small amount of thrombin. This thrombin is not sufficient for fibrinogen cleavage but is critical for hemostasis since it can activate platelets, activate and release FVIII from von Willebrand factor (vWF), activate platelet and plasma FV, and activate FXI. FIXa moves to the platelet surface, where it forms a complex with FVIIIa and activates FX on the platelet surface. This platelet surface FXa is relatively protected from normal plasma inhibitors and can complex with platelet surface FVa, where it activates thrombin in quantities sufficient to provide for fibrinogen cleavage. Hoffman M et al. Blood Coagul Fibrinolysis 1998;9(suppl 1):S61–S65. Xa IIa IXa VIIIa Va Activated Platelet VIIa IXa Va VIIIa Xa IIa IX II X Hoffman et al, Blood Coagul Fibrinolysis 1998;9(Suppl 1):S61

Inflammation has multiple humoral, cellular components, and undergoes amplification. Defining clinical outcomes from inflammation is difficult. Hemostatic activation/thrombin generation is an inflammatory response, and tissue injury is key.

Bleeding Ischemia/reperfusion injury Infection MOS dysfunction CNS dysfunction

6 HEMOSTASIS The stoppage of bleeding, hemorrhage, or blood flow through a blood vessel or body part.

Vasculature Coagulation proteins Platelets

Arterial clot is due to platelet-fibrinogen interactions. Heparin does not completely block this. Venous clot and venous thromboembolic phenomenon are prevented by thrombin inhibitors

9 THROMBIN: Proinflammatory mediator
Chemotactic for PMNs, monocytes Mast cell activator Stimulates endothelium Formed via endothelial injury by TF expression, induces cytokine expression

Contact (XIIa) Tissue Factor (TF:VIIa) BTG, PF4 Platelets activation/consumption IX * TFPI FV, FVIII, FXI FXIa, FVa/FVIIIa IXa FVi, FVIIIi X Xa Protein C VIIIa, Ca++ , PL Va, Ca++ , PL APC Thrombomodulin * Prothrombin THROMBIN XIII FPA bradykinin PT fragment 1.2 EC ATIII Fibrinogen Fibrin (M) XIIIa * tPA tPA:PAI1 FSP Fibrin (Ps) * TAT PAI1 Plasminogen PLASMIN -2-antiplasmin D-dimer Fibrin (Pi) PAP complexes Platelet GP1b * Endothelial-associated Despotis GJ et al, Anesthesiology 1999;91:

11 VASCULAR ENDOTHELIUM Huraux C et al: Circulation 1999;99:53-59

12 DIC Triggered by TF/endothelial injury
Produces fibrin deposition in microvasculature and MOS dysfunction Path: Microangiopathic hemolytic anemia Lab: platelets, fibrinogen, PT, PTT, D-dimers, ATIII

20 120 100 80 60 40 ANTITHROMBIN ACTIVITY Normal Activity Activity - % Group 1 Group 2 X ± SEM Heparin Protamine 1 2 3 4 5 6 7 8 10 9 11 12 13 Measurement Period Zaidan JR et al, Anesth Analg 1986;65:377-80

14 ACT (sec) PATIENTS ON HEPARIN THERAPY Baseline Heparin Heparin Heparin
900 800 700 678 612 ACT (sec) 600 567 500 496 478 400 453 AT III 300 No AT III 200 160 160 100 Baseline Heparin Heparin Heparin ACT 4.1 u/ml 5.4 u/ml 6.8 u/ml Levy JH et al, Anesth Analg 2000;90:1076-9

15 FACTORS AFFECTING ACT Factor deficiency: fibrinogen, XII, VIII
Contact activation inhibitors: aprotinin Warfarin therapy Heparin therapy Hypothermia Thrombocytopenia/cytosis Platelet inhibitors

16 Aprotinin Use in CABG Reoperations
Donor-Blood-Product Requirements P < .001 P < .001 Lemmer et al J Thorac Cardiovasc Surg 1994;107:543-53 Levy et al Circulation 1995;92:

17 Neurologic Deficit (Stroke)
Number of Patients % Placebo 5 / Aprotinin Pump Prime 1 / Low Dose 0 / High Dose 0 / P = 0.01 Incidence of Stroke in Repeat CABG Surgery Levy et al, Circulation 1995;92:

18 International Multicenter Aprotinin Graft Patency Experience
796 (91%) Patients assessable for blood loss, usage 703 (81%) Patients assessable by angiography for saphenous vein-graft patency (at mean of 10.8 days postop) 831 (95%) Patients assessable for MI by ECG and cardiac enzyme evaluation FDA rules for investigational study reporting requires that any protocol deviation must have the data excluded from analysis of drug efficacy. However, all data, including protocol violations are included in assessment for drug safety. 870 patients were randomized in this study (aprotinin = 436; placebo = 434). 74 patients were excluded from analysis of blood loss and replacement, for reasons that included protocol violation (n = 21), and exclusion for a confounding postop event (n = 53), the most common of which were re-exploration for surgical bleeding (n = 30) and an additional postop surgical procedure (n = 14). However, the data from patients in whom there had been a protocol violation were included in the angiographic analysis of graft patency. Assessment was not available in 167 patients, the majority of whom (n = 117) did not consent to the investigation.

19 IMAGE Study Blood Loss and Blood Product Replacement
Drainage and Transfusion Patients Requiring Any Blood Product P <.001 P <.001 Alderman, Levy, Rich et al, JTCS 1998;116:716-30

20 IMAGE Study P = .01 P = .03 P = .72 Alderman et al, J Thorac Cardiovasc Surg 1998;116:716-30

21 IMAGE Study Death 1.6% 1.4% (6/434) (5/436)
Adverse Outcome Placebo Aprotinin Death % % (6/434) (5/436) Myocardial Infarction Definite % % (16/421) (12/410) Def+probable % 8.6% (38/418) (35/407) Def+prob+possible 12.0% 12.3% (50/418) (50/408) Alderman et al, J Thorac Cardiovasc Surg 1998;116:716-30

22 Role of the Tissue Factor – Thrombin Pathway in Myocardial Ischemia-Reperfusion Injury

23 Inhibition of Thrombin PAR-1 Activation by Aprotinin
Protease (Thrombin) APROTININ X (Irreversible) Cell Membrane G protein Coughlin SR, Proc Natl Acad Sci USA 1999;96:

24 APROTININ: Use in Orthopedic Surgery (1)
Janssens M: High-dose aprotinin reduces blood loss in pts undergoing THR surgery. Anesthesiology 1994; 80: 23–9. Murkin JM: Aprotinin decreases blood loss in patients undergoing revision or bilateral total hip arthroplasty. Anesth Analg 1995; 80: 343–8. Murkin JM: Aprotinin decreases exposure to allog blood during primary unilateral THR. J Bone Joint Surg Am 2000; 82: 675–84. Capdevila X Aprotinin decreases blood loss and transfusions in pts undergoing major orthopedic surgery. Anesthesiology 1998; 88: 50–7.

25 APROTININ: Use in Orthopedic Surgery (2)
Hayes A The efficacy of single-dose aprotinin 2 million KIU in reducing blood loss and DVTs in THR surgery. J Clin Anesth 1996; 8: 357–60. Kasper SM A retrospective study of the effects of small-dose aprotinin on blood loss and transfusion needs during total hip arthroplasty. Eur J Anaesthesiol 1998; 15: 669–75. Amar D: Antifibrinolytic therapy and periop blood loss in cancer pts undergoing major orthopedic surgery. Anesthesiology 2003;98: Samama CM: Aprotinin vs placebo in major ortho surgery: a randomized/DB/, dose-ranging study. Anesth Analg 95:287-93,

Repeat sternotomy Jehovah’s witnesses Valve surgery/combined procedures Aortic root surgery/DHCA Dialysis patient Endocarditis Minimally invasive valve surgery Transplants/VADs Recent Plavix

27 SUMMARY Thrombin generation modulates the thrombotic effects of vascular injury and pharmacologic intervention Thrombin activation of PAR-1 receptors activates pathologic mechanism of injury Aprotinin inhibits pathologic hemostatic activation by blocking PAR-1 receptors Safety data from clinical studies including orthopedic surgery have not demonstrated a prothrombotic effect of aprotinin

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