Coatings: Are they really effective and how good is the evidence?

Transcription

1 Coatings: Are they really effective and how good is the evidence? or is this another example of the Emperor s New Clothes? Richard Tallman, Ph.D. Associate Professor, Emeritus The Ohio State University Adjunct Clinical Professor Midwestern University tallman.1@osu.edu

2 Fiduciary Disclosure Medtronic Gish Biomedical* Edwards Lifesciences No currently active consulting contracts

3 1 Nature of the Problem a Why Coatings?

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5 From Laffey et al. Anesthesiology 2002

6 Schematic Representation of Wound Healing Injury Complement Kinins Coagulation Platelets debridement Inflammation Granulocytes Macrophages Lymphocytes Endothelial Cells (Angiogenesis) Migration Proliferation Fibroblasts Collagen lysis Collagen synthesis contraction remodeling From Zabel and Hunt, Perspect Colon Rectal Surg. 6:192, Healed Wound

7 From Laffey et al. Anesthesiology 2002

8 2. What are we using to evaluate the amount or degree of contact activation in the perioperative period?

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14 From Kapoor et al. Annals of Cardiac Anaesthesia 2004; 7:

15 Should not activate the complement system Promote the reversible adsorption of plasma proteins to prevent platelet adhesion Bind albumin reversibly Prevent the adsorption of fibrinogen, factor XII & high molecular weight kininogen Decrease hemolysis Counter activated clotting factors

16 GBS GBS-HF TRILLIUM CARMEDA

17 POLYMER COATINGS Polypeptide (Human albumin) (Safeline Maquet) Hyaluranon (GBS-HF, GISH Biomedical) Poly(MetoxyEthyl)Acrylate (X Coating TM, Terumo) Phosphorylcholine Inert Surface (PHISIO, Sorin) (Biocompatibles, Ltd) Surface Modifying Additive (SMA) polysiloxanecontaining co-polymers (SMARxT Sorin)

18 POLYMER BASED HEPARIN BONDED COATINGS GBS Hyaluronan based, covalent heparin coating (GISH Biomedical Inc., USA) Bioline Human albumin based heparin coating (Maquet) Trillium Affinity Polyethylene oxide based heparin coating (Medtronic, USA) Carmeda Polyethyleneimine spacer, (Medtronic, USA)

19 3. What is the scientific evidence supporting the use of these surface coatings?

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26 2006

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28 TRILLIUM

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33 Anesthesia & Analgesia 2006:103;

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35 Anesthesia & Analgesia 2006:103;

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38 886 patients (12 centers) randomly assigned to HCC (n= 442) Control (n=444) Entry Criteria: One or more of the following patient or procedure related risk factors; Age > 75 yrs EF < 0.3 CHF COPD Diabetes Dialysis dependent Redo Combined procedures

39 Results: Heparin coated circuit group Shorter ICU stay Shorter Hospital stay Diabetics had less renal dysfunction COPD patients had better lung function

40 Presented at AmSECT 45 th Int. Conference, Atlanta, GA, April 2007

41 PARAMETERS SCORE Age (years) Female sex 1 Chronic pulmonary disease 1 Extracardiac arteriopathy (carotid occlusion >50%, claudication) Neurologic dysfunction 2 Previous cardiac surgery 3 Serum creatinine >200 µmol/l 2 Critical preoperative state b 3 Unstable angina 2 Left ventricular dysfunction EF 30-50% EF<30 Recent myocardial infarction (<90 days) 2 Pulmonary hypertension (Systolic PAP > 60 mmhg) Emergency 2 Other than isolated CABG 2 1 a

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52 Conclusions Data supporting the efficacy of our coatings is weak and contradictory Continued development is imperative Future studies should focus on the advantages provided to high risk patients

53 Epilogue What about Heparin? Should it be a component of a coating?

54 The Heparin molecule as a component of the coating 1. Leads to the Reduced, or Selective adhesion of plasma proteins, which in turn leads to a faster formation of a blood-friendly secondary superficial membrane. 2. Prevents a further denaturation and hence activation of the adhered proteins and blood cells From Wendel HP and Ziemer G. Coating techniques to improve the hemocompatability of artificial devices used for extracorporeal circulation. (Review) Euro J Cardio-Thorac Surg 1999: 16;

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