Ann Thorac Surg 2008;85:542. doi:10.1016/j.athoracsur.2007.10.092
© 2008 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Invited Commentary
Robert Colman, MD
Sol Sherry Thrombosis Research Center, Temple University, Thrombosis Research Center, 3400 N Broad St, OMS 418, Philadelphia, PA 19140
(Email: colmanr{at}temple.edu).
The title of the article by Raivio and colleagues is well supported by the data presented [1]. This is a well designed study testing a carefully crafted hypothesis that preoperative thrombophilic variables show a positive association with increased thrombin generation (F1+2), procoagulant activity (soluble fibrin monomer complex), and fibrin degradation products (D dimer) before, during, and after coronary artery bypass grafting. The conclusions on thrombin are solidly based, and in fact, the thrombin-related tests were measured serially at eight time points before during and after cardiopulmonary bypass (CPB).
Recently, other actors—monocytes and plasma tissue factor—have laid claim to the spotlight on the stage of thrombin formation during CPB. Monocytes are activated in the wound but not in prebypass or perfusate plasma. Wound plasma tissue factor is substantially elevated compared with other locations. When wound plasma tissue factor is centrifuged at high speeds, the supernatant wound plasma tissue factor contains about 80% of tissue factor, but only about 20% are in the microparticle fraction [2].
In the presence of plasma tissue factor, stimulated monocytes more efficiently convert factor VII to factor VIIa and activate factor X to factor Xa than do unstimulated monocytes or microparticle tissue factor. In all comparisons, stimulated monocytes are the most efficient platform for converting factor VII to VIIa, exceeding the platelet in this regard. The stimulated monocyte is especially efficient at low concentrations of tissue factor such as exist in vivo. These cells thus appear to be a major venue of thrombin formation in CPB.
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References
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- Raivio P, Petäjä J, Kuitunen A, Lassila R. Thrombophilic variables do not increase the generation or procoagulant activity of thrombin during cardiopulmonary bypass Ann Thorac Surg 2008;85:536-542.[Abstract/Free Full Text]
- Hattori T, Khan MM, Colman RW, Edmunds Jr LH. Plasma tissue factor plus activated peripheral mononuclear cells activate factors VII and X in cardiac surgical wounds J Am Coll Cardiol 2005;46:707-713.[Abstract/Free Full Text]
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