Ann Thorac Surg 1996;61:1157
© 1996 The Society of Thoracic Surgeons
Invited Commentary
Invited Commentary
Bo Nilsson, MDPhD
Department of Clinical Immunology and Transfusion Medicine, University Hospital, Uppsala S-75185, Sweden
See also page 1153.
Complement activation appears to be an important contributor to activation of inflammatory cells and platelets during cardiopulmonary bypass. This work confirms that complement activation during cardiopulmonary bypass can be reduced by using heparin-coated cardiopulmonary bypass circuits. It also adds further knowledge about the extent of classic pathway activation in connection with cardiopulmonary bypass, which obviously occurs mainly after protamine administration. The oxygenator is a device with two kinds of complement activating surfaces. The main activating surface is the biomaterial in the cardiopulmonary bypass circuit, but the blood-gas interface (in particular in bubble but also in membrane oxygenators) is also an important contributor to complement activation. With this in mind it is not surprising to find that binding of heparin to the biomaterial surface does not completely abolish complement activation.
However, considering that various studies have used different experimental protocols, one can suspect that some of the heparin-coated surfaces, even different batches from the same manufacturer, are less active with respect to complement inhibition. It seems likely that the manufacturer mainly concentrates on the antithrombogenic effect, which is correlated to the number of antithrombin-binding sites in heparin. In contrast, other properties of heparin affect complement activation. For example, the dose needed for complement inhibition is higher than that which inhibits the coagulation system. Another important parameter is the matrix to which the heparin is conjugated. To bind heparin to a biomaterial, different chemical groups often are used for conjugation that by themselves might potentiate complement activation, eg, amino or hydroxyl groups. Considering this, a study that compares heparin-coated oxygenators from different manufacturers would be of great interest.
Related Article
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Specific Complement Inhibition With Heparin-Coated Extracorporeal Circuits
- Henk te Velthuis, Piet G. M. Jansen, C. Erik Hack, León Eijsman, and Charles R. H. Wildevuur
Ann. Thorac. Surg. 1996 61: 1153-1157.
[Abstract]
[Full Text]
