In my opinion, heparinase is better than protamine sulfate due to anticoagulant action of protamine sulfate at high dose

best regards

Heparinase I can be used to neutralize the anticoagulant effects of unfractionated heparin and low molecular weight heparins in the TEG system. By cleaving the 1-6 glycosidic linkages in heparins, heparinase I breaks the UFH into low molecular weight heparins. For example Tinzaparine, a LMWH was obtained by heparinase digestion of UFH. However, if you subject the LMWH to controlled depolymerization by enzymatic action of heparinase, one could obtain lower LMWH. Further enzymatic digestion can result in disaccharides or terasaccharides which do not have any significant anticoagulant effects, thereby neutralizing the anticoagulant effects. In terms of concentrations of heparinase that can neutralize the UFH and LMWHs, I would suggest 0.1 or 1 Unit of heparinase in the TEG system.

Protamine treatments do not usually address the distinction between anticoagulation due to heparin from anticoagulation due to other causes (such as dilution, etc) (2009.11.01.blood cells mol.dis.43(3):256-259). One actually needs to know the exact heparin level present, rather than to infer it from clot times or other similar assays, which do not distinguish between different contributing causes of anticoagulation. Because of this, attempting to neutralize 'heparin' anticoagulation with protamine can lead to the addition of too much protamine, with subsequent complications. Heparinase treatment of patient blood samples should be a better option because it reduces the need for this.

Of course the best sample for TEG is citrate blood but if we cannot avoid heparin because of treatment we have to optimize heparinase I digestion.

Problem with heparin "decontamination" always appears when we have to analyze samples from heparin treated patient: MI (myocardial infarction) patients or patients after interventions, where heparin was used. If we cannot assume if a patient was treated UFH or LMWH, heparinase digestion is a method of choice (in my opinion). Protamine sulphate will neutralize UFH only.

Heparinase I cleaves heparin and heparan sulfate (relative activity about 3:1) at the linkages between hexosamines and O-sulfated iduronic acids, yielding mainly disaccharides. Thus heparinase I is active to neutralize both UFH and LMWH.

The question is also about units and approx. time of digestion.

Ewa is right. The units of heparinase I and time of digestion are important. One can have controlled enzymatic digestion of UFH. Perhaps a higher concentration of heparinase I may be preferred otherwise, heparinase I can cleave the unfractionated heparin into low molecular weight heparin which will also have anticoagulant activity. If you completely want to eliminate the anticoagulant activity you may have to increase the time of heparinase digestion or increase the heparinase I concentration.

On the other hand protamine in excess can itself cause anticoagulant effect.

I would suggest: use first protamine sulphate at low dose. Heparinase may improve the outcome if needed. Best.

the idea with protamine is not good, because protamine may only antagonize maximally 60% of LMWH effect.

I would recommend to try heparinase (there are standard cups for). If that is not sufficient try 5 U/ml polybrene. We did this in our project with heparinized samples.

Greets

Marcus Lancé

It is a good idea to try the heparinase I coated TEG cups which are commercially available.

Thank you Marcus for your suggestions about heparinased cups. We used them but in some patients they were not sufficient. Do you think that polybrene increases haparinase efficiency in blood samples without any influence of coagulation kinetics? Is 5 U/ml a final concentration or stock?

Dear Ewa,

as far as I know polybrene has no effect on the coagulation itself. The concnetration is the final concentration. We made good experience with this. We did not use both together (heparinase and polybrene), so I cannot give any comment on the question if the act additive or not. However I think polybrene only should be enough.

Kindly

Marcus

Thank you Marcus for explanation, I will tell you about my experience soon, regards Ewa

The relative limitation of Protamine in neutralising heparin is not a good reason to exclude it.

Dear Claudia,

of course you are right.

however protami ne has (if overdosed) itself anticoagulative effects and it will not neutralize LMWH. The max effect here is 60 % depending on the kind of LMWH.

kindly

Marcus

TEG data may look different when commercial heparinase cups are used; I think it may induce platelet retraction

http://www.archivesofpathology.org/doi/abs/10.1043/2010-0253-LER.1

If commercial heparinase-coated cups have any problem, one may use the heparinase and just add it to the blood in the cup separately. Perhaps there is no other agent as specific to neutralize the heparin than heparinase. Polybrene, histidine or platelet factor 4 may partially neutralize the heparin.

Thank you Kenichi for posting very interesting paper. Should we avoid heparinise cups in order to study fibrinolysis?

If you use fresh (non-citrated) whole blood, heparinase cup is more likely to cause this phenomenon. As the above paper showed, Hepzyme seems to be OK, and polybrene (hexadimethrine) is OK. In general, lysis % and D-dimer (or plasmin-A2 AP complex) do not correlate well unless there is extensive fibrinolysis.

http://www.schattauer.de/en/magazine/subject-areas/journals-a-z/haemostaseologie/contents/archive/issue/850/manuscript/8530/show.html

We tried to neutralize heparin in plasma samples from patients receiving unfractionated heparin with protamine, polybrene and heparinase. Polybrene was the most effective neutralizing agent (0.5 heparin units/mL was sufficient for all the samples). However, none of the agents neutralized heparin completely.