Other direct thrombin inhibitor such as Argatroban can also be used.  In one study Argatroban was used in interventional cardiology at a dose of 350ug/kg slow bolus followed by 25ug/kg/hr infusion.  With this dosage the level of anticoagulation achieved is about 400 seconds on the Activated Clotting Time.

Also in my institution bivalirudin is the choice in such cases. Same doses as the referred by the Loyola University Colleague.

Bivalurudine is a safe alternative to argatroban in HIT. It has a shorter half life of 25 mins. Once therapeutic levels are achieved it remains stable without much changes needed in dose adjustment. Heparin is still the preferred agent in CPB. 

Michael,

  Although some investigators have tried using Heparin in CPB in HIT patients, it is quite controversial.   Like you, many investigators prefer bivalirudin since larger clinical trials were performed using bivalirudin.  Bivalirudin, and other direct thrombin inhibitors have a shorter half-life and  a predictable anticoagulant effect.   However, if there is any bleeding complication due to their use there is no specific antagonist available.    Bivalirudin is a hirudin-based product.and there could be a tendency of developing anti-hirudin antibodies (HACA antibodies).  Furthermore, it is mainly cleared by the kidneys and hence in patients with concurrent renal failure, the dosage regimen may have to be modified or preferably to change the drug.  In those cases Argatroban, a synthetic direct thrombin inhibitorwith other mode of elimination and  which does not allow the development of antibodies may be a safer alternative.  Again, this drug is cleared mostly by hepatobiliary sytem and in patients where there is hepatic insufficiency or hepatic failure, one can always switch to other direct thrombin inhibitors.  Even Refludan (recombinant hirudin has been approved by the USFDA to be used in HIT patients.  So luckily we have several options available and one has to select the right drug for the right patient at appropriate dosages taking into account the overall health of the patient and especially the modes of elimination of different drugs and any associated renal or hepatic dysfunctions.

Omer

Dear Michael,

I hope it will give you some idea. At our center we use  Bivalirudin.

Currently Bivalirudin is the DTI of choice at NH. That overcomes many limitations seen with indirect thrombin inhibitors, such as heparin. Bivalirudin is a short, synthetic peptide that is potent, highly specific, and a reversible inhibitor of thrombin. It inhibits both circulating and clot-bound thrombin, while also inhibiting thrombin-mediated platelet activation and aggregation. Bivalirudin with quick onset of action and a short half-life ideal for interventions and on pump surgeries. It does not bind to plasma proteins or red blood cells. Therefore it has a predictable antithrombotic response. Heparin Induced Thrombosis-Thrombocytopenia Syndrome (HIT/HITTS). It does not require a binding cofactor such as antithrombin and does not activate platelets. These characteristics make bivalirudin an ideal alternative to heparin in patients with HIT. Patients proceeding to CABG surgery on-pump: Bivalirudin initial dosing guide:(Note this is not the package insert dose)

•Range: 0.03 - 0.2 mg/kg/hr

If deemed necessary by physician, bolus dose: 0.1-0.2 mg/kg ---- keep ACT above 400 Seconds.

We at our centre use 1mg/kg as an intravenous bolus dose, followed by an intravenous infusion of 1.75 mg/kg/hr for the duration of the procedure; check ACT 5 minutes after the bolus dose and if ACT less than 400 seconds, an additional bolus dose of 0.3 mg/kg should be given at our centre keeping ACT above 480 Seconds.

•Dose reduction is recommended in patients with hepatic or renal failure, critically ill or very high bleeding risk paients.

I think Bivalurudine is a safe alternative to Argatroban in HIT patients. It has a shorter half life of about 30 minutes. Heparin is still the preferred anticoagulant on CPB.