Severe Argatroban-Induced Coagulopathy in a Patient With a History of Heparin-Induced Thrombocytopenia

The Triple HIT: Perioperative Management of Heparin-Induced Thrombocytopenia Using Plasma Exchange, Intravenous Immunoglobulin, and Protamine Infusion for Left Ventricular Assist Device Implantation

Heparin-induced thrombocytopenia (HIT) is a serious complication in patients exposed to heparin, leading to thrombocytopenia and, potentially, thrombosis. This disorder is challenging in cardiac surgery when anticoagulation for cardiopulmonary bypass is required. Herein a patient with HIT who had active thrombosis and successfully underwent urgent left ventricular assist device implantation managed with plasma exchange, intravenous immunoglobulin, and protamine infusion is described. These therapies reduce the immune response to heparin and minimize thrombosis when heparin reexposure is planned. These approaches to perioperative management of HIT represent an attractive alternative to the use of non-heparin anticoagulants in the cardiac and vascular surgical population.

Pediatric Cardiac Intensive Care Society 2014 Consensus Statement: Pharmacotherapies in Cardiac Critical Care Anticoagulation and Thrombolysis

OBJECTIVE

Thrombotic complications are increasingly being recognized as a significant cause of morbidity and mortality in pediatric and congenital heart disease. The objective of this article is to review the medications currently available to prevent and treat such complications.

DATA SOURCES

Online searches were conducted using PubMed.

STUDY SELECTION

Studies were selected for inclusion based on their scientific merit and applicability to the pediatric cardiac population.

DATA EXTRACTION

Pertinent information from each selected study or scientific review was extracted for inclusion.

DATA SYNTHESIS

Four classes of medications were identified as potentially beneficial in this patient group: anticoagulants, antiplatelet agents, thrombolytic agents, and novel oral anticoagulants. Data on each class of medication were synthesized into the follow sections: mechanism of action, pharmacokinetics, dosing, monitoring, reversal, considerations for use, and evidence to support.

CONCLUSIONS

Anticoagulants, antiplatelet agents, and thrombolytic agents are routinely used successfully in the pediatric patient with heart disease for the prevention and treatment of a wide range of thrombotic complications. Although the novel oral anticoagulants have been approved for a limited number of indications in adults, studies on the safety and efficacy of these agents in children are pending.

[Argatroban, a new antithrombotic treatment for heparin-induced thrombocytopenia application in cardiac surgery and in intensive care]

OBJECTIVES

Although heparin-induced thrombocytopemia (HIT) is uncommon, its thromboembolic complications are potentially life-threatening. The low-molecular weight heparins are less responsible of HIT than unfractionated heparin (UFH) but this latter is still indicated in some circumstances such as cardiac surgery. Argatroban, a selective thrombin inhibitor, recently available, has been indicated in HIT treatment. This review presents the main pharmacological characteristics, its indications and uses in the context of cardiac surgery and in intensive care medicine.

METHODS

Review of the literature in Medline database over the past 15 years using the following keywords: argatroban, cardiac surgery, circulatory assistance, cardiopulmonary bypass.

RESULTS

Despite its short-acting pharmacokinetic, argatroban cannot be recommended during cardiopulmonary bypass. On the contrary, argatroban is indicated in many circumstances in postoperative period of various cardiac surgeries (on-pump, off-pump, circulatory assistance). Nevertheless, after cardiac surgery, doses have to be adapted according to coagulation laboratory testing (ACT), particularly in patients presenting acute organ failure (kidney injury, heart failure, liver failure). This compound has no antagonist and is excluded during severe hepatic failure. The continuous intravenous administration is a drawback.

CONCLUSION

Argatroban is a new direct competitive thrombin inhibitor well evaluated as treatment of HIT after cardiac surgery. In HIT management, argatroban is an interesting alternative to lepirudin that is not anymore available and danaparoid because of supply disturbances.

Pathology consultation on monitoring direct thrombin inhibitors and overcoming their effects in bleeding patients

OBJECTIVES

Direct thrombin inhibitors (DTIs), a relatively new class of anticoagulants, present several challenges regarding monitoring of their anticoagulant effects and overcoming bleeding associated with their use. The aim of this article is to (1) briefly present the pharmacologic properties of currently available DTIs, (2) discuss approaches to laboratory assessment of these drugs, and (3) review management of bleeding associated with their use.

METHODS

Published literature on DTIs, including clinical trials, case reports, and experimental animal models, was reviewed. The primary authors also reviewed their first-hand experiences with DTI anticoagulation.

RESULTS

Based on the literature review and the practical experiences of the authors, suggestions for the monitoring of DTIs and algorithmic approaches for the management of DTI-associated bleeding were developed.

CONCLUSIONS

Routine coagulation assays (eg, the prothrombin time) show a relatively poor correlation with the degree of anticoagulation and DTI drug concentrations. Newer assays, such as the ecarin clotting time and dilute thrombin time, may be more useful in assessing DTI anticoagulation, but these assays are not yet widely available. Low-grade DTI-associated bleeds are best managed with cessation of the drug and supportive care, while higher-grade and/or life-threatening bleeds may best be reversed by active drug removal (eg, via the administration of activated charcoal or hemodialysis). At present there is little evidence to suggest that transfusion products such as factor concentrates or thawed plasma are of any particular benefit in DTI reversal; however, these products may play a supportive role in the management of bleeding.

Non-recovery of ACT in a patient with heparin-induced thrombocytopenia type II during mitral valve replacement using argatroban anticoagulation

Argatroban was used as the anticoagulant during cardiopulmonary bypass (CPB) in a patient with heparin-induced thrombocytopenia (HIT) type II undergoing mitral valve replacement. Dosage was reduced because of preoperative congestive liver disorder. Perioperative coagulability was poor, and, ultimately, failure of hemostasis led to a fatal outcome. Although argatroban use as an anticoagulant for HIT is reported, the optimal dose has not been established. During long-term CPB, increasing the total dosage may extend anticoagulant ability, leading to dose dependence. Because no antagonist for argatroban exists, failure of hemostasis might occur.

Specificity and selectivity profile of EP217609: a new neutralizable dual-action anticoagulant that targets thrombin and factor Xa

EP217609 is a new dual-action parenteral anticoagulant that combines an indirect factor Xa inhibitor (fondaparinux analog) and a direct thrombin inhibitor (α-NAPAP analog) in a single molecule together with a biotin tag to allow avidin neutralization. EP217609 exhibits an unprecedented pharmacologic profile in showing high bioavailability, long plasma half-life, and potent antithrombotic activity in animals without the complications of thrombin rebound. Here we report the exceptional specificity and selectivity profile of EP217609. EP217609 inhibited thrombin with rapid kinetics (k(on) > 10(7)M(-1)s(-1)), a high affinity (K(I) = 30-40pM), and more than 1000-fold selectivity over other coagulation and fibrinolytic protease targets, comparing favorably with the best direct thrombin inhibitors known. EP217609 bound antithrombin with high affinity (K(D) = 30nM) and activated the serpin to rapidly (k(ass) ∼ 10(6)M(-1)s(-1)) and selectively (> 20-fold) inhibit factor Xa. The dual inhibitor moieties of EP217609 acted largely independently with only modest linkage effects of ligand occupancy of one inhibitor moiety on the potency of the other (∼ 5-fold). In contrast, avidin binding effectively neutralized the potency of both inhibitor moieties (20- to 100-fold). These findings demonstrate the superior anticoagulant efficacy and rapid avidin neutralizability of EP217609 compared with anticoagulants that target thrombin or factor Xa alone.

Coagulation considerations for infants and children undergoing cardiopulmonary bypass

Cardiac surgery involving cardiopulmonary bypass imposes a significant pathophysiologic burden on patients. Pediatric patients are especially predisposed to the adverse effects of surgery and bypass on the coagulation system, with resultant bleeding, transfusion, and poor outcomes. These risks accrue to pediatric patients in inverse proportion to their weight and are attributable to hematologic immaturity, coagulation defects associated with congenital heart disease, bypass equipment, and the nature of congenital heart surgery. Standard anticoagulation does not completely inhibit thrombin generation, and continuous consumption of coagulation factor continues throughout bypass. Conventional measurements of anticoagulation during bypass poorly reflect this incomplete anticoagulation, and alternate methods may improve anticoagulant therapy. Emerging therapies for blocking the effects of bypass on the coagulation system hold promise for decreasing bleeding and related complications, and improving outcomes in congenital heart surgery.

Prolonged elevation of plasma argatroban in a cardiac transplant patient with a suspected history of heparin-induced thrombocytopenia with thrombosis

BACKGROUND

Direct thrombin inhibitors (DTIs) provide an alternative method of anticoagulation for patients with a history of heparin-induced thrombocytopenia (HIT) or HIT with thrombosis (HITT) undergoing cardiopulmonary bypass (CPB). In the following report, a 65-year-old critically ill patient with a suspected history of HITT was administered argatroban for anticoagulation on bypass during heart transplantation. The patient required massive transfusion support (55 units of red blood cells, 42 units of fresh-frozen plasma, 40 units of cryoprecipitate, 40 units of platelets, and three doses of recombinant Factor VIIa) for severe intraoperative and postoperative bleeding.

STUDY DESIGN AND METHODS

Plasma samples from before and after CPB were analyzed postoperatively for argatroban concentration using a modified ecarin clotting time (ECT) assay.

RESULTS

Unexpectedly high concentrations of argatroban were measured in these samples (range, 0-32 microg/mL), and a prolonged plasma argatroban half life (t(1/2)) of 514 minutes was observed (published elimination t(1/2) is 39-51 minutes [< or = 181 minutes with hepatic impairment]).

CONCLUSIONS

Correlation of plasma argatroban concentration versus the patient's coagulation variables and clinical course suggest that prolonged elevated levels of plasma argatroban may have contributed to the patient's extended coagulopathy. Because DTIs do not have reversal agents, surgical teams and transfusion services should remain aware of the possibility of massive transfusion events during anticoagulation with these agents. This is the first report to measure plasma argatroban concentration in the context of CPB and extended coagulopathy.

[Direct thrombin inhibitors: pharmacology and application in cardiovascular anesthesia]

The options for drug-controlled anticoagulation are becoming noticeably more manifold. In the area of anaesthesiology and intensive care, there are furthermore special disease patterns, such as heparin-induced thrombocytopenia (HIT) to be known, diagnosed and treated. This article gives a review of the substance groups of the direct thrombin inhibitors (DTI) as alternative anticoagulants for HIT in combination with cardiovascular diseases. For the administration of DTIs, experience and the correct dose are the keys to success and are the deciding factors for the two sides of haemostasis: thrombosis and haemorrhage.

[Argatroban: pharmacological properties and anaesthesiological aspects]

Argatroban is a direct, selective and reversible active site thrombin inhibitor derived from L-arginine. It is a representative of a new class of antithrombotic drugs which offer inhibition of clot-bound as well as fluid-phase thrombin. Argatroban is characterised by favourable pharmacokinetics (beta-elimination half-time approximately 40-50 min) undergoing hepatic metabolism and mainly biliary excretion. Renal impairment will not result in altered or delayed elimination. For many years, argatroban has been used in Japan and in the United States and is approved by the FDA for anticoagulation in patients with heparin-induced thrombocytopenia (HIT type II). The ease of monitoring with the activated partial thromboplastin time, lack of induction of antibodies and adequate safety in renal failure patients, make this drug a favourable mode therapy in comparison with other anticoagulants such as lepirudin or heparinoids. Since June 2005 argatroban has been approved in Germany for the treatment of patients with HIT type II. The main characteristics of the drug with special considerations for anaesthesiologists and intensive care physicians are presented in this review.

Reducing thrombotic complications in the perioperative setting: an update on heparin-induced thrombocytopenia

Heparins are widely used in the perioperative setting. Immune heparin-induced thrombocytopenia (HIT) is a serious, antibody-mediated complication of heparin therapy that occurs in approximately 0.5%-5% of patients treated with heparin for at least 5 days. An extremely prothrombotic disorder, HIT confers significant risks of thrombosis and devastating consequences on affected patients: approximately 38%-76% develop thrombosis, approximately 10% with thrombosis require limb amputation, and approximately 20%-30% die within a month. HIT antibodies are transient and typically disappear within 3 mo. In patients with lingering antibodies, however, re-exposure to heparin can be catastrophic. In the perioperative setting, heightened awareness is important for the prompt recognition, diagnosis, and treatment of HIT. HIT should be considered if the platelet count decreases 50% and/or thrombosis occurs 5-14 days after starting heparin, with other diagnoses excluded. On strong clinical suspicion of HIT, heparin should be discontinued and a parenteral alternative anticoagulant initiated, even before laboratory confirmation of HIT is obtained. Subsequent laboratory test results may help with the decision to continue with nonheparin therapy or switch back to heparin. Heparin avoidance in patients with current or previous HIT is feasible in most clinical situations, except perhaps in cardiovascular surgery. If the surgery cannot be delayed until HIT antibodies have disappeared, intraoperative alternative anticoagulation is recommended.

Argatroban for anticoagulation during cardiac surgery

BACKGROUND

The aim of this study was to report our experience and review the published data on argatroban administration during adult cardiac surgery.

METHODS

The information on all reported cases of argatroban use in adults, during cardiac surgery was reviewed, including that of the patient described here. This analysis focused on patient characteristics, type of surgery, argatroban dosing schedule, monitoring of anticoagulation and outcomes.

RESULTS

Twenty-one cases have been reported. Fifteen patients underwent off-pump surgical procedures with the argatroban dose adjusted to maintain an activated clotting time (ACT) range between 200 and 300 s. Three intraoperative thrombi occurred in two patients when the ACT was <280 s. None had coagulopathy. Six cases reported the use of argatroban during on-pump cardiac surgery dosed to keep the ACT >400 s. Intraoperative thrombotic complications were not reported in this group; however, one clot in the pump was noted after the procedure when the ACT was between 300 and 350 s. All six cases required larger volumes of perioperative blood products and three had severe coagulopathy. Of the 21 cases, seven had an indication for continued anticoagulation following surgery. Four cases did not report further use of argatroban after surgery. Three patients received argatroban after surgery without complications. Recommendations for how to use argatroban during cardiac surgery are proposed.

CONCLUSIONS

Argatroban, with ACT monitoring, might be safely used for anticoagulation during cardiac surgery.

Hydroxyethyl starch enhances argatroban-mediated decreases in clot propagation and strength by diminishing thrombin–fibrinogen interactions

Direct thrombin inhibitors (DTIs) have been administered for anticoagulation during cardiopulmonary bypass for patients with heparin-induced thrombocytopenia. While DTIs prolonged clot initiation and decreased clot propagation, clot strength did not change. Hydroxyethyl starches (HES), however, significantly decreased clot propagation and strength. We hypothesized that DTI with HES could significantly decrease hemostasis more than DTI alone. Plasma was exposed to 0 or 5 microg/ml argatroban with 0 or 30% dilution with 0.9% NaCl, 10% pentastarch or 6% Voluven. Additional argatroban-exposed samples diluted with HES had addition of alpha-thrombin (0.25 U/ml) and fibrinogen (150 mg/ml). Clot kinetics were determined via thrombelastography. While dilution with 0.9% NaCl significantly (P < 0.05) decreased the clot strength by 17% compared with samples only exposed to argatroban, dilution with pentastarch and Voluven significantly (P < 0.05) markedly decreased clot strength (53 and 78%, respectively). Voluven dilution significantly increased the time to clot initiation and decreased the velocity of clot propagation compared with samples only exposed to argatroban. Addition of alpha-thrombin/fibrinogen restored clot strength. DTI/HES administration diminished hemostasis to a greater extent than DTI exposure alone. Further investigation is warranted to determine whether this therapeutic approach can improve the safety of anticoagulation during cardiopulmonary bypass in patients with heparin-induced thrombocytopenia.

Cardiopulmonary Bypass for Complex Cardiac Surgery using Bivalirudin Anticoagulation in a Patient with Heparin Antibodies

BACKGROUND

The presence of antibodies directed against heparin necessitates the use of an alternative anticoagulant in patients undergoing cardiac surgery. Bivalirudin is a short-acting direct thrombin inhibitor that has been used successfully in routine cardiac surgical cases. Experience in complicated cases requiring extended cardiopulmonary bypass is limited, however. We report the successful use of bivalirudin in a patient who underwent complex cardiac surgery.

METHOD

A 42-year-old patient with aortic regurgitation due to endocarditis who had heparin antibodies underwent a Ross procedure for aortic valve replacement using bivalirudin as anticoagulant during cardiopulmonary bypass (CPB). Bivalirudin was given with a bolus of 1 mg/kg and a continuous infusion of 2.5 mg/kg/hours during CPB. Monitoring of bivalirudin was performed using the ecarin clotting time (ECT).

RESULTS

After 128 minutes of extracorporeal circulation, the patient was weaned from CPB without problems. After termination of CPB, modified ultrafiltration (MUF) was commenced. Perioperatively, six units of fresh frozen plasma were transfused. The 12-hour postoperative blood loss was 550 mL. The postoperative course was uneventful and the patient was discharged from hospital after 5 days.

CONCLUSION

Bivalirudin can be safely used for anticoagulation during CPB even in complex cardiac surgery.