Thrombosis related to emergency factor VIIa treatment

Use of Recombinant Activated Factor VII after Axillofemoral Bypass Grafting

Recombinant activated factor VII (rFVIIa) is a powerful prohaemostatic agent that theoretically predisposes to thrombosis after peripheral vascular surgery. We report the use of rFVIIa to reduce bleeding in a patient after axillofemoral bypass grafting for ruptured aorto-iliac pseudoaneurysm. Despite the increased risk of thrombosis, the patient made an uneventful recovery with preserved graft patency. The favourable result suggests that rFVIIa should be considered even in vascular surgical patients, if the risks of continued bleeding outweigh those of thrombosis. Better risk estimation is only possible if reports of rFVIIa use in vascular patients continue to appear and through controlled trials.

Vascular Injury and Thrombotic Potential: A Note of Caution About Recombinant Factor VIIa

Postoperative hemorrhage following cardiac surgery increases morbidity, mortality, and costs. Several case reports have described the successful use of recombinant factor VIIa to decrease or stop bleeding in patients undergoing cardiac surgery. The mechanism of action of recombinant factor VIIa is thought to be increased site-specific thrombin generation by tissue factor—mediated activation of coagulation or from activated platelets. However, there have also been many reports of thrombotic complications after recombinant factor VIIa administration. Randomized clinical trials and further laboratory studies should help better clarify the efficacy, safety, cost-effectiveness, and optimal dosing of recombinant factor VIIa in the cardiac surgical setting.

Probable right atrial thrombus immediately after recombinant activated factor VII administration

We report the finding of a probable right atrial thrombus in a 33-yr-old male patient with severe head, chest, and abdominal trauma. Refractory coagulopathy and gross haemodynamic instability ensued, which was only partially controlled with massive blood product transfusion and high-dose inotropic support during laparotomy. Continuous transoesophageal echocardiography revealed a probable atrial thrombus partially occluding the right ventricular inflow tract, which appeared immediately after the patient received 100 microg kg(-1) of recombinant activated factor VII (rFVIIa) via a left internal jugular central line. This is the first report documenting an immediate temporal relationship between rFVIIa administration and a space-occupying lesion compatible with localized thrombosis, despite ongoing severe systemic coagulopathy. We review the clinical use of rFVIIa and discuss possible factors contributing to this event.

Uses of recombinant factor VIIa in trauma

PURPOSE OF REVIEW

Despite advances in the care of the injured, the morbidity and mortality of traumatic hemorrhage remain a significant problem. Traumatologists continue to look for ways to treat bleeding and prevent the sequelae of hemorrhagic shock. Recombinant factor VIIa, developed for the treatment of patients with hemophilia, has been used with some success in acute bleeding associated with injuries.

RECENT FINDINGS

The mechanism of action is via a tissue factor-dependent effect and/or platelet activation. Coagulation occurs at the site of tissue injury, where tissue factor is exposed. Case series have described the beneficial effects of recombinant factor VIIa in the treatment of acute hemorrhage, early treatment of traumatic brain injury, and reversal of premorbid anticoagulation. In addition, there have been numerous reports of recombinant factor VIIa use in acute bleeds secondary to other causes as well as some evidence that recombinant factor VIIa may be efficacious when used prophylactically in high-risk patients and for high-risk procedures. Typical doses range from 50 to 100 microg/kg as a single bolus. Although there has been concern over the risk of inappropriate thrombosis with recombinant factor VIIa administration, this complication has seldom been described in published series.

SUMMARY

Although case experience is encouraging, no level 1 evidence has been published that demonstrates clinical or economic benefit of the use of recombinant factor VIIa in trauma patients. Many questions remain to be answered, ideally through randomized, prospective clinical trials. In particular, the issues of patient selection, ideal dosing, and factors associated with futile administration need to be elucidated.

Managing Complications of Anticoagulant Therapy

Understanding the frequency, risk factors, and management of anticoagulant-induced adverse events will assist clinicians in optimizing patient outcomes. The most frequent adverse event of all anticoagulants is major bleeding. Risk factors for major bleeding have been identified with the heparin compounds, the direct thrombin inhibitors (DTIs), fondaparinux, and warfarin therapy. Understanding these risk factors can help prevent bleeding events. For cases of clinically significant bleeding, reversal agents exist primarily for heparin and warfarin. Although less common, nonbleeding adverse events of anticoagulant therapy can also be life threatening. The heparin compounds are associated with the development of heparin-induced thrombocytopenia (HIT) and osteoporosis. HIT can result in life-threatening thrombosis and is usually managed with a DTI. Nonbleeding adverse events with warfarin therapy include skin reactions and the development of venous limb gangrene. Appropriate initiation of warfarin therapy may decrease the risk of venous limb gangrene.

Recombinant factor VIIa

Human coagulation factor (F) VII is a single chain protease that circulates in the blood as a weakly active zymogen at concentrations of approximately 10 nmol/L. When converted to the active 2 chain form (FVIIa), it is a powerful initiator of haemostasis. Recombinant factor VIIa (rFVIIa, eptacog alfa, NovoSeven) is a genetically engineered product that was first introduced in 1988 for the treatment of patients with haemophilia A and B with high inhibitory antibody titres to factors VIII and IX. Recent reports in the form of case studies and series, and early trial data, have suggested a role for rFVIIa across a diverse range of indications including bleeding associated with trauma, surgery, thrombocytopaenia, liver disease and oral anticoagulant toxicity. This review describes the physiology of the coagulation pathway and in particular the role of recombinant factor VIIa. It will also focus on the emerging role of rFVIIa in both trauma and non-trauma bleeding and its potential use in the ED.