Management of acquired thrombophilic disorders in 2011: focus on heparin-induced thrombocytopenia, antiphospholipid syndrome, myeloproliferative neoplasms and paroxysmal nocturnal hemoglobinuria.

Arterial and venous thrombosis are interrelated disorders at the interplay of platelets and fibrin. Arterial thrombi are platelet-rich and occur at sites vulnerable to atherosclerotic plaque rupture where blood shear rates are high; on the contrary, venous thrombi occur in association with slow blood flow and shear rates. These differences may underlie why anti-platelet agents are more effective in prevention of arterial thrombosis, while anticoagulants are preferred for venous thrombosis. Although some common thrombophilic disorders (e.g., Factor V Leiden, prothrombin gene mutation, etc.) are almost exclusively associated with venous thromboembolism, there are several disorders that are important to consider when caring for patients with both arterial and venous thromboembolism. This article will review the evidence-based management of heparin induced thrombocytopenia with thrombosis, anti-phospholipid antibody syndrome and catastrophic anti-phospholipid antibody syndrome, thrombohemorrhagic manifestations of Philadelphia chromosome-negative chronic myeloproliferative neoplasms including polycythemia vera, essential thrombocythemia and primary myelofibrosis, as well as paroxysmal nocturnal hemoglobinuria.