Thrombosis

Excerpt

Thrombosis is the formation of a blood clot within arterial or venous blood vessels, limiting the natural flow of blood. The ability of blood to flow freely in vessels relies on a complex homeostasis between blood cells, platelets, plasma proteins, coagulation factors, inflammatory factors, and the endothelial lining within the arterial and venous lumens. Imbalances in this physiologic process cause an increased risk of developing a thrombosis or a coagulopathy. In certain clinical circumstances, patients can be at increased risk of both thrombosis and bleeding (eg, disseminated intravascular coagulopathy or underlying malignancy). As such, the diagnosis and management of thromboses are complex. Thrombosis can arise in any organ system, and clinical presentations can vary depending on underlying comorbidities and provoking factors.

Management decisions take into account whether the thrombosis is venous or arterial, acute or chronic, and if it is an initial or subsequent episode. Other contributing factors are family history, smoking history, and hemodynamic stability. The use and duration of anticoagulation or antiplatelet therapy depends on a careful evaluation of these factors. Furthermore, a decision to pursue an exhaustive hypercoagulable workup to evaluate for inherited or acquired conditions that predispose to thrombosis is controversial. Evaluation should be completed in selected patients and with hematologist input.

Together, acute venous and arterial thromboses account for the most common causes of death in developed countries, with myocardial infarction (MI) and cerebrovascular accident (CVA) accounting for the highest proportion of thrombosis-associated death in the United States. An understanding of the basic pathophysiology of thrombosis and provoking risk factors can aid clinicians in the diagnosis, workup, and management of this condition.

There are also many unique presentations that add complexity to diagnosis and treatment decisions, such as in acquired antiphospholipid syndrome (APS) or in heparin-induced thrombocytopenia and thrombosis (HITT). As such, many of these case- or disease-specific details and management aspects are beyond the scope of this review article. Readers are encouraged to consult additional references for further reading, including regularly updated subspecialty society guidelines (eg, American Society of Chest Physicians, American Heart Association, and American Society of Hematology). This review will focus primarily on the basic pathophysiology of venous and arterial thrombosis, including an assessment of risk factors, diagnostic workup, and management of venous and arterial thrombosis.