Acute venous thromboembolism (VTE), including deep venous thrombosis (DVT) and pulmonary embolism (PE), remains not only the leading cause of hospital death but continues to be a source of significant long-term morbidity (Hull et al, Chest 89:374S–383S, 1986; de Castro Silva et al, Int Angiol 10:152–157, 1991). Acute VTE can present in a multitude of ways and is best regarded as a spectrum of diseases rather than a single disease entity. Clinical manifestations can be varied, and patients can present with asymptomatic DVT, symptomatic DVT, asymptomatic PE, and symptomatic PE that can be mild, submassive, massive, or fatal. Some patients can also present with paradoxical embolism with systemic arterial embolization through a patent foramen ovale (PFO) resulting in stroke, acute limb, or visceral ischemia.