ABSTRACT
Venous thrombosis, including deep vein thrombosis (DVT) and pulmonary embolism (PE), occurs at an annual incidence of about 1 per 1000 adults. Rates increase sharply aer around age 45 years and are slightly higher in men than women of older age. Risk factors, other than age, include surgery, hospitalizations, immobility, trauma, pregnancy, hormone use, cancer, obesity and inherited disorders1 (see Table 45.1). DVT usually starts in the lower extremities, with the calf veins, oen extending into the proximal veins. e DVT may subsequently break free to cause pulmonary emboli. Other major outcomes are death, recurrence, post-thrombotic syndrome (PTS) and major bleeding due to anticoagulation. rombosis is also associated with impaired quality of life particularly when PTS develops.2,3 With DVT, death is reported within one month at 6% and 10% for those with PE.4 e morbidity impact of thrombosis on the elderly appears to be greater, with a steeper rise in the incidence of PE compared to DVT with aging.1,5 e development of symptoms depends on the extent of thrombosis, the adequacy of collateral vessels and the severity of associated disease.6,7
It was Baille who perhaps rst noted the importance of ‘stasis’ or reduced blood ow as a cause of thrombosis, and Rokitansky subsequently reported that thrombosis occurred in a vein at the site of an injury or adjacent to
inammation. Hunter noted the role of inammation and infection as causes of thrombi. In 1856, German physician Rudolf Virchow’s detailed pathological studies postulated that thrombosis may be caused by a slowing or cessation of blood ow (stasis), increased thrombotic potential of the blood (hypercoagulability) and abnormalities in the vessel wall.8 Today, these ndings are referred to as ‘Virchow’s triad’ (Figure 45.1). Oschner and DeBakey reported that DVT was common aer surgical operations and advocated its avoidance and treatment by vein ligation or anticoagulants to prevent PE.9 Homans had previously advocated vein ligation to prevent PE as a consequence of DVT. He also recognized that the post-thrombotic leg was an important cause of venous ulceration.10 Homans, Bauer and Linton advocated ligation of the deep veins in patients with post-thrombotic limbs to prevent venous reux and reduce the risk of recurrent venous ulceration.11,12
In 1966, John Gay recognized clot and thrombi in the deep veins of many of the limbs he dissected with venous ulcers, and he was also the rst person to recognize the importance of the calf-perforating veins and lipodermatosclerosis.13
