Thrombosis Knowledge Centre

Venous Thromboembolism

Pulmonary Embolism

Pulmonary embolism (PE) corresponds to an obstruction of part of the pulmonary vascular tree, usually caused by a thrombus that has travelled from a distant site, e.g. the deep veins in the leg or the pelvic region. Large thrombi may lodge at the bifurcation of the main pulmonary arteries, causing haemodynamic compromise. Smaller thrombi travel more distally, infarcting the lung and causing pleuritic pain.

Proximal DVT (above the knee) are more prone to embolise than distal DVT (below the knee).

Consequences of PE are:

Increased pulmonary vascular resistance
Impaired gas exchange
Right-ventricular dysfunction which may ultimately lead to circulatory arrest and death

Pulmonary embolism

Clinical symptoms and signs of PE are unspecific and unreliable:

Massive PE: severe hypoxaemia, cardiovascular collapse, death
Non-massive PE: pleuritic chest pain, haemoptysis, respiratory failure
Silent PE: up to 50% of patients with symptomatic DVT may have asymptomatic PE
Less than a third of patients with PE exhibits signs or symptoms of DVT