Pulmonary embolism

Untreated, the risk of symptomatic pulmonary embolism (PE) in the presence of deep venous thrombosis (DVT) is about 10%. The incidence of asymptomatic PE is presumed to be much higher. In one study, nearly 40 % of patients who had DVT but no symptoms of PE had evidence of PE on scintigraphic lung scanning.
DVT and PE should be considered part of the same pathological process. As thrombi extend into the wider parts of the deep veins, they may dislodge and embolize to the pulmonary arteries with potential serious consequences. Due to vasoactive substances released by platelets and due to the arterial obstruction, the vascular resistance of the pulmonary system increases. Reflex bronchoconstriction augments airway resistance, and lung edema increases pulmonary resistance. Altogether, the right sided blood flow becomes increasingly impaired being responsible for the seriousness of PE.
For further information regarding PE refer to guidelines.