Deep vein thrombosis of the legs (DVT) > Pulmonary embolism (PE) > elevation of pressure in the lung arteries (pulmonary Hypertension)

Deep leg vein thrombosis (DVT) is a serious condition, where a clot forms in a deep leg vein, usually in a deep calf vein.

Immobilization of the legs for longer than 4 hours, such as during a long haul flight for example, may be the mere trigger. However, a "hypercoagulable condition" (Increased blood clotting tendency), either inherited or acquired, may be the underlying initial pathology leading to clot formation within the blood vessels.

The risk of DVT is that the clot that had formed in a leg vein, may partially or completely dislodge and get flushed by the venous blood stream back to the heart and ultimately to the lungs, precipitating a potentially lethal condition called pulmonary embolism.

A large clot (embolus) may completely block a large lung artery, causing immediate death. Whereas, smaller clots (emboli) may cause only minimal symptoms and occasionally no symptoms at all. However, if smaller emboli recur again and again, they may at the end close many small lung vessels, leading to an abnormal elevation of pressure in the lung vessels, causing a ondition called pulmonary hypertension. This would ultimately lead to shortness of breath and eventually to failure of the right heart chamber leading to sudden death. Early diagnosis and treatment of this condition and proper identification of an underlying hypercoagulable condition may avoid irreversible damage to the heart and lungs.