[Pathophysiology of pulmonary embolism]

Massive pulmonary embolism causes an acute pressure overload for the right ventricle associated with a drop in cardiac output leading, if untreated, to cardiogenic shock. Main symptoms of acute pulmonary embolism comprise dyspnea, hyperventilation, tachycardia, hypotension and cyanosis, which are the consequences of tissue hypoxia caused by hypoperfusion. Mild to moderate arterial hypoxemia, which is observed in most of the cases, can be explained by intrapulmonary venous admixture.