Massive Pulmonary Embolism: Its Fatal Hemodynamic Consequences

Massive pulmonary embolism (PE) is distinct from submassive PE by hemodynamic compromise secondary to mechanical obstruction. Present literature defines massive PE based on occlusion area, which may or may not be proportional to hemodynamic changes, depending on the status of cardiopulmonary reserve in a particular patient. The pathophysiology of massive PE is characterized by a sudden elevation in the afterload to right ventricle (RV) from obstruction of pulmonary vasculature, which causes RV ischemia and dysfunction. The acutely dilated RV displaces the interventricular septum toward the left ventricle (LV) and in turn leads to LV compression and shock. Accordingly, the principles of management of massive PE are to reverse obstruction, maintain perfusion pressure to the right coronary artery, and be cautious with fluid resuscitation. Thrombolysis has been proven effective in resolving the embolus and in improving pulmonary blood flow. Previous studies on thrombolysis for PE have not documented mortality benefit. However, these studies included all cases of PE, among whom most had submassive PE, which is of low mortality. Presently, management of massive PE has to be individualized in that a clear understanding of its hemodynamic consequences is critical to guide clinical decision.