Pulmonary Embolism (PE)
� Obstruction of the pulmonary artery or one of its branches by material (thrombus, tumor,
air, fat) that originated elsewhere in the body. (UpToDate)
Overview
● Common and potentially lethal condition that can cause death in all age groups
● The diagnosis can be missed, because pulmonary embolism frequently causes only vague
and nonspecific symptoms
● The "classic" presentation with abrupt onset of pleuritic chest pain, shortness of breath,
and hypoxia is rarely the case
● Studies of patients who die unexpectedly of pulmonary embolism reveal that they
complained of nagging symptoms often for weeks before death related to pulmonary
embolism
Pathophysiology
Patho of a PE
, ● It is a complication of underlying venous thrombosis
● Under normal conditions, microthrombi (tiny aggregates of red cells, platelets, and fibrin)
are formed and lysed continually within the venous circulatory system
● Under pathological conditions, microthrombi may escape the normal fibrinolytic system
to grow and propagate
● Pulmonary embolism (PE) occurs when these propagating clots break loose and embolize
to block pulmonary blood vessels
● Thrombosis in the veins is triggered by venostasis, hypercoagulability, and vessel wall
inflammation
● These 3 underlying causes are known as the Virchow triad
● All known clinical risk factors for DVT and PE have their basis in one or more elements
of the triad
Risk factors for a PE
● Those factors that increase immobility (venous stasis)
○ Bed rest, post-op period, obesity, stroke, other neurologic or musculoskeletal
disorders
○ Those factors that increase blood viscosity
○ Pregnancy, polycythemia, low cardiac output
○ Hypercoagulable states
○ Hormone therapy, malignancy, hematologic disorders
Hereditary Blood Disorders causing hypercoaguability
○ Antithrombin III deficiency
○ Protein C deficiency
○ Protein S deficiency
○ Factor V Leiden (most common genetic risk factor for thrombophilia)
■ Activated protein C (aPC) is a natural anticoagulant that acts to limit the
extent of clotting by cleaving and degrading factor V.
■ Factor V Leiden is an autosomal dominant condition that exhibits
incomplete dominance and results in a factor V variant that cannot be as
easily degraded by aPC (activated Protein C)
� Obstruction of the pulmonary artery or one of its branches by material (thrombus, tumor,
air, fat) that originated elsewhere in the body. (UpToDate)
Overview
● Common and potentially lethal condition that can cause death in all age groups
● The diagnosis can be missed, because pulmonary embolism frequently causes only vague
and nonspecific symptoms
● The "classic" presentation with abrupt onset of pleuritic chest pain, shortness of breath,
and hypoxia is rarely the case
● Studies of patients who die unexpectedly of pulmonary embolism reveal that they
complained of nagging symptoms often for weeks before death related to pulmonary
embolism
Pathophysiology
Patho of a PE
, ● It is a complication of underlying venous thrombosis
● Under normal conditions, microthrombi (tiny aggregates of red cells, platelets, and fibrin)
are formed and lysed continually within the venous circulatory system
● Under pathological conditions, microthrombi may escape the normal fibrinolytic system
to grow and propagate
● Pulmonary embolism (PE) occurs when these propagating clots break loose and embolize
to block pulmonary blood vessels
● Thrombosis in the veins is triggered by venostasis, hypercoagulability, and vessel wall
inflammation
● These 3 underlying causes are known as the Virchow triad
● All known clinical risk factors for DVT and PE have their basis in one or more elements
of the triad
Risk factors for a PE
● Those factors that increase immobility (venous stasis)
○ Bed rest, post-op period, obesity, stroke, other neurologic or musculoskeletal
disorders
○ Those factors that increase blood viscosity
○ Pregnancy, polycythemia, low cardiac output
○ Hypercoagulable states
○ Hormone therapy, malignancy, hematologic disorders
Hereditary Blood Disorders causing hypercoaguability
○ Antithrombin III deficiency
○ Protein C deficiency
○ Protein S deficiency
○ Factor V Leiden (most common genetic risk factor for thrombophilia)
■ Activated protein C (aPC) is a natural anticoagulant that acts to limit the
extent of clotting by cleaving and degrading factor V.
■ Factor V Leiden is an autosomal dominant condition that exhibits
incomplete dominance and results in a factor V variant that cannot be as
easily degraded by aPC (activated Protein C)
