Embolism

EMBOLISM

An embolism is any intravascular mass that has been carried down the bloodstream from its site of origin, resulting in the occlusion of a vessel. There are many types of emboli:

·            Thromboemboli: most common (98%)

·            Atheromatous emboli (severe atherosclerosis)

·            Fat emboli (bone fractures and soft tissue trauma)

·            Bone marrow emboli (bone fractures and cardiopulmonary resuscitation [CPR])

·            Gas emboli cause decompression sickness (“the bends” and caisson disease) when rapid ascent results in nitrogen gas bubbles in the blood vessels

·            Amniotic fluid emboli are a complication of labor that may result in DIC; fetal squamous cells are seen in the maternal pulmonary vessels

·            Tumor emboli (metastasis)

·            Talc emboli (IV drug abuse)

·            Bacterial/septic emboli (infectious endocarditis)

Pulmonary emboli (PE) are often clinically silent and are the most commonlymissed diagnosis in hospitalized patients. They are found in almost 50% of all hos-pital autopsies. Most PE (95%) arise from deep leg vein thrombosis (DVT) in the leg; other sources include the right side of the heart and the pelvic venous plexuses of the prostate and uterus.

Diagnosis of a PE can be established when V/Q lung shows a scan V/Q mismatch. Doppler ultrasound of the leg veins can be used to detect a DVT. Additionally, plasma D-dimer ELISA test is elevated.

Most cases are clinically silent and resolve.

Infarction is more common in patients with cardiopulmonary compromise. Symp-toms include shortness of breath, hemoptysis, pleuritic chest pain, and pleural effu-sion. On gross examination there is typically a hemorrhagic wedge-shaped infarct. The infarction heals by regeneration or scar formation.

·            Sudden death can occur when large emboli lodge in the bifurcation (saddle embolus) or large pulmonary artery branches.

·            Chronic secondary pulmonary hypertension is caused by recurrent PEs, which increase pulmonary resistance and lead to secondary pulmonary hypertension.