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.
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 hospital 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. Symptoms include shortness of breath, hemoptysis, pleuritic chest pain, and pleural effusion. 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.