Embolism, paradoxical: Passage of a clot (thrombus) from a vein to an artery. When clots in veins break off (embolize) , they travel first to the right side of the heart and, normally, then to the lungs where they lodge. The lungs act as a filter to prevent the clots from entering the arterial circulation. However, when there is a hole in the wall between the two upper chambers of the heart (an atrial septal defect), a clot can cross from the right to the left side of the heart, then pass into the arteries as a paradoxical embolism. Once in the arterial circulation, a clot can travel to the brain, block a vessel there, and cause a stroke (cerebrovascular accident). Because of the risk of stroke from paradoxical embolism, it is usually recommended that even small atrial septal defects be repaired. Also called crossed embolism.
- Embolism, pulmonary
Embolism, pulmonary: The obstruction of the pulmonary artery or a branch of it leading to the lungs by a blood clot, usually from the leg, or foreign material causing sudden closure of the vessel. (Embolus is from the Greek “embolos” meaning plug.) The risk factors for pulmonary embolism include advanced age, cancer, genetic predisposition, immobilization […]
Embolization: A treatment that clogs small blood vessels and blocks the flow of blood, such as to a tumor.
Embolus: A blockage or plug that obstructs a blood ‘vessel. Examples of emboli are detached blood clots, clumps of bacteria, and clumps of other foreign material, such as air.
Embryo: An organism in the early stages of growth and differentiation, from fertilization to the beginning of the third month of pregnancy (in humans). After that point in time, an embryo is called a fetus.
- Embryonic hemoglobin
Embryonic hemoglobin: Hemoglobin E, the normal embryonic hemoglobin, the main type of hemoglobin found in the human embryo. The E stands for embryonic and also for epsilon, the chain unique to embryonic hemoglobin (which was originally known as Gower-2).