Emboli often have more serious consequences when they occur in the so-called "end circulation": areas of the body that have no redundant blood supply, such as the brain and heart. Venous
Assuming a normal circulation, an embolus formed in a systemic vein will always impact in the lungs, after passing through the right side of the heart. This will form a pulmonary embolism that will result in a blockage of the main artery of the lung and can be a complication of deep-vein thrombosis. The most common sites of origin of pulmonary emboli are the femoral veins. The deep veins of the calf are the most common sites of actual thrombi. Paradoxical (venous to arterial)
In paradoxical embolism, also known as crossed embolism, an embolus from the veins crosses to the arterial blood system. This is generally found only with heart problems such as septal defects  (holes in the cardiac septum) between the atria or ventricles. The most common such abnormality is patent foramen ovale, occurring in about 25% of the adult population, but here the defect functions as a valve which is normally closed, because pressure is slightly higher in the left side of the heart. Sometimes, for example if a patient coughs just when an embolus is passing, it might cross to the arterial system. Direction
The direction of the embolus can be one of two types:
Anterograde
RetrogradeIn anterograde embolism, the movement of emboli is in the direction of blood flow.
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Davidson, G.;  et al. (2008). Abnormal Psychology - 3rd Canadian Edition. Mississauga: John Wiley & Sons Canada, Ltd. p. 412. ISBN 978-0-470-84072-6. Prasad, A.; Oswald, A. G. (1985). "Munchausens syndrome: an annotation". Acta Psychiatrica Scandinavica. 72 (4): 319–22. doi:10.1111/j.1600-0447.1985.tb02615.x. PMID 4072733. S2CID 40707. Leila Schneps and Coralie Colmez (2013). "[Chapter 1:] Math error number 1: multiplying non-independent probabilities. The case of Sally Clark: motherhood under attack". Math on trial. How numbers get used and abused in the courtroom. Basic Books. ISBN 978-0-465-03292-1. Staff, Mayo Clinic (13 May 2011). "Munchausen syndrome". Mayo Foundation for Medical Education and Research. Retrieved 11 April 2013. External links

Article in Discover magazine, July 1993, by Abigail Zuger