Paradoxical embolism

A paradoxical embolism refers to an embolus that is carried from the venous side of circulation to the arterial side or vice versa. It is a kind of stroke or another form of arterial thrombosis caused by embolism of a thrombus (blood clot), air, tumor, fat, or amniotic fluid of venous origin, which travels to the arterial side through a lateral opening in the heart, such as a patent foramen ovale,[1] or arteriovenous shunts in the lungs.

Paradoxical embolism
Other namesCrossed embolism
SpecialtyCardiology 

The opening is typically an atrial septal defect, but can also be a ventricular septal defect. Other conditions that can cause paradoxical embolism includes pulmonary arteriovenous malformations, and patent foramen ovale.[2]

Paradoxical embolisms represent two per cent of arterial emboli.[3]

Pathophysiology

Passage of a clot (thrombus) from a systemic vein to a systemic artery. When clots in systemic veins break off (embolize), they travel first to the right side of the heart and, normally, then to the lungs where they lodge, causing pulmonary embolism. On the other hand, when there is a hole at the septum, either upper chambers of the heart (an atrial septal defect) or lower chambers of the heart (ventricular septal defects), a clot can cross from the right to the left side of the heart, then pass into the systemic 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).

Diagnosis

CT angiography; bubble echocardiography may also be used to detect a patent foramen ovale.

Treatment

Therapeutic preventional anticoagulation is the first line if correction of the underlying anatomical pathology is not already done, by using Heparin or other anticoagulative agents. This approach is also used in the treatment of a present embolism, albeit at higher doses. Once these are exhausted or the use of therapeutic anticoagulation is contraindicated (for example, in a co-occurring traumatic hemorrhage), mechanical thrombectomy may be used to physically remove the embolism from the blocked artery.

References
  1. Rakhit RD (November 2003). "Case 2: Patent foramen ovale (PFO) and paradoxical embolism". Heart. 89 (11): 1362. doi:10.1136/heart.89.11.1362. PMC 1767929. PMID 18069145.
  2. https://www.ncbi.nlm.nih.gov/books/NBK470196/. "Paradoxical Embolism". NCBI. Retrieved 28 April 2021.
  3. Tang CE (January 2004). "Paradoxical embolism: a rare life- and limb-threatening emergency". CJEM. 6 (1): 40–4. doi:10.1017/S1481803500008897. PMID 17433144.
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