Vascular obstruction

The embolus makes its way either in the form of a single bubble; a string of bubbles; or even as a foamy mixture if it has been mixed by cardiac action. As the size of the blood vessel decreases, the resistance to flow increases and the embolus is slowed, deformed into a cylinder shape, and eventually stopped as the increase in friction ultimately overcomes perfusion pressure - causing downstream ischemia18. Only certain bubbles get through capillaries towards veins. This depends on their volume, the vascular diameter and perfusion pressure overcoming the resistance19.

The severity of the ischemia caused in the downstream depends to a large extent on whether the circulation is endarterial or if there is collateral supply20.

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