injury that's going to happen from the stroke is going to depend how long the blood vessel the blood vessel is blocked by the clot and how good the collateral flow is right so if you have other blood vessels who are helping out then the stroke will progress much more slowly so again we hope that we have good collateral flow if we ever have a stroke we also hope that that clot can be dissolved quickly so TPA stands for tissue plasminogen activator and what that is is that in everybody's blood they have something called plasminogen