within the first 4 1/2 hours, you give interveneous forms of the drug p.t.a., the clot buster.here are certain risk factors for stroke that you cannot do anything about. >> those are age, things like family history. i think that you can't do anything about. >> and obviously your age. >> and your age, of course. >> and what are some of the things that you can change to help prevent a stroke? >> so smoking is one of the main things. if you are smoking you should stop. high blood pressure, which may be referred to as hyper tension. if you get your blood pressure checked, make sure it is under control. high cholesterol, obesity or being overweight are things you can do something about. >> and thinking about some of those things you can't change, it is important to know your family history. >> right, right. absolutely. it is important to know if you have family history of heart disease or stroke, high blood pressure. all those things are important for your stroke risk. >> and if you have a family member who has had a stroke, i think it probably would depend also if their factors wou