Clots can block the flow of blood to the heart or brain and cause a heart attack or stroke.

VOA: special.2009.10.20

The World Health Organization says passengers who sit still for four or more hours face a greater risk of developing blood clots.

VOA: special.2009.07.14

Many people take aspirin to reduce the risk of a heart attack or stroke from blood clots.

VOA: special.2009.10.20

He thought that this effect might help prevent heart attacks caused by blood clots.

VOA: special.2009.10.20

Scientists say aspirin prevents blood cells called platelets from sticking together to form clots.

VOA: special.2009.10.20

A drug called tissue plasminogen activator, or tPA,can break up blood clots.

VOA: special.2009.09.22

A drug called tPA can break up blood clots.

VOA: special.2009.08.12

Plaque inside the artery can restrict blood flow, and makes blood clots more likely.

VOA: standard.2010.03.04

Blood clots can block an artery and cause a heart attack.

VOA: standard.2010.03.04