Graham's death sparks questions on cardiac arrest that is caused by an electrical malfunction in the heart that disrupts its pumping action. The heart then stops beating.

Sen. Lindsey Graham died at 71 of an aortic dissection due to arteriosclerotic cardiovascular disease. An ER doctor explains why it kills so fast and the warning signs.

Graham's death sparks questions on cardiac arrest that is caused by an electrical malfunction in the heart that disrupts its pumping action. The heart then stops beating.

Many colleagues reacted to the news of the South Carolina Republican's death, calling him a friend and American patriot.