You are supposed to form clots only to protect you from bleeding, but any trauma or inflammation in your body can cause clots to form in blood vessels. If a clot breaks off from a blood vessel wall, it can block arteries to cause a heart attack, stroke or pulmonary embolism.

Clots can form wherever your body responds to injury or infection. When germs get into your body, they release chemicals that cause inflammation characterized by redness, itching, swelling, heat and clotting. Certain cells in your body, such as white blood cells and fat cells, also release chemicals that produce inflammation. Anything that damages tissue can cause inflammation, such as trauma, burns, frostbite, irritants such as corrosive chemicals, ultraviolet or other ionizing radiation, dying tissue from any cause such as lack of oxygen in a heart attack, obesity, periodontal disease, smoking, excessive alcohol, gastroesophageal reflux or allergic reactions.

Other factors that can lead to increased risk for clotting include genetic diseases such as Lp(a), dehydration, or physical blockage of arteries that can be caused by sitting in one position for a long time. Any clot has the potential to break off and cause damage, but you lessen your risk of blockage problems if your arteries are pliable and not already partially blocked with plaques.

You may remember when NBC reporter David Bloom died suddenly while he was covering the war in Iraq, from a pulmonary embolism. A clot that formed in his leg broke lose from the vein, and traveled in his bloodstream to his lungs where it blocked the flow of blood to his lungs. He had a pulmonary embolism, a deadly consequence of