There are many acute and sudden events that can be catastrophic. The first of these to come to mind would be a heart attack where the heart is suddenly deprived of the needed oxygen and other nutrients because of a sudden blockage of one or more of the coronary arteries feeding it.
Just as potentially catastrophic and deadly is an event called a pulmonary embolism or PE. A pulmonary embolism occurs when a large blood clot usually from the leg breaks off and travels to the lungs and lodges in one of the large blood vessels of the lungs called pulmonary arteries. Unlike a heart attack, a pulmonary embolism does not cause its potential life threating consequences by depriving the lungs of oxygen.
The serious problems caused by a large blood clot in the lungs are due to several things mostly related around the increased stress on the right side of the heart which is the chamber that pumps the blood through the lungs. This blockage may lead to irregular heart rhythms and failure of the right side of the heart to be able to pump at all.
Symptoms of a pulmonary embolism may include sudden shortness of breath, chest pain and marked irregular heart rhythm.
The problem really stems from the clots that form in the legs because of inactivity or some other underlying condition such as a known or previously unknown cancer. Long periods of inactivity such as long car rides or being bedridden increase the risk.
