How the Blood Clots; How to Prevent Abnormal Clotting

The clotting mechanism, continued.

Figure 5. A mature clot is now present, superimposed on the atherosclerotic plaque. This clot makes the partial obstruction of the coronary artery substantially worse. The arrow indicates the increased sluggishness and turbulence of blood flow through the artery. This patient most likely now has unstable angina, and if blood flow is sluggish enough, some of the heart cells supplied by this artery may die.

If the artery becomes totally occluded by a clot, a classic heart attack (myocardial infarction) will occur.

How can the clotting mechanism produce problems?

The clotting system, like all complex physiologic systems, can produce problems. Blood clots forming on atherosclerotic plaques in the arteries are the major cause of heart attack and stroke. Blood clots forming in the veins of the legs produce a painful condition called phlebitis, and when these venous blood clots break off (“embolize”) they move into the lungs and produce a dangerous condition called pulmonary embolus.

Page 4 - How can abnormal blood clotting be treated?