When the cause of the arteriosclerosis is due to the fatty deposits in the inner wall of the vessel, this is termed atherosclerosis. Atherosclerosis usually occurs very slowly over a long period of time and finally it not only narrows the blood vessel, but also hardens it too. The hardened and narrowed blood vessel losses its volume and elasticity, and ultimately, the blood flow becomes slower and inefficient, providing less oxygen-rich blood to the heart muscle. Another case is that small unstable plaques may rupture and form blood clots on the surface of the vessel, blocking the artery and causing the myocardial infarction. .
There are other conditions regarding the blood vessel including both artery and vein. These include aneurysms which are caused by weakness in the vessel wall and thrombophlebitis which is an inflammation due to clot formation in the vein, commonly found in veins from lower limbs. .
Contributing to the atherosclerosis, cholesterol is most common factor. As mentioned in earlier section, LDL lipoprotein deposits cholesterol and forms plaques on the artery walls, causing atherosclerosis. On the other hand, HDL lipoprotein extracts cholesterol from the artery walls and disposes of it through the liver and prevents atherosclerosis. Thus, having a high level of HDL is, once again, not harmful. More detail of this mechanism is followed in the later section.
3. What are the symptoms?.
There are no defined symptoms for the CAD. The earliest detectable symptoms may include angina or shortness of breathe. Angina can be sub-categorized as stable and unstable angina. While both anginas refer to pain or discomfort in the chest due to the insufficient blood supply to the cardiac muscle, stable angina usually lasts 1 ~ 15 minutes and is provoked by excess exercise or stress and can be relieved by rest or use of nitroglycerin. Unstable angina, the more severe and frequent form, can occur even at rest and can last much longer than stable angina.