CORONARY ARTERY DISEASE B - Coursewareobjects.com

1 806 Section 7 Problems of Oxygenation: PerfusionCardiovascular SystemCORONARY ARTERY DISEASEC oronary ARTERY DISEASE is a type of blood vessel disorder that is included in the general category of atherosclerosis. The term ath-erosclerosis is derived from two Greek words: athere, meaning fatty mush, and skleros, meaning hard. This combination indi-cates that atherosclerosis begins as soft deposits of fat that harden with age. Atherosclerosis is often referred to as hardening of the arteries. Although this condition can occur in any ARTERY in the body, the atheromas (fatty deposits) have a preference for the coro-nary arteries. Arteriosclerotic heart DISEASE , cardiovascular heart DISEASE , ischemic heart DISEASE , CORONARY heart DISEASE , and CAD are all terms used to describe this DISEASE and PathophysiologyAtherosclerosis is the major cause of CAD.

2 It is characterized by a focal deposit of cholesterol and lipids, primarily within the intimal wall of the ARTERY . The genesis of plaque formation is the result of complex interactions between the components of the blood and the elements forming the vascular Infl ammation and endothelial injury play a central role in the development of normal endothelium is more than a simple barrier be-tween the vessel wall and the lumen of the vessel. Normally, it is nonreactive to platelets and leukocytes, as well as coagulation, fi -brinolytic, and complement factors. However, the endothelial lin-ing can be injured as a result of tobacco use, hyperlipidemia, hy-pertension, diabetes, hyperhomocysteinemia, and infection ( , Chlamydia pneumoniae, herpes) causing a local infl ammatory re-sponse3,4 (Fig. 34-2, A).C-reactive protein (CRP), a nonspecifi c marker of infl amma-tion, is increased in many patients with CAD.

3 Chronic exposure to even minor elevations of CRP can trigger the rupture of plaques and promote the oxidation of low-density lipoprotein (LDL) cho-lesterol, leading to increased uptake by macrophages in the endo-thelial ,6 Developmental Stages. CAD is a progressive DISEASE that takes many years to develop. When it becomes symptomatic, the DISEASE process is usually well advanced. The stages of development in atherosclerosis are (1) fatty streak, (2) fi brous plaque resulting from smooth muscle cell proliferation, and (3) complicated Streak. Fatty streaks, the earliest lesions of atherosclero-sis, are characterized by lipid-fi lled smooth muscle As streaks of fat develop within the smooth muscle cells, a yellow tinge appears. Fatty streaks can be observed in the CORONARY arter-ies by age 15 and involve an increasing amount of surface area as the patient ages.

4 It is generally believed that treatment that lowers LDL cholesterol may reverse this process4 (Fig. 34-2, B). Fibrous Plaque. The fi brous plaque stage is the beginning of progressive changes in the endothelium of the arterial wall. These changes can appear in the CORONARY arteries by age 30 and increase with the endothelium repairs itself immediately, but in the person with CAD the endothelium is not rapidly replaced, allow-ing LDLs and growth factors from platelets to stimulate smooth muscle proliferation and thickening of the arterial wall. Once en-dothelial injury has occurred, lipoproteins (carrier proteins within the bloodstream) transport cholesterol and other lipids into the ar-terial intima. The fatty streak is eventually covered by collagen forming a fi brous plaque that appears grayish or ,4 These plaques can form on one portion of the ARTERY or in a circular fashion involving the entire lumen.

5 The borders can be smooth or irregular with rough, jagged The result is a narrowing of the vessel lumen and a reduction in blood fl ow to the distal tissues (Fig. 34-2, C).Complicated Lesion. The fi nal stage in the development of the atherosclerotic lesion is the most dangerous. As the fi brous plaque grows, continued infl ammation can result in plaque instability, ul-ceration, and Once the integrity of the ARTERY s inner wall has become compromised, platelets accumulate in large numbers, leading to a thrombus. The thrombus may adhere to the wall of the 433,825 ABCDEAB DEFD eaths in thousands1000200300400500288,76869,25760 ,71334,301493,623268,50364,10341,87738,9 48 MalesFemalesTotal CVD (Preliminary)CancerAccidentsABCDEFC hronic Lower Respiratory DiseasesDiabetes MellitusAlzheimer s DiseaseFIG. 34-1 Leading causes of death for all men and women. CVD, Cardiovas-cular DIFFERENCESC oronary ARTERY DiseaseMen Men tend to manifest CAD 10-15 years earlier than women.

6 Initial cardiac event for men is more often MI than angina. Men have a higher incidence of left ven-tricular hypertrophy than , CORONARY ARTERY DISEASE ; HDL, high-density lipoprotein; LDL, low-density lipoprotein; MI, myocardial CAD causes more deaths in women than in men. Initial cardiac event for women is more often angina than MI. Women with the long Q-T syndrome have an increased incidence of sudden cardiac death compared to men with the same disorder. Before menopause, women have higher HDL cholesterol levels and lower LDL cholesterol levels than men. After menopause, LDL levels increase. Women complain of palpitations more frequently than 8068/6/06 9:38:01 AM8/6/06 9:38:01 AM