Atherosclerosis Complicating Chronic Hypertension

The accelerating effect of hypertension on atherogenesis in the aorta and iliofemoral and coronary arteries is presented here as a graded function of elevated intraarterial pressure. Predilection of the abdominal aorta and iliofemoral arteries for atherosclerosis can be explained on the basis of pressure augmentation by reflected pressure pulse waves and the increase in hydrostatic pressure that is produced by standing. Wave reflection is intensified by vasoconstriction, which is a characteristic not only of hypertension but also occurs with upright posture. Standing also raises the hydrostatic pressure of blood in vessels below heart level. Coronary atherosclerosis seems likely to relate to the fact that the coronary vessels are located in an area of high pressure in the arterial system and that their intramyocardial branches are normally completely occluded during systole — a condition which could be accompanied by subtle differences in the pressure-volume characteristics of the epicardial vessels. Evidence is presented from actuarial statistics, epidemiologic studies, and laboratory experiments to indicate that the level of arterial pressure has a measurable effect on the metabolism of arterial smooth muscle cells. Thus arterial pressure is viewed as having a metabolic determinant role in addition to its vital role in the circulation of blood.