The nurse assesses an older adult client. Which assessment finding places the client at greatest risk for developing isolated systolic hypertension?

Isolated systolic hypertension, defined as an elevated systolic blood pressure with a normal or low diastolic pressure, is the most common form of hypertension in older adults. Its primary mechanism is age-related thickening and stiffening of the large central arteries, particularly the aorta. As arteries lose their compliance — their ability to expand during systole and recoil during diastole — the systolic pressure rises because the stiffened vessel cannot adequately accommodate the stroke volume ejected by the ventricle. The diastolic pressure remains normal or may even decrease because the stiff arteries cannot maintain pressure during the relaxation phase. This combination produces a widened pulse pressure and elevated systolic reading. Decreased peripheral vascular resistance would actually lower both systolic and diastolic pressures, not raise the systolic selectively. Increased elasticity of arterial walls is the opposite of what occurs in aging; increased elasticity would improve vascular compliance and reduce systolic hypertension rather than cause it. Decreased cardiac output would tend to lower blood pressure overall rather than selectively raise the systolic component. Therefore, thickening and stiffening of large arteries is the pathophysiological process most directly responsible for isolated systolic hypertension in the older adult population.