The principal hemodynamic abnormality responsible for isolated systolic hypertension in an otherwise healthy 72-year-old man is:

• A Increased resting cardiac output
• B Expansion of plasma volume
• C Reduced compliance of the large elastic arteries ✓
• D Increased circulating renin activity

Explanation

With aging, the aorta and large elastic arteries lose elastin and accumulate collagen, reducing their compliance. Systolic runoff during ejection becomes less buffered, so systolic pressure rises while earlier diastolic recoil falls, producing a widened pulse pressure and isolated systolic hypertension. Cardiac output and plasma volume are typically normal or low in older hypertensives, and renin tends to fall with age, so options A, B, and D contradict the physiology of this entity.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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