An 82-year-old man comes to the office for evaluation of chronic back pain. On physical examination, he is found to have a blood pressure of 160/85 mm Hg while supine and 135/70 mm Hg while standing. He is otherwise healthy; his only medicine is occasional ibuprofen for back pain. Which of the following age-related changes best explains the observed finding?

Question

An 82-year-old man comes to the office for evaluation of chronic back pain.  On physical examination, he is found to have a blood pressure of 160/85 mm Hg while supine and 135/70 mm Hg while standing.  He is otherwise healthy; his only medicine is occasional ibuprofen for back pain.  Which of the following age-related changes best explains the observed finding?

Quizplus · Accepted Answer

This patient has orthostatic hypotension, which is defined as a postural decrease in blood pressure by 20 mm Hg systolic or 10 mm Hg diastolic (sometimes accompanied by an increase in heart rate) that occurs on standing. In general, orthostatic hypotension results from insufficient constriction of blood vessels in the lower extremities on standing, which may be due to a defect in autonomic reflexes, decreased intravascular volume, or medications. Some baroreceptor sensitivity is lost as a normal part of aging. Arterial stiffness, decreased norepinephrine content of sympathetic nerve endings, and reduced sensitivity of the myocardium to sympathetic stimulation all contribute to a tendency toward orthostatic hypotension with age. (Choices A and B) Normal changes to the aging heart include decreased resting and maximal cardiac output, decreased maximum heart rate, increased contraction and relaxation time of heart muscle, increased myocardial stiffness during diastole, decreased myocyte number, and pigment accumulation in myocardial cells. Increased ventricular wall stiffness contributes to the development of heart failure with preserved ejection failure (diastolic dysfunction) but does not play a role in orthostatic hypotension. (Choice D) The adrenal medulla continues to release catecholamines in response to stress (fight or flight) throughout life. It does not participate in the fine control of blood pressure. (Choice E) Although the glomerular filtration rate (GFR) tends to decline with old age, a decreased GFR would promote sodium retention and expansion of the intravascular volume, counteracting orthostatic hypotension. Educational objective: Progressively decreasing baroreceptor sensitivity and defects in the myocardial response to this reflex are the main reasons for the increased incidence of orthostatic hypotension in the elderly.

An 82-Year-Old Man Comes to the Office for Evaluation of Chronic