Monday, September 21, 2009

Geriatric Cardiac Function

Afterload increases in the geriatric patient. This is largely due to increased vascular tone and decreased vascular elasticity. Vascular tone increases secondary to stimulation of the renin-angiotensin system in an attempt to maintain perfusion of aging kidneys. Stimulation of the renin-angiotensin system results in vasoconstriction, which increases vascular tone and blood pressure. Vascular elasticity decreases over time as a result of the atherosclerotic process. These effects cause a decrease in arterial vascular elasticity (compliance).

In the elderly patient, cardiac output decreases due to atherosclerosis and decreased perfusion of the heart. Previous cardiac insults, such as unstable angina and myocardial infarction, add to the dysfunction. The sympathetic nervous system is one of the compensatory mechanisms that maintain blood pressure in different body positions. The sensors that stimulate the sympathetic nervous system become blunted in the elderly patient, leading to orthostatic hypotension.

Keep these changes in mind when assessing your elderly patient: decreased cardiac output will result in decreased systolic pressure, unless compensatory mechanisms take over and cause vasoconstriction. Decreased arterial compliance and increased arterial pressure causes additional stress on the elderly heart leading to heart failure over time. Lastly, watch carefully for orthostatic hypotension which can cause the elderly patient to fall and become injured.

From: Magauran, B, Kahn, J, & Olkshaker, J. (2006). Geriatric Emergency Medicine, An Issue of Emergency Medicine Clinics. St. Louis: Saunders.

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