MODULE SUPPLEMENT: CARDIOVASCULAR SYSTEM
Clinical Significance

One clinical event is atrial fibrillation, which eliminates the atrial kick. Another is tachycardia because it limits diastolic filling time.

Another feature that is commonly found in older adults is an S4. This occurs as a result of increased myocardial stiffness and a reliance on atrial contraction. This is probably a normal finding in older adults whereas in younger adults it is generally felt to be abnormal. However, it is always wise to assess whether other symptoms suggest a problem if this is a new finding.

Heart rate may be slightly decreased but this is generally not significantly changed at rest. In the Baltimore Longitudinal Study on Aging, they found no change in supine position and about a 10% decrease in sitting position in both men and women (Lakatta & Sollott, 2002).

There is also no significant decrease in cardiac index at rest in healthy elderly individuals. This is often well maintained although it may vary slightly between men and women. Men appear to maintain their cardiac index better than women, which may relate to the higher proportion of adipose tissue in women (loss of LBM also => loss of capillary density) (Lakatta, 1999). There is a slight increase in stroke volume of about 10% and some increase in end diastolic volume in men (about 12%) but no apparent change in women.

In addition to changes within the heart, there is some decreased baroreceptor sensitivity. This, along with the heart's own inability to increase its rate as quickly or as high when stressed, leads to an increased vulnerability to orthostatic hypotension and to the effects of anti-hypertensive medications.

Peripheral vascular resistance was found to be minimally changed in men but was slightly increased in women. Lakatta (1999) suggests that this may be related to a decrease in skeletal muscle mass which decreases capillary density.