In older adults, heart disease is the leading cause of death worldwide and is the most common cause for hospitalization. Physiological changes of the cardiovascular system in aging may modify the presentation of cardiac disease.
In using data on physiological changes of the cardiovascular system, it is important to recognize the selection criteria of the population studied. Because the prevalence of coronary artery disease in asymptomatic individuals may be 50% in the eighth and ninth decades of life, screening to exclude occult cardiovascular disease may modify findings.
In a population screened for occult coronary artery disease, there is no change in cardiac output at rest over the third to eighth decades (Gerstenblith et al, 1987) (Table 11-1). There is a slight decrease in heart rate and a compensatory slight increase in stroke volume. This pattern is in contrast to studies in unscreened individuals, where cardiac output falls from the second to the ninth decades. Consistent with the principle of decreased responsiveness to stress in aging, during maximal exercise, other changes are manifest even in the screened population (Table 11-2). Heart rate response to exercise is decreased in older adults compared to younger individuals, reflecting a diminished β-adrenergic responsiveness in aging. Cardiac output is decreased slightly. Cardiac output is maintained by increasing cardiac volumes—increasing end-diastolic and end-systolic volumes. With this increase in workload and the work of pumping blood against less-compliant arteries and a higher blood pressure, cardiac hypertrophy occurs even in the screened elderly population.
TABLE 11-1.Resting Cardiac Function in Persons Aged 30 to 80 Years Old Compared With That in Persons Aged 30 Years Old ||Download (.pdf) TABLE 11-1. Resting Cardiac Function in Persons Aged 30 to 80 Years Old Compared With That in Persons Aged 30 Years Old
| ||Unscreened for occult CAD ||Screened for occult CAD |
|Heart rate ||– ||– |
|Stroke volume ||– – ||+ |
|Stroke volume index ||– – ||0 |
|Cardiac output ||– – ||0 |
|Cardiac index ||– – ||0 |
|Peripheral vascular resistance ||+ + ||0 |
|Peak systolic blood pressure ||+ + ||+ + |
|Diastolic pressure ||0 ||0 |
TABLE 11-2.Performance at Maximum Exercise in Sample Screened for Coronary Artery Disease Aged 30 to 80 Years ||Download (.pdf) TABLE 11-2. Performance at Maximum Exercise in Sample Screened for Coronary Artery Disease Aged 30 to 80 Years
| ||Compared with 30-year-olds |
|Heart rate ||– – |
|End-diastolic volume ||+ + |
|Stroke volume ||+ + |
|Cardiac output ||– |
|End-systolic volume ||+ + |
|Ejection fraction ||– – |
|Total peripheral vascular resistance ||0 |
|Systolic blood pressure ||0 |