Healthy Aging and Cardiovascular Function: Invasive Hemodynamics During Rest and Exercise in 104 Healthy Volunteers

Abstract

Objectives: The aim of this study was to evaluate the association between age and invasive cardiovascular hemodynamics during upright exercise among healthy adults.

Background: The marked age-related decline in maximal exercise oxygen uptake (peak VO₂) may contribute to the high burden of heart failure among older individuals and their greater severity of exertional symptoms. However, the mechanisms underlying this decline are not well understood.

Methods: A total of 104 healthy community-dwelling volunteers age 20 to 76 years well screened for cardiovascular disease underwent exhaustive upright exercise with brachial and pulmonary artery catheters; radionuclide ventriculography; and expired gas analysis for the measurement of peak VO₂, cardiac output, left ventricular stroke volume, end-diastolic volume, end-systolic volume, ejection fraction, pulmonary capillary wedge pressure, and arteriovenous oxygen difference.

Results: Over a 5.5-decade age range, there was a 40% decline in peak VO₂ due primarily to reduced peak exercise cardiac output; peak arteriovenous oxygen difference was unaffected by age. The lower age-related exercise cardiac output was related to lower peak exercise heart rate and stroke volume. Aging was also associated with lower peak exercise ejection fraction, indicating reduced inotropic reserve. Peak exercise end-diastolic volume was lower with aging despite similar left ventricular filling pressure, suggesting age-related reduced diastolic compliance limiting the use of the Frank-Starling mechanism to compensate for reduced chronotropic and inotropic reserves. These age relationships were unaffected by sex.

Conclusions: The age-related decline in exercise capacity among healthy persons is due predominantly to cardiac mechanisms, including reduced chronotropic and inotropic reserve and possibly reduced Frank-Starling reserve. Peak exercise left ventricular filling pressure and arteriovenous oxygen difference are unchanged with healthy aging.

Keywords: aging; cardiovascular hemodynamics; exercise reserve; peak exercise oxygen capacity; pulmonary capillary filling pressure.

FIGURE 1. Association of Age With Oxygen Uptake and its Determinants at Rest

Correlations between age and the following parameters at upright rest: (A) oxygen consumption, (B) cardiac index, (C) stroke volume index, and (D) arteriovenous oxygen (A-V O₂) difference.

FIGURE 2. Association of Age With Cardiac Function and Hemodynamic Parameters at Rest

Correlations between age and the following parameters at upright rest: (A) pulmonary capillary wedge pressure (PCWP), (B) heart rate, (C) ejection fraction, and (D) left ventricular end-diastolic volume index (LVEDV).

FIGURE 3. Association of Age With Oxygen Uptake and its Determinants at Peak Exercise

Correlations between age and the following parameters at upright peak exercise: (A) oxygen consumption, (B) cardiac index, (C) stroke volume index, and (D) arteriovenous oxygen (A-V O₂) difference.

FIGURE 4. Association of Age With Cardiac Function and Hemodynamic Parameters at Peak Exercise

Correlations between age and the following parameters at upright peak exercise: (A) PCWP, (B) heart rate, (C) ejection fraction, and (D) LVEDV. Abbreviations as in Figure 2.

CENTRAL ILLUSTRATION. Mechanisms of Decline in Exercise Capacity With Healthy Aging

Changes in peak exercise hemodynamic parameters associated with healthy aging. A-V O₂ diff. = exercise arteriovenous-oxygen difference; CO = cardiac output; HR = heart rate; PCWP = pulmonary capillary wedge pressure; SV = stroke volume; VO₂ = oxygen uptake.