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. 1998 Mar;79(3):289–294. doi: 10.1136/hrt.79.3.289

Physiological cardiac reserve: development of a non-invasive method and first estimates in man

G Cooke 1, P Marshall 1, J Al-Timman 1, D Wright 1, R Riley 1, R Hainsworth 1, L Tan 1
PMCID: PMC1728626  PMID: 9602665

Abstract

Objective—To investigate whether physiological cardiac reserve can be measured in man without invasive procedures and whether it is a major determinant of exercise capacity.
Design—Development of method of measurement and an observational study.
Setting—A regional cardiothoracic centre.
Subjects—70 subjects with a wide range of cardiac function, from heart failure patients to athletes.
Methods—Subjects underwent treadmill, symptom limited cardiopulmonary exercise tests to measure aerobic exercise capacity (represented by V̇O2max) and cardiac reserve. Cardiac output was measured non-invasively using the CO2 rebreathing technique.
Results—Cardiac power output (CPOmax) at peak exercise was found to be significantly related to aerobic capacity: CPOmax (W) = 0.35 + 1.5V̇O2max (l/min), r = 0.87, p < 0.001. It also correlated well with exercise duration (r = 0.62, p < 0.001), suggesting that cardiac reserve is a major determinant of exercise capacity. In the study, cardiac reserve ranged from 0.27 to 5.65 W, indicating a 20-fold difference between the most impaired cardiac function and that of the fittest subject.
Conclusions—A non-invasive method of estimating physiological cardiac reserve was developed. The reserve was found to be a major determinant of exercise capacity in a population of normal subjects and patients with heart disease. This method may thus be used to provide a clearer definition of the extent of cardiac impairment in patients with heart failure.

 Keywords: cardiac reserve;  cardiac power output;  oxygen consumption;  congestive heart failure

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Figure 1  .

Figure 1  

A plot of cardiac output during peak exercise (COmax) against an indicator of aerobic exercise capacity, V̇O2max (peak oxygen consumption).

Figure 2  .

Figure 2  

A plot of cardiac power output during peak exercise (CPOmax) against aerobic exercise capacity, V̇O2max.

Figure 3  .

Figure 3  

Bland and Altman plots18,19 of the differences against the means of repeated measurements of (A) maximum oxygen consumption (V̇O2max), (B) cardiac output (COmax), and (C) cardiac power output (CPOmax) during peak exercise, to indicate reproducibility of measurements (means and ± 2 SD limits indicated). See text for details.

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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