gms | German Medical Science

Objective: Cardiac power output (CPO) measures cardiac function by taking into account both pressure [mean arterial pressure (MAP)] and flow [(cardiac output (CO)] generating capacities of the heart. Peak cardiac power output (CPOpeak) achieved during maximal physical activity is the best method of measuring overall cardiac function and one of the major determinant of exercise capacity. Cardiac reserve (CR) is calculated as difference between cardiac power output at maximal exercise and at rest (CPOpeak-CPOrest) [1]. Previous investigations into peak cardiac power output measured CO using rebreathing method and have been mostly limited to clinical populations [2], [3]. Data about healthy sedentary adults using echocardiography exam would allow a greater understanding of CPOpeak and CR parameters as measures of cardiac function. The aim of this study was to determine CPOpeak and CR in young, healthy physical non-active women in our population by echocardiography.

Material/Methods: The study included 46 sedentary female subjects (mean±SD, age 21.17±0.69) who were subsequently divided into two groups of 23 women, by achieved values of heart reserve (Group 1 with higher and Group 2 with lower heart reserve). Values of heart work and circulatory condition were measured before and after maximal physical activity on cycle ergometer with echocardiography exam. From these values peak cardiac power output and heart reserve were calculated as described by Cooke et al. [1].

Results: In whole group CPOpeak was 4.22 (±0.73) W and heart reserve was 3.08 (±0.52) W. After maximal physical activity significant differences (p<0.05) between Group 1 and Group 2 were found in values of systolic blood pressure (TASy), mean arterial pressure, cardiac output, peak cardiac power output and heart reserve. There was significant correlation (r=0.44, Pearson’s coefficient) between level of achieved load on cycle ergometer (W) and cardiac reserve in both groups. Heart’s size and volumes of the subjects were in physiological limits compared with the values of relevant categories (Guidelines for Quantification chamber, the British Association of Echocardiography [4].

Conclusion: In our population value of peak cardiac power output in women is 4.22 (±0.73) W and value of cardiac reserve is 3.08 (±0.52) W. Women with higher cardiac reserve had better results on exercise test and could endure to higher level of maximum load. Cardiac reserve is important factor in achieving maximal load during physical activity. The advantage of echocardiography in estimating CPOpeak and CR is in its noninvasiveness and capability of measuring cardiac dimensions and pumping parameters during examination.