Ambulatory monitoring of left ventricular function during cardiopulmonary exercise tests in normal sedentary subjects

Ambulatory monitoring (VEST) of left ventricular (LV) function is a useful and accurate method to measure cardiac function during exercise and rest. The aim of this study was to evaluate LV response to exercise in normal sedentary subjects. Methods: Ten normal sedentary subjects underwent continuous ambulatory monitoring of LV function by VEST during upright bicycle exercise associated with combined analysis of pulmonary gas exchange. All parameters of LV function were measured in control conditions at rest, at the anaerobic threshold (point of nonlinear increase in ventilation relative to oxygen uptake) and at peak oxygen uptake (peak VO₂). Results: Heart rate and cardiac output significantly increased from control conditions to anaerobic threshold (p <0.001) and from anaerobic threshold to peak VO₂ (p <0.001). Ejection fraction, end diastolic volume and stroke volume significantly increased from control conditions to anaerobic threshold (p <0.001), showing no significant change from anaerobic threshold to peak VO₂. Finally, end- systolic volume significantly decreased from control conditions to anaerobic threshold (p <0.001), showing no significant change from anaerobic threshold to peak VO₂. Conclusion: VEST is particularly useful in the evaluation of cardiac response to exercise in normal sedentary subjects, providing a better understanding of the spectrum of the normal LVEF response to exercise. Our data demonstrate that ejection fraction response to exercise is variable after anaerobic threshold, and a uniform increase is not necessarily expected in normal sedentary subjects.