AMBULATORY MONITORING OF LEFT-VENTRICULAR FUNCTION DURING CARDIOPULMONARY EXERCISE TESTS IN NORMAL SEDENTARY SUBJECTS

Ambulatory monitoring (VEST) of left ventricular (LV) function is a us eful and accurate method to measure cardiac function during exercise a nd 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 duri ng upright bicycle exercise associated with combined analysis of pulmo nary gas exchange. All parameters of LV function were measured in cont rol 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 significant ly increased from control conditions to anaerobic threshold (p < 0.001 ) and from anaerobic threshold to peak VO2 (p < 0.001). Ejection fract ion, end diastolic volume and stroke volume significantly increased fr om control conditions to anaerobic threshold (p < 0.001), showing no s ignificant change from anaerobic threshold to peak VO2. Finally, end-s ystolic volume significantly decreased from control conditions to anae robic threshold (p < 0.001), showing no significant change from anaero bic threshold to peak VO2. Conclusion: VEST is particularly useful in the evaluation of cardiac response to exercise in normal sedentary sub jects, 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 uni form increase is not necessarily expected in normal sedentary subjects .