Influence Of Left Ventricular Diastolic Function On Ventilatory Responses During Exercise In Healthy Individuals

Abstract

Healthy aging is associated with changes in left ventricular (LV) diastolic function, namely a prolongation of LV relaxation and increased filling pressures. This could influence ventilation through afferent cardiac pulmonary receptors sensitive to stretch or pressure and/or to changes in lung compliance. Such cardio-pulmonary interdependence may be accentuated with exercise. PURPOSE: To determine if indices of LV diastolic function influence ventilation, breathing pattern and gas exchange during exercise in healthy adults, and to determine if these associations are age related. METHODS: 103 adults (age: 50±2, range 22-76yr, 42 females, VO2peak: 34.8±0.8 ml/kg/min, FEV1: 105±1 %pred) underwent echocardiography and cardiopulmonary exercise testing. Isovolumic relaxation time (IVRT) and the ratio of peak early mitral inflow velocity to peak early mitral annular velocity (E/E') were used as indices of LV relaxation and filling pressure. Respiratory rate (RR), tidal volume (VT), ventilation (VE), all indexed to individual vital capacities (VC), as well as ventilatory efficiency (VE/VCO2) and VT/TI, an index of VE drive, were obtained during exercise. RESULTS: Age was positively correlated with IVRT and E/E' (r=0.32, 0.58, p<0.001). An increase in LV filling pressure was positively associated with VE/VC at a matched submaximal workload (r=0.21, p<0.05), and with RR/VC and VE/VCO2 at peak exercise (r=0.21, 0.26, p<0.05). Prolonged LV relaxation was associated with VE/VC, VE/VCO2 and VT/TI at the matched workload (r=0.35, 0.26, 0.21, p<0.05), and with RR/VC, VT/VC and VE/VCO2 at peak exercise (r=-0.22, 0.23, 0.22, p<0.05). The relationship between diastolic function and ventilatory function was not independent of age at the submaximal workload. The associations between RR/VC and LV filling pressure and relaxation, as well as the association between VE/VC and filling pressure were independent of age at peak exercise. CONCLUSION: Resting measures of LV diastolic function are associated with breathing pattern, gas exchange and ventilation, however only measures of breathing pattern at peak exercise appeared to be associated with diastolic function independently of age. NIH Grant HL71478.