[Determination of the ventilatory threshold during the exercise test in patients with cardiac insufficiency. Relation of the lactate threshold]

Abstract

The non-invasive assessment of the lactate threshold during exercise test is possible in normal subjects by the study of respiratory gas exchange: a ventilatory threshold may be determined using Wasserman's criteria. This determination is more unreliable in cardiac failure. Forty-four patients with cardiac failure underwent exercise tests with measurement of lactate concentrations and respiratory gas exchanges during the exercise. Despite a regular increase in the lactate concentration from the onset of exercise, it was possible to determine a lactate threshold in the majority of patients. A ventilatory threshold could be determined in 27 to 38 patients depending on the method used. The correlation between these two thresholds was excellent (r = 0.87). The determination of the ventilatory threshold during exercise is therefore possible in cardiac failure. The main limitation of the method is that no result can be obtained in a large number of patients (15 to 20%) which restricts its value as a principal method of therapeutic evaluation.