title: Measurement and validity of the ventilatory threshold in patients with congenital heart disease.
abstract: The purpose of the present study was to measure oxygen uptake (VO2) at the ventilatory threshold (VT) in patients with congenital heart disease using a progressive exercise protocol on a treadmill and to evaluate the validity and feasibility of this procedure. Eight control subjects and seventeen patients performed a maximal exercise test with breath-by-breath measurement of ventilation and gas exchange variables. VT(VE) was determined by the change in the ventilatory equivalent for VO2 and carbon dioxide output, VT(V-sl) by the V-slope method, and the lactate threshold (LT) by the change in blood lactate concentration; these parameters were determined in 100%, 88%, and 96% of subjects, respectively. The interobserver error among three evaluators was not significant, and LT was correlated with each VT (r = 0.97, 0.92; p = 0.0001) and with peak VO2 (r = 0.91; p = 0.0001). The VTs were correlated with each other when expressed as milliliter per minute and milliliters per kilogram per minute. It was concluded that a progressive exercise protocol on a treadmill was a feasible procedure for determining the VTs in most individuals and that VTs were valid, useful parameters for evaluating submaximal exercise tolerance in patients with congenital heart disease.
authors.affiliation: Department of Pediatrics, National Cardiovascular Center, Osaka, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ohuchi
authors.forename: T
authors.initials: T
authors.lastname: Nakajima
authors.forename: M
authors.initials: M
authors.lastname: Kawade
authors.forename: M
authors.initials: M
authors.lastname: Matsuda
authors.forename: T
authors.initials: T
authors.lastname: Kamiya
mesh_terms: D000293:Adolescent; D000328:Adult; D015308:Anaerobic Threshold; D000704:Analysis of Variance; D001784:Blood Gas Analysis; D002648:Child; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006330:Heart Defects, Congenital / Q000503:physiopathology*; D006801:Humans; D007773:Lactates / Q000097:blood; D016014:Linear Models; D008297:Male; D015588:Observer Variation; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange; D015203:Reproducibility of Results
chemical_list: D007773:Lactates