title: Overshoot phenomenon of oxygen uptake during recovery from maximal exercise in patients with previous myocardial infarction.
abstract: The overshoot in oxygen uptake (VO2 overshoot) during recovery from maximal exercise is thought to reflect an overshoot in cardiac output. We investigated whether this phenomenon is related to cardiopulmonary function during exercise in cardiac patients. A total of 201 consecutive patients with previous myocardial infarction underwent cardiopulmonary exercise testing (CPX). An apparent VO2 overshoot during the recovery from CPX (6.5+/-8.1% increase relative to the peak VO2) was observed in ten patients. A comparison of patients with the VO2 overshoot to those without the VO2 overshoot revealed that the former had a significantly lower left ventricular ejection fraction (40.1+/-19.1 vs. 55. 2+/-14.9%, respectively, p = 0.002) and larger left ventricular diastolic and systolic dimensions. Patients with the VO2 overshoot also had a significantly lower peak VO2 (13.1+/-6.1 vs. 18.1+/-4.5 ml/min/kg, p < 0.001), lower DeltaVO2/DeltaWR (work rate) (6.6+/-3.8 vs. 9.5+/-1.7 mL/min/W, p < 0.0001), and a higher E (minute ventilation)/VCO2 (carbon dioxide output) slope (45.0+/-18.6 vs. 32.6+/-6.6, p < 0.0001) than those without the overshoot. A VO2 overshoot during recovery from maximal exercise was found in 5% of patients with previous myocardial infarction. This condition, which suggests a transient mismatch between cardiac contractility and afterload reduction, was found to be related to impaired cardiopulmonary function during exercise.
authors.affiliation: The Cardiovascular Institute, 3-10, Roppongi 7-chome, Minato-ku, Tokyo 106-0032, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Nagayama
authors.forename: Akira
authors.initials: A
authors.lastname: Koike
authors.forename: Takeya
authors.initials: T
authors.lastname: Suzuki
authors.forename: Masayo
authors.initials: M
authors.lastname: Hoshimoto-Iwamoto
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sawada
authors.forename: Tadanori
authors.initials: T
authors.lastname: Aizawa
mesh_terms: D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D010807:Physical Endurance; D020127:Recovery of Function / Q000502:physiology*
chemical_list: D010100:Oxygen