Overshoot phenomenon of oxygen uptake during recovery from maximal exercise in patients with previous myocardial infarction |
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Authors: | Osamu Nagayama Akira Koike Takeya Suzuki Masayo Hoshimoto-Iwamoto Hitoshi Sawada Tadanori Aizawa |
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Institution: | (1) The Cardiovascular Institute, 3-10, Roppongi 7-chome, Minato-ku, Tokyo 106-0032, Japan;(2) Department of Cardiovascular Medicine, Toho University Omori Medical Center, Tokyo, Japan;(3) School of Health and Sports Science, Juntendo University, Chiba, Japan; |
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Abstract: | The overshoot in oxygen uptake ((V)\dot] \dot{\rm{V}} O2 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 (V)\dot] \dot{\rm{V}} O2 overshoot during the recovery from CPX (6.5 ± 8.1% increase relative to the peak (V)\dot] \dot{\rm{V}} O2) was observed in ten patients. A comparison of patients with the (V)\dot] \dot{\rm{V}} O2 overshoot to those without the (V)\dot] \dot{\rm{V}} O2 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 (V)\dot] \dot{\rm{V}} O2 overshoot also had a significantly lower peak (V)\dot] \dot{\rm{V}} O2 (13.1 ± 6.1 vs. 18.1 ± 4.5 ml/min/kg, p < 0.001), lower Δ(V)\dot] \dot{\rm{V}} O2/ΔWR (work rate) (6.6 ± 3.8 vs. 9.5 ± 1.7 mL/min/W, p < 0.0001), and a higher (V)\dot] \dot{\rm{V}} E (minute ventilation)/(V)\dot] \dot{\rm{V}} CO2 (carbon dioxide output) slope (45.0 ± 18.6 vs. 32.6 ± 6.6, p < 0.0001) than those without the overshoot. A (V)\dot] \dot{\rm{V}} O2 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. |
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