著者

KOIKE Akira NAGAYAMA Osamu GODA Ayumi HOSHIMOTO Masayo YAMAGUCHI Kaori TAJIMA Akihiko UEJIMA Tokuhisa ITOH Haruki AIZAWA Tadanori

出版者

社団法人日本循環器学会

雑誌

Circulation journal : official journal of the Japanese Circulation Society (ISSN:13469843)

巻号頁・発行日

vol.71, no.9, pp.1418-1423, 2007-08-20

被引用文献数

1 5

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<b>Background</b> It has been recently reported that cerebral oxyhemoglobin (O₂Hb) decreases during exercise in nearly 50% of patients with dilated cardiomyopathy. The present study evaluated whether the inhalation of supplemental O₂ diminishes the decrease in cerebral O₂Hb during exercise. <b>Methods and Results</b> Ten patients with a left ventricular ejection fraction <50% and a clearly observable decrease in cerebral O₂Hb during preliminary exercise testing underwent 2 additional symptom-limited incremental exercise tests: 1 while breathing room air (control) and the other while breathing 50% O₂. In the latter test, the switch from room air to 50% O₂ was performed, on average, at 43.0±14.2 W. Cerebral O₂Hb was continuously monitored during exercise using near-infrared spectroscopy. In the control exercise test, cerebral O₂Hb gradually decreased as the work rate increased in all the subjects. When the subjects breathed 50% O₂, this decrease in cerebral O₂Hb was diminished. The change in cerebral O₂Hb from rest to peak exercise during the test under 50% O₂ was significantly higher than that during the control test (-0.23 ±1.89 vs -2.47±1.57 μmol/L, p=0.002). Similarly, the change in the cerebral tissue oxygenation index was significantly higher in the test under 50% O₂ (0.45 ±4.46 vs -3.33±3.06%, p=0.023). <b>Conclusions</b> Impaired cerebral oxygenation during moderate to heavy intensity exercise in patients with left ventricular dysfunction can be offset by breathing supplemental O₂. (<i>Circ J</i> 2007; <b>71:</b> 1418 - 1423)<br>