著者

Koike Akira Hoshimoto Masayo Tajima Akihiko Nagayama Osamu Yamaguchi Kaori Goda Ayumi Yamashita Takeshi Sagara Koichi 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.70, no.11, pp.1457-1461, 2006-10-20

被引用文献数

6 20

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Background In a recent study the indexes of cerebral oxygenation decreased during maximal exercise in nearly half of all patients with left ventricular dysfunction. Whether these levels decrease severely enough to influence mental status or level of consciousness was evaluated in the present study. Methods and Results Forty-two patients with idiopathic dilated cardiomyopathy (IDC) and 29 healthy subjects underwent a symptom-limited maximal exercise test. The cerebral oxyhemoglobin (O_2Hb) and tissue oxygenation index (TOI) were continuously monitored using near-infrared spectroscopy. The changes in O_2Hb and TOI were also measured in 7 subjects: 2 who experienced episodes of reduced consciousness caused by sudden decreases in blood pressure during exercise recovery and 5 who exhibited sustained ventricular tachycardia during an electrophysiological study. The change in cerebral O_2Hb during exercise in patients with IDC averaged 0.38±3.39μmol/L, significantly lower than in the normal subjects (4.30±4.47μmol/L, p<0.0001). The cerebral O_2Hb decreased during exercise in 18 of 42 patients with IDC. The change in cerebral TOI in the IDC patients during exercise was significantly less than that in the normal subjects (-2.0±4.7 vs 2.1±5.8%, p=0.002). The mean decreases in cerebral O_2Hb and TOI were -5.34μmol/L and -9.7%, respectively, in the patients with reduced consciousness during exercise recovery, and -2.52μmol/L and -16.5%, respectively, in those with ventricular tachycardia. Conclusion The indexes of cerebral oxygenation may drop severely enough during maximal exercise in some patients with severe IDC that consciousness is affected.

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>