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Kokyu to Junkan Volume 45, Issue 1 （January 1997）

呼吸と循環 45巻1号（1997年1月発行）

Japanese English

研究

失神発作症例におけるhead-up tilt試験と心拍数変動および脳循環動態に関する検討 Heart Rate Variability, Cerebral Circulation, and Head-up Tilt Testing in Patients with Syncope of Undetermined Etiology 高瀬凡平 ¹ , 栗田明 ¹ , 中村琢治 ¹ , 永井知雄 ¹ , 永吉広和 ¹ , 上畑昭美 ¹ , 荒川宏 ¹ , 里村公生 ¹ , 中村治雄 ¹ , 越智文雄 ² , 近藤陽一 ² , 石神重信 ² Bonpei Takase ¹ , Akira Kurita ¹ , Takusi Nakamura ¹ , Tomoo Nagai ¹ , Hirokazu Nagayoshi ¹ , Akimi Uehata ¹ , Koh Arakawa ¹ , Kimio Satomura ¹ , Haruo Nakamura ¹ , Humio Oti ² , Yoiti Kondo ² , Shigenobu Isigami ² ¹防衛医科大学校第一内科 ²防衛医科大学校理学療法部 ¹Department of Internal Medicine-1 National Defense Medical College ²Department of Rehabilitation Services, National Defense Medical College キーワード：自律神経調節性失神発作 , head-up tilt試験 , 心拍数変動周波数解析指標 , 脳循環障害 , neurally mediated syncope , heart rate variability , cerebral blood flow Keyword: 自律神経調節性失神発作 , head-up tilt試験 , 心拍数変動周波数解析指標 , 脳循環障害 , neurally mediated syncope , heart rate variability , cerebral blood flow pp.65-71

発行日 1997年1月15日 Published Date 1997/1/15

DOI https://doi.org/10.11477/mf.1404901404

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Abstract 文献概要
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　原因不明の失神発作症例における周波数解析心拍数変動指標と脳循環の変化を検討するために，原因不明の失神発作を有する連続33症例（平均57歳）に80度傾斜のhead-up tilt試験を施行した。心電図を連続記録し2分毎の正常洞調律RRよりFast Fourier Transformにて周波数解析心拍数変動指標［total spectra（TS；0.01-1.00 Hz），low frequency spec—tra（LF；0.04-0.15 Hz），high frequency spectra（HF；0.15-0.40 Hz）およびLF／HFratio］をもとめ，一部の症例（n＝9）でDoppler法にて脳動脈血流速度を計測した．その結果，head-up tilt試験陽性例10例と陰性例23例が認められ，陰性例に比較し陽性例では症状が誘発された時の収縮期血圧および平均血圧の有意の低下とHFの有意の増加（12±8vs7±4ms,p＜0.05,mean±standard deviation）が認められた．脳血流速度の指標であるpulsatility index（PI）＝Vs-Vd／V meanとresistance index（RI）＝Vs-Vd／Vsは陽性例で大である傾向が認められた．原困不明の失神発作の病態に自律神経系を介した脳循環障害の関与が示唆された．

To investigate the pathophysiology in neurally mediated syncope, we measured temporal changes of frequency domain heart rate variability indices and cerebral circulation using transcranial Doppler sonogra-phy during head-up tilt testing in patients with syncope of undetermined etiology.

Thirty three patients (16 men and 17 women: mean age 57±22 years) with unexplained syncope were evaluated by 80 degree head-up tilt testing for 40 minutes. Two-channel ambulatory electrocardiogram (CC5 and CM5 leads) recordings were obtained through-out a head-up tilt testing. Power spectral components of heart rate variability were calculated from ambulatory electrocardiogram recordings using Fast Fourier Trans-formation. Mean heart rate and power spectral compo-nents were measured in consecutive 2 minute periods throughout the study. Power spectrum consist of low frequency (0.04-0.15Hz), high frequency (0.15-0.40Hz) and total spectra (0.01-1.0Hz). A low frequency/high frequency spectra ratio which is suggested to represent relative sympathetic tone was derived. Transcranial Doppler sonography was used to evaluate middle cere-bral artery flow velocity in 9 patients. Systolic velocity (Vs), diastolic velocity (Vd), mean velocity (V mean), pulsatility index (PI=Vs-Vd/Vmean), and resistance index (RI=Vs-Vd/Vs) were obtained every one minute throughout the study.

Ten patients showed a positive and 23 patients a negative response. At the onset of the symptom, high frequency spectra increased significantly. Also positive response patients had significantly larger high frequency spectra values than those of negative response patients during head-up tilt testing (onset of symptom in posi-tive response vs. peak tilt in negative response, 12±8 vs. 7±4ms, p＜0.05). Out of 9 patients, 3 patients showed a positive response and 6 patients a negative response. Percent changes of pulsatility index during symptom in positive response patients were significantly larger than those of negative response patients.

These findings suggest that increased vagal activity and impairment of cerebral circulation induced by head -up tilt testing have a significant role in the patho-genesis of neurally mediated syncope.