マイクロ波反射計を用いた非接触・無拘束・着衣下での心拍変動解析の試み  [in Japanese] Heart Rate Variability Analysis of Human Volunteers under Noncontact, Noninvasive and Clothed Condition Using Microwave Reflectometry : Feasibility Study  [in Japanese]

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Author(s)

    • 丸山 徹 Maruyama Toru
    • 九州大学基幹教育院|九州大学大学院病態修復内科学 Faculty of Art and Science, Kyushu University|Department of Medicine and Biosystemic Science, Kyushu University School of Medical Sciences
    • 安田 潮人 Yasuda Shioto
    • 九州大学大学院病態修復内科学 Department of Medicine and Biosystemic Science, Kyushu University School of Medical Sciences
    • 間瀬 淳 Mase Atsushi
    • 九州大学産学連携センター Art, Science and Technology Center for Cooperative Research, Kyushu University

Abstract

心拍変動は,自律神経の活動状態を非観血的に評価する有用な方法であるが,接触型電極を長時間接着する不快感や拘束感が生じる.一方,マイクロ波は着衣下の非接触状態で干渉測定により反射波の位相変化,すなわち体表面の微小動を計測できる.この原理を応用して,われわれは健常者に接触型電極を用いた心電計を装着してマイクロ波を照射し,暗算負荷試験前後の心拍変動解析を両者で比較検討した.実際のマイクロ波反射計の送受信アンテナは,背中・大腿部・側頭部に対して設置した.マイクロ波反射波は,必要に応じて相互相関処理を繰り返して体動のアーチファクトを除去し,オートゲインコントロール付加の位相検出システムとテンプレート相関方式を用いて,心拍のピークシグナルを検出した.両者のLF/HF値のトレンドグラムはよく一致し,暗算負荷試験前後で高度の正の相関を示した(<I>y</I>=0.90504 ・<I>x</I>,r=0.769,p<0.001).今後さらなるパソコン化やモバイル化が進めば,運転中のドライバーや乳児・高齢者のモニタリングなどへの応用が期待される.

Heart rate variability (HRV) reflects cardiac autonomic functions including sympathovagal balance, and conventional electrocardiographic (ECG) monitoring (Holter) is a major tool for evaluating HRV. However, conventional ECG requires patients to be tethered to the monitoring devices. We have therefore attempted to develop a noninvasive and noncontact cardiac monitoring system. Our laboratory recentry developed a microwave reflectometry system which senses heart beats and pulse waves. An auto-gain control system, template-matching system, and signal cross-correlation technique obtained by multiple reflectometric sensors enable motion artifact elimination, signal peak detection, and real-time data processing. HRV of healthy volunteers (n=11, mean age of 28.4±12.3 y.o.) was evaluated simultaneously by both conventional ECG and microwave reflectometry under mental arithmetic loading. Frequency-domain HRV parameter of LF/HF obtained by reflectometric analysis showed a good correlation with this parameter obtained by conventional ECG monitoring (r=0.769, y=0.90504 · x, p < 0.001). HRV evaluation using this microwave reflectometry is completely noninvasive and feasible even through thick clothing, though more sophisticated improvements would be needed for this device to be widely used in mobile PC system.

Journal

  • Japanese Journal of Electrocardiology

    Japanese Journal of Electrocardiology 35(2), 133-142, 2015

    Japanese Heart Rhythm Society

Codes

  • NII Article ID (NAID)
    130005139471
  • Text Lang
    JPN
  • ISSN
    0285-1660
  • Data Source
    J-STAGE 
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