田中 元直¹, 坂本 二哉², 西條 芳文³, 片平 美明⁴, 菅原 重生⁵, 中島 博行¹, 黒川 貴史¹, 金井 浩⁶

Motonao TANAKA¹, Tsuguya SAKAMOTO², Yoshifumi SAIJO³, Yoshiaki KATAHIRA⁴, Shigeo SUGAWARA⁵, Hiroyuki NAKAJIMA¹, Takafumi KUROKAWA¹, Hiroshi KANAI⁶

¹東北医科大学薬科大学病院検査部, ²半蔵門病院, ³東北大学大学院医工学研究科, ⁴公立刈田病院循環器科, ⁵日本海総合病院循環器内科, ⁶東北大学大学院工学研究科電子工学専攻

¹Department of Cardiovascular Medicine, Tohoku Medical and Pharmaceutical University Hospital, ²Hanzomon Hospital, ³Graduate School of Biomedical Engineering, Tohoku University, ⁴Katta General Hospital, ⁵Nihonkai General Hospital, ⁶Department of Electronic Engineering, Tohoku University

キーワード : echo-dynamography, vortex, wall dynamics, flow structure, axial strain rate

目的：エコーダイナモグラフィーを使用して分析した左室（LV）の血流動態と壁動態との間の相関関係から，LV駆出前の非常に短い期間である駆出前過渡期（pre-ETP）中の駆出メカニズムと心室内渦の役割とを詳細に解明した．手法：研究には10名の健康なボランティアが参加した．エコーダイナモグラフィーを使用して血流構造を分析し，LV壁動態を，我々が開発した高フレームレート断層心エコー法と位相差追跡法との両方を使用して測定した．結果：この駆出前過渡期中，LVの心基部中央域に大きな加速渦が発生する．LVの主血流軸速度線は，直線的に増加するパターンを呈する．この速度パターンの傾斜は，pre-ETP中のLV収縮が誘発した流出路の変形を反映しており，渦の主流との接点で，遠心力は，最大駆出速度の約50％の段階的な増加を引き起こすことを示した．結論：LVからの血液の駆出は，心室壁の押し出す動きと，この期間中の加速渦の遠心力とによって生じる．駆出中，加速渦はバルサルバ洞の球形構造に助けられて，大動脈内でらせん流を引き起こすと考えられた．

Purpose: From the correlation between the blood flow dynamics and wall dynamics in the left ventriocle (LV) analyzed using echo-dynamography, the ejection mechanisms and role of the intra-ventricular vortex in the LV were elucidated in detail during the pre-ejection transitional period (pre-ETP), the very short period preceding LV ejection. Methods: The study included 10 healthy volunteers. Flow structure was analyzed using echo-dynamography, and LV wall dynamics were measured using both high-frame-rate two-dimensional echocardiography and a phase difference tracking method we developed. Results: A large accelerated vortex occurred at the central basal area of the LV during this period. The main flow axis velocity line of the LV showed a linearly increasing pattern. The slope of the velocity pattern reflected the deformity of the flow route induced by LV contraction during the pre-ETP. The centrifugal force of the vortex at its junction with the main outflow created a stepwise increase of about 50% of the ejection velocity. Conclusion: Ejection of blood from the LV was accomplished by the extruding action of the ventricular wall and the centrifugal force of the accelerated vortex during this period. During ejection, acceralated outflow was considered to create a spiral flow in the aorta with help from the spherical structure of the Valsalva sinus.