榛沢 和彦

Kazuhiko HANZAWA

新潟大学大学院呼吸循環外科

Thoracic and Cardiovascular Surgery, Niigata University Graduate School of Medicine

キーワード : TCD, CBF, cardiovascular surgery, microembolic signals, cerebral impairment

心臓血管外科術後脳障害の機序は脳循環不全と塞栓である．経頭蓋超音波検査（TCD）を術中に行うことで一度に両者の検出が可能である．しかし，高齢の日本人では，側頭骨から中大脳動脈（MCA）を検出することが難しいため顎下部からの頭蓋外内頸動脈（ICA）でのモニタリングが推奨される．TCDによる脳血流速度は人工心肺や脳分離体外循環時の潅流量の目安になる．術中の微小栓子シグナル（HITS/MES）の殆どは微小気泡を示すが，数が多いと脳障害を起こす．多数のHITS/MESが検出された際には術後の脳保護治療が必要である．

The leading causes of cerebral injury during cardiovascular (CV) surgery are cerebral blood flow (CBF) insufficiency and embolism. TCD can detect both CBF velocity and micro-emboli in cerebral arteries. However, the middle cerebral artery (MCA) cannot always be detected by the temporal bone approach in elderly Japanese, in whom monitoring of the extra-cranial internal carotid artery (ICA) by the infra-mandible approach is recommended. CBF velocity measured by TCD is useful for cardiopulmonary bypass or selective cerebral perfusion. Most HITS/MES detected by TCD during CV surgery indicate micro-bubbles. However, many micro-bubbles cause cerebral injury. Cerebral protection therapy is needed in case numerous HITS/MES are detected during CV surgery.