頚動脈内膜剝離術の全身麻酔導入を契機に冠攣縮による心停止を来した1例

A Case of Cardiac Arrest Caused by Coronary Spasm Related to Induction of General Anesthesia before Carotid Endarterectomy

Ⅰ．はじめに

　内頚動脈狭窄症（internal carotid stenosis：ICS）の外科的血行再建術〔頚動脈内膜剝離術（carotid endarterectomy：CEA）もしくは頚動脈ステント留置術（carotid artery stenting：CAS）〕では，高い安全性が求められる^3,17)．ICSに対するrandomized clinical trialsでは，心筋梗塞（myocardial infarction：MI）や死亡がendpointとして含まれていることも多く^{2,5,6,9,14,22,24)}，ICS患者の治療では心臓合併症にも留意する必要がある¹³⁾．

　MIを含む急性冠症候群の28%は冠動脈に責任病変が認められず，そのうちの49%は冠攣縮が原因とされる¹⁹⁾．冠攣縮はMIや重症不整脈の原因となり，非心臓手術の周術期にも起こり得る^11,12,16,26)．しかし，術前に予測できるまでには至っていない．

　今回，CEA術前の精査で異常を指摘できず，全身麻酔導入を契機に完全房室ブロックから心停止となり，後日冠攣縮と診断した1例を経験した．

　Coronary vasospasm（CV）can cause severe arrhythmia and myocardial infarction（MI). Intraoperative CV is not limited to cardiac surgery alone. We report the case of a patient who experienced cardiac arrest after the induction of general anesthesia, but did not demonstrate any abnormalities on preoperative examination.

　The patient was a 60-year-old man with no history of ischemic heart disease, with NASCET 80% asymptomatic left internal carotid stenosis（ICS). We decided to perform carotid endarterectomy（CEA). Preoperative stress myocardial scintigraphy did not reveal decreased local uptake. General anesthesia was rapidly induced with propofol and remifentanil, and maintained with sevoflurane. Shortly before the start of CEA, systolic blood pressure dropped to 80 mmHg. Electrocardiography indicated decreased ST, followed by an increase, after which complete atrioventricular block occurred. Cardiopulmonary resuscitation was initiated immediately as the patient's pulse was not palpable;heart beat resumed quickly. CEA was canceled. CV was suspected by the test of nitrate administration to coronary artery performed afterwards. A temporary pacemaker was inserted and carotid artery stenting was performed under local anesthesia. Hence, no pacemaker was used intraoperatively and no abnormality was observed on electrocardiography.

　In the present case, CV in the coronary artery caused complete atrioventricular block, leading to cardiac arrest after inducing general anesthesia. For ICS treatment performed under general anesthesia, care must be taken regarding the possibility of the occurrence of CV.