非完全血行再建例およびバイパスグラフト部分閉塞例における心筋虚血の改善

Improvement of myocardial ischemia in jeopardized area with a remote AC bypass graft evaluated by stress myocardial scintigraphy

　冠動脈バイパス術の適応の決定および術後の心筋虚血改善度の評価における運動負荷心筋シンチグラムの有用性に関する報告は多い^1〜8）。

　冠動脈バイパス術の狭心症に対する効果については異論はないが，バイパスグラフトが一部閉塞をきたした例や非完全血行再建例においても，術前みられた狭心症が消失してしまうことがしばしば経験される。この機序として，開存するグラフトからの側副血行による虚血の改善が示唆されている^9）。

We evaluated an improvement of myocardial ischemia in a jeopardized area with a remote AC bypass graft (ACBG), using stress myocardial scin-tigraphy (S-SG). Ninety patients (pts) who under-went ACBG and S-SG before and after ACBG were entered in this study. The patients were divided into four groups ; group (Gr) A consisted of 35 pts with complete revascularization and complete paten-cy, Gr B of 26 pts with imcomplete revascularization with complete patency, Gr C of 26 pts with par-tially occluded ACBG and Gr D of 3 pts with complete occlusion of ACBG. Gr B and C were considered to have jeopardized myocardium with aromote ACBG. Three methods were used for quan-titative analysis of S-SG ; ischemic score (IS) which is a sum of four graded perfusion score in 18 ROIs, wash-out rate (%WR) and relative thallium activity of a ROI (%D).

IS was improved in Gr A, B and C, and there was no significant differences in the extent of improvement among these three groups. %WR in the jeopardized area in Gr B and C was increased from 26% to 42% and 25% to 39%, and %D from 68% to 78% and 71% to 79%, respectively, indica-ting an improvement of ischemia in the region. In Gr D, there were no significant changes in IS, %WR and %D. Myocardial ischemia could still be detected in 51% of pts in Gr B, C and D, while chest pain and significant ST depression was seen in only 38% and 27%, respectively. We conclude that ischemia in jeopardized myocardium improves by a remote ACBG.