術前血管造影検査にて判断された左内胸動脈使用不能症例に対する冠動脈バイパス術の工夫  [in Japanese] Coronary Artery Bypass Grafting for Patients in Whom Preoperative Angiography Determined That the In Situ Left Internal Thoracic Artery Could Not Be Used  [in Japanese]

1998年1月から2001年8月までに当科で施行したCABG274例中,術前血管造影検査にて左内胸動脈(LITA)使用不能と判断された7例(7/262=2.7%)を対象として検討した.全例男性で,平均年齢は68.6歳,4例が鎖骨下動脈閉塞あるいは狭窄,3例がLITA閉塞あるいは狭窄であった.3例でRITAに橈骨動脈を端側吻合しcomposite Y graftとして使用,ほかの3例で橈骨動脈をsequential graftとして使用し,バイパス枝数は2.7±1.0であった.グラフト開存率は94.7%(18/19)で,1例にPMIを合併したが,対症療法にて軽快しており,ほかの症例に合併症はなく全例軽快退院した.冠動脈疾患を有する患者は高脂血症,末梢血管病変を有することが多く,このような症例においてはLITAの動脈硬化が有意に高率に認められるとの報告も見受けられ,有茎動脈グラフトに対する術前の十分な検討が重要であると考える.

Use of the internal thoracic artery for myocardial revascularization has regained general acceptance because it offers better long-term results than do venous conduits. However, according to angiographic studies, it has been reported that atherosclerotic changes in the internal thoracic artery occurred in 1-5% of patients with coronary artery disease, although, generally, it is considered that atherosclerotic changes in internal thoracic artery are rare. From January 1998 to August 2001, of the 274 patients who underwent coronary artery bypass grafting, it was estimated that the left internal thoracic artery could not be used for coronary revascularization by preoperative angiography in 7 patients (7/262=2.7%). Two hundred sixty-two patients underwent preoperative angiography to evaluate the grafts for coronary revascularization. All were men and age at the time of operation ranged from 62 to 81 years (mean, 68.6years). The reason for the left internal thoracic artery being useless were occlusion or stenosis of the subclavian artery in 4 and stenosis or occlusion of the left internal thoracic artery in 3. One patient needed an emergency operation. Four patients had a history of myocardial infarction, 3 patients had hypertension, 2 patients had diabetes mellitus, 4 patients had hyperlipidemia, 1 patient had aortitis and 3 patients had a history of percutaneous transluminal coronary angioplasty. There were 4 patients with peripheral vascular disease. Four right internal thoracic arteries, 9 radial arteries and 6 gastroepiploic arteries were used for coronary revascularization. A composite Y graft (right internal thoracic artery-radial artery) was used in 3 patients, and sequential bypass was performed in the other 3 patients. The total number of distal anastomoses was 2.7±1.0/patient. The angiographic patency of the distal anastmoses was 94.7% (18/19). One patient required intra-aortic balloon pumping postoperatively for perioperative myocardial infarction (Max CK-MB 200 IU/l). All other patients had an uneventful postoperative course. In conclusion, although the internal thoracic artery is a protective vessel,there is a certain extent of atherosclerosis, which correlates with known risk factors. Our observations should not preclude use of the internal thoracic artery, but they should be considered for patients who are at risk for atherosclerotic changes of the internal thoracic artery. We considered that it is important to evaluate condition of in situ arterial grafts for patients with coronary artery disease preoperatively. Although further studies are required, in situ arterial grafting with sequential arterial conduit and composite arterial graft were associated with excellent results and achieved complete revascularization.