Campisi R, Czernin J, Karpman H L, Schelbert H R
Department of Molecular and Medical Pharmacology, UCLA School of Medicine, University of California, Los Angeles 90095-6948, USA.
Am J Cardiol. 1997 Jul 1;80(1):27-31. doi: 10.1016/s0002-9149(97)00278-6.
Coronary artery bypass surgery is used widely for treating myocardial ischemia. However, blood flow and flow reserve of normally perfused myocardium subtended by bypass grafts have not been evaluated late after surgery. Also, it is unknown whether pharmacologic vasodilation evokes comparable myocardial flow responses in arterial and venous conduits. Myocardial blood flow was quantified at rest and during dipyridamole hyperemia using N-13 ammonia and positron emission tomography (PET) in 15 patients 9 +/- 3 years after bypass surgery and in 10 healthy volunteers. Blood flow was analyzed in 26 territories subtended by bypass grafts with normal wall motion and normal perfusion. Myocardial blood flow at rest did not differ between patients and controls (0.65 +/- 0.14 vs 0.68 +/- 0.16 ml/ g/min) and was similar in normal myocardium subtended by saphenous vein (n = 16) and internal mammary artery grafts (n = 10; 0.64 +/- 0.13 vs 0.66 +/- 0.15 ml/g/min). However, the hyperemic response in normal myocardium supplied by bypass grafts was less than that in controls (1.61 +/- 0.33 vs 2.04 +/- 0.30 ml/g/min, p <0.005). No differences between territories supplied by venous and arterial conduits were observed (1.61 +/- 0.35 vs 1.63 +/- 0.32 ml/g/min). Normal myocardium subtended by bypass grafts exhibited a lower flow reserve than that in controls (2.54 +/- 0.51 vs 3.16 +/- 0.85, p <0.02). Myocardial flow reserve was almost identical in regions supplied by venous and arterial grafts (2.55 +/- 0.48 vs 2.52 +/- 0.58). The similar reduction in vasodilatory capacity together with the normal PET polar map findings during dipyridamole argue against flow limiting stenoses in both venous and arterial bypass conduits late after revascularization. Rather, nonobstructive proliferative fibrointimal changes of the bypass conduits or atherosclerosis of the native resistance vessels might account for this finding.
冠状动脉搭桥手术被广泛用于治疗心肌缺血。然而，术后晚期旁路移植血管所供应的正常灌注心肌的血流和血流储备尚未得到评估。此外，尚不清楚药物性血管舒张在动脉和静脉移植物中是否能引起相似的心肌血流反应。在15例搭桥手术后9±3年的患者和10名健康志愿者中，使用N-13氨和正电子发射断层扫描（PET）对静息和双嘧达莫充血时的心肌血流进行了定量分析。对26个由旁路移植血管供应、壁运动正常且灌注正常的区域的血流进行了分析。患者和对照组静息时的心肌血流无差异（0.65±0.14对0.68±0.16 ml/g/min），在由大隐静脉（n = 16）和乳内动脉移植物供应的正常心肌中也相似（0.64±0.13对0.66±0.15 ml/g/min）。然而，旁路移植血管供应的正常心肌的充血反应低于对照组（1.61±0.33对2.04±0.30 ml/g/min，p<0.005）。在由静脉和动脉移植物供应的区域之间未观察到差异（1.61±0.35对1.63±0.32 ml/g/min）。旁路移植血管所供应的正常心肌的血流储备低于对照组（2.54±0.51对3.16±0.85，p<0.02）。静脉和动脉移植物供应区域的心肌血流储备几乎相同（2.55±0.48对2.52±0.58）。双嘧达莫期间血管舒张能力的类似降低以及正常的PET极坐标图结果表明，血管重建术后晚期静脉和动脉旁路血管中不存在血流限制性狭窄。相反，旁路血管的非阻塞性增殖性纤维内膜改变或天然阻力血管的动脉粥样硬化可能是这一发现的原因。
