Grover-McKay M, Schelbert H R, Schwaiger M, Sochor H, Guzy P M, Krivokapich J, Child J S, Phelps M E
Circulation. 1986 Aug;74(2):281-92. doi: 10.1161/01.cir.74.2.281.
We investigated myocardial 11C-palmitate clearance kinetics at a resting heart rate (control) and during pacing using positron-emission tomography in 10 patients with significant coronary artery stenosis (greater than 70%) and evidence of exercise-induced ischemia. Serial 11C-palmitate images acquired at control and during pacing revealed biexponential myocardial 11C clearance both in myocardium supplied by a stenotic coronary artery (myocardium "at risk") and in myocardium supplied by a normal coronary artery (normal myocardium). At control, the average rate of myocardial 11C clearance from the early rapid curve component (the clearance half-time) was similar in normal myocardium and in that at risk (22.2 +/- 5.2 vs 21.0 +/- 5.4 min, NS), as was the amount of myocardial 11C activity at the end of the early rapid phase (residual fraction 56.3 +/- 7.2% vs 54.7 +/- 7.3%, NS). Thus, myocardial clearance was homogeneous at control, suggesting a similar rate and amount of 11C-palmitate oxidation in normal myocardium and in that at risk. Pacing shortened clearance half-times and decreased residual fraction in both normal myocardium and that at risk compared with control. However, clearance half-times were 17% longer and residual fractions 14% higher in myocardium at risk compared with normal myocardium (p less than .005 and p less than .01, respectively). Therefore, during pacing myocardial 11C clearance became heterogeneous, suggesting impaired 11C-palmitate oxidation in myocardium at risk compared with normal myocardium. Increased substrate utilization in response to increased workload can be thought of as a measure of metabolic reserve. Our data suggest metabolic reserve for free fatty acid oxidation is impaired in myocardium supplied by a significantly stenosed coronary artery and that this impairment can be detected by analysis of myocardial 11C-palmitate clearance.
我们使用正电子发射断层扫描技术，在静息心率（对照）和起搏过程中，对10例患有严重冠状动脉狭窄（大于70%）且有运动诱发缺血证据的患者的心肌11C-棕榈酸清除动力学进行了研究。在对照和起搏过程中采集的系列11C-棕榈酸图像显示，在由狭窄冠状动脉供血的心肌（“危险”心肌）和由正常冠状动脉供血的心肌（正常心肌）中，心肌11C清除均呈双指数形式。在对照时，正常心肌和危险心肌中早期快速曲线成分的心肌11C清除平均速率（清除半衰期）相似（分别为22.2±5.2分钟和21.0±5.4分钟，无显著性差异），早期快速相结束时的心肌11C活性量也相似（残留分数分别为56.3±7.2%和54.7±7.3%，无显著性差异）。因此，对照时心肌清除是均匀的，表明正常心肌和危险心肌中11C-棕榈酸氧化的速率和量相似。与对照相比，起搏缩短了正常心肌和危险心肌的清除半衰期，并降低了残留分数。然而，与正常心肌相比，危险心肌的清除半衰期长17%，残留分数高14%（分别为p<0.005和p<0.01）。因此，在起搏过程中，心肌11C清除变得不均匀，表明与正常心肌相比，危险心肌中11C-棕榈酸氧化受损。因工作量增加而导致的底物利用增加可被视为代谢储备的一种衡量指标。我们的数据表明，由严重狭窄的冠状动脉供血的心肌中，游离脂肪酸氧化的代谢储备受损，并且这种损害可通过分析心肌11C-棕榈酸清除来检测。
