Hammerman H, Kloner R A, Alker K J, Schoen F J, Braunwald E
Am J Cardiol. 1985 Feb 15;55(5):566-70. doi: 10.1016/0002-9149(85)90248-6.
Alterations in afterload may occur during acute myocardial infarction (AMI), but it is unknown whether such alterations cause long-term changes in the left ventricular topography or alter healing of the AMI. AMI was produced by ligation of the left anterior descending coronary artery in open-chest dogs. Eight dogs were randomized to a methoxamine group with an infusion dose of 30 micrograms/kg/min starting 1 hour after ligation for 4 hours to increase systemic systolic pressure by 40 to 50 mm Hg, and 8 were randomized to a saline control group (n = 8). Seven days later the dogs were killed and the hearts examined. The ratio of infarct wall thickness to noninfarct wall thickness was 1.13 +/- 0.03 (mean +/- standard error of the mean) in control dogs and was 0.98 +/- 0.03 in the dogs treated with methoxamine (p less than 0.005). An expansion index was determined as previously reported and expansion was considered to have occurred if this index exceeded 1.09. The expansion index was 0.98 +/- 0.06 in the control group and 1.18 +/- 0.07 in the methoxamine group (p less than 0.05). Histologic analysis suggested a lag in the healing rate in the methoxamine-treated dogs. Thus, early, brief increases in afterload cause infarct expansion and thinning and appears to slow the early healing phase of AMI in dogs.
急性心肌梗死（AMI）期间后负荷可能会发生改变，但尚不清楚这种改变是否会导致左心室形态的长期变化或改变 AMI 的愈合情况。通过结扎开胸犬的左前降支冠状动脉制造 AMI 模型。8 只犬被随机分为甲氧明组，在结扎后 1 小时开始以 30 微克/千克/分钟的输注剂量给药 4 小时，以使体循环收缩压升高 40 至 50 毫米汞柱，另外 8 只被随机分为生理盐水对照组（n = 8）。7 天后处死犬并检查心脏。对照组犬梗死壁厚度与非梗死壁厚度之比为 1.13±0.03（均值±均值标准误），甲氧明治疗组犬为 0.98±0.03（p＜0.005）。按照先前报道的方法确定扩张指数，如果该指数超过 1.09 则认为发生了扩张。对照组扩张指数为 0.98±0.06，甲氧明组为 1.18±0.07（p＜0.05）。组织学分析表明甲氧明治疗的犬愈合速度滞后。因此，早期、短暂的后负荷增加会导致梗死扩展和变薄，并且似乎会延缓犬 AMI 的早期愈合阶段。
