Dell'Italia L J, Walsh R A
University of Texas Health Science Center, San Antonio 78284-7872.
Am J Cardiol. 1989 Jan 15;63(3):166-71. doi: 10.1016/0002-9149(89)90279-8.
To determine the effects of intravenous metoprolol on left ventricular (LV) function in acute myocardial infarction (AMI), 16 patients were studied within 48 hours of Q-wave AMI (mean ejection fraction 47 +/- 6%, mean pulmonary artery wedge pressure 22 +/- 6 mm Hg) with high fidelity pressure and biplane cineventriculography before and after intravenous metoprolol (dose 12 +/- 4 mg). Heart rate decreased from 90 +/- 13 to 74 +/- 11 beats/min (p less than 0.001), pulmonary arterial wedge pressure and LV end-diastolic pressure were unchanged (22 +/- 6 to 21 +/- 6 and 27 +/- 8 to 26 +/- 8 mm Hg, respectively), despite impaired LV relaxation (P = Poe-t/T) after intravenous metoprolol (T from 59 +/- 13 to 72 +/- 12 ms, p less than 0.001). Peak systolic circumferential LV wall stress decreased after beta-adrenergic blockade (330 +/- 93 to 268 +/- 89 g/cm2, p less than 0.05) and LV contractility decreased (dP/dtmax from 1,480 +/- 450 to 1,061 +/- 340 mm Hg/s, p less than 0.001). The ejection fraction decreased (48 +/- 7 to 43 +/- 7%, p less than 0.05) due to an increase in LV end-systolic volume (85 +/- 19 to 93 +/- 19 ml, p less than 0.05) since LV end-diastolic volume was unchanged (161 +/- 30 to 163 +/- 30 ml, difference not significant). In patients with Q-wave AMI, intravenous metoprolol reduces the major determinants of myocardial oxygen demand including heart rate, contractility and peak systolic wall stress. Further, despite decreased heart rate, (+)dP/dtmax, ejection fraction, isovolumic relaxation, LV end-diastolic pressure and end-diastolic volume remain unchanged.
为确定静脉注射美托洛尔对急性心肌梗死（AMI）患者左心室（LV）功能的影响，对16例Q波型AMI患者（平均射血分数47±6%，平均肺动脉楔压22±6mmHg）在静脉注射美托洛尔（剂量12±4mg）前后，采用高保真压力测量和双平面电影心室造影术进行研究。心率从90±13次/分钟降至74±11次/分钟（p<0.001），肺动脉楔压和左心室舒张末期压力未改变（分别从22±6mmHg变为21±6mmHg，以及从27±8mmHg变为26±8mmHg），尽管静脉注射美托洛尔后左心室舒张功能受损（P = Poe - t/T）（T从59±13毫秒增至72±12毫秒，p<0.001）。β肾上腺素能阻滞剂治疗后，左心室壁收缩期峰值周向应力降低（从330±93g/cm²降至268±89g/cm²，p<0.05），左心室收缩力降低（dP/dtmax从1480±450mmHg/s降至1061±340mmHg/s，p<0.001）。由于左心室收缩末期容积增加（从85±19ml增至93±19ml，p<0.05），射血分数降低（从48±7%降至43±7%，p<0.05），而左心室舒张末期容积未改变（从161±30ml变为163±30ml，差异无统计学意义）。在Q波型AMI患者中，静脉注射美托洛尔可降低心肌氧需求的主要决定因素，包括心率、收缩力和收缩期峰值壁应力。此外，尽管心率降低，但（+）dP/dtmax、射血分数、等容舒张、左心室舒张末期压力和舒张末期容积保持不变。
