Ino-oka E, Maruyama Y
Jpn Circ J. 1984 Apr;48(4):373-9. doi: 10.1253/jcj.48.373.
To evaluate the effects of vasodilator therapy, the quantitative relationships between peripheral resistance, LVEDP, coronary circulation and cardiac output were analyzed by using 23 isolated coronary perfused canine heart which afterload, preload, coronary blood flow and heart rate are able to regulate independently. Peripheral resistance was decreased incrementally to lower mean arterial pressure from 107-97 mmHg to 48-22 mmHg keeping preload and heart rate at constant level. A decrease in mean arterial blood pressure to 72 ( physiologically coronary perfused heart) and 68 mmHg (coronary stenosed model) increased cardiac output, respectively. However, myocardial oxygen consumption in each group decreased under 5.5 ml/min/100g LV which suggested myocardial ischemia worsen and further decrease in blood pressure lowered cardiac output. LVEDP also decreased incrementally from 18-20 mmHg to 5 mmHg keeping afterload at 100 mmHg of mean arterial blood pressure constantly. A decrease in LVEDP from 20 to 14 mmHg reduced stroke work index in normal heart but increased slightly in failing heart. Further lowering in LVEDP resulted decreasing in stroke work index in both group. Thus modest and adequate reduction in preload and afterload has beneficial effects to cardiac function. In contrast, further decrease will worsen myocardial perfusion and cardiac function.
为评估血管扩张剂治疗的效果，利用23个离体冠状动脉灌注犬心分析外周阻力、左室舒张末压、冠状动脉循环和心输出量之间的定量关系，这些犬心的后负荷、前负荷、冠状动脉血流量和心率能够独立调节。外周阻力逐渐降低，以使平均动脉压从107 - 97 mmHg降至48 - 22 mmHg，同时将前负荷和心率维持在恒定水平。平均动脉血压分别降至72 mmHg（生理性冠状动脉灌注心脏）和68 mmHg（冠状动脉狭窄模型）时，心输出量增加。然而，每组心肌耗氧量均降至5.5 ml/min/100g左室以下，提示心肌缺血加重，血压进一步降低会使心输出量减少。左室舒张末压也逐渐从18 - 20 mmHg降至5 mmHg，同时将后负荷维持在平均动脉血压100 mmHg。左室舒张末压从20 mmHg降至14 mmHg会使正常心脏的每搏功指数降低，但在衰竭心脏中略有增加。左室舒张末压进一步降低会导致两组的每搏功指数均降低。因此，适度且充分地降低前负荷和后负荷对心脏功能有益。相反，进一步降低会使心肌灌注和心脏功能恶化。
