下体负压-立位作用下ST-T改变与心肌氧耗的关系

Relationship between Changes of ST Segment and T Wave of ECG and Myocardial Oxygen Consumption during Head-up Tilt Plus Lower Body Negative Pressure

目的探讨负压 -立位作用下心电图ST T改变与心肌氧耗的关系。方法 68只雄性新西兰大耳白兔 ,对照组 2 1只 ,负压 -立位组 47只 ,根据家兔在负压 -立位过程中的ST T变化 ,将负压 -立位组分为阳性组和阴性组。测量的指标有 :心率、血压、左室内压及室内压变化速率峰值、室内压差×心率等指标。结果同对照组比 ,负压 -立位作用下血压、左室峰压、室内压变化速率峰值、室内压差与心率乘积出现了明显下降 ,阳性组的左室峰压、室内压变化速率峰值、室内压差与心率乘积在 - 30mmHg 2min和4min时下降幅度明显小于阴性组 ,而阳性组和阴性组的动脉血压在负压初期无明显差别。结论负压-立位作用下ST T改变不仅与动脉血压明显下降有关 ,还与心肌氧耗水平较高有关。

Objective To study relationship between changes of ST segment and T wave of ECG and myocardial oxygen consumption during head up tilt plus lower body negative pressure (HUT-LBNP). Method Sixty eight male New Zealand rabbits were divided into control group (21) and HUT-LBNP group (47). The latter group was divided further into positive group and negative group based on the changes of ST segment and T wave of ECG during HUT-LBNP. The analyzed indices were as follows: heart rate, blood pressure, left ventricular pressure,maximum rate of intraventricular pressure change, [LVSP-LVEDP]×HR. Result As compared with control group, blood pressure, LVSP, ±(dp/dt) max, [LVSP-LVEDP]×HR values in HUT-LBNP group decreased. The magnitude of decrease of LVSP, ±(dp/dt) max, [LVSP-LVEDP]×HR of the positive group were significantly smaller than those of the negative group at -30 mmHg 2 min and 4 min. There was no significant difference between blood pressures of the positive group and the negative group in the initial stage of HUT-LBNP. Conclusion The changes of ST segment and T wave of ECG during HUT-LBNP are related not only with the obvious decrease in blood pressure but also with higher myocardial oxygen consumption.