THE EFFECT OF HEART-RATE ON INUTERO LEFT-VENTRICULAR OUTPUT IN THE FETAL SHEEP
THE EFFECT OF HEART-RATE ON INUTERO LEFT-VENTRICULAR OUTPUT IN THE FETAL SHEEP
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DOI：
10.1113/jphysiol.1986.sp016025
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发表时间：
1986-03-01
影响因子：
5.5
通讯作者：
MAINWARING, RD
中科院分区：
文献类型：
--
作者：
ANDERSON, PAW;GLICK, KL;MAINWARING, RD
在 128 至 140 胎龄的 7 只羔羊身上检查了心率对左心室输出量的影响。胎儿至少在 4 天前通过手术安装了升主动脉血流探针、左心室尺寸传感器以及左心房和右心房起搏电极。羔羊群体心率的自然变化与左心室输出量呈正相关，与心室舒张末期尺寸和每搏输出量呈负相关（P < 0.0001）。速率不影响右心房起搏的输出。对于左心房起搏，它与输出量呈负相关（P < 0.0001）。在两个起搏点，频率与舒张末期尺寸和每搏输出量呈负相关（P < 0.0001）。在每个起搏频率期间引入更长的间隔避免了与频率相关的尺寸变化，并允许心室填充到相同的舒张末期尺寸。较长间隔结束时的收缩期比之前的收缩期具有更大的每搏输出量。先前起搏速率越快，每搏输出量越大（P < 0.0001）。这项研究表明，实验引起的心率变化会导致舒张末期容量和收缩力发生变化，从而显着影响每搏输出量。然而，在较大的心率范围内，心率对左心室输出量的影响要么是负的，要么是不存在的。随着自然发生的心率变化，收缩力和静脉回流也会发生额外的变化，从而影响每搏输出量。这些结合起来在心率和左心室输出量之间产生正相关。心率对输出的影响在质量上与成年动物的描述相似。
The effect of heart rate on left ventricular output was examined in seven fetal lambs at ages of 128 to 140 gestational days. The fetuses had been surgically instrumented at least 4 days previously with an ascending aortic flow probe, left ventricular dimension transducers, and left and right atrial pacing electrodes. Natural variations in heart rate of the lambs taken as a group correlated positively with left ventricular output, and negatively with ventricular end-diastolic dimension and stroke volume (P < 0.0001). Rate did not affect output with right atrial pacing. With left atrial pacing, it correlated negatively with output (P < 0.0001). At both pacing sites, rate correlated negatively with end-diastolic dimension and stroke volume (P < 0.0001). The introduction of a longer interval during each pacing rate circumvented the rate-related changes in dimension and allowed the ventricle to fill to the same end-diastolic dimension. The systole at the end of the longer interval had a greater stroke volume than the preceding systoles. The faster the preceding paced rate, the greater was the stroke volume (P < 0.0001). This study demonstrates that experimentally induced variations in heart rate produce changes in end-diastolic volume and contractility which prominently affect stroke volume. Over a broad range of rates, however, the effect of rate on left ventricular output is either negative or absent. With naturally occurring rate changes, there are additional changes in contractility and venous return which affect stroke volume. These combine to produce a positive relation between heart rate and left ventricular output. These effects of heart rate on output are qualitatively similar to those described for the adult animal.