Anderson P A, Manring A, Glick K L, Crenshaw C C
Am J Obstet Gynecol. 1982 May 15;143(2):195-203.
Changes in heart rate, left ventricular dimensions, and inotropic state of chronically instrumented lambs from in utero to neonatal life are described and analyzed. Six lambs were instrumented from 5 to 23 days prior to parturition and studied prior to and after birth. Heart rate, aortic systolic and diastolic pressure, left ventricular end-diastolic and peak systolic pressure, and left ventricular minor axis end-diastolic (EDD) and end-systolic dimension (ESD) were monitored. The maximum rate of rise of left ventricular pressure (Pmax), percentage fractional shortening [(EDD - ESD divided by EDD) x 100%; %FS], and the Pmax -interval ratio (this ratio of Pmax of the postextrasystolic potentiated systole to Pmax of the previous regular systole is independent of volume) described contractility. Subsequent to birth: heart rate, aortic systolic and diastolic pressure and left ventricular dimensions increased; during spontaneous rhythm and at equal fetal and neonatal heart rates and ventricular dimensions, %FS and P max increased significantly; and P max -interval ratio changed significantly. An increase in myocardial inotropic state occurs with birth. This enhancement is in addition to the effects of the increase in heart rate and end-diastolic volume that occur with the adaptation to birth.
本文描述并分析了长期植入仪器的羔羊从子宫内到新生儿期心率、左心室尺寸和心肌收缩状态的变化。六只羔羊在分娩前5至23天植入仪器，并在出生前后进行研究。监测心率、主动脉收缩压和舒张压、左心室舒张末期和收缩期峰值压力，以及左心室短轴舒张末期（EDD）和收缩末期尺寸（ESD）。左心室压力最大上升速率（Pmax）、缩短分数百分比[（EDD - ESD除以EDD）×100%；%FS]以及Pmax区间比（早搏后增强收缩期的Pmax与前一个正常收缩期的Pmax之比，与容积无关）描述了收缩性。出生后：心率、主动脉收缩压和舒张压以及左心室尺寸增加；在自发节律下，以及在胎儿和新生儿心率及心室尺寸相等时，%FS和Pmax显著增加；Pmax区间比也有显著变化。出生时心肌收缩状态增强。这种增强除了是适应出生时心率和舒张末期容积增加的影响之外。
