Kimball T R, Ralston M A, Khoury P, Crump R G, Cho F S, Reuter J H
Children's Heart Association Applied Echocardiography Laboratory, Cincinnati, Ohio 45229, USA.
J Am Coll Cardiol. 1996 Jan;27(1):193-7. doi: 10.1016/0735-1097(95)00452-1.
The purpose of this study was to determine in preterm newborn infants the effects of ductal ligation on ventricular performance and its determinants: preload, afterload and contractility.
Neonatal ventricular performance is highly sensitive to afterload. Therefore, the increase in systemic vascular resistance associated with ligation of a patent ductus arteriosus might worsen ventricular performance in the preterm infant.
All 14 premature infants undergoing patent ductus arteriosus ligation in a 1-year period at our institution underwent echocardiography at three times: before, immediately after and 24 h after ligation. Indexes studied included ventricular performance (fractional area change), preload (left ventricular end-diastolic dimension), afterload (end-systolic wall stress) and contractility (the difference between the measured and predicted velocity of circumferential fiber shortening). Blood pressure was measured; systemic resistance was calculated. These data were compared with those of 14 preterm infants without patent ductus arteriosus.
The infants with patent ductus arteriosus had higher values for ventricular performance (mean +/- SD fractional area change 60 +/- 9% vs. 52 +/- 11%, p < 0.05) and lower values for wall stress (22 +/- 6 vs. 44 +/- 17 g/cm2, p < 0.05) before ligation than did the control group. At 24 h after ligation, ventricular performance was not significantly changed (fractional area change 60 +/- 9% to 57 +/- 12%). There were significant increases in blood pressure and systemic vascular resistance but no changes in wall stress or contractility.
Ventricular performance is higher in premature infants with than in those without patent ductus arteriosus because afterload is lower in the former group. Although ductal ligation increases blood pressure and systemic resistance, wall stress and ventricular performance are maintained. Our results suggest that the premature newborn maintains ventricular performance during stress, at least in part, by manipulating afterload.
本研究旨在确定在早产新生儿中，动脉导管结扎对心室功能及其决定因素（前负荷、后负荷和收缩力）的影响。
新生儿心室功能对后负荷高度敏感。因此，与动脉导管未闭结扎相关的体循环血管阻力增加可能会使早产儿的心室功能恶化。
在我们机构1年期间接受动脉导管未闭结扎的所有14例早产儿在三个时间点接受了超声心动图检查：结扎前、结扎后即刻和结扎后24小时。研究的指标包括心室功能（面积变化分数）、前负荷（左心室舒张末期内径）、后负荷（收缩末期壁应力）和收缩力（圆周纤维缩短的测量速度与预测速度之差）。测量血压；计算体循环阻力。将这些数据与14例无动脉导管未闭的早产儿的数据进行比较。
动脉导管未闭的婴儿在结扎前心室功能值较高（平均±标准差面积变化分数60±9%对52±11%，p<0.05），壁应力值较低（22±6对44±17g/cm²，p<0.05），比对照组。结扎后24小时，心室功能无显著变化（面积变化分数60±9%至57±12%）。血压和体循环血管阻力显著增加，但壁应力或收缩力无变化。
有动脉导管未闭的早产儿的心室功能高于无动脉导管未闭的早产儿，因为前一组的后负荷较低。尽管导管结扎会增加血压和体循环阻力，但壁应力和心室功能得以维持。我们的结果表明，早产新生儿至少部分通过控制后负荷在应激期间维持心室功能。
